[Lldb-commits] [lldb] [lldb][AIX] Added base files for NativeProcess Support for AIX (PR #118160)

[David Spickett via lldb-commits]

================
@@ -0,0 +1,265 @@
+//===-- NativeProcessAIX.cpp --------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "NativeProcessAIX.h"
+#include "lldb/Host/Host.h"
+#include "lldb/Host/HostProcess.h"
+#include "lldb/Host/ProcessLaunchInfo.h"
+#include "lldb/Symbol/ObjectFile.h"
+#include "lldb/Utility/Log.h"
+#include "lldb/Utility/State.h"
+#include "lldb/Utility/Status.h"
+#include "llvm/Support/Errno.h"
+#include "llvm/Support/Error.h"
+#include <cerrno>
+#include <cstdint>
+#include <cstring>
+#include <sstream>
+#include <string>
+#include <unistd.h>
+
+using namespace lldb;
+using namespace lldb_private;
+using namespace lldb_private::process_aix;
+using namespace llvm;
+
+static constexpr unsigned k_ptrace_word_size = sizeof(void *);
+static_assert(sizeof(long) >= k_ptrace_word_size,
+              "Size of long must be larger than ptrace word size");
+
+// Simple helper function to ensure flags are enabled on the given file
+// descriptor.
+static llvm::Error EnsureFDFlags(int fd, int flags) {
+  Error error;
+
+  int status = fcntl(fd, F_GETFL);
+  if (status == -1) {
+    error = errorCodeToError(errnoAsErrorCode());
+    return error;
+  }
+
+  if (fcntl(fd, F_SETFL, status | flags) == -1) {
+    error = errorCodeToError(errnoAsErrorCode());
+    return error;
+  }
+
+  return error;
+}
+
+NativeProcessAIX::Manager::Manager(MainLoop &mainloop)
+    : NativeProcessProtocol::Manager(mainloop) {
+  Status status;
+  m_sigchld_handle = mainloop.RegisterSignal(
+      SIGCHLD, [this](MainLoopBase &) { SigchldHandler(); }, status);
+  assert(m_sigchld_handle && status.Success());
+}
+
+// Public Static Methods
+
+llvm::Expected<std::unique_ptr<NativeProcessProtocol>>
+NativeProcessAIX::Manager::Launch(ProcessLaunchInfo &launch_info,
+                                  NativeDelegate &native_delegate) {
+  Log *log = GetLog(POSIXLog::Process);
+
+  Status status;
+  ::pid_t pid = ProcessLauncherPosixFork()
+                    .LaunchProcess(launch_info, status)
+                    .GetProcessId();
+  LLDB_LOG(log, "pid = {0:x}", pid);
+  if (status.Fail()) {
+    LLDB_LOG(log, "failed to launch process: {0}", status);
+    return status.ToError();
+  }
+
+  // Wait for the child process to trap on its call to execve.
+  int wstatus = 0;
+  ::pid_t wpid = llvm::sys::RetryAfterSignal(-1, ::waitpid, pid, &wstatus, 0);
+  assert(wpid == pid);
+  UNUSED_IF_ASSERT_DISABLED(wpid);
+  if (!WIFSTOPPED(wstatus)) {
+    LLDB_LOG(log, "Could not sync with inferior process: wstatus={1}",
+             WaitStatus::Decode(wstatus));
+    return llvm::make_error<StringError>("Could not sync with inferior process",
+                                         llvm::inconvertibleErrorCode());
+  }
+  LLDB_LOG(log, "inferior started, now in stopped state");
+
+  ProcessInstanceInfo Info;
+  if (!Host::GetProcessInfo(pid, Info)) {
+    return llvm::make_error<StringError>("Cannot get process architectrue",
+                                         llvm::inconvertibleErrorCode());
+  }
+
+  // Set the architecture to the exe architecture.
+  LLDB_LOG(log, "pid = {0}, detected architecture {1}", pid,
+           Info.GetArchