[lldb-dev] [PATCH 1/2] Refactor ProcessMonitor into an abstract base class.

eatnumber1 at google.com eatnumber1 at google.com
Fri Sep 26 09:56:47 PDT 2014


From: Russell Harmon <eatnumber1 at google.com>

---
 source/Plugins/Process/Linux/CMakeLists.txt        |    2 +-
 source/Plugins/Process/Linux/ProcessMonitor.cpp    | 2326 -------------------
 source/Plugins/Process/Linux/ProcessMonitor.h      |  243 +-
 .../Plugins/Process/Linux/ProcessMonitorOther.cpp  | 2328 ++++++++++++++++++++
 source/Plugins/Process/Linux/ProcessMonitorOther.h |  324 +++
 source/Plugins/Process/POSIX/ProcessPOSIX.cpp      |    5 +-
 6 files changed, 2701 insertions(+), 2527 deletions(-)
 delete mode 100644 source/Plugins/Process/Linux/ProcessMonitor.cpp
 create mode 100644 source/Plugins/Process/Linux/ProcessMonitorOther.cpp
 create mode 100644 source/Plugins/Process/Linux/ProcessMonitorOther.h

diff --git a/source/Plugins/Process/Linux/CMakeLists.txt b/source/Plugins/Process/Linux/CMakeLists.txt
index 4753219..9b04315 100644
--- a/source/Plugins/Process/Linux/CMakeLists.txt
+++ b/source/Plugins/Process/Linux/CMakeLists.txt
@@ -9,7 +9,7 @@ add_lldb_library(lldbPluginProcessLinux
   NativeRegisterContextLinux_x86_64.cpp
   NativeThreadLinux.cpp
   ProcessLinux.cpp
-  ProcessMonitor.cpp
+  ProcessMonitorOther.cpp
   ProcFileReader.cpp
   LinuxThread.cpp
   )
diff --git a/source/Plugins/Process/Linux/ProcessMonitor.cpp b/source/Plugins/Process/Linux/ProcessMonitor.cpp
deleted file mode 100644
index 9e5f844..0000000
--- a/source/Plugins/Process/Linux/ProcessMonitor.cpp
+++ /dev/null
@@ -1,2326 +0,0 @@
-//===-- ProcessMonitor.cpp ------------------------------------ -*- C++ -*-===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-
-#include "lldb/lldb-python.h"
-
-// C Includes
-#include <errno.h>
-#include <poll.h>
-#include <string.h>
-#include <stdint.h>
-#include <unistd.h>
-#include <sys/ptrace.h>
-#include <sys/socket.h>
-#include <sys/syscall.h>
-#include <sys/types.h>
-#include <sys/user.h>
-#include <sys/wait.h>
-
-// C++ Includes
-// Other libraries and framework includes
-#include "lldb/Core/Debugger.h"
-#include "lldb/Core/Error.h"
-#include "lldb/Core/RegisterValue.h"
-#include "lldb/Core/Scalar.h"
-#include "lldb/Host/Host.h"
-#include "lldb/Target/Thread.h"
-#include "lldb/Target/RegisterContext.h"
-#include "lldb/Utility/PseudoTerminal.h"
-
-#include "POSIXThread.h"
-#include "ProcessLinux.h"
-#include "ProcessPOSIXLog.h"
-#include "ProcessMonitor.h"
-
-#define DEBUG_PTRACE_MAXBYTES 20
-
-// Support ptrace extensions even when compiled without required kernel support
-#ifndef PTRACE_GETREGSET
-  #define PTRACE_GETREGSET 0x4204
-#endif
-#ifndef PTRACE_SETREGSET
-  #define PTRACE_SETREGSET 0x4205
-#endif
-#ifndef PTRACE_GET_THREAD_AREA
-  #define PTRACE_GET_THREAD_AREA 25
-#endif
-#ifndef PTRACE_ARCH_PRCTL
-  #define PTRACE_ARCH_PRCTL      30
-#endif
-#ifndef ARCH_GET_FS
-  #define ARCH_SET_GS 0x1001
-  #define ARCH_SET_FS 0x1002
-  #define ARCH_GET_FS 0x1003
-  #define ARCH_GET_GS 0x1004
-#endif
-
-
-// Support hardware breakpoints in case it has not been defined
-#ifndef TRAP_HWBKPT
-  #define TRAP_HWBKPT 4
-#endif
-
-// Try to define a macro to encapsulate the tgkill syscall
-// fall back on kill() if tgkill isn't available
-#define tgkill(pid, tid, sig)  syscall(SYS_tgkill, pid, tid, sig)
-
-using namespace lldb_private;
-
-// FIXME: this code is host-dependent with respect to types and
-// endianness and needs to be fixed.  For example, lldb::addr_t is
-// hard-coded to uint64_t, but on a 32-bit Linux host, ptrace requires
-// 32-bit pointer arguments.  This code uses casts to work around the
-// problem.
-
-// We disable the tracing of ptrace calls for integration builds to
-// avoid the additional indirection and checks.
-#ifndef LLDB_CONFIGURATION_BUILDANDINTEGRATION
-
-static void
-DisplayBytes (lldb_private::StreamString &s, void *bytes, uint32_t count)
-{
-    uint8_t *ptr = (uint8_t *)bytes;
-    const uint32_t loop_count = std::min<uint32_t>(DEBUG_PTRACE_MAXBYTES, count);
-    for(uint32_t i=0; i<loop_count; i++)
-    {
-        s.Printf ("[%x]", *ptr);
-        ptr++;
-    }
-}
-
-static void PtraceDisplayBytes(int &req, void *data, size_t data_size)
-{
-    StreamString buf;
-    Log *verbose_log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (
-                                        POSIX_LOG_PTRACE | POSIX_LOG_VERBOSE));
-
-    if (verbose_log)
-    {
-        switch(req)
-        {
-        case PTRACE_POKETEXT:
-            {
-                DisplayBytes(buf, &data, 8);
-                verbose_log->Printf("PTRACE_POKETEXT %s", buf.GetData());
-                break;
-            }
-        case PTRACE_POKEDATA:
-            {
-                DisplayBytes(buf, &data, 8);
-                verbose_log->Printf("PTRACE_POKEDATA %s", buf.GetData());
-                break;
-            }
-        case PTRACE_POKEUSER:
-            {
-                DisplayBytes(buf, &data, 8);
-                verbose_log->Printf("PTRACE_POKEUSER %s", buf.GetData());
-                break;
-            }
-#ifdef PT_SETREGS
-        case PTRACE_SETREGS:
-            {
-                DisplayBytes(buf, data, data_size);
-                verbose_log->Printf("PTRACE_SETREGS %s", buf.GetData());
-                break;
-            }
-#endif
-#ifdef PT_SETFPREGS
-        case PTRACE_SETFPREGS:
-            {
-                DisplayBytes(buf, data, data_size);
-                verbose_log->Printf("PTRACE_SETFPREGS %s", buf.GetData());
-                break;
-            }
-#endif
-        case PTRACE_SETSIGINFO:
-            {
-                DisplayBytes(buf, data, sizeof(siginfo_t));
-                verbose_log->Printf("PTRACE_SETSIGINFO %s", buf.GetData());
-                break;
-            }
-        case PTRACE_SETREGSET:
-            {
-                // Extract iov_base from data, which is a pointer to the struct IOVEC
-                DisplayBytes(buf, *(void **)data, data_size);
-                verbose_log->Printf("PTRACE_SETREGSET %s", buf.GetData());
-                break;
-            }
-        default:
-            {
-            }
-        }
-    }
-}
-
-// Wrapper for ptrace to catch errors and log calls.
-// Note that ptrace sets errno on error because -1 can be a valid result (i.e. for PTRACE_PEEK*)
-extern long
-PtraceWrapper(int req, lldb::pid_t pid, void *addr, void *data, size_t data_size,
-              const char* reqName, const char* file, int line)
-{
-    long int result;
-
-    Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_PTRACE));
-
-    PtraceDisplayBytes(req, data, data_size);
-
-    errno = 0;
-    if (req == PTRACE_GETREGSET || req == PTRACE_SETREGSET)
-        result = ptrace(static_cast<__ptrace_request>(req), static_cast<pid_t>(pid), *(unsigned int *)addr, data);
-    else
-        result = ptrace(static_cast<__ptrace_request>(req), static_cast<pid_t>(pid), addr, data);
-
-    if (log)
-        log->Printf("ptrace(%s, %" PRIu64 ", %p, %p, %zu)=%lX called from file %s line %d",
-                    reqName, pid, addr, data, data_size, result, file, line);
-
-    PtraceDisplayBytes(req, data, data_size);
-
-    if (log && errno != 0)
-    {
-        const char* str;
-        switch (errno)
-        {
-        case ESRCH:  str = "ESRCH"; break;
-        case EINVAL: str = "EINVAL"; break;
-        case EBUSY:  str = "EBUSY"; break;
-        case EPERM:  str = "EPERM"; break;
-        default:     str = "<unknown>";
-        }
-        log->Printf("ptrace() failed; errno=%d (%s)", errno, str);
-    }
-
-    return result;
-}
-
-// Wrapper for ptrace when logging is not required.
-// Sets errno to 0 prior to calling ptrace.
-extern long
-PtraceWrapper(int req, pid_t pid, void *addr, void *data, size_t data_size)
-{
-    long result = 0;
-    errno = 0;
-    if (req == PTRACE_GETREGSET || req == PTRACE_SETREGSET)
-        result = ptrace(static_cast<__ptrace_request>(req), pid, *(unsigned int *)addr, data);
-    else
-        result = ptrace(static_cast<__ptrace_request>(req), pid, addr, data);
-    return result;
-}
-
-#define PTRACE(req, pid, addr, data, data_size) \
-    PtraceWrapper((req), (pid), (addr), (data), (data_size), #req, __FILE__, __LINE__)
-#else
-    PtraceWrapper((req), (pid), (addr), (data), (data_size))
-#endif
-
-//------------------------------------------------------------------------------
-// Static implementations of ProcessMonitor::ReadMemory and
-// ProcessMonitor::WriteMemory.  This enables mutual recursion between these
-// functions without needed to go thru the thread funnel.
-
-static size_t
-DoReadMemory(lldb::pid_t pid,
-             lldb::addr_t vm_addr, void *buf, size_t size, Error &error)
-{
-    // ptrace word size is determined by the host, not the child
-    static const unsigned word_size = sizeof(void*);
-    unsigned char *dst = static_cast<unsigned char*>(buf);
-    size_t bytes_read;
-    size_t remainder;
-    long data;
-
-    Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_ALL));
-    if (log)
-        ProcessPOSIXLog::IncNestLevel();
-    if (log && ProcessPOSIXLog::AtTopNestLevel() && log->GetMask().Test(POSIX_LOG_MEMORY))
-        log->Printf ("ProcessMonitor::%s(%" PRIu64 ", %d, %p, %p, %zd, _)", __FUNCTION__,
-                     pid, word_size, (void*)vm_addr, buf, size);
-
-    assert(sizeof(data) >= word_size);
-    for (bytes_read = 0; bytes_read < size; bytes_read += remainder)
-    {
-        errno = 0;
-        data = PTRACE(PTRACE_PEEKDATA, pid, (void*)vm_addr, NULL, 0);
-        if (errno)
-        {
-            error.SetErrorToErrno();
-            if (log)
-                ProcessPOSIXLog::DecNestLevel();
-            return bytes_read;
-        }
-
-        remainder = size - bytes_read;
-        remainder = remainder > word_size ? word_size : remainder;
-
-        // Copy the data into our buffer
-        for (unsigned i = 0; i < remainder; ++i)
-            dst[i] = ((data >> i*8) & 0xFF);
-
-        if (log && ProcessPOSIXLog::AtTopNestLevel() &&
-            (log->GetMask().Test(POSIX_LOG_MEMORY_DATA_LONG) ||
-             (log->GetMask().Test(POSIX_LOG_MEMORY_DATA_SHORT) &&
-              size <= POSIX_LOG_MEMORY_SHORT_BYTES)))
-            {
-                uintptr_t print_dst = 0;
-                // Format bytes from data by moving into print_dst for log output
-                for (unsigned i = 0; i < remainder; ++i)
-                    print_dst |= (((data >> i*8) & 0xFF) << i*8);
-                log->Printf ("ProcessMonitor::%s() [%p]:0x%lx (0x%lx)", __FUNCTION__,
-                             (void*)vm_addr, print_dst, (unsigned long)data);
-            }
-
-        vm_addr += word_size;
-        dst += word_size;
-    }
-
-    if (log)
-        ProcessPOSIXLog::DecNestLevel();
-    return bytes_read;
-}
-
-static size_t
-DoWriteMemory(lldb::pid_t pid,
-              lldb::addr_t vm_addr, const void *buf, size_t size, Error &error)
-{
-    // ptrace word size is determined by the host, not the child
-    static const unsigned word_size = sizeof(void*);
-    const unsigned char *src = static_cast<const unsigned char*>(buf);
-    size_t bytes_written = 0;
-    size_t remainder;
-
-    Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_ALL));
-    if (log)
-        ProcessPOSIXLog::IncNestLevel();
-    if (log && ProcessPOSIXLog::AtTopNestLevel() && log->GetMask().Test(POSIX_LOG_MEMORY))
-        log->Printf ("ProcessMonitor::%s(%" PRIu64 ", %d, %p, %p, %zd, _)", __FUNCTION__,
-                     pid, word_size, (void*)vm_addr, buf, size);
-
-    for (bytes_written = 0; bytes_written < size; bytes_written += remainder)
-    {
-        remainder = size - bytes_written;
-        remainder = remainder > word_size ? word_size : remainder;
-
-        if (remainder == word_size)
-        {
-            unsigned long data = 0;
-            assert(sizeof(data) >= word_size);
-            for (unsigned i = 0; i < word_size; ++i)
-                data |= (unsigned long)src[i] << i*8;
-
-            if (log && ProcessPOSIXLog::AtTopNestLevel() &&
-                (log->GetMask().Test(POSIX_LOG_MEMORY_DATA_LONG) ||
-                 (log->GetMask().Test(POSIX_LOG_MEMORY_DATA_SHORT) &&
-                  size <= POSIX_LOG_MEMORY_SHORT_BYTES)))
-                 log->Printf ("ProcessMonitor::%s() [%p]:0x%lx (0x%lx)", __FUNCTION__,
-                              (void*)vm_addr, *(unsigned long*)src, data);
-
-            if (PTRACE(PTRACE_POKEDATA, pid, (void*)vm_addr, (void*)data, 0))
-            {
-                error.SetErrorToErrno();
-                if (log)
-                    ProcessPOSIXLog::DecNestLevel();
-                return bytes_written;
-            }
-        }
-        else
-        {
-            unsigned char buff[8];
-            if (DoReadMemory(pid, vm_addr,
-                             buff, word_size, error) != word_size)
-            {
-                if (log)
-                    ProcessPOSIXLog::DecNestLevel();
-                return bytes_written;
-            }
-
-            memcpy(buff, src, remainder);
-
-            if (DoWriteMemory(pid, vm_addr,
-                              buff, word_size, error) != word_size)
-            {
-                if (log)
-                    ProcessPOSIXLog::DecNestLevel();
-                return bytes_written;
-            }
-
-            if (log && ProcessPOSIXLog::AtTopNestLevel() &&
-                (log->GetMask().Test(POSIX_LOG_MEMORY_DATA_LONG) ||
-                 (log->GetMask().Test(POSIX_LOG_MEMORY_DATA_SHORT) &&
-                  size <= POSIX_LOG_MEMORY_SHORT_BYTES)))
-                 log->Printf ("ProcessMonitor::%s() [%p]:0x%lx (0x%lx)", __FUNCTION__,
-                              (void*)vm_addr, *(unsigned long*)src, *(unsigned long*)buff);
-        }
-
-        vm_addr += word_size;
-        src += word_size;
-    }
-    if (log)
-        ProcessPOSIXLog::DecNestLevel();
-    return bytes_written;
-}
-
-// Simple helper function to ensure flags are enabled on the given file
-// descriptor.
-static bool
-EnsureFDFlags(int fd, int flags, Error &error)
-{
-    int status;
-
-    if ((status = fcntl(fd, F_GETFL)) == -1)
-    {
-        error.SetErrorToErrno();
-        return false;
-    }
-
-    if (fcntl(fd, F_SETFL, status | flags) == -1)
-    {
-        error.SetErrorToErrno();
-        return false;
-    }
-
-    return true;
-}
-
-//------------------------------------------------------------------------------
-/// @class Operation
-/// @brief Represents a ProcessMonitor operation.
-///
-/// Under Linux, it is not possible to ptrace() from any other thread but the
-/// one that spawned or attached to the process from the start.  Therefore, when
-/// a ProcessMonitor is asked to deliver or change the state of an inferior
-/// process the operation must be "funneled" to a specific thread to perform the
-/// task.  The Operation class provides an abstract base for all services the
-/// ProcessMonitor must perform via the single virtual function Execute, thus
-/// encapsulating the code that needs to run in the privileged context.
-class Operation
-{
-public:
-    virtual ~Operation() {}
-    virtual void Execute(ProcessMonitor *monitor) = 0;
-};
-
-//------------------------------------------------------------------------------
-/// @class ReadOperation
-/// @brief Implements ProcessMonitor::ReadMemory.
-class ReadOperation : public Operation
-{
-public:
-    ReadOperation(lldb::addr_t addr, void *buff, size_t size,
-                  Error &error, size_t &result)
-        : m_addr(addr), m_buff(buff), m_size(size),
-          m_error(error), m_result(result)
-        { }
-
-    void Execute(ProcessMonitor *monitor);
-
-private:
-    lldb::addr_t m_addr;
-    void *m_buff;
-    size_t m_size;
-    Error &m_error;
-    size_t &m_result;
-};
-
-void
-ReadOperation::Execute(ProcessMonitor *monitor)
-{
-    lldb::pid_t pid = monitor->GetPID();
-
-    m_result = DoReadMemory(pid, m_addr, m_buff, m_size, m_error);
-}
-
-//------------------------------------------------------------------------------
-/// @class WriteOperation
-/// @brief Implements ProcessMonitor::WriteMemory.
-class WriteOperation : public Operation
-{
-public:
-    WriteOperation(lldb::addr_t addr, const void *buff, size_t size,
-                   Error &error, size_t &result)
-        : m_addr(addr), m_buff(buff), m_size(size),
-          m_error(error), m_result(result)
-        { }
-
-    void Execute(ProcessMonitor *monitor);
-
-private:
-    lldb::addr_t m_addr;
-    const void *m_buff;
-    size_t m_size;
-    Error &m_error;
-    size_t &m_result;
-};
-
-void
-WriteOperation::Execute(ProcessMonitor *monitor)
-{
-    lldb::pid_t pid = monitor->GetPID();
-
-    m_result = DoWriteMemory(pid, m_addr, m_buff, m_size, m_error);
-}
-
-
-//------------------------------------------------------------------------------
-/// @class ReadRegOperation
-/// @brief Implements ProcessMonitor::ReadRegisterValue.
-class ReadRegOperation : public Operation
-{
-public:
-    ReadRegOperation(lldb::tid_t tid, unsigned offset, const char *reg_name,
-                     RegisterValue &value, bool &result)
-        : m_tid(tid), m_offset(offset), m_reg_name(reg_name),
-          m_value(value), m_result(result)
-        { }
-
-    void Execute(ProcessMonitor *monitor);
-
-private:
-    lldb::tid_t m_tid;
-    uintptr_t m_offset;
-    const char *m_reg_name;
-    RegisterValue &m_value;
-    bool &m_result;
-};
-
-void
-ReadRegOperation::Execute(ProcessMonitor *monitor)
-{
-    Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_REGISTERS));
-
-    // Set errno to zero so that we can detect a failed peek.
-    errno = 0;
-    lldb::addr_t data = PTRACE(PTRACE_PEEKUSER, m_tid, (void*)m_offset, NULL, 0);
-    if (errno)
-        m_result = false;
-    else
-    {
-        m_value = data;
-        m_result = true;
-    }
-    if (log)
-        log->Printf ("ProcessMonitor::%s() reg %s: 0x%" PRIx64, __FUNCTION__,
-                     m_reg_name, data);
-}
-
-//------------------------------------------------------------------------------
-/// @class WriteRegOperation
-/// @brief Implements ProcessMonitor::WriteRegisterValue.
-class WriteRegOperation : public Operation
-{
-public:
-    WriteRegOperation(lldb::tid_t tid, unsigned offset, const char *reg_name,
-                      const RegisterValue &value, bool &result)
-        : m_tid(tid), m_offset(offset), m_reg_name(reg_name),
-          m_value(value), m_result(result)
-        { }
-
-    void Execute(ProcessMonitor *monitor);
-
-private:
-    lldb::tid_t m_tid;
-    uintptr_t m_offset;
-    const char *m_reg_name;
-    const RegisterValue &m_value;
-    bool &m_result;
-};
-
-void
-WriteRegOperation::Execute(ProcessMonitor *monitor)
-{
-    void* buf;
-    Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_REGISTERS));
-
-    buf = (void*) m_value.GetAsUInt64();
-
-    if (log)
-        log->Printf ("ProcessMonitor::%s() reg %s: %p", __FUNCTION__, m_reg_name, buf);
-    if (PTRACE(PTRACE_POKEUSER, m_tid, (void*)m_offset, buf, 0))
-        m_result = false;
-    else
-        m_result = true;
-}
-
-//------------------------------------------------------------------------------
-/// @class ReadGPROperation
-/// @brief Implements ProcessMonitor::ReadGPR.
-class ReadGPROperation : public Operation
-{
-public:
-    ReadGPROperation(lldb::tid_t tid, void *buf, size_t buf_size, bool &result)
-        : m_tid(tid), m_buf(buf), m_buf_size(buf_size), m_result(result)
-        { }
-
-    void Execute(ProcessMonitor *monitor);
-
-private:
-    lldb::tid_t m_tid;
-    void *m_buf;
-    size_t m_buf_size;
-    bool &m_result;
-};
-
-void
-ReadGPROperation::Execute(ProcessMonitor *monitor)
-{
-#ifdef PT_GETREGS
-    if (PTRACE(PTRACE_GETREGS, m_tid, NULL, m_buf, m_buf_size) < 0)
-        m_result = false;
-    else
-        m_result = true;
-#else
-    m_result = false;
-#endif
-}
-
-//------------------------------------------------------------------------------
-/// @class ReadFPROperation
-/// @brief Implements ProcessMonitor::ReadFPR.
-class ReadFPROperation : public Operation
-{
-public:
-    ReadFPROperation(lldb::tid_t tid, void *buf, size_t buf_size, bool &result)
-        : m_tid(tid), m_buf(buf), m_buf_size(buf_size), m_result(result)
-        { }
-
-    void Execute(ProcessMonitor *monitor);
-
-private:
-    lldb::tid_t m_tid;
-    void *m_buf;
-    size_t m_buf_size;
-    bool &m_result;
-};
-
-void
-ReadFPROperation::Execute(ProcessMonitor *monitor)
-{
-#ifdef PT_GETFPREGS
-    if (PTRACE(PTRACE_GETFPREGS, m_tid, NULL, m_buf, m_buf_size) < 0)
-        m_result = false;
-    else
-        m_result = true;
-#else
-    m_result = false;
-#endif
-}
-
-//------------------------------------------------------------------------------
-/// @class ReadRegisterSetOperation
-/// @brief Implements ProcessMonitor::ReadRegisterSet.
-class ReadRegisterSetOperation : public Operation
-{
-public:
-    ReadRegisterSetOperation(lldb::tid_t tid, void *buf, size_t buf_size, unsigned int regset, bool &result)
-        : m_tid(tid), m_buf(buf), m_buf_size(buf_size), m_regset(regset), m_result(result)
-        { }
-
-    void Execute(ProcessMonitor *monitor);
-
-private:
-    lldb::tid_t m_tid;
-    void *m_buf;
-    size_t m_buf_size;
-    const unsigned int m_regset;
-    bool &m_result;
-};
-
-void
-ReadRegisterSetOperation::Execute(ProcessMonitor *monitor)
-{
-    if (PTRACE(PTRACE_GETREGSET, m_tid, (void *)&m_regset, m_buf, m_buf_size) < 0)
-        m_result = false;
-    else
-        m_result = true;
-}
-
-//------------------------------------------------------------------------------
-/// @class WriteGPROperation
-/// @brief Implements ProcessMonitor::WriteGPR.
-class WriteGPROperation : public Operation
-{
-public:
-    WriteGPROperation(lldb::tid_t tid, void *buf, size_t buf_size, bool &result)
-        : m_tid(tid), m_buf(buf), m_buf_size(buf_size), m_result(result)
-        { }
-
-    void Execute(ProcessMonitor *monitor);
-
-private:
-    lldb::tid_t m_tid;
-    void *m_buf;
-    size_t m_buf_size;
-    bool &m_result;
-};
-
-void
-WriteGPROperation::Execute(ProcessMonitor *monitor)
-{
-#ifdef PT_SETREGS
-    if (PTRACE(PTRACE_SETREGS, m_tid, NULL, m_buf, m_buf_size) < 0)
-        m_result = false;
-    else
-        m_result = true;
-#else
-    m_result = false;
-#endif
-}
-
-//------------------------------------------------------------------------------
-/// @class WriteFPROperation
-/// @brief Implements ProcessMonitor::WriteFPR.
-class WriteFPROperation : public Operation
-{
-public:
-    WriteFPROperation(lldb::tid_t tid, void *buf, size_t buf_size, bool &result)
-        : m_tid(tid), m_buf(buf), m_buf_size(buf_size), m_result(result)
-        { }
-
-    void Execute(ProcessMonitor *monitor);
-
-private:
-    lldb::tid_t m_tid;
-    void *m_buf;
-    size_t m_buf_size;
-    bool &m_result;
-};
-
-void
-WriteFPROperation::Execute(ProcessMonitor *monitor)
-{
-#ifdef PT_SETFPREGS
-    if (PTRACE(PTRACE_SETFPREGS, m_tid, NULL, m_buf, m_buf_size) < 0)
-        m_result = false;
-    else
-        m_result = true;
-#else
-    m_result = false;
-#endif
-}
-
-//------------------------------------------------------------------------------
-/// @class WriteRegisterSetOperation
-/// @brief Implements ProcessMonitor::WriteRegisterSet.
-class WriteRegisterSetOperation : public Operation
-{
-public:
-    WriteRegisterSetOperation(lldb::tid_t tid, void *buf, size_t buf_size, unsigned int regset, bool &result)
-        : m_tid(tid), m_buf(buf), m_buf_size(buf_size), m_regset(regset), m_result(result)
-        { }
-
-    void Execute(ProcessMonitor *monitor);
-
-private:
-    lldb::tid_t m_tid;
-    void *m_buf;
-    size_t m_buf_size;
-    const unsigned int m_regset;
-    bool &m_result;
-};
-
-void
-WriteRegisterSetOperation::Execute(ProcessMonitor *monitor)
-{
-    if (PTRACE(PTRACE_SETREGSET, m_tid, (void *)&m_regset, m_buf, m_buf_size) < 0)
-        m_result = false;
-    else
-        m_result = true;
-}
-
-//------------------------------------------------------------------------------
-/// @class ReadThreadPointerOperation
-/// @brief Implements ProcessMonitor::ReadThreadPointer.
-class ReadThreadPointerOperation : public Operation
-{
-public:
-    ReadThreadPointerOperation(lldb::tid_t tid, lldb::addr_t *addr, bool &result)
-        : m_tid(tid), m_addr(addr), m_result(result)
-        { }
-
-    void Execute(ProcessMonitor *monitor);
-
-private:
-    lldb::tid_t m_tid;
-    lldb::addr_t *m_addr;
-    bool &m_result;
-};
-
-void
-ReadThreadPointerOperation::Execute(ProcessMonitor *monitor)
-{
-    Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_REGISTERS));
-    if (log)
-        log->Printf ("ProcessMonitor::%s()", __FUNCTION__);
-
-    // The process for getting the thread area on Linux is
-    // somewhat... obscure. There's several different ways depending on
-    // what arch you're on, and what kernel version you have.
-
-    const ArchSpec& arch = monitor->GetProcess().GetTarget().GetArchitecture();
-    switch(arch.GetMachine())
-    {
-#if defined(__i386__) || defined(__x86_64__)
-    // Note that struct user below has a field named i387 which is x86-specific.
-    // Therefore, this case should be compiled only for x86-based systems.
-    case llvm::Triple::x86:
-    {
-        // Find the GS register location for our host architecture.
-        size_t gs_user_offset = offsetof(struct user, regs);
-#ifdef __x86_64__
-        gs_user_offset += offsetof(struct user_regs_struct, gs);
-#endif
-#ifdef __i386__
-        gs_user_offset += offsetof(struct user_regs_struct, xgs);
-#endif
-
-        // Read the GS register value to get the selector.
-        errno = 0;
-        long gs = PTRACE(PTRACE_PEEKUSER, m_tid, (void*)gs_user_offset, NULL, 0);
-        if (errno)
-        {
-            m_result = false;
-            break;
-        }
-
-        // Read the LDT base for that selector.
-        uint32_t tmp[4];
-        m_result = (PTRACE(PTRACE_GET_THREAD_AREA, m_tid, (void *)(gs >> 3), &tmp, 0) == 0);
-        *m_addr = tmp[1];
-        break;
-    }
-#endif
-    case llvm::Triple::x86_64:
-        // Read the FS register base.
-        m_result = (PTRACE(PTRACE_ARCH_PRCTL, m_tid, m_addr, (void *)ARCH_GET_FS, 0) == 0);
-        break;
-    default:
-        m_result = false;
-        break;
-    }
-}
-
-//------------------------------------------------------------------------------
-/// @class ResumeOperation
-/// @brief Implements ProcessMonitor::Resume.
-class ResumeOperation : public Operation
-{
-public:
-    ResumeOperation(lldb::tid_t tid, uint32_t signo, bool &result) :
-        m_tid(tid), m_signo(signo), m_result(result) { }
-
-    void Execute(ProcessMonitor *monitor);
-
-private:
-    lldb::tid_t m_tid;
-    uint32_t m_signo;
-    bool &m_result;
-};
-
-void
-ResumeOperation::Execute(ProcessMonitor *monitor)
-{
-    intptr_t data = 0;
-
-    if (m_signo != LLDB_INVALID_SIGNAL_NUMBER)
-        data = m_signo;
-
-    if (PTRACE(PTRACE_CONT, m_tid, NULL, (void*)data, 0))
-    {
-        Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_PROCESS));
-
-        if (log)
-            log->Printf ("ResumeOperation (%"  PRIu64 ") failed: %s", m_tid, strerror(errno));
-        m_result = false;
-    }
-    else
-        m_result = true;
-}
-
-//------------------------------------------------------------------------------
-/// @class SingleStepOperation
-/// @brief Implements ProcessMonitor::SingleStep.
-class SingleStepOperation : public Operation
-{
-public:
-    SingleStepOperation(lldb::tid_t tid, uint32_t signo, bool &result)
-        : m_tid(tid), m_signo(signo), m_result(result) { }
-
-    void Execute(ProcessMonitor *monitor);
-
-private:
-    lldb::tid_t m_tid;
-    uint32_t m_signo;
-    bool &m_result;
-};
-
-void
-SingleStepOperation::Execute(ProcessMonitor *monitor)
-{
-    intptr_t data = 0;
-
-    if (m_signo != LLDB_INVALID_SIGNAL_NUMBER)
-        data = m_signo;
-
-    if (PTRACE(PTRACE_SINGLESTEP, m_tid, NULL, (void*)data, 0))
-        m_result = false;
-    else
-        m_result = true;
-}
-
-//------------------------------------------------------------------------------
-/// @class SiginfoOperation
-/// @brief Implements ProcessMonitor::GetSignalInfo.
-class SiginfoOperation : public Operation
-{
-public:
-    SiginfoOperation(lldb::tid_t tid, void *info, bool &result, int &ptrace_err)
-        : m_tid(tid), m_info(info), m_result(result), m_err(ptrace_err) { }
-
-    void Execute(ProcessMonitor *monitor);
-
-private:
-    lldb::tid_t m_tid;
-    void *m_info;
-    bool &m_result;
-    int &m_err;
-};
-
-void
-SiginfoOperation::Execute(ProcessMonitor *monitor)
-{
-    if (PTRACE(PTRACE_GETSIGINFO, m_tid, NULL, m_info, 0)) {
-        m_result = false;
-        m_err = errno;
-    }
-    else
-        m_result = true;
-}
-
-//------------------------------------------------------------------------------
-/// @class EventMessageOperation
-/// @brief Implements ProcessMonitor::GetEventMessage.
-class EventMessageOperation : public Operation
-{
-public:
-    EventMessageOperation(lldb::tid_t tid, unsigned long *message, bool &result)
-        : m_tid(tid), m_message(message), m_result(result) { }
-
-    void Execute(ProcessMonitor *monitor);
-
-private:
-    lldb::tid_t m_tid;
-    unsigned long *m_message;
-    bool &m_result;
-};
-
-void
-EventMessageOperation::Execute(ProcessMonitor *monitor)
-{
-    if (PTRACE(PTRACE_GETEVENTMSG, m_tid, NULL, m_message, 0))
-        m_result = false;
-    else
-        m_result = true;
-}
-
-//------------------------------------------------------------------------------
-/// @class DetachOperation
-/// @brief Implements ProcessMonitor::Detach.
-class DetachOperation : public Operation
-{
-public:
-    DetachOperation(lldb::tid_t tid, Error &result) : m_tid(tid), m_error(result) { }
-
-    void Execute(ProcessMonitor *monitor);
-
-private:
-    lldb::tid_t m_tid;
-    Error &m_error;
-};
-
-void
-DetachOperation::Execute(ProcessMonitor *monitor)
-{
-    if (ptrace(PT_DETACH, m_tid, NULL, 0) < 0)
-        m_error.SetErrorToErrno();
-}
-
-ProcessMonitor::OperationArgs::OperationArgs(ProcessMonitor *monitor)
-    : m_monitor(monitor)
-{
-    sem_init(&m_semaphore, 0, 0);
-}
-
-ProcessMonitor::OperationArgs::~OperationArgs()
-{
-    sem_destroy(&m_semaphore);
-}
-
-ProcessMonitor::LaunchArgs::LaunchArgs(ProcessMonitor *monitor,
-                                       lldb_private::Module *module,
-                                       char const **argv,
-                                       char const **envp,
-                                       const char *stdin_path,
-                                       const char *stdout_path,
-                                       const char *stderr_path,
-                                       const char *working_dir)
-    : OperationArgs(monitor),
-      m_module(module),
-      m_argv(argv),
-      m_envp(envp),
-      m_stdin_path(stdin_path),
-      m_stdout_path(stdout_path),
-      m_stderr_path(stderr_path),
-      m_working_dir(working_dir) { }
-
-ProcessMonitor::LaunchArgs::~LaunchArgs()
-{ }
-
-ProcessMonitor::AttachArgs::AttachArgs(ProcessMonitor *monitor,
-                                       lldb::pid_t pid)
-    : OperationArgs(monitor), m_pid(pid) { }
-
-ProcessMonitor::AttachArgs::~AttachArgs()
-{ }
-
-//------------------------------------------------------------------------------
-/// The basic design of the ProcessMonitor is built around two threads.
-///
-/// One thread (@see SignalThread) simply blocks on a call to waitpid() looking
-/// for changes in the debugee state.  When a change is detected a
-/// ProcessMessage is sent to the associated ProcessLinux instance.  This thread
-/// "drives" state changes in the debugger.
-///
-/// The second thread (@see OperationThread) is responsible for two things 1)
-/// launching or attaching to the inferior process, and then 2) servicing
-/// operations such as register reads/writes, stepping, etc.  See the comments
-/// on the Operation class for more info as to why this is needed.
-ProcessMonitor::ProcessMonitor(ProcessPOSIX *process,
-                               Module *module,
-                               const char *argv[],
-                               const char *envp[],
-                               const char *stdin_path,
-                               const char *stdout_path,
-                               const char *stderr_path,
-                               const char *working_dir,
-                               lldb_private::Error &error)
-    : m_process(static_cast<ProcessLinux *>(process)),
-      m_operation_thread(LLDB_INVALID_HOST_THREAD),
-      m_monitor_thread(LLDB_INVALID_HOST_THREAD),
-      m_pid(LLDB_INVALID_PROCESS_ID),
-      m_terminal_fd(-1),
-      m_operation(0)
-{
-    std::unique_ptr<LaunchArgs> args(new LaunchArgs(this, module, argv, envp,
-                                     stdin_path, stdout_path, stderr_path,
-                                     working_dir));
-
-    sem_init(&m_operation_pending, 0, 0);
-    sem_init(&m_operation_done, 0, 0);
-
-    StartLaunchOpThread(args.get(), error);
-    if (!error.Success())
-        return;
-
-WAIT_AGAIN:
-    // Wait for the operation thread to initialize.
-    if (sem_wait(&args->m_semaphore))
-    {
-        if (errno == EINTR)
-            goto WAIT_AGAIN;
-        else
-        {
-            error.SetErrorToErrno();
-            return;
-        }
-    }
-
-    // Check that the launch was a success.
-    if (!args->m_error.Success())
-    {
-        StopOpThread();
-        error = args->m_error;
-        return;
-    }
-
-    // Finally, start monitoring the child process for change in state.
-    m_monitor_thread = Host::StartMonitoringChildProcess(
-        ProcessMonitor::MonitorCallback, this, GetPID(), true);
-    if (!IS_VALID_LLDB_HOST_THREAD(m_monitor_thread))
-    {
-        error.SetErrorToGenericError();
-        error.SetErrorString("Process launch failed.");
-        return;
-    }
-}
-
-ProcessMonitor::ProcessMonitor(ProcessPOSIX *process,
-                               lldb::pid_t pid,
-                               lldb_private::Error &error)
-  : m_process(static_cast<ProcessLinux *>(process)),
-      m_operation_thread(LLDB_INVALID_HOST_THREAD),
-      m_monitor_thread(LLDB_INVALID_HOST_THREAD),
-      m_pid(LLDB_INVALID_PROCESS_ID),
-      m_terminal_fd(-1),
-      m_operation(0)
-{
-    sem_init(&m_operation_pending, 0, 0);
-    sem_init(&m_operation_done, 0, 0);
-
-    std::unique_ptr<AttachArgs> args(new AttachArgs(this, pid));
-
-    StartAttachOpThread(args.get(), error);
-    if (!error.Success())
-        return;
-
-WAIT_AGAIN:
-    // Wait for the operation thread to initialize.
-    if (sem_wait(&args->m_semaphore))
-    {
-        if (errno == EINTR)
-            goto WAIT_AGAIN;
-        else
-        {
-            error.SetErrorToErrno();
-            return;
-        }
-    }
-
-    // Check that the attach was a success.
-    if (!args->m_error.Success())
-    {
-        StopOpThread();
-        error = args->m_error;
-        return;
-    }
-
-    // Finally, start monitoring the child process for change in state.
-    m_monitor_thread = Host::StartMonitoringChildProcess(
-        ProcessMonitor::MonitorCallback, this, GetPID(), true);
-    if (!IS_VALID_LLDB_HOST_THREAD(m_monitor_thread))
-    {
-        error.SetErrorToGenericError();
-        error.SetErrorString("Process attach failed.");
-        return;
-    }
-}
-
-ProcessMonitor::~ProcessMonitor()
-{
-    StopMonitor();
-}
-
-//------------------------------------------------------------------------------
-// Thread setup and tear down.
-void
-ProcessMonitor::StartLaunchOpThread(LaunchArgs *args, Error &error)
-{
-    static const char *g_thread_name = "lldb.process.linux.operation";
-
-    if (IS_VALID_LLDB_HOST_THREAD(m_operation_thread))
-        return;
-
-    m_operation_thread =
-        Host::ThreadCreate(g_thread_name, LaunchOpThread, args, &error);
-}
-
-void *
-ProcessMonitor::LaunchOpThread(void *arg)
-{
-    LaunchArgs *args = static_cast<LaunchArgs*>(arg);
-
-    if (!Launch(args)) {
-        sem_post(&args->m_semaphore);
-        return NULL;
-    }
-
-    ServeOperation(args);
-    return NULL;
-}
-
-bool
-ProcessMonitor::Launch(LaunchArgs *args)
-{
-    ProcessMonitor *monitor = args->m_monitor;
-    ProcessLinux &process = monitor->GetProcess();
-    const char **argv = args->m_argv;
-    const char **envp = args->m_envp;
-    const char *stdin_path = args->m_stdin_path;
-    const char *stdout_path = args->m_stdout_path;
-    const char *stderr_path = args->m_stderr_path;
-    const char *working_dir = args->m_working_dir;
-
-    lldb_utility::PseudoTerminal terminal;
-    const size_t err_len = 1024;
-    char err_str[err_len];
-    lldb::pid_t pid;
-
-    lldb::ThreadSP inferior;
-    Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_PROCESS));
-
-    // Propagate the environment if one is not supplied.
-    if (envp == NULL || envp[0] == NULL)
-        envp = const_cast<const char **>(environ);
-
-    if ((pid = terminal.Fork(err_str, err_len)) == static_cast<lldb::pid_t>(-1))
-    {
-        args->m_error.SetErrorToGenericError();
-        args->m_error.SetErrorString("Process fork failed.");
-        goto FINISH;
-    }
-
-    // Recognized child exit status codes.
-    enum {
-        ePtraceFailed = 1,
-        eDupStdinFailed,
-        eDupStdoutFailed,
-        eDupStderrFailed,
-        eChdirFailed,
-        eExecFailed,
-        eSetGidFailed
-    };
-
-    // Child process.
-    if (pid == 0)
-    {
-        // Trace this process.
-        if (PTRACE(PTRACE_TRACEME, 0, NULL, NULL, 0) < 0)
-            exit(ePtraceFailed);
-
-        // Do not inherit setgid powers.
-        if (setgid(getgid()) != 0)
-            exit(eSetGidFailed);
-
-        // Let us have our own process group.
-        setpgid(0, 0);
-
-        // Dup file descriptors if needed.
-        //
-        // FIXME: If two or more of the paths are the same we needlessly open
-        // the same file multiple times.
-        if (stdin_path != NULL && stdin_path[0])
-            if (!DupDescriptor(stdin_path, STDIN_FILENO, O_RDONLY))
-                exit(eDupStdinFailed);
-
-        if (stdout_path != NULL && stdout_path[0])
-            if (!DupDescriptor(stdout_path, STDOUT_FILENO, O_WRONLY | O_CREAT))
-                exit(eDupStdoutFailed);
-
-        if (stderr_path != NULL && stderr_path[0])
-            if (!DupDescriptor(stderr_path, STDERR_FILENO, O_WRONLY | O_CREAT))
-                exit(eDupStderrFailed);
-
-        // Change working directory
-        if (working_dir != NULL && working_dir[0])
-          if (0 != ::chdir(working_dir))
-              exit(eChdirFailed);
-
-        // Execute.  We should never return.
-        execve(argv[0],
-               const_cast<char *const *>(argv),
-               const_cast<char *const *>(envp));
-        exit(eExecFailed);
-    }
-
-    // Wait for the child process to to trap on its call to execve.
-    lldb::pid_t wpid;
-    ::pid_t raw_pid;
-    int status;
-
-    raw_pid = waitpid(pid, &status, 0);
-    wpid = static_cast <lldb::pid_t> (raw_pid);
-    if (raw_pid < 0)
-    {
-        args->m_error.SetErrorToErrno();
-        goto FINISH;
-    }
-    else if (WIFEXITED(status))
-    {
-        // open, dup or execve likely failed for some reason.
-        args->m_error.SetErrorToGenericError();
-        switch (WEXITSTATUS(status))
-        {
-            case ePtraceFailed:
-                args->m_error.SetErrorString("Child ptrace failed.");
-                break;
-            case eDupStdinFailed:
-                args->m_error.SetErrorString("Child open stdin failed.");
-                break;
-            case eDupStdoutFailed:
-                args->m_error.SetErrorString("Child open stdout failed.");
-                break;
-            case eDupStderrFailed:
-                args->m_error.SetErrorString("Child open stderr failed.");
-                break;
-            case eChdirFailed:
-                args->m_error.SetErrorString("Child failed to set working directory.");
-                break;
-            case eExecFailed:
-                args->m_error.SetErrorString("Child exec failed.");
-                break;
-            case eSetGidFailed:
-                args->m_error.SetErrorString("Child setgid failed.");
-                break;
-            default:
-                args->m_error.SetErrorString("Child returned unknown exit status.");
-                break;
-        }
-        goto FINISH;
-    }
-    assert(WIFSTOPPED(status) && wpid == pid &&
-           "Could not sync with inferior process.");
-
-    if (!SetDefaultPtraceOpts(pid))
-    {
-        args->m_error.SetErrorToErrno();
-        goto FINISH;
-    }
-
-    // Release the master terminal descriptor and pass it off to the
-    // ProcessMonitor instance.  Similarly stash the inferior pid.
-    monitor->m_terminal_fd = terminal.ReleaseMasterFileDescriptor();
-    monitor->m_pid = pid;
-
-    // Set the terminal fd to be in non blocking mode (it simplifies the
-    // implementation of ProcessLinux::GetSTDOUT to have a non-blocking
-    // descriptor to read from).
-    if (!EnsureFDFlags(monitor->m_terminal_fd, O_NONBLOCK, args->m_error))
-        goto FINISH;
-
-    // Update the process thread list with this new thread.
-    // FIXME: should we be letting UpdateThreadList handle this?
-    // FIXME: by using pids instead of tids, we can only support one thread.
-    inferior.reset(process.CreateNewPOSIXThread(process, pid));
-
-    if (log)
-        log->Printf ("ProcessMonitor::%s() adding pid = %" PRIu64, __FUNCTION__, pid);
-    process.GetThreadList().AddThread(inferior);
-
-    process.AddThreadForInitialStopIfNeeded(pid);
-
-    // Let our process instance know the thread has stopped.
-    process.SendMessage(ProcessMessage::Trace(pid));
-
-FINISH:
-    return args->m_error.Success();
-}
-
-void
-ProcessMonitor::StartAttachOpThread(AttachArgs *args, lldb_private::Error &error)
-{
-    static const char *g_thread_name = "lldb.process.linux.operation";
-
-    if (IS_VALID_LLDB_HOST_THREAD(m_operation_thread))
-        return;
-
-    m_operation_thread =
-        Host::ThreadCreate(g_thread_name, AttachOpThread, args, &error);
-}
-
-void *
-ProcessMonitor::AttachOpThread(void *arg)
-{
-    AttachArgs *args = static_cast<AttachArgs*>(arg);
-
-    if (!Attach(args)) {
-        sem_post(&args->m_semaphore);
-        return NULL;
-    }
-
-    ServeOperation(args);
-    return NULL;
-}
-
-bool
-ProcessMonitor::Attach(AttachArgs *args)
-{
-    lldb::pid_t pid = args->m_pid;
-
-    ProcessMonitor *monitor = args->m_monitor;
-    ProcessLinux &process = monitor->GetProcess();
-    lldb::ThreadSP inferior;
-    Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_PROCESS));
-
-    // Use a map to keep track of the threads which we have attached/need to attach.
-    Host::TidMap tids_to_attach;
-    if (pid <= 1)
-    {
-        args->m_error.SetErrorToGenericError();
-        args->m_error.SetErrorString("Attaching to process 1 is not allowed.");
-        goto FINISH;
-    }
-
-    while (Host::FindProcessThreads(pid, tids_to_attach))
-    {
-        for (Host::TidMap::iterator it = tids_to_attach.begin();
-             it != tids_to_attach.end(); ++it)
-        {
-            if (it->second == false)
-            {
-                lldb::tid_t tid = it->first;
-
-                // Attach to the requested process.
-                // An attach will cause the thread to stop with a SIGSTOP.
-                if (PTRACE(PTRACE_ATTACH, tid, NULL, NULL, 0) < 0)
-                {
-                    // No such thread. The thread may have exited.
-                    // More error handling may be needed.
-                    if (errno == ESRCH)
-                    {
-                        tids_to_attach.erase(it);
-                        continue;
-                    }
-                    else
-                    {
-                        args->m_error.SetErrorToErrno();
-                        goto FINISH;
-                    }
-                }
-
-                ::pid_t wpid;
-                // Need to use __WALL otherwise we receive an error with errno=ECHLD
-                // At this point we should have a thread stopped if waitpid succeeds.
-                if ((wpid = waitpid(tid, NULL, __WALL)) < 0)
-                {
-                    // No such thread. The thread may have exited.
-                    // More error handling may be needed.
-                    if (errno == ESRCH)
-                    {
-                        tids_to_attach.erase(it);
-                        continue;
-                    }
-                    else
-                    {
-                        args->m_error.SetErrorToErrno();
-                        goto FINISH;
-                    }
-                }
-
-                if (!SetDefaultPtraceOpts(tid))
-                {
-                    args->m_error.SetErrorToErrno();
-                    goto FINISH;
-                }
-
-                // Update the process thread list with the attached thread.
-                inferior.reset(process.CreateNewPOSIXThread(process, tid));
-
-                if (log)
-                    log->Printf ("ProcessMonitor::%s() adding tid = %" PRIu64, __FUNCTION__, tid);
-                process.GetThreadList().AddThread(inferior);
-                it->second = true;
-                process.AddThreadForInitialStopIfNeeded(tid);
-            }
-        }
-    }
-
-    if (tids_to_attach.size() > 0)
-    {
-        monitor->m_pid = pid;
-        // Let our process instance know the thread has stopped.
-        process.SendMessage(ProcessMessage::Trace(pid));
-    }
-    else
-    {
-        args->m_error.SetErrorToGenericError();
-        args->m_error.SetErrorString("No such process.");
-    }
-
- FINISH:
-    return args->m_error.Success();
-}
-
-bool
-ProcessMonitor::SetDefaultPtraceOpts(lldb::pid_t pid)
-{
-    long ptrace_opts = 0;
-
-    // Have the child raise an event on exit.  This is used to keep the child in
-    // limbo until it is destroyed.
-    ptrace_opts |= PTRACE_O_TRACEEXIT;
-
-    // Have the tracer trace threads which spawn in the inferior process.
-    // TODO: if we want to support tracing the inferiors' child, add the
-    // appropriate ptrace flags here (PTRACE_O_TRACEFORK, PTRACE_O_TRACEVFORK)
-    ptrace_opts |= PTRACE_O_TRACECLONE;
-
-    // Have the tracer notify us before execve returns
-    // (needed to disable legacy SIGTRAP generation)
-    ptrace_opts |= PTRACE_O_TRACEEXEC;
-
-    return PTRACE(PTRACE_SETOPTIONS, pid, NULL, (void*)ptrace_opts, 0) >= 0;
-}
-
-bool
-ProcessMonitor::MonitorCallback(void *callback_baton,
-                                lldb::pid_t pid,
-                                bool exited,
-                                int signal,
-                                int status)
-{
-    ProcessMessage message;
-    ProcessMonitor *monitor = static_cast<ProcessMonitor*>(callback_baton);
-    ProcessLinux *process = monitor->m_process;
-    assert(process);
-    bool stop_monitoring;
-    siginfo_t info;
-    int ptrace_err;
-
-    Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_PROCESS));
-
-    if (exited)
-    {
-        if (log)
-            log->Printf ("ProcessMonitor::%s() got exit signal, tid = %"  PRIu64, __FUNCTION__, pid);
-        message = ProcessMessage::Exit(pid, status);
-        process->SendMessage(message);
-        return pid == process->GetID();
-    }
-
-    if (!monitor->GetSignalInfo(pid, &info, ptrace_err)) {
-        if (ptrace_err == EINVAL) {
-            if (log)
-                log->Printf ("ProcessMonitor::%s() resuming from group-stop", __FUNCTION__);
-            // inferior process is in 'group-stop', so deliver SIGSTOP signal
-            if (!monitor->Resume(pid, SIGSTOP)) {
-              assert(0 && "SIGSTOP delivery failed while in 'group-stop' state");
-            }
-            stop_monitoring = false;
-        } else {
-            // ptrace(GETSIGINFO) failed (but not due to group-stop). Most likely,
-            // this means the child pid is gone (or not being debugged) therefore
-            // stop the monitor thread if this is the main pid.
-            if (log)
-                log->Printf ("ProcessMonitor::%s() GetSignalInfo failed: %s, tid = %" PRIu64 ", signal = %d, status = %d", 
-                              __FUNCTION__, strerror(ptrace_err), pid, signal, status);
-            stop_monitoring = pid == monitor->m_process->GetID();
-            // If we are going to stop monitoring, we need to notify our process object
-            if (stop_monitoring)
-            {
-                message = ProcessMessage::Exit(pid, status);
-                process->SendMessage(message);
-            }
-        }
-    }
-    else {
-        switch (info.si_signo)
-        {
-        case SIGTRAP:
-            message = MonitorSIGTRAP(monitor, &info, pid);
-            break;
-
-        default:
-            message = MonitorSignal(monitor, &info, pid);
-            break;
-        }
-
-        process->SendMessage(message);
-        stop_monitoring = false;
-    }
-
-    return stop_monitoring;
-}
-
-ProcessMessage
-ProcessMonitor::MonitorSIGTRAP(ProcessMonitor *monitor,
-                               const siginfo_t *info, lldb::pid_t pid)
-{
-    ProcessMessage message;
-
-    Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_PROCESS));
-
-    assert(monitor);
-    assert(info && info->si_signo == SIGTRAP && "Unexpected child signal!");
-
-    switch (info->si_code)
-    {
-    default:
-        assert(false && "Unexpected SIGTRAP code!");
-        break;
-
-    // TODO: these two cases are required if we want to support tracing
-    // of the inferiors' children
-    // case (SIGTRAP | (PTRACE_EVENT_FORK << 8)):
-    // case (SIGTRAP | (PTRACE_EVENT_VFORK << 8)):
-
-    case (SIGTRAP | (PTRACE_EVENT_CLONE << 8)):
-    {
-        if (log)
-            log->Printf ("ProcessMonitor::%s() received thread creation event, code = %d", __FUNCTION__, info->si_code ^ SIGTRAP);
-
-        unsigned long tid = 0;
-        if (!monitor->GetEventMessage(pid, &tid))
-            tid = -1;
-        message = ProcessMessage::NewThread(pid, tid);
-        break;
-    }
-
-    case (SIGTRAP | (PTRACE_EVENT_EXEC << 8)):
-        if (log)
-            log->Printf ("ProcessMonitor::%s() received exec event, code = %d", __FUNCTION__, info->si_code ^ SIGTRAP);
-
-        message = ProcessMessage::Exec(pid);
-        break;
-
-    case (SIGTRAP | (PTRACE_EVENT_EXIT << 8)):
-    {
-        // The inferior process or one of its threads is about to exit.
-        // Maintain the process or thread in a state of "limbo" until we are
-        // explicitly commanded to detach, destroy, resume, etc.
-        unsigned long data = 0;
-        if (!monitor->GetEventMessage(pid, &data))
-            data = -1;
-        if (log)
-            log->Printf ("ProcessMonitor::%s() received limbo event, data = %lx, pid = %" PRIu64, __FUNCTION__, data, pid);
-        message = ProcessMessage::Limbo(pid, (data >> 8));
-        break;
-    }
-
-    case 0:
-    case TRAP_TRACE:
-        if (log)
-            log->Printf ("ProcessMonitor::%s() received trace event, pid = %" PRIu64, __FUNCTION__, pid);
-        message = ProcessMessage::Trace(pid);
-        break;
-
-    case SI_KERNEL:
-    case TRAP_BRKPT:
-        if (log)
-            log->Printf ("ProcessMonitor::%s() received breakpoint event, pid = %" PRIu64, __FUNCTION__, pid);
-        message = ProcessMessage::Break(pid);
-        break;
-
-    case TRAP_HWBKPT:
-        if (log)
-            log->Printf ("ProcessMonitor::%s() received watchpoint event, pid = %" PRIu64, __FUNCTION__, pid);
-        message = ProcessMessage::Watch(pid, (lldb::addr_t)info->si_addr);
-        break;
-
-    case SIGTRAP:
-    case (SIGTRAP | 0x80):
-        if (log)
-            log->Printf ("ProcessMonitor::%s() received system call stop event, pid = %" PRIu64, __FUNCTION__, pid);
-        // Ignore these signals until we know more about them
-        monitor->Resume(pid, eResumeSignalNone);
-    }
-
-    return message;
-}
-
-ProcessMessage
-ProcessMonitor::MonitorSignal(ProcessMonitor *monitor,
-                              const siginfo_t *info, lldb::pid_t pid)
-{
-    ProcessMessage message;
-    int signo = info->si_signo;
-
-    Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_PROCESS));
-
-    // POSIX says that process behaviour is undefined after it ignores a SIGFPE,
-    // SIGILL, SIGSEGV, or SIGBUS *unless* that signal was generated by a
-    // kill(2) or raise(3).  Similarly for tgkill(2) on Linux.
-    //
-    // IOW, user generated signals never generate what we consider to be a
-    // "crash".
-    //
-    // Similarly, ACK signals generated by this monitor.
-    if (info->si_code == SI_TKILL || info->si_code == SI_USER)
-    {
-        if (log)
-            log->Printf ("ProcessMonitor::%s() received signal %s with code %s, pid = %d",
-                            __FUNCTION__,
-                            monitor->m_process->GetUnixSignals().GetSignalAsCString (signo),
-                            (info->si_code == SI_TKILL ? "SI_TKILL" : "SI_USER"),
-                            info->si_pid);
-
-        if (info->si_pid == getpid())
-            return ProcessMessage::SignalDelivered(pid, signo);
-        else
-            return ProcessMessage::Signal(pid, signo);
-    }
-
-    if (log)
-        log->Printf ("ProcessMonitor::%s() received signal %s", __FUNCTION__, monitor->m_process->GetUnixSignals().GetSignalAsCString (signo));
-
-    if (signo == SIGSEGV) {
-        lldb::addr_t fault_addr = reinterpret_cast<lldb::addr_t>(info->si_addr);
-        ProcessMessage::CrashReason reason = GetCrashReasonForSIGSEGV(info);
-        return ProcessMessage::Crash(pid, reason, signo, fault_addr);
-    }
-
-    if (signo == SIGILL) {
-        lldb::addr_t fault_addr = reinterpret_cast<lldb::addr_t>(info->si_addr);
-        ProcessMessage::CrashReason reason = GetCrashReasonForSIGILL(info);
-        return ProcessMessage::Crash(pid, reason, signo, fault_addr);
-    }
-
-    if (signo == SIGFPE) {
-        lldb::addr_t fault_addr = reinterpret_cast<lldb::addr_t>(info->si_addr);
-        ProcessMessage::CrashReason reason = GetCrashReasonForSIGFPE(info);
-        return ProcessMessage::Crash(pid, reason, signo, fault_addr);
-    }
-
-    if (signo == SIGBUS) {
-        lldb::addr_t fault_addr = reinterpret_cast<lldb::addr_t>(info->si_addr);
-        ProcessMessage::CrashReason reason = GetCrashReasonForSIGBUS(info);
-        return ProcessMessage::Crash(pid, reason, signo, fault_addr);
-    }
-
-    // Everything else is "normal" and does not require any special action on
-    // our part.
-    return ProcessMessage::Signal(pid, signo);
-}
-
-// On Linux, when a new thread is created, we receive to notifications,
-// (1) a SIGTRAP|PTRACE_EVENT_CLONE from the main process thread with the
-// child thread id as additional information, and (2) a SIGSTOP|SI_USER from
-// the new child thread indicating that it has is stopped because we attached.
-// We have no guarantee of the order in which these arrive, but we need both
-// before we are ready to proceed.  We currently keep a list of threads which
-// have sent the initial SIGSTOP|SI_USER event.  Then when we receive the
-// SIGTRAP|PTRACE_EVENT_CLONE notification, if the initial stop has not occurred
-// we call ProcessMonitor::WaitForInitialTIDStop() to wait for it.
-
-bool
-ProcessMonitor::WaitForInitialTIDStop(lldb::tid_t tid)
-{
-    Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_PROCESS));
-    if (log)
-        log->Printf ("ProcessMonitor::%s(%" PRIu64 ") waiting for thread to stop...", __FUNCTION__, tid);
-
-    // Wait for the thread to stop
-    while (true)
-    {
-        int status = -1;
-        if (log)
-            log->Printf ("ProcessMonitor::%s(%" PRIu64 ") waitpid...", __FUNCTION__, tid);
-        ::pid_t wait_pid = waitpid(tid, &status, __WALL);
-        if (status == -1)
-        {
-            // If we got interrupted by a signal (in our process, not the
-            // inferior) try again.
-            if (errno == EINTR)
-                continue;
-            else
-            {
-                if (log)
-                    log->Printf("ProcessMonitor::%s(%" PRIu64 ") waitpid error -- %s", __FUNCTION__, tid, strerror(errno));
-                return false; // This is bad, but there's nothing we can do.
-            }
-        }
-
-        if (log)
-            log->Printf ("ProcessMonitor::%s(%" PRIu64 ") waitpid, status = %d", __FUNCTION__, tid, status);
-
-        assert(static_cast<lldb::tid_t>(wait_pid) == tid);
-
-        siginfo_t info;
-        int ptrace_err;
-        if (!GetSignalInfo(wait_pid, &info, ptrace_err))
-        {
-            if (log)
-            {
-                log->Printf ("ProcessMonitor::%s() GetSignalInfo failed. errno=%d (%s)", __FUNCTION__, ptrace_err, strerror(ptrace_err));
-            }
-            return false;
-        }
-
-        // If this is a thread exit, we won't get any more information.
-        if (WIFEXITED(status))
-        {
-            m_process->SendMessage(ProcessMessage::Exit(wait_pid, WEXITSTATUS(status)));
-            if (static_cast<lldb::tid_t>(wait_pid) == tid)
-                return true;
-            continue;
-        }
-
-        assert(info.si_code == SI_USER);
-        assert(WSTOPSIG(status) == SIGSTOP);
-
-        if (log)
-            log->Printf ("ProcessMonitor::%s(bp) received thread stop signal", __FUNCTION__);
-        m_process->AddThreadForInitialStopIfNeeded(wait_pid);
-        return true;
-    }
-    return false;
-}
-
-bool
-ProcessMonitor::StopThread(lldb::tid_t tid)
-{
-    Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_PROCESS));
-
-    // FIXME: Try to use tgkill or tkill
-    int ret = tgkill(m_pid, tid, SIGSTOP);
-    if (log)
-        log->Printf ("ProcessMonitor::%s(bp) stopping thread, tid = %" PRIu64 ", ret = %d", __FUNCTION__, tid, ret);
-
-    // This can happen if a thread exited while we were trying to stop it.  That's OK.
-    // We'll get the signal for that later.
-    if (ret < 0)
-        return false;
-
-    // Wait for the thread to stop
-    while (true)
-    {
-        int status = -1;
-        if (log)
-            log->Printf ("ProcessMonitor::%s(bp) waitpid...", __FUNCTION__);
-        ::pid_t wait_pid = ::waitpid (-1*getpgid(m_pid), &status, __WALL);
-        if (log)
-            log->Printf ("ProcessMonitor::%s(bp) waitpid, pid = %" PRIu64 ", status = %d",
-                         __FUNCTION__, static_cast<lldb::pid_t>(wait_pid), status);
-
-        if (wait_pid == -1)
-        {
-            // If we got interrupted by a signal (in our process, not the
-            // inferior) try again.
-            if (errno == EINTR)
-                continue;
-            else
-                return false; // This is bad, but there's nothing we can do.
-        }
-
-        // If this is a thread exit, we won't get any more information.
-        if (WIFEXITED(status))
-        {
-            m_process->SendMessage(ProcessMessage::Exit(wait_pid, WEXITSTATUS(status)));
-            if (static_cast<lldb::tid_t>(wait_pid) == tid)
-                return true;
-            continue;
-        }
-
-        siginfo_t info;
-        int ptrace_err;
-        if (!GetSignalInfo(wait_pid, &info, ptrace_err))
-        {
-            // another signal causing a StopAllThreads may have been received
-            // before wait_pid's group-stop was processed, handle it now
-            if (ptrace_err == EINVAL)
-            {
-                assert(WIFSTOPPED(status) && WSTOPSIG(status) == SIGSTOP);
-
-                if (log)
-                  log->Printf ("ProcessMonitor::%s() resuming from group-stop", __FUNCTION__);
-                // inferior process is in 'group-stop', so deliver SIGSTOP signal
-                if (!Resume(wait_pid, SIGSTOP)) {
-                  assert(0 && "SIGSTOP delivery failed while in 'group-stop' state");
-                }
-                continue;
-            }
-
-            if (log)
-                log->Printf ("ProcessMonitor::%s() GetSignalInfo failed.", __FUNCTION__);
-            return false;
-        }
-
-        // Handle events from other threads
-        if (log)
-            log->Printf ("ProcessMonitor::%s(bp) handling event, tid == %" PRIu64,
-                         __FUNCTION__, static_cast<lldb::tid_t>(wait_pid));
-
-        ProcessMessage message;
-        if (info.si_signo == SIGTRAP)
-            message = MonitorSIGTRAP(this, &info, wait_pid);
-        else
-            message = MonitorSignal(this, &info, wait_pid);
-
-        POSIXThread *thread = static_cast<POSIXThread*>(m_process->GetThreadList().FindThreadByID(wait_pid).get());
-
-        // When a new thread is created, we may get a SIGSTOP for the new thread
-        // just before we get the SIGTRAP that we use to add the thread to our
-        // process thread list.  We don't need to worry about that signal here.
-        assert(thread || message.GetKind() == ProcessMessage::eSignalMessage);
-
-        if (!thread)
-        {
-            m_process->SendMessage(message);
-            continue;
-        }
-
-        switch (message.GetKind())
-        {
-            case ProcessMessage::eExecMessage:
-                llvm_unreachable("unexpected message");
-            case ProcessMessage::eAttachMessage:
-            case ProcessMessage::eInvalidMessage:
-                break;
-
-            // These need special handling because we don't want to send a
-            // resume even if we already sent a SIGSTOP to this thread. In
-            // this case the resume will cause the thread to disappear.  It is
-            // unlikely that we'll ever get eExitMessage here, but the same
-            // reasoning applies.
-            case ProcessMessage::eLimboMessage:
-            case ProcessMessage::eExitMessage:
-                if (log)
-                    log->Printf ("ProcessMonitor::%s(bp) handling message", __FUNCTION__);
-                // SendMessage will set the thread state as needed.
-                m_process->SendMessage(message);
-                // If this is the thread we're waiting for, stop waiting. Even
-                // though this wasn't the signal we expected, it's the last
-                // signal we'll see while this thread is alive.
-                if (static_cast<lldb::tid_t>(wait_pid) == tid)
-                    return true;
-                break;
-
-            case ProcessMessage::eSignalMessage:
-                if (log)
-                    log->Printf ("ProcessMonitor::%s(bp) handling message", __FUNCTION__);
-                if (WSTOPSIG(status) == SIGSTOP)
-                {
-                    m_process->AddThreadForInitialStopIfNeeded(tid);
-                    thread->SetState(lldb::eStateStopped);
-                }
-                else
-                {
-                    m_process->SendMessage(message);
-                    // This isn't the stop we were expecting, but the thread is
-                    // stopped. SendMessage will handle processing of this event,
-                    // but we need to resume here to get the stop we are waiting
-                    // for (otherwise the thread will stop again immediately when
-                    // we try to resume).
-                    if (static_cast<lldb::tid_t>(wait_pid) == tid)
-                        Resume(wait_pid, eResumeSignalNone);
-                }
-                break;
-
-            case ProcessMessage::eSignalDeliveredMessage:
-                // This is the stop we're expecting.
-                if (static_cast<lldb::tid_t>(wait_pid) == tid &&
-                    WIFSTOPPED(status) &&
-                    WSTOPSIG(status) == SIGSTOP &&
-                    info.si_code == SI_TKILL)
-                {
-                    if (log)
-                        log->Printf ("ProcessMonitor::%s(bp) received signal, done waiting", __FUNCTION__);
-                    thread->SetState(lldb::eStateStopped);
-                    return true;
-                }
-                // else fall-through
-            case ProcessMessage::eBreakpointMessage:
-            case ProcessMessage::eTraceMessage:
-            case ProcessMessage::eWatchpointMessage:
-            case ProcessMessage::eCrashMessage:
-            case ProcessMessage::eNewThreadMessage:
-                if (log)
-                    log->Printf ("ProcessMonitor::%s(bp) handling message", __FUNCTION__);
-                // SendMessage will set the thread state as needed.
-                m_process->SendMessage(message);
-                // This isn't the stop we were expecting, but the thread is
-                // stopped. SendMessage will handle processing of this event,
-                // but we need to resume here to get the stop we are waiting
-                // for (otherwise the thread will stop again immediately when
-                // we try to resume).
-                if (static_cast<lldb::tid_t>(wait_pid) == tid)
-                    Resume(wait_pid, eResumeSignalNone);
-                break;
-        }
-    }
-    return false;
-}
-
-ProcessMessage::CrashReason
-ProcessMonitor::GetCrashReasonForSIGSEGV(const siginfo_t *info)
-{
-    ProcessMessage::CrashReason reason;
-    assert(info->si_signo == SIGSEGV);
-
-    reason = ProcessMessage::eInvalidCrashReason;
-
-    switch (info->si_code)
-    {
-    default:
-        assert(false && "unexpected si_code for SIGSEGV");
-        break;
-    case SI_KERNEL:
-        // Linux will occasionally send spurious SI_KERNEL codes.
-        // (this is poorly documented in sigaction)
-        // One way to get this is via unaligned SIMD loads.
-        reason = ProcessMessage::eInvalidAddress; // for lack of anything better
-        break;
-    case SEGV_MAPERR:
-        reason = ProcessMessage::eInvalidAddress;
-        break;
-    case SEGV_ACCERR:
-        reason = ProcessMessage::ePrivilegedAddress;
-        break;
-    }
-
-    return reason;
-}
-
-ProcessMessage::CrashReason
-ProcessMonitor::GetCrashReasonForSIGILL(const siginfo_t *info)
-{
-    ProcessMessage::CrashReason reason;
-    assert(info->si_signo == SIGILL);
-
-    reason = ProcessMessage::eInvalidCrashReason;
-
-    switch (info->si_code)
-    {
-    default:
-        assert(false && "unexpected si_code for SIGILL");
-        break;
-    case ILL_ILLOPC:
-        reason = ProcessMessage::eIllegalOpcode;
-        break;
-    case ILL_ILLOPN:
-        reason = ProcessMessage::eIllegalOperand;
-        break;
-    case ILL_ILLADR:
-        reason = ProcessMessage::eIllegalAddressingMode;
-        break;
-    case ILL_ILLTRP:
-        reason = ProcessMessage::eIllegalTrap;
-        break;
-    case ILL_PRVOPC:
-        reason = ProcessMessage::ePrivilegedOpcode;
-        break;
-    case ILL_PRVREG:
-        reason = ProcessMessage::ePrivilegedRegister;
-        break;
-    case ILL_COPROC:
-        reason = ProcessMessage::eCoprocessorError;
-        break;
-    case ILL_BADSTK:
-        reason = ProcessMessage::eInternalStackError;
-        break;
-    }
-
-    return reason;
-}
-
-ProcessMessage::CrashReason
-ProcessMonitor::GetCrashReasonForSIGFPE(const siginfo_t *info)
-{
-    ProcessMessage::CrashReason reason;
-    assert(info->si_signo == SIGFPE);
-
-    reason = ProcessMessage::eInvalidCrashReason;
-
-    switch (info->si_code)
-    {
-    default:
-        assert(false && "unexpected si_code for SIGFPE");
-        break;
-    case FPE_INTDIV:
-        reason = ProcessMessage::eIntegerDivideByZero;
-        break;
-    case FPE_INTOVF:
-        reason = ProcessMessage::eIntegerOverflow;
-        break;
-    case FPE_FLTDIV:
-        reason = ProcessMessage::eFloatDivideByZero;
-        break;
-    case FPE_FLTOVF:
-        reason = ProcessMessage::eFloatOverflow;
-        break;
-    case FPE_FLTUND:
-        reason = ProcessMessage::eFloatUnderflow;
-        break;
-    case FPE_FLTRES:
-        reason = ProcessMessage::eFloatInexactResult;
-        break;
-    case FPE_FLTINV:
-        reason = ProcessMessage::eFloatInvalidOperation;
-        break;
-    case FPE_FLTSUB:
-        reason = ProcessMessage::eFloatSubscriptRange;
-        break;
-    }
-
-    return reason;
-}
-
-ProcessMessage::CrashReason
-ProcessMonitor::GetCrashReasonForSIGBUS(const siginfo_t *info)
-{
-    ProcessMessage::CrashReason reason;
-    assert(info->si_signo == SIGBUS);
-
-    reason = ProcessMessage::eInvalidCrashReason;
-
-    switch (info->si_code)
-    {
-    default:
-        assert(false && "unexpected si_code for SIGBUS");
-        break;
-    case BUS_ADRALN:
-        reason = ProcessMessage::eIllegalAlignment;
-        break;
-    case BUS_ADRERR:
-        reason = ProcessMessage::eIllegalAddress;
-        break;
-    case BUS_OBJERR:
-        reason = ProcessMessage::eHardwareError;
-        break;
-    }
-
-    return reason;
-}
-
-void
-ProcessMonitor::ServeOperation(OperationArgs *args)
-{
-    ProcessMonitor *monitor = args->m_monitor;
-
-    // We are finised with the arguments and are ready to go.  Sync with the
-    // parent thread and start serving operations on the inferior.
-    sem_post(&args->m_semaphore);
-
-    for(;;)
-    {
-        // wait for next pending operation
-        if (sem_wait(&monitor->m_operation_pending))
-        {
-            if (errno == EINTR)
-                continue;
-            assert(false && "Unexpected errno from sem_wait");
-        }
-
-        monitor->m_operation->Execute(monitor);
-
-        // notify calling thread that operation is complete
-        sem_post(&monitor->m_operation_done);
-    }
-}
-
-void
-ProcessMonitor::DoOperation(Operation *op)
-{
-    Mutex::Locker lock(m_operation_mutex);
-
-    m_operation = op;
-
-    // notify operation thread that an operation is ready to be processed
-    sem_post(&m_operation_pending);
-
-    // wait for operation to complete
-    while (sem_wait(&m_operation_done))
-    {
-        if (errno == EINTR)
-            continue;
-        assert(false && "Unexpected errno from sem_wait");
-    }
-}
-
-size_t
-ProcessMonitor::ReadMemory(lldb::addr_t vm_addr, void *buf, size_t size,
-                           Error &error)
-{
-    size_t result;
-    ReadOperation op(vm_addr, buf, size, error, result);
-    DoOperation(&op);
-    return result;
-}
-
-size_t
-ProcessMonitor::WriteMemory(lldb::addr_t vm_addr, const void *buf, size_t size,
-                            lldb_private::Error &error)
-{
-    size_t result;
-    WriteOperation op(vm_addr, buf, size, error, result);
-    DoOperation(&op);
-    return result;
-}
-
-bool
-ProcessMonitor::ReadRegisterValue(lldb::tid_t tid, unsigned offset, const char* reg_name,
-                                  unsigned size, RegisterValue &value)
-{
-    bool result;
-    ReadRegOperation op(tid, offset, reg_name, value, result);
-    DoOperation(&op);
-    return result;
-}
-
-bool
-ProcessMonitor::WriteRegisterValue(lldb::tid_t tid, unsigned offset,
-                                   const char* reg_name, const RegisterValue &value)
-{
-    bool result;
-    WriteRegOperation op(tid, offset, reg_name, value, result);
-    DoOperation(&op);
-    return result;
-}
-
-bool
-ProcessMonitor::ReadGPR(lldb::tid_t tid, void *buf, size_t buf_size)
-{
-    bool result;
-    ReadGPROperation op(tid, buf, buf_size, result);
-    DoOperation(&op);
-    return result;
-}
-
-bool
-ProcessMonitor::ReadFPR(lldb::tid_t tid, void *buf, size_t buf_size)
-{
-    bool result;
-    ReadFPROperation op(tid, buf, buf_size, result);
-    DoOperation(&op);
-    return result;
-}
-
-bool
-ProcessMonitor::ReadRegisterSet(lldb::tid_t tid, void *buf, size_t buf_size, unsigned int regset)
-{
-    bool result;
-    ReadRegisterSetOperation op(tid, buf, buf_size, regset, result);
-    DoOperation(&op);
-    return result;
-}
-
-bool
-ProcessMonitor::WriteGPR(lldb::tid_t tid, void *buf, size_t buf_size)
-{
-    bool result;
-    WriteGPROperation op(tid, buf, buf_size, result);
-    DoOperation(&op);
-    return result;
-}
-
-bool
-ProcessMonitor::WriteFPR(lldb::tid_t tid, void *buf, size_t buf_size)
-{
-    bool result;
-    WriteFPROperation op(tid, buf, buf_size, result);
-    DoOperation(&op);
-    return result;
-}
-
-bool
-ProcessMonitor::WriteRegisterSet(lldb::tid_t tid, void *buf, size_t buf_size, unsigned int regset)
-{
-    bool result;
-    WriteRegisterSetOperation op(tid, buf, buf_size, regset, result);
-    DoOperation(&op);
-    return result;
-}
-
-bool
-ProcessMonitor::ReadThreadPointer(lldb::tid_t tid, lldb::addr_t &value)
-{
-    bool result;
-    ReadThreadPointerOperation op(tid, &value, result);
-    DoOperation(&op);
-    return result;
-}
-
-bool
-ProcessMonitor::Resume(lldb::tid_t tid, uint32_t signo)
-{
-    bool result;
-    Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_PROCESS));
-
-    if (log)
-        log->Printf ("ProcessMonitor::%s() resuming thread = %"  PRIu64 " with signal %s", __FUNCTION__, tid,
-                                 m_process->GetUnixSignals().GetSignalAsCString (signo));
-    ResumeOperation op(tid, signo, result);
-    DoOperation(&op);
-    if (log)
-        log->Printf ("ProcessMonitor::%s() resuming result = %s", __FUNCTION__, result ? "true" : "false");
-    return result;
-}
-
-bool
-ProcessMonitor::SingleStep(lldb::tid_t tid, uint32_t signo)
-{
-    bool result;
-    SingleStepOperation op(tid, signo, result);
-    DoOperation(&op);
-    return result;
-}
-
-bool
-ProcessMonitor::Kill()
-{
-    return kill(GetPID(), SIGKILL) == 0;
-}
-
-bool
-ProcessMonitor::GetSignalInfo(lldb::tid_t tid, void *siginfo, int &ptrace_err)
-{
-    bool result;
-    SiginfoOperation op(tid, siginfo, result, ptrace_err);
-    DoOperation(&op);
-    return result;
-}
-
-bool
-ProcessMonitor::GetEventMessage(lldb::tid_t tid, unsigned long *message)
-{
-    bool result;
-    EventMessageOperation op(tid, message, result);
-    DoOperation(&op);
-    return result;
-}
-
-lldb_private::Error
-ProcessMonitor::Detach(lldb::tid_t tid)
-{
-    lldb_private::Error error;
-    if (tid != LLDB_INVALID_THREAD_ID)
-    {
-        DetachOperation op(tid, error);
-        DoOperation(&op);
-    }
-    return error;
-}
-
-bool
-ProcessMonitor::DupDescriptor(const char *path, int fd, int flags)
-{
-    int target_fd = open(path, flags, 0666);
-
-    if (target_fd == -1)
-        return false;
-
-    return (dup2(target_fd, fd) == -1) ? false : true;
-}
-
-void
-ProcessMonitor::StopMonitoringChildProcess()
-{
-    lldb::thread_result_t thread_result;
-
-    if (IS_VALID_LLDB_HOST_THREAD(m_monitor_thread))
-    {
-        Host::ThreadCancel(m_monitor_thread, NULL);
-        Host::ThreadJoin(m_monitor_thread, &thread_result, NULL);
-        m_monitor_thread = LLDB_INVALID_HOST_THREAD;
-    }
-}
-
-void
-ProcessMonitor::StopMonitor()
-{
-    StopMonitoringChildProcess();
-    StopOpThread();
-    sem_destroy(&m_operation_pending);
-    sem_destroy(&m_operation_done);
-
-    // Note: ProcessPOSIX passes the m_terminal_fd file descriptor to
-    // Process::SetSTDIOFileDescriptor, which in turn transfers ownership of
-    // the descriptor to a ConnectionFileDescriptor object.  Consequently
-    // even though still has the file descriptor, we shouldn't close it here.
-}
-
-void
-ProcessMonitor::StopOpThread()
-{
-    lldb::thread_result_t result;
-
-    if (!IS_VALID_LLDB_HOST_THREAD(m_operation_thread))
-        return;
-
-    Host::ThreadCancel(m_operation_thread, NULL);
-    Host::ThreadJoin(m_operation_thread, &result, NULL);
-    m_operation_thread = LLDB_INVALID_HOST_THREAD;
-}
diff --git a/source/Plugins/Process/Linux/ProcessMonitor.h b/source/Plugins/Process/Linux/ProcessMonitor.h
index 3e289ff..96ddf28 100644
--- a/source/Plugins/Process/Linux/ProcessMonitor.h
+++ b/source/Plugins/Process/Linux/ProcessMonitor.h
@@ -44,37 +44,11 @@ class Operation;
 class ProcessMonitor
 {
 public:
-
-    /// Launches an inferior process ready for debugging.  Forms the
-    /// implementation of Process::DoLaunch.
-    ProcessMonitor(ProcessPOSIX *process,
-                   lldb_private::Module *module,
-                   char const *argv[],
-                   char const *envp[],
-                   const char *stdin_path,
-                   const char *stdout_path,
-                   const char *stderr_path,
-                   const char *working_dir,
-                   lldb_private::Error &error);
-
-    ProcessMonitor(ProcessPOSIX *process,
-                   lldb::pid_t pid,
-                   lldb_private::Error &error);
-
-    ~ProcessMonitor();
-
-    enum ResumeSignals 
-    {
-        eResumeSignalNone = 0
-    };
+    virtual ~ProcessMonitor() {};
 
     /// Provides the process number of debugee.
-    lldb::pid_t
-    GetPID() const { return m_pid; }
-
-    /// Returns the process associated with this ProcessMonitor.
-    ProcessLinux &
-    GetProcess() { return *m_process; }
+    virtual lldb::pid_t
+    GetPID() const = 0;
 
     /// Returns a file descriptor to the controlling terminal of the inferior
     /// process.
@@ -86,237 +60,110 @@ public:
     ///
     /// If this monitor was attached to an existing process this method returns
     /// -1.
-    int
-    GetTerminalFD() const { return m_terminal_fd; }
+    virtual int
+    GetTerminalFD() const = 0;
 
     /// Reads @p size bytes from address @vm_adder in the inferior process
     /// address space.
     ///
     /// This method is provided to implement Process::DoReadMemory.
-    size_t
+    virtual size_t
     ReadMemory(lldb::addr_t vm_addr, void *buf, size_t size,
-               lldb_private::Error &error);
+               lldb_private::Error &error) = 0;
 
     /// Writes @p size bytes from address @p vm_adder in the inferior process
     /// address space.
     ///
     /// This method is provided to implement Process::DoWriteMemory.
-    size_t
+    virtual size_t
     WriteMemory(lldb::addr_t vm_addr, const void *buf, size_t size,
-                lldb_private::Error &error);
+                lldb_private::Error &error) = 0;
 
     /// Reads the contents from the register identified by the given (architecture
     /// dependent) offset.
     ///
     /// This method is provided for use by RegisterContextLinux derivatives.
-    bool
+    virtual bool
     ReadRegisterValue(lldb::tid_t tid, unsigned offset, const char *reg_name,
-                      unsigned size, lldb_private::RegisterValue &value);
+                      unsigned size, lldb_private::RegisterValue &value) = 0;
 
     /// Writes the given value to the register identified by the given
     /// (architecture dependent) offset.
     ///
     /// This method is provided for use by RegisterContextLinux derivatives.
-    bool
+    virtual bool
     WriteRegisterValue(lldb::tid_t tid, unsigned offset, const char *reg_name,
-                       const lldb_private::RegisterValue &value);
+                       const lldb_private::RegisterValue &value) = 0;
 
     /// Reads all general purpose registers into the specified buffer.
-    bool
-    ReadGPR(lldb::tid_t tid, void *buf, size_t buf_size);
+    virtual bool
+    ReadGPR(lldb::tid_t tid, void *buf, size_t buf_size) = 0;
 
     /// Reads generic floating point registers into the specified buffer.
-    bool
-    ReadFPR(lldb::tid_t tid, void *buf, size_t buf_size);
+    virtual bool
+    ReadFPR(lldb::tid_t tid, void *buf, size_t buf_size) = 0;
 
     /// Reads the specified register set into the specified buffer.
     /// For instance, the extended floating-point register set.
-    bool
-    ReadRegisterSet(lldb::tid_t tid, void *buf, size_t buf_size, unsigned int regset);
+    virtual bool
+    ReadRegisterSet(lldb::tid_t tid, void *buf, size_t buf_size, unsigned int regset) = 0;
 
     /// Writes all general purpose registers into the specified buffer.
-    bool
-    WriteGPR(lldb::tid_t tid, void *buf, size_t buf_size);
+    virtual bool
+    WriteGPR(lldb::tid_t tid, void *buf, size_t buf_size) = 0;
 
     /// Writes generic floating point registers into the specified buffer.
-    bool
-    WriteFPR(lldb::tid_t tid, void *buf, size_t buf_size);
+    virtual bool
+    WriteFPR(lldb::tid_t tid, void *buf, size_t buf_size) = 0;
 
     /// Writes the specified register set into the specified buffer.
     /// For instance, the extended floating-point register set.
-    bool
-    WriteRegisterSet(lldb::tid_t tid, void *buf, size_t buf_size, unsigned int regset);
+    virtual bool
+    WriteRegisterSet(lldb::tid_t tid, void *buf, size_t buf_size, unsigned int regset) = 0;
 
     /// Reads the value of the thread-specific pointer for a given thread ID.
-    bool
-    ReadThreadPointer(lldb::tid_t tid, lldb::addr_t &value);
+    virtual bool
+    ReadThreadPointer(lldb::tid_t tid, lldb::addr_t &value) = 0;
 
     /// Writes a siginfo_t structure corresponding to the given thread ID to the
     /// memory region pointed to by @p siginfo.
-    bool
-    GetSignalInfo(lldb::tid_t tid, void *siginfo, int &ptrace_err);
+    virtual bool
+    GetSignalInfo(lldb::tid_t tid, void *siginfo, int &ptrace_err) = 0;
 
     /// Writes the raw event message code (vis-a-vis PTRACE_GETEVENTMSG)
     /// corresponding to the given thread IDto the memory pointed to by @p
     /// message.
-    bool
-    GetEventMessage(lldb::tid_t tid, unsigned long *message);
+    virtual bool
+    GetEventMessage(lldb::tid_t tid, unsigned long *message) = 0;
 
     /// Resumes the given thread.  If @p signo is anything but
     /// LLDB_INVALID_SIGNAL_NUMBER, deliver that signal to the thread.
-    bool
-    Resume(lldb::tid_t tid, uint32_t signo);
+    virtual bool
+    Resume(lldb::tid_t tid, uint32_t signo) = 0;
 
     /// Single steps the given thread.  If @p signo is anything but
     /// LLDB_INVALID_SIGNAL_NUMBER, deliver that signal to the thread.
-    bool
-    SingleStep(lldb::tid_t tid, uint32_t signo);
+    virtual bool
+    SingleStep(lldb::tid_t tid, uint32_t signo) = 0;
 
     /// Terminate the traced process.
-    bool
-    Kill();
+    virtual bool
+    Kill() = 0;
 
-    lldb_private::Error
-    Detach(lldb::tid_t tid);
+    virtual lldb_private::Error
+    Detach(lldb::tid_t tid) = 0;
 
     /// Stops the monitoring the child process thread.
-    void
-    StopMonitor();
+    virtual void
+    StopMonitor() = 0;
 
     /// Stops the requested thread and waits for the stop signal.
-    bool
-    StopThread(lldb::tid_t tid);
+    virtual bool
+    StopThread(lldb::tid_t tid) = 0;
 
     // Waits for the initial stop message from a new thread.
-    bool
-    WaitForInitialTIDStop(lldb::tid_t tid);
-
-private:
-    ProcessLinux *m_process;
-
-    lldb::thread_t m_operation_thread;
-    lldb::thread_t m_monitor_thread;
-    lldb::pid_t m_pid;
-    int m_terminal_fd;
-
-    // current operation which must be executed on the priviliged thread
-    Operation *m_operation;
-    lldb_private::Mutex m_operation_mutex;
-
-    // semaphores notified when Operation is ready to be processed and when
-    // the operation is complete.
-    sem_t m_operation_pending;
-    sem_t m_operation_done;
-
-
-    struct OperationArgs
-    {
-        OperationArgs(ProcessMonitor *monitor);
-
-        ~OperationArgs();
-
-        ProcessMonitor *m_monitor;      // The monitor performing the attach.
-        sem_t m_semaphore;              // Posted to once operation complete.
-        lldb_private::Error m_error;    // Set if process operation failed.
-    };
-
-    /// @class LauchArgs
-    ///
-    /// @brief Simple structure to pass data to the thread responsible for
-    /// launching a child process.
-    struct LaunchArgs : OperationArgs
-    {
-        LaunchArgs(ProcessMonitor *monitor,
-                   lldb_private::Module *module,
-                   char const **argv,
-                   char const **envp,
-                   const char *stdin_path,
-                   const char *stdout_path,
-                   const char *stderr_path,
-                   const char *working_dir);
-
-        ~LaunchArgs();
-
-        lldb_private::Module *m_module; // The executable image to launch.
-        char const **m_argv;            // Process arguments.
-        char const **m_envp;            // Process environment.
-        const char *m_stdin_path;       // Redirect stdin or NULL.
-        const char *m_stdout_path;      // Redirect stdout or NULL.
-        const char *m_stderr_path;      // Redirect stderr or NULL.
-        const char *m_working_dir;      // Working directory or NULL.
-    };
-
-    void
-    StartLaunchOpThread(LaunchArgs *args, lldb_private::Error &error);
-
-    static void *
-    LaunchOpThread(void *arg);
-
-    static bool
-    Launch(LaunchArgs *args);
-
-    struct AttachArgs : OperationArgs
-    {
-        AttachArgs(ProcessMonitor *monitor,
-                   lldb::pid_t pid);
-
-        ~AttachArgs();
-
-        lldb::pid_t m_pid;              // pid of the process to be attached.
-    };
-
-    void
-    StartAttachOpThread(AttachArgs *args, lldb_private::Error &error);
-
-    static void *
-    AttachOpThread(void *args);
-
-    static bool
-    Attach(AttachArgs *args);
-
-    static bool
-    SetDefaultPtraceOpts(const lldb::pid_t);
-
-    static void
-    ServeOperation(OperationArgs *args);
-
-    static bool
-    DupDescriptor(const char *path, int fd, int flags);
-
-    static bool
-    MonitorCallback(void *callback_baton,
-                    lldb::pid_t pid, bool exited, int signal, int status);
-
-    static ProcessMessage
-    MonitorSIGTRAP(ProcessMonitor *monitor,
-                   const siginfo_t *info, lldb::pid_t pid);
-
-    static ProcessMessage
-    MonitorSignal(ProcessMonitor *monitor, 
-                  const siginfo_t *info, lldb::pid_t pid);
-
-    static ProcessMessage::CrashReason
-    GetCrashReasonForSIGSEGV(const siginfo_t *info);
-
-    static ProcessMessage::CrashReason
-    GetCrashReasonForSIGILL(const siginfo_t *info);
-
-    static ProcessMessage::CrashReason
-    GetCrashReasonForSIGFPE(const siginfo_t *info);
-
-    static ProcessMessage::CrashReason
-    GetCrashReasonForSIGBUS(const siginfo_t *info);
-
-    void
-    DoOperation(Operation *op);
-
-    /// Stops the child monitor thread.
-    void
-    StopMonitoringChildProcess();
-
-    /// Stops the operation thread used to attach/launch a process.
-    void
-    StopOpThread();
+    virtual bool
+    WaitForInitialTIDStop(lldb::tid_t tid) = 0;
 };
 
 #endif // #ifndef liblldb_ProcessMonitor_H_
diff --git a/source/Plugins/Process/Linux/ProcessMonitorOther.cpp b/source/Plugins/Process/Linux/ProcessMonitorOther.cpp
new file mode 100644
index 0000000..6ba900d
--- /dev/null
+++ b/source/Plugins/Process/Linux/ProcessMonitorOther.cpp
@@ -0,0 +1,2328 @@
+//===-- ProcessMonitorOther.cpp ------------------------------------ -*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "lldb/lldb-python.h"
+
+// C Includes
+#include <errno.h>
+#include <poll.h>
+#include <string.h>
+#include <stdint.h>
+#include <unistd.h>
+#include <sys/ptrace.h>
+#include <sys/socket.h>
+#include <sys/syscall.h>
+#include <sys/types.h>
+#include <sys/user.h>
+#include <sys/wait.h>
+
+// C++ Includes
+// Other libraries and framework includes
+#include "lldb/Core/Debugger.h"
+#include "lldb/Core/Error.h"
+#include "lldb/Core/RegisterValue.h"
+#include "lldb/Core/Scalar.h"
+#include "lldb/Host/Host.h"
+#include "lldb/Target/Thread.h"
+#include "lldb/Target/RegisterContext.h"
+#include "lldb/Utility/PseudoTerminal.h"
+
+#include "POSIXThread.h"
+#include "ProcessLinux.h"
+#include "ProcessPOSIXLog.h"
+#include "ProcessMonitorOther.h"
+
+#define DEBUG_PTRACE_MAXBYTES 20
+
+// Support ptrace extensions even when compiled without required kernel support
+#ifndef PTRACE_GETREGSET
+  #define PTRACE_GETREGSET 0x4204
+#endif
+#ifndef PTRACE_SETREGSET
+  #define PTRACE_SETREGSET 0x4205
+#endif
+#ifndef PTRACE_GET_THREAD_AREA
+  #define PTRACE_GET_THREAD_AREA 25
+#endif
+#ifndef PTRACE_ARCH_PRCTL
+  #define PTRACE_ARCH_PRCTL      30
+#endif
+#ifndef ARCH_GET_FS
+  #define ARCH_SET_GS 0x1001
+  #define ARCH_SET_FS 0x1002
+  #define ARCH_GET_FS 0x1003
+  #define ARCH_GET_GS 0x1004
+#endif
+
+
+// Support hardware breakpoints in case it has not been defined
+#ifndef TRAP_HWBKPT
+  #define TRAP_HWBKPT 4
+#endif
+
+// Try to define a macro to encapsulate the tgkill syscall
+// fall back on kill() if tgkill isn't available
+#define tgkill(pid, tid, sig)  syscall(SYS_tgkill, pid, tid, sig)
+
+using namespace lldb_private;
+
+// FIXME: this code is host-dependent with respect to types and
+// endianness and needs to be fixed.  For example, lldb::addr_t is
+// hard-coded to uint64_t, but on a 32-bit Linux host, ptrace requires
+// 32-bit pointer arguments.  This code uses casts to work around the
+// problem.
+
+// We disable the tracing of ptrace calls for integration builds to
+// avoid the additional indirection and checks.
+#ifndef LLDB_CONFIGURATION_BUILDANDINTEGRATION
+
+static void
+DisplayBytes (lldb_private::StreamString &s, void *bytes, uint32_t count)
+{
+    uint8_t *ptr = (uint8_t *)bytes;
+    const uint32_t loop_count = std::min<uint32_t>(DEBUG_PTRACE_MAXBYTES, count);
+    for(uint32_t i=0; i<loop_count; i++)
+    {
+        s.Printf ("[%x]", *ptr);
+        ptr++;
+    }
+}
+
+static void PtraceDisplayBytes(int &req, void *data, size_t data_size)
+{
+    StreamString buf;
+    Log *verbose_log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (
+                                        POSIX_LOG_PTRACE | POSIX_LOG_VERBOSE));
+
+    if (verbose_log)
+    {
+        switch(req)
+        {
+        case PTRACE_POKETEXT:
+            {
+                DisplayBytes(buf, &data, 8);
+                verbose_log->Printf("PTRACE_POKETEXT %s", buf.GetData());
+                break;
+            }
+        case PTRACE_POKEDATA:
+            {
+                DisplayBytes(buf, &data, 8);
+                verbose_log->Printf("PTRACE_POKEDATA %s", buf.GetData());
+                break;
+            }
+        case PTRACE_POKEUSER:
+            {
+                DisplayBytes(buf, &data, 8);
+                verbose_log->Printf("PTRACE_POKEUSER %s", buf.GetData());
+                break;
+            }
+#ifdef PT_SETREGS
+        case PTRACE_SETREGS:
+            {
+                DisplayBytes(buf, data, data_size);
+                verbose_log->Printf("PTRACE_SETREGS %s", buf.GetData());
+                break;
+            }
+#endif
+#ifdef PT_SETFPREGS
+        case PTRACE_SETFPREGS:
+            {
+                DisplayBytes(buf, data, data_size);
+                verbose_log->Printf("PTRACE_SETFPREGS %s", buf.GetData());
+                break;
+            }
+#endif
+        case PTRACE_SETSIGINFO:
+            {
+                DisplayBytes(buf, data, sizeof(siginfo_t));
+                verbose_log->Printf("PTRACE_SETSIGINFO %s", buf.GetData());
+                break;
+            }
+        case PTRACE_SETREGSET:
+            {
+                // Extract iov_base from data, which is a pointer to the struct IOVEC
+                DisplayBytes(buf, *(void **)data, data_size);
+                verbose_log->Printf("PTRACE_SETREGSET %s", buf.GetData());
+                break;
+            }
+        default:
+            {
+            }
+        }
+    }
+}
+
+// Wrapper for ptrace to catch errors and log calls.
+// Note that ptrace sets errno on error because -1 can be a valid result (i.e. for PTRACE_PEEK*)
+extern long
+PtraceWrapper(int req, lldb::pid_t pid, void *addr, void *data, size_t data_size,
+              const char* reqName, const char* file, int line)
+{
+    long int result;
+
+    Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_PTRACE));
+
+    PtraceDisplayBytes(req, data, data_size);
+
+    errno = 0;
+    if (req == PTRACE_GETREGSET || req == PTRACE_SETREGSET)
+        result = ptrace(static_cast<__ptrace_request>(req), static_cast<pid_t>(pid), *(unsigned int *)addr, data);
+    else
+        result = ptrace(static_cast<__ptrace_request>(req), static_cast<pid_t>(pid), addr, data);
+
+    if (log)
+        log->Printf("ptrace(%s, %" PRIu64 ", %p, %p, %zu)=%lX called from file %s line %d",
+                    reqName, pid, addr, data, data_size, result, file, line);
+
+    PtraceDisplayBytes(req, data, data_size);
+
+    if (log && errno != 0)
+    {
+        const char* str;
+        switch (errno)
+        {
+        case ESRCH:  str = "ESRCH"; break;
+        case EINVAL: str = "EINVAL"; break;
+        case EBUSY:  str = "EBUSY"; break;
+        case EPERM:  str = "EPERM"; break;
+        default:     str = "<unknown>";
+        }
+        log->Printf("ptrace() failed; errno=%d (%s)", errno, str);
+    }
+
+    return result;
+}
+
+// Wrapper for ptrace when logging is not required.
+// Sets errno to 0 prior to calling ptrace.
+extern long
+PtraceWrapper(int req, pid_t pid, void *addr, void *data, size_t data_size)
+{
+    long result = 0;
+    errno = 0;
+    if (req == PTRACE_GETREGSET || req == PTRACE_SETREGSET)
+        result = ptrace(static_cast<__ptrace_request>(req), pid, *(unsigned int *)addr, data);
+    else
+        result = ptrace(static_cast<__ptrace_request>(req), pid, addr, data);
+    return result;
+}
+
+#define PTRACE(req, pid, addr, data, data_size) \
+    PtraceWrapper((req), (pid), (addr), (data), (data_size), #req, __FILE__, __LINE__)
+#else
+    PtraceWrapper((req), (pid), (addr), (data), (data_size))
+#endif
+
+//------------------------------------------------------------------------------
+// Static implementations of ProcessMonitorOther::ReadMemory and
+// ProcessMonitorOther::WriteMemory.  This enables mutual recursion between these
+// functions without needed to go thru the thread funnel.
+
+static size_t
+DoReadMemory(lldb::pid_t pid,
+             lldb::addr_t vm_addr, void *buf, size_t size, Error &error)
+{
+    // ptrace word size is determined by the host, not the child
+    static const unsigned word_size = sizeof(void*);
+    unsigned char *dst = static_cast<unsigned char*>(buf);
+    size_t bytes_read;
+    size_t remainder;
+    long data;
+
+    Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_ALL));
+    if (log)
+        ProcessPOSIXLog::IncNestLevel();
+    if (log && ProcessPOSIXLog::AtTopNestLevel() && log->GetMask().Test(POSIX_LOG_MEMORY))
+        log->Printf ("ProcessMonitorOther::%s(%" PRIu64 ", %d, %p, %p, %zd, _)", __FUNCTION__,
+                     pid, word_size, (void*)vm_addr, buf, size);
+
+    assert(sizeof(data) >= word_size);
+    for (bytes_read = 0; bytes_read < size; bytes_read += remainder)
+    {
+        errno = 0;
+        data = PTRACE(PTRACE_PEEKDATA, pid, (void*)vm_addr, NULL, 0);
+        if (errno)
+        {
+            error.SetErrorToErrno();
+            if (log)
+                ProcessPOSIXLog::DecNestLevel();
+            return bytes_read;
+        }
+
+        remainder = size - bytes_read;
+        remainder = remainder > word_size ? word_size : remainder;
+
+        // Copy the data into our buffer
+        for (unsigned i = 0; i < remainder; ++i)
+            dst[i] = ((data >> i*8) & 0xFF);
+
+        if (log && ProcessPOSIXLog::AtTopNestLevel() &&
+            (log->GetMask().Test(POSIX_LOG_MEMORY_DATA_LONG) ||
+             (log->GetMask().Test(POSIX_LOG_MEMORY_DATA_SHORT) &&
+              size <= POSIX_LOG_MEMORY_SHORT_BYTES)))
+            {
+                uintptr_t print_dst = 0;
+                // Format bytes from data by moving into print_dst for log output
+                for (unsigned i = 0; i < remainder; ++i)
+                    print_dst |= (((data >> i*8) & 0xFF) << i*8);
+                log->Printf ("ProcessMonitorOther::%s() [%p]:0x%lx (0x%lx)", __FUNCTION__,
+                             (void*)vm_addr, print_dst, (unsigned long)data);
+            }
+
+        vm_addr += word_size;
+        dst += word_size;
+    }
+
+    if (log)
+        ProcessPOSIXLog::DecNestLevel();
+    return bytes_read;
+}
+
+static size_t
+DoWriteMemory(lldb::pid_t pid,
+              lldb::addr_t vm_addr, const void *buf, size_t size, Error &error)
+{
+    // ptrace word size is determined by the host, not the child
+    static const unsigned word_size = sizeof(void*);
+    const unsigned char *src = static_cast<const unsigned char*>(buf);
+    size_t bytes_written = 0;
+    size_t remainder;
+
+    Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_ALL));
+    if (log)
+        ProcessPOSIXLog::IncNestLevel();
+    if (log && ProcessPOSIXLog::AtTopNestLevel() && log->GetMask().Test(POSIX_LOG_MEMORY))
+        log->Printf ("ProcessMonitorOther::%s(%" PRIu64 ", %d, %p, %p, %zd, _)", __FUNCTION__,
+                     pid, word_size, (void*)vm_addr, buf, size);
+
+    for (bytes_written = 0; bytes_written < size; bytes_written += remainder)
+    {
+        remainder = size - bytes_written;
+        remainder = remainder > word_size ? word_size : remainder;
+
+        if (remainder == word_size)
+        {
+            unsigned long data = 0;
+            assert(sizeof(data) >= word_size);
+            for (unsigned i = 0; i < word_size; ++i)
+                data |= (unsigned long)src[i] << i*8;
+
+            if (log && ProcessPOSIXLog::AtTopNestLevel() &&
+                (log->GetMask().Test(POSIX_LOG_MEMORY_DATA_LONG) ||
+                 (log->GetMask().Test(POSIX_LOG_MEMORY_DATA_SHORT) &&
+                  size <= POSIX_LOG_MEMORY_SHORT_BYTES)))
+                 log->Printf ("ProcessMonitorOther::%s() [%p]:0x%lx (0x%lx)", __FUNCTION__,
+                              (void*)vm_addr, *(unsigned long*)src, data);
+
+            if (PTRACE(PTRACE_POKEDATA, pid, (void*)vm_addr, (void*)data, 0))
+            {
+                error.SetErrorToErrno();
+                if (log)
+                    ProcessPOSIXLog::DecNestLevel();
+                return bytes_written;
+            }
+        }
+        else
+        {
+            unsigned char buff[8];
+            if (DoReadMemory(pid, vm_addr,
+                             buff, word_size, error) != word_size)
+            {
+                if (log)
+                    ProcessPOSIXLog::DecNestLevel();
+                return bytes_written;
+            }
+
+            memcpy(buff, src, remainder);
+
+            if (DoWriteMemory(pid, vm_addr,
+                              buff, word_size, error) != word_size)
+            {
+                if (log)
+                    ProcessPOSIXLog::DecNestLevel();
+                return bytes_written;
+            }
+
+            if (log && ProcessPOSIXLog::AtTopNestLevel() &&
+                (log->GetMask().Test(POSIX_LOG_MEMORY_DATA_LONG) ||
+                 (log->GetMask().Test(POSIX_LOG_MEMORY_DATA_SHORT) &&
+                  size <= POSIX_LOG_MEMORY_SHORT_BYTES)))
+                 log->Printf ("ProcessMonitorOther::%s() [%p]:0x%lx (0x%lx)", __FUNCTION__,
+                              (void*)vm_addr, *(unsigned long*)src, *(unsigned long*)buff);
+        }
+
+        vm_addr += word_size;
+        src += word_size;
+    }
+    if (log)
+        ProcessPOSIXLog::DecNestLevel();
+    return bytes_written;
+}
+
+// Simple helper function to ensure flags are enabled on the given file
+// descriptor.
+static bool
+EnsureFDFlags(int fd, int flags, Error &error)
+{
+    int status;
+
+    if ((status = fcntl(fd, F_GETFL)) == -1)
+    {
+        error.SetErrorToErrno();
+        return false;
+    }
+
+    if (fcntl(fd, F_SETFL, status | flags) == -1)
+    {
+        error.SetErrorToErrno();
+        return false;
+    }
+
+    return true;
+}
+
+//------------------------------------------------------------------------------
+/// @class Operation
+/// @brief Represents a ProcessMonitorOther operation.
+///
+/// Under Linux, it is not possible to ptrace() from any other thread but the
+/// one that spawned or attached to the process from the start.  Therefore, when
+/// a ProcessMonitorOther is asked to deliver or change the state of an inferior
+/// process the operation must be "funneled" to a specific thread to perform the
+/// task.  The Operation class provides an abstract base for all services the
+/// ProcessMonitorOther must perform via the single virtual function Execute, thus
+/// encapsulating the code that needs to run in the privileged context.
+class Operation
+{
+public:
+    virtual ~Operation() {}
+    virtual void Execute(ProcessMonitorOther *monitor) = 0;
+};
+
+//------------------------------------------------------------------------------
+/// @class ReadOperation
+/// @brief Implements ProcessMonitorOther::ReadMemory.
+class ReadOperation : public Operation
+{
+public:
+    ReadOperation(lldb::addr_t addr, void *buff, size_t size,
+                  Error &error, size_t &result)
+        : m_addr(addr), m_buff(buff), m_size(size),
+          m_error(error), m_result(result)
+        { }
+
+    void Execute(ProcessMonitorOther *monitor);
+
+private:
+    lldb::addr_t m_addr;
+    void *m_buff;
+    size_t m_size;
+    Error &m_error;
+    size_t &m_result;
+};
+
+void
+ReadOperation::Execute(ProcessMonitorOther *monitor)
+{
+    lldb::pid_t pid = monitor->GetPID();
+
+    m_result = DoReadMemory(pid, m_addr, m_buff, m_size, m_error);
+}
+
+//------------------------------------------------------------------------------
+/// @class WriteOperation
+/// @brief Implements ProcessMonitorOther::WriteMemory.
+class WriteOperation : public Operation
+{
+public:
+    WriteOperation(lldb::addr_t addr, const void *buff, size_t size,
+                   Error &error, size_t &result)
+        : m_addr(addr), m_buff(buff), m_size(size),
+          m_error(error), m_result(result)
+        { }
+
+    void Execute(ProcessMonitorOther *monitor);
+
+private:
+    lldb::addr_t m_addr;
+    const void *m_buff;
+    size_t m_size;
+    Error &m_error;
+    size_t &m_result;
+};
+
+void
+WriteOperation::Execute(ProcessMonitorOther *monitor)
+{
+    lldb::pid_t pid = monitor->GetPID();
+
+    m_result = DoWriteMemory(pid, m_addr, m_buff, m_size, m_error);
+}
+
+
+//------------------------------------------------------------------------------
+/// @class ReadRegOperation
+/// @brief Implements ProcessMonitorOther::ReadRegisterValue.
+class ReadRegOperation : public Operation
+{
+public:
+    ReadRegOperation(lldb::tid_t tid, unsigned offset, const char *reg_name,
+                     RegisterValue &value, bool &result)
+        : m_tid(tid), m_offset(offset), m_reg_name(reg_name),
+          m_value(value), m_result(result)
+        { }
+
+    void Execute(ProcessMonitorOther *monitor);
+
+private:
+    lldb::tid_t m_tid;
+    uintptr_t m_offset;
+    const char *m_reg_name;
+    RegisterValue &m_value;
+    bool &m_result;
+};
+
+void
+ReadRegOperation::Execute(ProcessMonitorOther *monitor)
+{
+    Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_REGISTERS));
+
+    // Set errno to zero so that we can detect a failed peek.
+    errno = 0;
+    lldb::addr_t data = PTRACE(PTRACE_PEEKUSER, m_tid, (void*)m_offset, NULL, 0);
+    if (errno)
+        m_result = false;
+    else
+    {
+        m_value = data;
+        m_result = true;
+    }
+    if (log)
+        log->Printf ("ProcessMonitorOther::%s() reg %s: 0x%" PRIx64, __FUNCTION__,
+                     m_reg_name, data);
+}
+
+//------------------------------------------------------------------------------
+/// @class WriteRegOperation
+/// @brief Implements ProcessMonitorOther::WriteRegisterValue.
+class WriteRegOperation : public Operation
+{
+public:
+    WriteRegOperation(lldb::tid_t tid, unsigned offset, const char *reg_name,
+                      const RegisterValue &value, bool &result)
+        : m_tid(tid), m_offset(offset), m_reg_name(reg_name),
+          m_value(value), m_result(result)
+        { }
+
+    void Execute(ProcessMonitorOther *monitor);
+
+private:
+    lldb::tid_t m_tid;
+    uintptr_t m_offset;
+    const char *m_reg_name;
+    const RegisterValue &m_value;
+    bool &m_result;
+};
+
+void
+WriteRegOperation::Execute(ProcessMonitorOther *monitor)
+{
+    void* buf;
+    Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_REGISTERS));
+
+    buf = (void*) m_value.GetAsUInt64();
+
+    if (log)
+        log->Printf ("ProcessMonitorOther::%s() reg %s: %p", __FUNCTION__, m_reg_name, buf);
+    if (PTRACE(PTRACE_POKEUSER, m_tid, (void*)m_offset, buf, 0))
+        m_result = false;
+    else
+        m_result = true;
+}
+
+//------------------------------------------------------------------------------
+/// @class ReadGPROperation
+/// @brief Implements ProcessMonitorOther::ReadGPR.
+class ReadGPROperation : public Operation
+{
+public:
+    ReadGPROperation(lldb::tid_t tid, void *buf, size_t buf_size, bool &result)
+        : m_tid(tid), m_buf(buf), m_buf_size(buf_size), m_result(result)
+        { }
+
+    void Execute(ProcessMonitorOther *monitor);
+
+private:
+    lldb::tid_t m_tid;
+    void *m_buf;
+    size_t m_buf_size;
+    bool &m_result;
+};
+
+void
+ReadGPROperation::Execute(ProcessMonitorOther *monitor)
+{
+#ifdef PT_GETREGS
+    if (PTRACE(PTRACE_GETREGS, m_tid, NULL, m_buf, m_buf_size) < 0)
+        m_result = false;
+    else
+        m_result = true;
+#else
+    m_result = false;
+#endif
+}
+
+//------------------------------------------------------------------------------
+/// @class ReadFPROperation
+/// @brief Implements ProcessMonitorOther::ReadFPR.
+class ReadFPROperation : public Operation
+{
+public:
+    ReadFPROperation(lldb::tid_t tid, void *buf, size_t buf_size, bool &result)
+        : m_tid(tid), m_buf(buf), m_buf_size(buf_size), m_result(result)
+        { }
+
+    void Execute(ProcessMonitorOther *monitor);
+
+private:
+    lldb::tid_t m_tid;
+    void *m_buf;
+    size_t m_buf_size;
+    bool &m_result;
+};
+
+void
+ReadFPROperation::Execute(ProcessMonitorOther *monitor)
+{
+#ifdef PT_GETFPREGS
+    if (PTRACE(PTRACE_GETFPREGS, m_tid, NULL, m_buf, m_buf_size) < 0)
+        m_result = false;
+    else
+        m_result = true;
+#else
+    m_result = false;
+#endif
+}
+
+//------------------------------------------------------------------------------
+/// @class ReadRegisterSetOperation
+/// @brief Implements ProcessMonitorOther::ReadRegisterSet.
+class ReadRegisterSetOperation : public Operation
+{
+public:
+    ReadRegisterSetOperation(lldb::tid_t tid, void *buf, size_t buf_size, unsigned int regset, bool &result)
+        : m_tid(tid), m_buf(buf), m_buf_size(buf_size), m_regset(regset), m_result(result)
+        { }
+
+    void Execute(ProcessMonitorOther *monitor);
+
+private:
+    lldb::tid_t m_tid;
+    void *m_buf;
+    size_t m_buf_size;
+    const unsigned int m_regset;
+    bool &m_result;
+};
+
+void
+ReadRegisterSetOperation::Execute(ProcessMonitorOther *monitor)
+{
+    if (PTRACE(PTRACE_GETREGSET, m_tid, (void *)&m_regset, m_buf, m_buf_size) < 0)
+        m_result = false;
+    else
+        m_result = true;
+}
+
+//------------------------------------------------------------------------------
+/// @class WriteGPROperation
+/// @brief Implements ProcessMonitorOther::WriteGPR.
+class WriteGPROperation : public Operation
+{
+public:
+    WriteGPROperation(lldb::tid_t tid, void *buf, size_t buf_size, bool &result)
+        : m_tid(tid), m_buf(buf), m_buf_size(buf_size), m_result(result)
+        { }
+
+    void Execute(ProcessMonitorOther *monitor);
+
+private:
+    lldb::tid_t m_tid;
+    void *m_buf;
+    size_t m_buf_size;
+    bool &m_result;
+};
+
+void
+WriteGPROperation::Execute(ProcessMonitorOther *monitor)
+{
+#ifdef PT_SETREGS
+    if (PTRACE(PTRACE_SETREGS, m_tid, NULL, m_buf, m_buf_size) < 0)
+        m_result = false;
+    else
+        m_result = true;
+#else
+    m_result = false;
+#endif
+}
+
+//------------------------------------------------------------------------------
+/// @class WriteFPROperation
+/// @brief Implements ProcessMonitorOther::WriteFPR.
+class WriteFPROperation : public Operation
+{
+public:
+    WriteFPROperation(lldb::tid_t tid, void *buf, size_t buf_size, bool &result)
+        : m_tid(tid), m_buf(buf), m_buf_size(buf_size), m_result(result)
+        { }
+
+    void Execute(ProcessMonitorOther *monitor);
+
+private:
+    lldb::tid_t m_tid;
+    void *m_buf;
+    size_t m_buf_size;
+    bool &m_result;
+};
+
+void
+WriteFPROperation::Execute(ProcessMonitorOther *monitor)
+{
+#ifdef PT_SETFPREGS
+    if (PTRACE(PTRACE_SETFPREGS, m_tid, NULL, m_buf, m_buf_size) < 0)
+        m_result = false;
+    else
+        m_result = true;
+#else
+    m_result = false;
+#endif
+}
+
+//------------------------------------------------------------------------------
+/// @class WriteRegisterSetOperation
+/// @brief Implements ProcessMonitorOther::WriteRegisterSet.
+class WriteRegisterSetOperation : public Operation
+{
+public:
+    WriteRegisterSetOperation(lldb::tid_t tid, void *buf, size_t buf_size, unsigned int regset, bool &result)
+        : m_tid(tid), m_buf(buf), m_buf_size(buf_size), m_regset(regset), m_result(result)
+        { }
+
+    void Execute(ProcessMonitorOther *monitor);
+
+private:
+    lldb::tid_t m_tid;
+    void *m_buf;
+    size_t m_buf_size;
+    const unsigned int m_regset;
+    bool &m_result;
+};
+
+void
+WriteRegisterSetOperation::Execute(ProcessMonitorOther *monitor)
+{
+    if (PTRACE(PTRACE_SETREGSET, m_tid, (void *)&m_regset, m_buf, m_buf_size) < 0)
+        m_result = false;
+    else
+        m_result = true;
+}
+
+//------------------------------------------------------------------------------
+/// @class ReadThreadPointerOperation
+/// @brief Implements ProcessMonitorOther::ReadThreadPointer.
+class ReadThreadPointerOperation : public Operation
+{
+public:
+    ReadThreadPointerOperation(lldb::tid_t tid, lldb::addr_t *addr, bool &result)
+        : m_tid(tid), m_addr(addr), m_result(result)
+        { }
+
+    void Execute(ProcessMonitorOther *monitor);
+
+private:
+    lldb::tid_t m_tid;
+    lldb::addr_t *m_addr;
+    bool &m_result;
+};
+
+void
+ReadThreadPointerOperation::Execute(ProcessMonitorOther *monitor)
+{
+    Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_REGISTERS));
+    if (log)
+        log->Printf ("ProcessMonitorOther::%s()", __FUNCTION__);
+
+    // The process for getting the thread area on Linux is
+    // somewhat... obscure. There's several different ways depending on
+    // what arch you're on, and what kernel version you have.
+
+    const ArchSpec& arch = monitor->GetProcess().GetTarget().GetArchitecture();
+    switch(arch.GetMachine())
+    {
+#if defined(__i386__) || defined(__x86_64__)
+    // Note that struct user below has a field named i387 which is x86-specific.
+    // Therefore, this case should be compiled only for x86-based systems.
+    case llvm::Triple::x86:
+    {
+        // Find the GS register location for our host architecture.
+        size_t gs_user_offset = offsetof(struct user, regs);
+#ifdef __x86_64__
+        gs_user_offset += offsetof(struct user_regs_struct, gs);
+#endif
+#ifdef __i386__
+        gs_user_offset += offsetof(struct user_regs_struct, xgs);
+#endif
+
+        // Read the GS register value to get the selector.
+        errno = 0;
+        long gs = PTRACE(PTRACE_PEEKUSER, m_tid, (void*)gs_user_offset, NULL, 0);
+        if (errno)
+        {
+            m_result = false;
+            break;
+        }
+
+        // Read the LDT base for that selector.
+        uint32_t tmp[4];
+        m_result = (PTRACE(PTRACE_GET_THREAD_AREA, m_tid, (void *)(gs >> 3), &tmp, 0) == 0);
+        *m_addr = tmp[1];
+        break;
+    }
+#endif
+    case llvm::Triple::x86_64:
+        // Read the FS register base.
+        m_result = (PTRACE(PTRACE_ARCH_PRCTL, m_tid, m_addr, (void *)ARCH_GET_FS, 0) == 0);
+        break;
+    default:
+        m_result = false;
+        break;
+    }
+}
+
+//------------------------------------------------------------------------------
+/// @class ResumeOperation
+/// @brief Implements ProcessMonitorOther::Resume.
+class ResumeOperation : public Operation
+{
+public:
+    ResumeOperation(lldb::tid_t tid, uint32_t signo, bool &result) :
+        m_tid(tid), m_signo(signo), m_result(result) { }
+
+    void Execute(ProcessMonitorOther *monitor);
+
+private:
+    lldb::tid_t m_tid;
+    uint32_t m_signo;
+    bool &m_result;
+};
+
+void
+ResumeOperation::Execute(ProcessMonitorOther *monitor)
+{
+    intptr_t data = 0;
+
+    if (m_signo != LLDB_INVALID_SIGNAL_NUMBER)
+        data = m_signo;
+
+    if (PTRACE(PTRACE_CONT, m_tid, NULL, (void*)data, 0))
+    {
+        Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_PROCESS));
+
+        if (log)
+            log->Printf ("ResumeOperation (%"  PRIu64 ") failed: %s", m_tid, strerror(errno));
+        m_result = false;
+    }
+    else
+        m_result = true;
+}
+
+//------------------------------------------------------------------------------
+/// @class SingleStepOperation
+/// @brief Implements ProcessMonitorOther::SingleStep.
+class SingleStepOperation : public Operation
+{
+public:
+    SingleStepOperation(lldb::tid_t tid, uint32_t signo, bool &result)
+        : m_tid(tid), m_signo(signo), m_result(result) { }
+
+    void Execute(ProcessMonitorOther *monitor);
+
+private:
+    lldb::tid_t m_tid;
+    uint32_t m_signo;
+    bool &m_result;
+};
+
+void
+SingleStepOperation::Execute(ProcessMonitorOther *monitor)
+{
+    intptr_t data = 0;
+
+    if (m_signo != LLDB_INVALID_SIGNAL_NUMBER)
+        data = m_signo;
+
+    if (PTRACE(PTRACE_SINGLESTEP, m_tid, NULL, (void*)data, 0))
+        m_result = false;
+    else
+        m_result = true;
+}
+
+//------------------------------------------------------------------------------
+/// @class SiginfoOperation
+/// @brief Implements ProcessMonitorOther::GetSignalInfo.
+class SiginfoOperation : public Operation
+{
+public:
+    SiginfoOperation(lldb::tid_t tid, void *info, bool &result, int &ptrace_err)
+        : m_tid(tid), m_info(info), m_result(result), m_err(ptrace_err) { }
+
+    void Execute(ProcessMonitorOther *monitor);
+
+private:
+    lldb::tid_t m_tid;
+    void *m_info;
+    bool &m_result;
+    int &m_err;
+};
+
+void
+SiginfoOperation::Execute(ProcessMonitorOther *monitor)
+{
+    if (PTRACE(PTRACE_GETSIGINFO, m_tid, NULL, m_info, 0)) {
+        m_result = false;
+        m_err = errno;
+    }
+    else
+        m_result = true;
+}
+
+//------------------------------------------------------------------------------
+/// @class EventMessageOperation
+/// @brief Implements ProcessMonitorOther::GetEventMessage.
+class EventMessageOperation : public Operation
+{
+public:
+    EventMessageOperation(lldb::tid_t tid, unsigned long *message, bool &result)
+        : m_tid(tid), m_message(message), m_result(result) { }
+
+    void Execute(ProcessMonitorOther *monitor);
+
+private:
+    lldb::tid_t m_tid;
+    unsigned long *m_message;
+    bool &m_result;
+};
+
+void
+EventMessageOperation::Execute(ProcessMonitorOther *monitor)
+{
+    if (PTRACE(PTRACE_GETEVENTMSG, m_tid, NULL, m_message, 0))
+        m_result = false;
+    else
+        m_result = true;
+}
+
+//------------------------------------------------------------------------------
+/// @class DetachOperation
+/// @brief Implements ProcessMonitorOther::Detach.
+class DetachOperation : public Operation
+{
+public:
+    DetachOperation(lldb::tid_t tid, Error &result) : m_tid(tid), m_error(result) { }
+
+    void Execute(ProcessMonitorOther *monitor);
+
+private:
+    lldb::tid_t m_tid;
+    Error &m_error;
+};
+
+void
+DetachOperation::Execute(ProcessMonitorOther *monitor)
+{
+    if (ptrace(PT_DETACH, m_tid, NULL, 0) < 0)
+        m_error.SetErrorToErrno();
+}
+
+ProcessMonitorOther::OperationArgs::OperationArgs(ProcessMonitorOther *monitor)
+    : m_monitor(monitor)
+{
+    sem_init(&m_semaphore, 0, 0);
+}
+
+ProcessMonitorOther::OperationArgs::~OperationArgs()
+{
+    sem_destroy(&m_semaphore);
+}
+
+ProcessMonitorOther::LaunchArgs::LaunchArgs(ProcessMonitorOther *monitor,
+                                       lldb_private::Module *module,
+                                       char const **argv,
+                                       char const **envp,
+                                       const char *stdin_path,
+                                       const char *stdout_path,
+                                       const char *stderr_path,
+                                       const char *working_dir)
+    : OperationArgs(monitor),
+      m_module(module),
+      m_argv(argv),
+      m_envp(envp),
+      m_stdin_path(stdin_path),
+      m_stdout_path(stdout_path),
+      m_stderr_path(stderr_path),
+      m_working_dir(working_dir) { }
+
+ProcessMonitorOther::LaunchArgs::~LaunchArgs()
+{ }
+
+ProcessMonitorOther::AttachArgs::AttachArgs(ProcessMonitorOther *monitor,
+                                       lldb::pid_t pid)
+    : OperationArgs(monitor), m_pid(pid) { }
+
+ProcessMonitorOther::AttachArgs::~AttachArgs()
+{ }
+
+//------------------------------------------------------------------------------
+/// The basic design of the ProcessMonitorOther is built around two threads.
+///
+/// One thread (@see SignalThread) simply blocks on a call to waitpid() looking
+/// for changes in the debugee state.  When a change is detected a
+/// ProcessMessage is sent to the associated ProcessLinux instance.  This thread
+/// "drives" state changes in the debugger.
+///
+/// The second thread (@see OperationThread) is responsible for two things 1)
+/// launching or attaching to the inferior process, and then 2) servicing
+/// operations such as register reads/writes, stepping, etc.  See the comments
+/// on the Operation class for more info as to why this is needed.
+ProcessMonitorOther::ProcessMonitorOther(ProcessPOSIX *process,
+                               Module *module,
+                               const char *argv[],
+                               const char *envp[],
+                               const char *stdin_path,
+                               const char *stdout_path,
+                               const char *stderr_path,
+                               const char *working_dir,
+                               lldb_private::Error &error)
+    : ProcessMonitor(),
+      m_process(static_cast<ProcessLinux *>(process)),
+      m_operation_thread(LLDB_INVALID_HOST_THREAD),
+      m_monitor_thread(LLDB_INVALID_HOST_THREAD),
+      m_pid(LLDB_INVALID_PROCESS_ID),
+      m_terminal_fd(-1),
+      m_operation(0)
+{
+    std::unique_ptr<LaunchArgs> args(new LaunchArgs(this, module, argv, envp,
+                                     stdin_path, stdout_path, stderr_path,
+                                     working_dir));
+
+    sem_init(&m_operation_pending, 0, 0);
+    sem_init(&m_operation_done, 0, 0);
+
+    StartLaunchOpThread(args.get(), error);
+    if (!error.Success())
+        return;
+
+WAIT_AGAIN:
+    // Wait for the operation thread to initialize.
+    if (sem_wait(&args->m_semaphore))
+    {
+        if (errno == EINTR)
+            goto WAIT_AGAIN;
+        else
+        {
+            error.SetErrorToErrno();
+            return;
+        }
+    }
+
+    // Check that the launch was a success.
+    if (!args->m_error.Success())
+    {
+        StopOpThread();
+        error = args->m_error;
+        return;
+    }
+
+    // Finally, start monitoring the child process for change in state.
+    m_monitor_thread = Host::StartMonitoringChildProcess(
+        ProcessMonitorOther::MonitorCallback, this, GetPID(), true);
+    if (!IS_VALID_LLDB_HOST_THREAD(m_monitor_thread))
+    {
+        error.SetErrorToGenericError();
+        error.SetErrorString("Process launch failed.");
+        return;
+    }
+}
+
+ProcessMonitorOther::ProcessMonitorOther(ProcessPOSIX *process,
+                               lldb::pid_t pid,
+                               lldb_private::Error &error)
+  : ProcessMonitor(),
+      m_process(static_cast<ProcessLinux *>(process)),
+      m_operation_thread(LLDB_INVALID_HOST_THREAD),
+      m_monitor_thread(LLDB_INVALID_HOST_THREAD),
+      m_pid(LLDB_INVALID_PROCESS_ID),
+      m_terminal_fd(-1),
+      m_operation(0)
+{
+    sem_init(&m_operation_pending, 0, 0);
+    sem_init(&m_operation_done, 0, 0);
+
+    std::unique_ptr<AttachArgs> args(new AttachArgs(this, pid));
+
+    StartAttachOpThread(args.get(), error);
+    if (!error.Success())
+        return;
+
+WAIT_AGAIN:
+    // Wait for the operation thread to initialize.
+    if (sem_wait(&args->m_semaphore))
+    {
+        if (errno == EINTR)
+            goto WAIT_AGAIN;
+        else
+        {
+            error.SetErrorToErrno();
+            return;
+        }
+    }
+
+    // Check that the attach was a success.
+    if (!args->m_error.Success())
+    {
+        StopOpThread();
+        error = args->m_error;
+        return;
+    }
+
+    // Finally, start monitoring the child process for change in state.
+    m_monitor_thread = Host::StartMonitoringChildProcess(
+        ProcessMonitorOther::MonitorCallback, this, GetPID(), true);
+    if (!IS_VALID_LLDB_HOST_THREAD(m_monitor_thread))
+    {
+        error.SetErrorToGenericError();
+        error.SetErrorString("Process attach failed.");
+        return;
+    }
+}
+
+ProcessMonitorOther::~ProcessMonitorOther()
+{
+    StopMonitor();
+}
+
+//------------------------------------------------------------------------------
+// Thread setup and tear down.
+void
+ProcessMonitorOther::StartLaunchOpThread(LaunchArgs *args, Error &error)
+{
+    static const char *g_thread_name = "lldb.process.linux.operation";
+
+    if (IS_VALID_LLDB_HOST_THREAD(m_operation_thread))
+        return;
+
+    m_operation_thread =
+        Host::ThreadCreate(g_thread_name, LaunchOpThread, args, &error);
+}
+
+void *
+ProcessMonitorOther::LaunchOpThread(void *arg)
+{
+    LaunchArgs *args = static_cast<LaunchArgs*>(arg);
+
+    if (!Launch(args)) {
+        sem_post(&args->m_semaphore);
+        return NULL;
+    }
+
+    ServeOperation(args);
+    return NULL;
+}
+
+bool
+ProcessMonitorOther::Launch(LaunchArgs *args)
+{
+    ProcessMonitorOther *monitor = args->m_monitor;
+    ProcessLinux &process = monitor->GetProcess();
+    const char **argv = args->m_argv;
+    const char **envp = args->m_envp;
+    const char *stdin_path = args->m_stdin_path;
+    const char *stdout_path = args->m_stdout_path;
+    const char *stderr_path = args->m_stderr_path;
+    const char *working_dir = args->m_working_dir;
+
+    lldb_utility::PseudoTerminal terminal;
+    const size_t err_len = 1024;
+    char err_str[err_len];
+    lldb::pid_t pid;
+
+    lldb::ThreadSP inferior;
+    Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_PROCESS));
+
+    // Propagate the environment if one is not supplied.
+    if (envp == NULL || envp[0] == NULL)
+        envp = const_cast<const char **>(environ);
+
+    if ((pid = terminal.Fork(err_str, err_len)) == static_cast<lldb::pid_t>(-1))
+    {
+        args->m_error.SetErrorToGenericError();
+        args->m_error.SetErrorString("Process fork failed.");
+        goto FINISH;
+    }
+
+    // Recognized child exit status codes.
+    enum {
+        ePtraceFailed = 1,
+        eDupStdinFailed,
+        eDupStdoutFailed,
+        eDupStderrFailed,
+        eChdirFailed,
+        eExecFailed,
+        eSetGidFailed
+    };
+
+    // Child process.
+    if (pid == 0)
+    {
+        // Trace this process.
+        if (PTRACE(PTRACE_TRACEME, 0, NULL, NULL, 0) < 0)
+            exit(ePtraceFailed);
+
+        // Do not inherit setgid powers.
+        if (setgid(getgid()) != 0)
+            exit(eSetGidFailed);
+
+        // Let us have our own process group.
+        setpgid(0, 0);
+
+        // Dup file descriptors if needed.
+        //
+        // FIXME: If two or more of the paths are the same we needlessly open
+        // the same file multiple times.
+        if (stdin_path != NULL && stdin_path[0])
+            if (!DupDescriptor(stdin_path, STDIN_FILENO, O_RDONLY))
+                exit(eDupStdinFailed);
+
+        if (stdout_path != NULL && stdout_path[0])
+            if (!DupDescriptor(stdout_path, STDOUT_FILENO, O_WRONLY | O_CREAT))
+                exit(eDupStdoutFailed);
+
+        if (stderr_path != NULL && stderr_path[0])
+            if (!DupDescriptor(stderr_path, STDERR_FILENO, O_WRONLY | O_CREAT))
+                exit(eDupStderrFailed);
+
+        // Change working directory
+        if (working_dir != NULL && working_dir[0])
+          if (0 != ::chdir(working_dir))
+              exit(eChdirFailed);
+
+        // Execute.  We should never return.
+        execve(argv[0],
+               const_cast<char *const *>(argv),
+               const_cast<char *const *>(envp));
+        exit(eExecFailed);
+    }
+
+    // Wait for the child process to to trap on its call to execve.
+    lldb::pid_t wpid;
+    ::pid_t raw_pid;
+    int status;
+
+    raw_pid = waitpid(pid, &status, 0);
+    wpid = static_cast <lldb::pid_t> (raw_pid);
+    if (raw_pid < 0)
+    {
+        args->m_error.SetErrorToErrno();
+        goto FINISH;
+    }
+    else if (WIFEXITED(status))
+    {
+        // open, dup or execve likely failed for some reason.
+        args->m_error.SetErrorToGenericError();
+        switch (WEXITSTATUS(status))
+        {
+            case ePtraceFailed:
+                args->m_error.SetErrorString("Child ptrace failed.");
+                break;
+            case eDupStdinFailed:
+                args->m_error.SetErrorString("Child open stdin failed.");
+                break;
+            case eDupStdoutFailed:
+                args->m_error.SetErrorString("Child open stdout failed.");
+                break;
+            case eDupStderrFailed:
+                args->m_error.SetErrorString("Child open stderr failed.");
+                break;
+            case eChdirFailed:
+                args->m_error.SetErrorString("Child failed to set working directory.");
+                break;
+            case eExecFailed:
+                args->m_error.SetErrorString("Child exec failed.");
+                break;
+            case eSetGidFailed:
+                args->m_error.SetErrorString("Child setgid failed.");
+                break;
+            default:
+                args->m_error.SetErrorString("Child returned unknown exit status.");
+                break;
+        }
+        goto FINISH;
+    }
+    assert(WIFSTOPPED(status) && wpid == pid &&
+           "Could not sync with inferior process.");
+
+    if (!SetDefaultPtraceOpts(pid))
+    {
+        args->m_error.SetErrorToErrno();
+        goto FINISH;
+    }
+
+    // Release the master terminal descriptor and pass it off to the
+    // ProcessMonitorOther instance.  Similarly stash the inferior pid.
+    monitor->m_terminal_fd = terminal.ReleaseMasterFileDescriptor();
+    monitor->m_pid = pid;
+
+    // Set the terminal fd to be in non blocking mode (it simplifies the
+    // implementation of ProcessLinux::GetSTDOUT to have a non-blocking
+    // descriptor to read from).
+    if (!EnsureFDFlags(monitor->m_terminal_fd, O_NONBLOCK, args->m_error))
+        goto FINISH;
+
+    // Update the process thread list with this new thread.
+    // FIXME: should we be letting UpdateThreadList handle this?
+    // FIXME: by using pids instead of tids, we can only support one thread.
+    inferior.reset(process.CreateNewPOSIXThread(process, pid));
+
+    if (log)
+        log->Printf ("ProcessMonitorOther::%s() adding pid = %" PRIu64, __FUNCTION__, pid);
+    process.GetThreadList().AddThread(inferior);
+
+    process.AddThreadForInitialStopIfNeeded(pid);
+
+    // Let our process instance know the thread has stopped.
+    process.SendMessage(ProcessMessage::Trace(pid));
+
+FINISH:
+    return args->m_error.Success();
+}
+
+void
+ProcessMonitorOther::StartAttachOpThread(AttachArgs *args, lldb_private::Error &error)
+{
+    static const char *g_thread_name = "lldb.process.linux.operation";
+
+    if (IS_VALID_LLDB_HOST_THREAD(m_operation_thread))
+        return;
+
+    m_operation_thread =
+        Host::ThreadCreate(g_thread_name, AttachOpThread, args, &error);
+}
+
+void *
+ProcessMonitorOther::AttachOpThread(void *arg)
+{
+    AttachArgs *args = static_cast<AttachArgs*>(arg);
+
+    if (!Attach(args)) {
+        sem_post(&args->m_semaphore);
+        return NULL;
+    }
+
+    ServeOperation(args);
+    return NULL;
+}
+
+bool
+ProcessMonitorOther::Attach(AttachArgs *args)
+{
+    lldb::pid_t pid = args->m_pid;
+
+    ProcessMonitorOther *monitor = args->m_monitor;
+    ProcessLinux &process = monitor->GetProcess();
+    lldb::ThreadSP inferior;
+    Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_PROCESS));
+
+    // Use a map to keep track of the threads which we have attached/need to attach.
+    Host::TidMap tids_to_attach;
+    if (pid <= 1)
+    {
+        args->m_error.SetErrorToGenericError();
+        args->m_error.SetErrorString("Attaching to process 1 is not allowed.");
+        goto FINISH;
+    }
+
+    while (Host::FindProcessThreads(pid, tids_to_attach))
+    {
+        for (Host::TidMap::iterator it = tids_to_attach.begin();
+             it != tids_to_attach.end(); ++it)
+        {
+            if (it->second == false)
+            {
+                lldb::tid_t tid = it->first;
+
+                // Attach to the requested process.
+                // An attach will cause the thread to stop with a SIGSTOP.
+                if (PTRACE(PTRACE_ATTACH, tid, NULL, NULL, 0) < 0)
+                {
+                    // No such thread. The thread may have exited.
+                    // More error handling may be needed.
+                    if (errno == ESRCH)
+                    {
+                        tids_to_attach.erase(it);
+                        continue;
+                    }
+                    else
+                    {
+                        args->m_error.SetErrorToErrno();
+                        goto FINISH;
+                    }
+                }
+
+                ::pid_t wpid;
+                // Need to use __WALL otherwise we receive an error with errno=ECHLD
+                // At this point we should have a thread stopped if waitpid succeeds.
+                if ((wpid = waitpid(tid, NULL, __WALL)) < 0)
+                {
+                    // No such thread. The thread may have exited.
+                    // More error handling may be needed.
+                    if (errno == ESRCH)
+                    {
+                        tids_to_attach.erase(it);
+                        continue;
+                    }
+                    else
+                    {
+                        args->m_error.SetErrorToErrno();
+                        goto FINISH;
+                    }
+                }
+
+                if (!SetDefaultPtraceOpts(tid))
+                {
+                    args->m_error.SetErrorToErrno();
+                    goto FINISH;
+                }
+
+                // Update the process thread list with the attached thread.
+                inferior.reset(process.CreateNewPOSIXThread(process, tid));
+
+                if (log)
+                    log->Printf ("ProcessMonitorOther::%s() adding tid = %" PRIu64, __FUNCTION__, tid);
+                process.GetThreadList().AddThread(inferior);
+                it->second = true;
+                process.AddThreadForInitialStopIfNeeded(tid);
+            }
+        }
+    }
+
+    if (tids_to_attach.size() > 0)
+    {
+        monitor->m_pid = pid;
+        // Let our process instance know the thread has stopped.
+        process.SendMessage(ProcessMessage::Trace(pid));
+    }
+    else
+    {
+        args->m_error.SetErrorToGenericError();
+        args->m_error.SetErrorString("No such process.");
+    }
+
+ FINISH:
+    return args->m_error.Success();
+}
+
+bool
+ProcessMonitorOther::SetDefaultPtraceOpts(lldb::pid_t pid)
+{
+    long ptrace_opts = 0;
+
+    // Have the child raise an event on exit.  This is used to keep the child in
+    // limbo until it is destroyed.
+    ptrace_opts |= PTRACE_O_TRACEEXIT;
+
+    // Have the tracer trace threads which spawn in the inferior process.
+    // TODO: if we want to support tracing the inferiors' child, add the
+    // appropriate ptrace flags here (PTRACE_O_TRACEFORK, PTRACE_O_TRACEVFORK)
+    ptrace_opts |= PTRACE_O_TRACECLONE;
+
+    // Have the tracer notify us before execve returns
+    // (needed to disable legacy SIGTRAP generation)
+    ptrace_opts |= PTRACE_O_TRACEEXEC;
+
+    return PTRACE(PTRACE_SETOPTIONS, pid, NULL, (void*)ptrace_opts, 0) >= 0;
+}
+
+bool
+ProcessMonitorOther::MonitorCallback(void *callback_baton,
+                                lldb::pid_t pid,
+                                bool exited,
+                                int signal,
+                                int status)
+{
+    ProcessMessage message;
+    ProcessMonitorOther *monitor = static_cast<ProcessMonitorOther*>(callback_baton);
+    ProcessLinux *process = monitor->m_process;
+    assert(process);
+    bool stop_monitoring;
+    siginfo_t info;
+    int ptrace_err;
+
+    Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_PROCESS));
+
+    if (exited)
+    {
+        if (log)
+            log->Printf ("ProcessMonitorOther::%s() got exit signal, tid = %"  PRIu64, __FUNCTION__, pid);
+        message = ProcessMessage::Exit(pid, status);
+        process->SendMessage(message);
+        return pid == process->GetID();
+    }
+
+    if (!monitor->GetSignalInfo(pid, &info, ptrace_err)) {
+        if (ptrace_err == EINVAL) {
+            if (log)
+                log->Printf ("ProcessMonitorOther::%s() resuming from group-stop", __FUNCTION__);
+            // inferior process is in 'group-stop', so deliver SIGSTOP signal
+            if (!monitor->Resume(pid, SIGSTOP)) {
+              assert(0 && "SIGSTOP delivery failed while in 'group-stop' state");
+            }
+            stop_monitoring = false;
+        } else {
+            // ptrace(GETSIGINFO) failed (but not due to group-stop). Most likely,
+            // this means the child pid is gone (or not being debugged) therefore
+            // stop the monitor thread if this is the main pid.
+            if (log)
+                log->Printf ("ProcessMonitorOther::%s() GetSignalInfo failed: %s, tid = %" PRIu64 ", signal = %d, status = %d", 
+                              __FUNCTION__, strerror(ptrace_err), pid, signal, status);
+            stop_monitoring = pid == monitor->m_process->GetID();
+            // If we are going to stop monitoring, we need to notify our process object
+            if (stop_monitoring)
+            {
+                message = ProcessMessage::Exit(pid, status);
+                process->SendMessage(message);
+            }
+        }
+    }
+    else {
+        switch (info.si_signo)
+        {
+        case SIGTRAP:
+            message = MonitorSIGTRAP(monitor, &info, pid);
+            break;
+
+        default:
+            message = MonitorSignal(monitor, &info, pid);
+            break;
+        }
+
+        process->SendMessage(message);
+        stop_monitoring = false;
+    }
+
+    return stop_monitoring;
+}
+
+ProcessMessage
+ProcessMonitorOther::MonitorSIGTRAP(ProcessMonitorOther *monitor,
+                               const siginfo_t *info, lldb::pid_t pid)
+{
+    ProcessMessage message;
+
+    Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_PROCESS));
+
+    assert(monitor);
+    assert(info && info->si_signo == SIGTRAP && "Unexpected child signal!");
+
+    switch (info->si_code)
+    {
+    default:
+        assert(false && "Unexpected SIGTRAP code!");
+        break;
+
+    // TODO: these two cases are required if we want to support tracing
+    // of the inferiors' children
+    // case (SIGTRAP | (PTRACE_EVENT_FORK << 8)):
+    // case (SIGTRAP | (PTRACE_EVENT_VFORK << 8)):
+
+    case (SIGTRAP | (PTRACE_EVENT_CLONE << 8)):
+    {
+        if (log)
+            log->Printf ("ProcessMonitorOther::%s() received thread creation event, code = %d", __FUNCTION__, info->si_code ^ SIGTRAP);
+
+        unsigned long tid = 0;
+        if (!monitor->GetEventMessage(pid, &tid))
+            tid = -1;
+        message = ProcessMessage::NewThread(pid, tid);
+        break;
+    }
+
+    case (SIGTRAP | (PTRACE_EVENT_EXEC << 8)):
+        if (log)
+            log->Printf ("ProcessMonitorOther::%s() received exec event, code = %d", __FUNCTION__, info->si_code ^ SIGTRAP);
+
+        message = ProcessMessage::Exec(pid);
+        break;
+
+    case (SIGTRAP | (PTRACE_EVENT_EXIT << 8)):
+    {
+        // The inferior process or one of its threads is about to exit.
+        // Maintain the process or thread in a state of "limbo" until we are
+        // explicitly commanded to detach, destroy, resume, etc.
+        unsigned long data = 0;
+        if (!monitor->GetEventMessage(pid, &data))
+            data = -1;
+        if (log)
+            log->Printf ("ProcessMonitorOther::%s() received limbo event, data = %lx, pid = %" PRIu64, __FUNCTION__, data, pid);
+        message = ProcessMessage::Limbo(pid, (data >> 8));
+        break;
+    }
+
+    case 0:
+    case TRAP_TRACE:
+        if (log)
+            log->Printf ("ProcessMonitorOther::%s() received trace event, pid = %" PRIu64, __FUNCTION__, pid);
+        message = ProcessMessage::Trace(pid);
+        break;
+
+    case SI_KERNEL:
+    case TRAP_BRKPT:
+        if (log)
+            log->Printf ("ProcessMonitorOther::%s() received breakpoint event, pid = %" PRIu64, __FUNCTION__, pid);
+        message = ProcessMessage::Break(pid);
+        break;
+
+    case TRAP_HWBKPT:
+        if (log)
+            log->Printf ("ProcessMonitorOther::%s() received watchpoint event, pid = %" PRIu64, __FUNCTION__, pid);
+        message = ProcessMessage::Watch(pid, (lldb::addr_t)info->si_addr);
+        break;
+
+    case SIGTRAP:
+    case (SIGTRAP | 0x80):
+        if (log)
+            log->Printf ("ProcessMonitorOther::%s() received system call stop event, pid = %" PRIu64, __FUNCTION__, pid);
+        // Ignore these signals until we know more about them
+        monitor->Resume(pid, eResumeSignalNone);
+    }
+
+    return message;
+}
+
+ProcessMessage
+ProcessMonitorOther::MonitorSignal(ProcessMonitorOther *monitor,
+                              const siginfo_t *info, lldb::pid_t pid)
+{
+    ProcessMessage message;
+    int signo = info->si_signo;
+
+    Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_PROCESS));
+
+    // POSIX says that process behaviour is undefined after it ignores a SIGFPE,
+    // SIGILL, SIGSEGV, or SIGBUS *unless* that signal was generated by a
+    // kill(2) or raise(3).  Similarly for tgkill(2) on Linux.
+    //
+    // IOW, user generated signals never generate what we consider to be a
+    // "crash".
+    //
+    // Similarly, ACK signals generated by this monitor.
+    if (info->si_code == SI_TKILL || info->si_code == SI_USER)
+    {
+        if (log)
+            log->Printf ("ProcessMonitorOther::%s() received signal %s with code %s, pid = %d",
+                            __FUNCTION__,
+                            monitor->m_process->GetUnixSignals().GetSignalAsCString (signo),
+                            (info->si_code == SI_TKILL ? "SI_TKILL" : "SI_USER"),
+                            info->si_pid);
+
+        if (info->si_pid == getpid())
+            return ProcessMessage::SignalDelivered(pid, signo);
+        else
+            return ProcessMessage::Signal(pid, signo);
+    }
+
+    if (log)
+        log->Printf ("ProcessMonitorOther::%s() received signal %s", __FUNCTION__, monitor->m_process->GetUnixSignals().GetSignalAsCString (signo));
+
+    if (signo == SIGSEGV) {
+        lldb::addr_t fault_addr = reinterpret_cast<lldb::addr_t>(info->si_addr);
+        ProcessMessage::CrashReason reason = GetCrashReasonForSIGSEGV(info);
+        return ProcessMessage::Crash(pid, reason, signo, fault_addr);
+    }
+
+    if (signo == SIGILL) {
+        lldb::addr_t fault_addr = reinterpret_cast<lldb::addr_t>(info->si_addr);
+        ProcessMessage::CrashReason reason = GetCrashReasonForSIGILL(info);
+        return ProcessMessage::Crash(pid, reason, signo, fault_addr);
+    }
+
+    if (signo == SIGFPE) {
+        lldb::addr_t fault_addr = reinterpret_cast<lldb::addr_t>(info->si_addr);
+        ProcessMessage::CrashReason reason = GetCrashReasonForSIGFPE(info);
+        return ProcessMessage::Crash(pid, reason, signo, fault_addr);
+    }
+
+    if (signo == SIGBUS) {
+        lldb::addr_t fault_addr = reinterpret_cast<lldb::addr_t>(info->si_addr);
+        ProcessMessage::CrashReason reason = GetCrashReasonForSIGBUS(info);
+        return ProcessMessage::Crash(pid, reason, signo, fault_addr);
+    }
+
+    // Everything else is "normal" and does not require any special action on
+    // our part.
+    return ProcessMessage::Signal(pid, signo);
+}
+
+// On Linux, when a new thread is created, we receive to notifications,
+// (1) a SIGTRAP|PTRACE_EVENT_CLONE from the main process thread with the
+// child thread id as additional information, and (2) a SIGSTOP|SI_USER from
+// the new child thread indicating that it has is stopped because we attached.
+// We have no guarantee of the order in which these arrive, but we need both
+// before we are ready to proceed.  We currently keep a list of threads which
+// have sent the initial SIGSTOP|SI_USER event.  Then when we receive the
+// SIGTRAP|PTRACE_EVENT_CLONE notification, if the initial stop has not occurred
+// we call ProcessMonitorOther::WaitForInitialTIDStop() to wait for it.
+
+bool
+ProcessMonitorOther::WaitForInitialTIDStop(lldb::tid_t tid)
+{
+    Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_PROCESS));
+    if (log)
+        log->Printf ("ProcessMonitorOther::%s(%" PRIu64 ") waiting for thread to stop...", __FUNCTION__, tid);
+
+    // Wait for the thread to stop
+    while (true)
+    {
+        int status = -1;
+        if (log)
+            log->Printf ("ProcessMonitorOther::%s(%" PRIu64 ") waitpid...", __FUNCTION__, tid);
+        ::pid_t wait_pid = waitpid(tid, &status, __WALL);
+        if (status == -1)
+        {
+            // If we got interrupted by a signal (in our process, not the
+            // inferior) try again.
+            if (errno == EINTR)
+                continue;
+            else
+            {
+                if (log)
+                    log->Printf("ProcessMonitorOther::%s(%" PRIu64 ") waitpid error -- %s", __FUNCTION__, tid, strerror(errno));
+                return false; // This is bad, but there's nothing we can do.
+            }
+        }
+
+        if (log)
+            log->Printf ("ProcessMonitorOther::%s(%" PRIu64 ") waitpid, status = %d", __FUNCTION__, tid, status);
+
+        assert(static_cast<lldb::tid_t>(wait_pid) == tid);
+
+        siginfo_t info;
+        int ptrace_err;
+        if (!GetSignalInfo(wait_pid, &info, ptrace_err))
+        {
+            if (log)
+            {
+                log->Printf ("ProcessMonitorOther::%s() GetSignalInfo failed. errno=%d (%s)", __FUNCTION__, ptrace_err, strerror(ptrace_err));
+            }
+            return false;
+        }
+
+        // If this is a thread exit, we won't get any more information.
+        if (WIFEXITED(status))
+        {
+            m_process->SendMessage(ProcessMessage::Exit(wait_pid, WEXITSTATUS(status)));
+            if (static_cast<lldb::tid_t>(wait_pid) == tid)
+                return true;
+            continue;
+        }
+
+        assert(info.si_code == SI_USER);
+        assert(WSTOPSIG(status) == SIGSTOP);
+
+        if (log)
+            log->Printf ("ProcessMonitorOther::%s(bp) received thread stop signal", __FUNCTION__);
+        m_process->AddThreadForInitialStopIfNeeded(wait_pid);
+        return true;
+    }
+    return false;
+}
+
+bool
+ProcessMonitorOther::StopThread(lldb::tid_t tid)
+{
+    Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_PROCESS));
+
+    // FIXME: Try to use tgkill or tkill
+    int ret = tgkill(m_pid, tid, SIGSTOP);
+    if (log)
+        log->Printf ("ProcessMonitorOther::%s(bp) stopping thread, tid = %" PRIu64 ", ret = %d", __FUNCTION__, tid, ret);
+
+    // This can happen if a thread exited while we were trying to stop it.  That's OK.
+    // We'll get the signal for that later.
+    if (ret < 0)
+        return false;
+
+    // Wait for the thread to stop
+    while (true)
+    {
+        int status = -1;
+        if (log)
+            log->Printf ("ProcessMonitorOther::%s(bp) waitpid...", __FUNCTION__);
+        ::pid_t wait_pid = ::waitpid (-1*getpgid(m_pid), &status, __WALL);
+        if (log)
+            log->Printf ("ProcessMonitorOther::%s(bp) waitpid, pid = %" PRIu64 ", status = %d",
+                         __FUNCTION__, static_cast<lldb::pid_t>(wait_pid), status);
+
+        if (wait_pid == -1)
+        {
+            // If we got interrupted by a signal (in our process, not the
+            // inferior) try again.
+            if (errno == EINTR)
+                continue;
+            else
+                return false; // This is bad, but there's nothing we can do.
+        }
+
+        // If this is a thread exit, we won't get any more information.
+        if (WIFEXITED(status))
+        {
+            m_process->SendMessage(ProcessMessage::Exit(wait_pid, WEXITSTATUS(status)));
+            if (static_cast<lldb::tid_t>(wait_pid) == tid)
+                return true;
+            continue;
+        }
+
+        siginfo_t info;
+        int ptrace_err;
+        if (!GetSignalInfo(wait_pid, &info, ptrace_err))
+        {
+            // another signal causing a StopAllThreads may have been received
+            // before wait_pid's group-stop was processed, handle it now
+            if (ptrace_err == EINVAL)
+            {
+                assert(WIFSTOPPED(status) && WSTOPSIG(status) == SIGSTOP);
+
+                if (log)
+                  log->Printf ("ProcessMonitorOther::%s() resuming from group-stop", __FUNCTION__);
+                // inferior process is in 'group-stop', so deliver SIGSTOP signal
+                if (!Resume(wait_pid, SIGSTOP)) {
+                  assert(0 && "SIGSTOP delivery failed while in 'group-stop' state");
+                }
+                continue;
+            }
+
+            if (log)
+                log->Printf ("ProcessMonitorOther::%s() GetSignalInfo failed.", __FUNCTION__);
+            return false;
+        }
+
+        // Handle events from other threads
+        if (log)
+            log->Printf ("ProcessMonitorOther::%s(bp) handling event, tid == %" PRIu64,
+                         __FUNCTION__, static_cast<lldb::tid_t>(wait_pid));
+
+        ProcessMessage message;
+        if (info.si_signo == SIGTRAP)
+            message = MonitorSIGTRAP(this, &info, wait_pid);
+        else
+            message = MonitorSignal(this, &info, wait_pid);
+
+        POSIXThread *thread = static_cast<POSIXThread*>(m_process->GetThreadList().FindThreadByID(wait_pid).get());
+
+        // When a new thread is created, we may get a SIGSTOP for the new thread
+        // just before we get the SIGTRAP that we use to add the thread to our
+        // process thread list.  We don't need to worry about that signal here.
+        assert(thread || message.GetKind() == ProcessMessage::eSignalMessage);
+
+        if (!thread)
+        {
+            m_process->SendMessage(message);
+            continue;
+        }
+
+        switch (message.GetKind())
+        {
+            case ProcessMessage::eExecMessage:
+                llvm_unreachable("unexpected message");
+            case ProcessMessage::eAttachMessage:
+            case ProcessMessage::eInvalidMessage:
+                break;
+
+            // These need special handling because we don't want to send a
+            // resume even if we already sent a SIGSTOP to this thread. In
+            // this case the resume will cause the thread to disappear.  It is
+            // unlikely that we'll ever get eExitMessage here, but the same
+            // reasoning applies.
+            case ProcessMessage::eLimboMessage:
+            case ProcessMessage::eExitMessage:
+                if (log)
+                    log->Printf ("ProcessMonitorOther::%s(bp) handling message", __FUNCTION__);
+                // SendMessage will set the thread state as needed.
+                m_process->SendMessage(message);
+                // If this is the thread we're waiting for, stop waiting. Even
+                // though this wasn't the signal we expected, it's the last
+                // signal we'll see while this thread is alive.
+                if (static_cast<lldb::tid_t>(wait_pid) == tid)
+                    return true;
+                break;
+
+            case ProcessMessage::eSignalMessage:
+                if (log)
+                    log->Printf ("ProcessMonitorOther::%s(bp) handling message", __FUNCTION__);
+                if (WSTOPSIG(status) == SIGSTOP)
+                {
+                    m_process->AddThreadForInitialStopIfNeeded(tid);
+                    thread->SetState(lldb::eStateStopped);
+                }
+                else
+                {
+                    m_process->SendMessage(message);
+                    // This isn't the stop we were expecting, but the thread is
+                    // stopped. SendMessage will handle processing of this event,
+                    // but we need to resume here to get the stop we are waiting
+                    // for (otherwise the thread will stop again immediately when
+                    // we try to resume).
+                    if (static_cast<lldb::tid_t>(wait_pid) == tid)
+                        Resume(wait_pid, eResumeSignalNone);
+                }
+                break;
+
+            case ProcessMessage::eSignalDeliveredMessage:
+                // This is the stop we're expecting.
+                if (static_cast<lldb::tid_t>(wait_pid) == tid &&
+                    WIFSTOPPED(status) &&
+                    WSTOPSIG(status) == SIGSTOP &&
+                    info.si_code == SI_TKILL)
+                {
+                    if (log)
+                        log->Printf ("ProcessMonitorOther::%s(bp) received signal, done waiting", __FUNCTION__);
+                    thread->SetState(lldb::eStateStopped);
+                    return true;
+                }
+                // else fall-through
+            case ProcessMessage::eBreakpointMessage:
+            case ProcessMessage::eTraceMessage:
+            case ProcessMessage::eWatchpointMessage:
+            case ProcessMessage::eCrashMessage:
+            case ProcessMessage::eNewThreadMessage:
+                if (log)
+                    log->Printf ("ProcessMonitorOther::%s(bp) handling message", __FUNCTION__);
+                // SendMessage will set the thread state as needed.
+                m_process->SendMessage(message);
+                // This isn't the stop we were expecting, but the thread is
+                // stopped. SendMessage will handle processing of this event,
+                // but we need to resume here to get the stop we are waiting
+                // for (otherwise the thread will stop again immediately when
+                // we try to resume).
+                if (static_cast<lldb::tid_t>(wait_pid) == tid)
+                    Resume(wait_pid, eResumeSignalNone);
+                break;
+        }
+    }
+    return false;
+}
+
+ProcessMessage::CrashReason
+ProcessMonitorOther::GetCrashReasonForSIGSEGV(const siginfo_t *info)
+{
+    ProcessMessage::CrashReason reason;
+    assert(info->si_signo == SIGSEGV);
+
+    reason = ProcessMessage::eInvalidCrashReason;
+
+    switch (info->si_code)
+    {
+    default:
+        assert(false && "unexpected si_code for SIGSEGV");
+        break;
+    case SI_KERNEL:
+        // Linux will occasionally send spurious SI_KERNEL codes.
+        // (this is poorly documented in sigaction)
+        // One way to get this is via unaligned SIMD loads.
+        reason = ProcessMessage::eInvalidAddress; // for lack of anything better
+        break;
+    case SEGV_MAPERR:
+        reason = ProcessMessage::eInvalidAddress;
+        break;
+    case SEGV_ACCERR:
+        reason = ProcessMessage::ePrivilegedAddress;
+        break;
+    }
+
+    return reason;
+}
+
+ProcessMessage::CrashReason
+ProcessMonitorOther::GetCrashReasonForSIGILL(const siginfo_t *info)
+{
+    ProcessMessage::CrashReason reason;
+    assert(info->si_signo == SIGILL);
+
+    reason = ProcessMessage::eInvalidCrashReason;
+
+    switch (info->si_code)
+    {
+    default:
+        assert(false && "unexpected si_code for SIGILL");
+        break;
+    case ILL_ILLOPC:
+        reason = ProcessMessage::eIllegalOpcode;
+        break;
+    case ILL_ILLOPN:
+        reason = ProcessMessage::eIllegalOperand;
+        break;
+    case ILL_ILLADR:
+        reason = ProcessMessage::eIllegalAddressingMode;
+        break;
+    case ILL_ILLTRP:
+        reason = ProcessMessage::eIllegalTrap;
+        break;
+    case ILL_PRVOPC:
+        reason = ProcessMessage::ePrivilegedOpcode;
+        break;
+    case ILL_PRVREG:
+        reason = ProcessMessage::ePrivilegedRegister;
+        break;
+    case ILL_COPROC:
+        reason = ProcessMessage::eCoprocessorError;
+        break;
+    case ILL_BADSTK:
+        reason = ProcessMessage::eInternalStackError;
+        break;
+    }
+
+    return reason;
+}
+
+ProcessMessage::CrashReason
+ProcessMonitorOther::GetCrashReasonForSIGFPE(const siginfo_t *info)
+{
+    ProcessMessage::CrashReason reason;
+    assert(info->si_signo == SIGFPE);
+
+    reason = ProcessMessage::eInvalidCrashReason;
+
+    switch (info->si_code)
+    {
+    default:
+        assert(false && "unexpected si_code for SIGFPE");
+        break;
+    case FPE_INTDIV:
+        reason = ProcessMessage::eIntegerDivideByZero;
+        break;
+    case FPE_INTOVF:
+        reason = ProcessMessage::eIntegerOverflow;
+        break;
+    case FPE_FLTDIV:
+        reason = ProcessMessage::eFloatDivideByZero;
+        break;
+    case FPE_FLTOVF:
+        reason = ProcessMessage::eFloatOverflow;
+        break;
+    case FPE_FLTUND:
+        reason = ProcessMessage::eFloatUnderflow;
+        break;
+    case FPE_FLTRES:
+        reason = ProcessMessage::eFloatInexactResult;
+        break;
+    case FPE_FLTINV:
+        reason = ProcessMessage::eFloatInvalidOperation;
+        break;
+    case FPE_FLTSUB:
+        reason = ProcessMessage::eFloatSubscriptRange;
+        break;
+    }
+
+    return reason;
+}
+
+ProcessMessage::CrashReason
+ProcessMonitorOther::GetCrashReasonForSIGBUS(const siginfo_t *info)
+{
+    ProcessMessage::CrashReason reason;
+    assert(info->si_signo == SIGBUS);
+
+    reason = ProcessMessage::eInvalidCrashReason;
+
+    switch (info->si_code)
+    {
+    default:
+        assert(false && "unexpected si_code for SIGBUS");
+        break;
+    case BUS_ADRALN:
+        reason = ProcessMessage::eIllegalAlignment;
+        break;
+    case BUS_ADRERR:
+        reason = ProcessMessage::eIllegalAddress;
+        break;
+    case BUS_OBJERR:
+        reason = ProcessMessage::eHardwareError;
+        break;
+    }
+
+    return reason;
+}
+
+void
+ProcessMonitorOther::ServeOperation(OperationArgs *args)
+{
+    ProcessMonitorOther *monitor = args->m_monitor;
+
+    // We are finised with the arguments and are ready to go.  Sync with the
+    // parent thread and start serving operations on the inferior.
+    sem_post(&args->m_semaphore);
+
+    for(;;)
+    {
+        // wait for next pending operation
+        if (sem_wait(&monitor->m_operation_pending))
+        {
+            if (errno == EINTR)
+                continue;
+            assert(false && "Unexpected errno from sem_wait");
+        }
+
+        monitor->m_operation->Execute(monitor);
+
+        // notify calling thread that operation is complete
+        sem_post(&monitor->m_operation_done);
+    }
+}
+
+void
+ProcessMonitorOther::DoOperation(Operation *op)
+{
+    Mutex::Locker lock(m_operation_mutex);
+
+    m_operation = op;
+
+    // notify operation thread that an operation is ready to be processed
+    sem_post(&m_operation_pending);
+
+    // wait for operation to complete
+    while (sem_wait(&m_operation_done))
+    {
+        if (errno == EINTR)
+            continue;
+        assert(false && "Unexpected errno from sem_wait");
+    }
+}
+
+size_t
+ProcessMonitorOther::ReadMemory(lldb::addr_t vm_addr, void *buf, size_t size,
+                           Error &error)
+{
+    size_t result;
+    ReadOperation op(vm_addr, buf, size, error, result);
+    DoOperation(&op);
+    return result;
+}
+
+size_t
+ProcessMonitorOther::WriteMemory(lldb::addr_t vm_addr, const void *buf, size_t size,
+                            lldb_private::Error &error)
+{
+    size_t result;
+    WriteOperation op(vm_addr, buf, size, error, result);
+    DoOperation(&op);
+    return result;
+}
+
+bool
+ProcessMonitorOther::ReadRegisterValue(lldb::tid_t tid, unsigned offset, const char* reg_name,
+                                  unsigned size, RegisterValue &value)
+{
+    bool result;
+    ReadRegOperation op(tid, offset, reg_name, value, result);
+    DoOperation(&op);
+    return result;
+}
+
+bool
+ProcessMonitorOther::WriteRegisterValue(lldb::tid_t tid, unsigned offset,
+                                   const char* reg_name, const RegisterValue &value)
+{
+    bool result;
+    WriteRegOperation op(tid, offset, reg_name, value, result);
+    DoOperation(&op);
+    return result;
+}
+
+bool
+ProcessMonitorOther::ReadGPR(lldb::tid_t tid, void *buf, size_t buf_size)
+{
+    bool result;
+    ReadGPROperation op(tid, buf, buf_size, result);
+    DoOperation(&op);
+    return result;
+}
+
+bool
+ProcessMonitorOther::ReadFPR(lldb::tid_t tid, void *buf, size_t buf_size)
+{
+    bool result;
+    ReadFPROperation op(tid, buf, buf_size, result);
+    DoOperation(&op);
+    return result;
+}
+
+bool
+ProcessMonitorOther::ReadRegisterSet(lldb::tid_t tid, void *buf, size_t buf_size, unsigned int regset)
+{
+    bool result;
+    ReadRegisterSetOperation op(tid, buf, buf_size, regset, result);
+    DoOperation(&op);
+    return result;
+}
+
+bool
+ProcessMonitorOther::WriteGPR(lldb::tid_t tid, void *buf, size_t buf_size)
+{
+    bool result;
+    WriteGPROperation op(tid, buf, buf_size, result);
+    DoOperation(&op);
+    return result;
+}
+
+bool
+ProcessMonitorOther::WriteFPR(lldb::tid_t tid, void *buf, size_t buf_size)
+{
+    bool result;
+    WriteFPROperation op(tid, buf, buf_size, result);
+    DoOperation(&op);
+    return result;
+}
+
+bool
+ProcessMonitorOther::WriteRegisterSet(lldb::tid_t tid, void *buf, size_t buf_size, unsigned int regset)
+{
+    bool result;
+    WriteRegisterSetOperation op(tid, buf, buf_size, regset, result);
+    DoOperation(&op);
+    return result;
+}
+
+bool
+ProcessMonitorOther::ReadThreadPointer(lldb::tid_t tid, lldb::addr_t &value)
+{
+    bool result;
+    ReadThreadPointerOperation op(tid, &value, result);
+    DoOperation(&op);
+    return result;
+}
+
+bool
+ProcessMonitorOther::Resume(lldb::tid_t tid, uint32_t signo)
+{
+    bool result;
+    Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_PROCESS));
+
+    if (log)
+        log->Printf ("ProcessMonitorOther::%s() resuming thread = %"  PRIu64 " with signal %s", __FUNCTION__, tid,
+                                 m_process->GetUnixSignals().GetSignalAsCString (signo));
+    ResumeOperation op(tid, signo, result);
+    DoOperation(&op);
+    if (log)
+        log->Printf ("ProcessMonitorOther::%s() resuming result = %s", __FUNCTION__, result ? "true" : "false");
+    return result;
+}
+
+bool
+ProcessMonitorOther::SingleStep(lldb::tid_t tid, uint32_t signo)
+{
+    bool result;
+    SingleStepOperation op(tid, signo, result);
+    DoOperation(&op);
+    return result;
+}
+
+bool
+ProcessMonitorOther::Kill()
+{
+    return kill(GetPID(), SIGKILL) == 0;
+}
+
+bool
+ProcessMonitorOther::GetSignalInfo(lldb::tid_t tid, void *siginfo, int &ptrace_err)
+{
+    bool result;
+    SiginfoOperation op(tid, siginfo, result, ptrace_err);
+    DoOperation(&op);
+    return result;
+}
+
+bool
+ProcessMonitorOther::GetEventMessage(lldb::tid_t tid, unsigned long *message)
+{
+    bool result;
+    EventMessageOperation op(tid, message, result);
+    DoOperation(&op);
+    return result;
+}
+
+lldb_private::Error
+ProcessMonitorOther::Detach(lldb::tid_t tid)
+{
+    lldb_private::Error error;
+    if (tid != LLDB_INVALID_THREAD_ID)
+    {
+        DetachOperation op(tid, error);
+        DoOperation(&op);
+    }
+    return error;
+}
+
+bool
+ProcessMonitorOther::DupDescriptor(const char *path, int fd, int flags)
+{
+    int target_fd = open(path, flags, 0666);
+
+    if (target_fd == -1)
+        return false;
+
+    return (dup2(target_fd, fd) == -1) ? false : true;
+}
+
+void
+ProcessMonitorOther::StopMonitoringChildProcess()
+{
+    lldb::thread_result_t thread_result;
+
+    if (IS_VALID_LLDB_HOST_THREAD(m_monitor_thread))
+    {
+        Host::ThreadCancel(m_monitor_thread, NULL);
+        Host::ThreadJoin(m_monitor_thread, &thread_result, NULL);
+        m_monitor_thread = LLDB_INVALID_HOST_THREAD;
+    }
+}
+
+void
+ProcessMonitorOther::StopMonitor()
+{
+    StopMonitoringChildProcess();
+    StopOpThread();
+    sem_destroy(&m_operation_pending);
+    sem_destroy(&m_operation_done);
+
+    // Note: ProcessPOSIX passes the m_terminal_fd file descriptor to
+    // Process::SetSTDIOFileDescriptor, which in turn transfers ownership of
+    // the descriptor to a ConnectionFileDescriptor object.  Consequently
+    // even though still has the file descriptor, we shouldn't close it here.
+}
+
+void
+ProcessMonitorOther::StopOpThread()
+{
+    lldb::thread_result_t result;
+
+    if (!IS_VALID_LLDB_HOST_THREAD(m_operation_thread))
+        return;
+
+    Host::ThreadCancel(m_operation_thread, NULL);
+    Host::ThreadJoin(m_operation_thread, &result, NULL);
+    m_operation_thread = LLDB_INVALID_HOST_THREAD;
+}
diff --git a/source/Plugins/Process/Linux/ProcessMonitorOther.h b/source/Plugins/Process/Linux/ProcessMonitorOther.h
new file mode 100644
index 0000000..7a61cc2
--- /dev/null
+++ b/source/Plugins/Process/Linux/ProcessMonitorOther.h
@@ -0,0 +1,324 @@
+//===-- ProcessMonitorOther.h -------------------------------------- -*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef liblldb_ProcessMonitorOther_H_
+#define liblldb_ProcessMonitorOther_H_
+
+// C Includes
+#include <semaphore.h>
+#include <signal.h>
+
+// C++ Includes
+// Other libraries and framework includes
+#include "lldb/lldb-types.h"
+#include "lldb/Host/Mutex.h"
+
+#include "ProcessMonitor.h"
+
+namespace lldb_private
+{
+class Error;
+class Module;
+class Scalar;
+} // End lldb_private namespace.
+
+class ProcessLinux;
+class Operation;
+
+/// @class ProcessMonitorOther
+/// @brief Manages communication with the inferior (debugee) process.
+///
+/// Upon construction, this class prepares and launches an inferior process for
+/// debugging.
+///
+/// Changes in the inferior process state are propagated to the associated
+/// ProcessLinux instance by calling ProcessLinux::SendMessage with the
+/// appropriate ProcessMessage events.
+///
+/// A purposely minimal set of operations are provided to interrogate and change
+/// the inferior process state.
+class ProcessMonitorOther : public ProcessMonitor
+{
+public:
+
+    /// Launches an inferior process ready for debugging.  Forms the
+    /// implementation of Process::DoLaunch.
+    ProcessMonitorOther(ProcessPOSIX *process,
+                   lldb_private::Module *module,
+                   char const *argv[],
+                   char const *envp[],
+                   const char *stdin_path,
+                   const char *stdout_path,
+                   const char *stderr_path,
+                   const char *working_dir,
+                   lldb_private::Error &error);
+
+    ProcessMonitorOther(ProcessPOSIX *process,
+                   lldb::pid_t pid,
+                   lldb_private::Error &error);
+
+    ~ProcessMonitorOther();
+
+    enum ResumeSignals 
+    {
+        eResumeSignalNone = 0
+    };
+
+    /// Provides the process number of debugee.
+    virtual lldb::pid_t
+    GetPID() const { return m_pid; }
+
+    /// Returns the process associated with this ProcessMonitorOther.
+    ProcessLinux &
+    GetProcess() { return *m_process; }
+
+    /// Returns a file descriptor to the controlling terminal of the inferior
+    /// process.
+    ///
+    /// Reads from this file descriptor yield both the standard output and
+    /// standard error of this debugee.  Even if stderr and stdout were
+    /// redirected on launch it may still happen that data is available on this
+    /// descriptor (if the inferior process opens /dev/tty, for example).
+    ///
+    /// If this monitor was attached to an existing process this method returns
+    /// -1.
+    virtual int
+    GetTerminalFD() const { return m_terminal_fd; }
+
+    /// Reads @p size bytes from address @vm_adder in the inferior process
+    /// address space.
+    ///
+    /// This method is provided to implement Process::DoReadMemory.
+    size_t
+    ReadMemory(lldb::addr_t vm_addr, void *buf, size_t size,
+               lldb_private::Error &error);
+
+    /// Writes @p size bytes from address @p vm_adder in the inferior process
+    /// address space.
+    ///
+    /// This method is provided to implement Process::DoWriteMemory.
+    size_t
+    WriteMemory(lldb::addr_t vm_addr, const void *buf, size_t size,
+                lldb_private::Error &error);
+
+    /// Reads the contents from the register identified by the given (architecture
+    /// dependent) offset.
+    ///
+    /// This method is provided for use by RegisterContextLinux derivatives.
+    bool
+    ReadRegisterValue(lldb::tid_t tid, unsigned offset, const char *reg_name,
+                      unsigned size, lldb_private::RegisterValue &value);
+
+    /// Writes the given value to the register identified by the given
+    /// (architecture dependent) offset.
+    ///
+    /// This method is provided for use by RegisterContextLinux derivatives.
+    bool
+    WriteRegisterValue(lldb::tid_t tid, unsigned offset, const char *reg_name,
+                       const lldb_private::RegisterValue &value);
+
+    /// Reads all general purpose registers into the specified buffer.
+    bool
+    ReadGPR(lldb::tid_t tid, void *buf, size_t buf_size);
+
+    /// Reads generic floating point registers into the specified buffer.
+    bool
+    ReadFPR(lldb::tid_t tid, void *buf, size_t buf_size);
+
+    /// Reads the specified register set into the specified buffer.
+    /// For instance, the extended floating-point register set.
+    bool
+    ReadRegisterSet(lldb::tid_t tid, void *buf, size_t buf_size, unsigned int regset);
+
+    /// Writes all general purpose registers into the specified buffer.
+    bool
+    WriteGPR(lldb::tid_t tid, void *buf, size_t buf_size);
+
+    /// Writes generic floating point registers into the specified buffer.
+    bool
+    WriteFPR(lldb::tid_t tid, void *buf, size_t buf_size);
+
+    /// Writes the specified register set into the specified buffer.
+    /// For instance, the extended floating-point register set.
+    bool
+    WriteRegisterSet(lldb::tid_t tid, void *buf, size_t buf_size, unsigned int regset);
+
+    /// Reads the value of the thread-specific pointer for a given thread ID.
+    bool
+    ReadThreadPointer(lldb::tid_t tid, lldb::addr_t &value);
+
+    /// Writes a siginfo_t structure corresponding to the given thread ID to the
+    /// memory region pointed to by @p siginfo.
+    bool
+    GetSignalInfo(lldb::tid_t tid, void *siginfo, int &ptrace_err);
+
+    /// Writes the raw event message code (vis-a-vis PTRACE_GETEVENTMSG)
+    /// corresponding to the given thread IDto the memory pointed to by @p
+    /// message.
+    bool
+    GetEventMessage(lldb::tid_t tid, unsigned long *message);
+
+    /// Resumes the given thread.  If @p signo is anything but
+    /// LLDB_INVALID_SIGNAL_NUMBER, deliver that signal to the thread.
+    bool
+    Resume(lldb::tid_t tid, uint32_t signo);
+
+    /// Single steps the given thread.  If @p signo is anything but
+    /// LLDB_INVALID_SIGNAL_NUMBER, deliver that signal to the thread.
+    bool
+    SingleStep(lldb::tid_t tid, uint32_t signo);
+
+    /// Terminate the traced process.
+    bool
+    Kill();
+
+    lldb_private::Error
+    Detach(lldb::tid_t tid);
+
+    /// Stops the monitoring the child process thread.
+    void
+    StopMonitor();
+
+    /// Stops the requested thread and waits for the stop signal.
+    bool
+    StopThread(lldb::tid_t tid);
+
+    // Waits for the initial stop message from a new thread.
+    bool
+    WaitForInitialTIDStop(lldb::tid_t tid);
+
+private:
+    ProcessLinux *m_process;
+
+    lldb::thread_t m_operation_thread;
+    lldb::thread_t m_monitor_thread;
+    lldb::pid_t m_pid;
+    int m_terminal_fd;
+
+    // current operation which must be executed on the priviliged thread
+    Operation *m_operation;
+    lldb_private::Mutex m_operation_mutex;
+
+    // semaphores notified when Operation is ready to be processed and when
+    // the operation is complete.
+    sem_t m_operation_pending;
+    sem_t m_operation_done;
+
+
+    struct OperationArgs
+    {
+        OperationArgs(ProcessMonitorOther *monitor);
+
+        ~OperationArgs();
+
+        ProcessMonitorOther *m_monitor;      // The monitor performing the attach.
+        sem_t m_semaphore;              // Posted to once operation complete.
+        lldb_private::Error m_error;    // Set if process operation failed.
+    };
+
+    /// @class LauchArgs
+    ///
+    /// @brief Simple structure to pass data to the thread responsible for
+    /// launching a child process.
+    struct LaunchArgs : OperationArgs
+    {
+        LaunchArgs(ProcessMonitorOther *monitor,
+                   lldb_private::Module *module,
+                   char const **argv,
+                   char const **envp,
+                   const char *stdin_path,
+                   const char *stdout_path,
+                   const char *stderr_path,
+                   const char *working_dir);
+
+        ~LaunchArgs();
+
+        lldb_private::Module *m_module; // The executable image to launch.
+        char const **m_argv;            // Process arguments.
+        char const **m_envp;            // Process environment.
+        const char *m_stdin_path;       // Redirect stdin or NULL.
+        const char *m_stdout_path;      // Redirect stdout or NULL.
+        const char *m_stderr_path;      // Redirect stderr or NULL.
+        const char *m_working_dir;      // Working directory or NULL.
+    };
+
+    void
+    StartLaunchOpThread(LaunchArgs *args, lldb_private::Error &error);
+
+    static void *
+    LaunchOpThread(void *arg);
+
+    static bool
+    Launch(LaunchArgs *args);
+
+    struct AttachArgs : OperationArgs
+    {
+        AttachArgs(ProcessMonitorOther *monitor,
+                   lldb::pid_t pid);
+
+        ~AttachArgs();
+
+        lldb::pid_t m_pid;              // pid of the process to be attached.
+    };
+
+    void
+    StartAttachOpThread(AttachArgs *args, lldb_private::Error &error);
+
+    static void *
+    AttachOpThread(void *args);
+
+    static bool
+    Attach(AttachArgs *args);
+
+    static bool
+    SetDefaultPtraceOpts(const lldb::pid_t);
+
+    static void
+    ServeOperation(OperationArgs *args);
+
+    static bool
+    DupDescriptor(const char *path, int fd, int flags);
+
+    static bool
+    MonitorCallback(void *callback_baton,
+                    lldb::pid_t pid, bool exited, int signal, int status);
+
+    static ProcessMessage
+    MonitorSIGTRAP(ProcessMonitorOther *monitor,
+                   const siginfo_t *info, lldb::pid_t pid);
+
+    static ProcessMessage
+    MonitorSignal(ProcessMonitorOther *monitor, 
+                  const siginfo_t *info, lldb::pid_t pid);
+
+    static ProcessMessage::CrashReason
+    GetCrashReasonForSIGSEGV(const siginfo_t *info);
+
+    static ProcessMessage::CrashReason
+    GetCrashReasonForSIGILL(const siginfo_t *info);
+
+    static ProcessMessage::CrashReason
+    GetCrashReasonForSIGFPE(const siginfo_t *info);
+
+    static ProcessMessage::CrashReason
+    GetCrashReasonForSIGBUS(const siginfo_t *info);
+
+    void
+    DoOperation(Operation *op);
+
+    /// Stops the child monitor thread.
+    void
+    StopMonitoringChildProcess();
+
+    /// Stops the operation thread used to attach/launch a process.
+    void
+    StopOpThread();
+};
+
+#endif // #ifndef liblldb_ProcessMonitorOther_H_
diff --git a/source/Plugins/Process/POSIX/ProcessPOSIX.cpp b/source/Plugins/Process/POSIX/ProcessPOSIX.cpp
index 031405a..8333f01 100644
--- a/source/Plugins/Process/POSIX/ProcessPOSIX.cpp
+++ b/source/Plugins/Process/POSIX/ProcessPOSIX.cpp
@@ -29,6 +29,7 @@
 #include "ProcessPOSIXLog.h"
 #include "Plugins/Process/Utility/InferiorCallPOSIX.h"
 #include "ProcessMonitor.h"
+#include "ProcessMonitorOther.h"
 #include "POSIXThread.h"
 
 using namespace lldb;
@@ -123,7 +124,7 @@ ProcessPOSIX::DoAttachToProcessWithID(lldb::pid_t pid)
     if (log && log->GetMask().Test(POSIX_LOG_VERBOSE))
         log->Printf ("ProcessPOSIX::%s(pid = %" PRIi64 ")", __FUNCTION__, GetID());
 
-    m_monitor = new ProcessMonitor(this, pid, error);
+    m_monitor = new ProcessMonitorOther(this, pid, error);
 
     if (!error.Success())
         return error;
@@ -235,7 +236,7 @@ ProcessPOSIX::DoLaunch (Module *module,
     file_action = launch_info.GetFileActionForFD (STDERR_FILENO);
     stderr_path = GetFilePath(file_action, stderr_path);
 
-    m_monitor = new ProcessMonitor (this, 
+    m_monitor = new ProcessMonitorOther (this, 
                                     module,
                                     launch_info.GetArguments().GetConstArgumentVector(), 
                                     launch_info.GetEnvironmentEntries().GetConstArgumentVector(),
-- 
2.1.0.rc2.206.gedb03e5




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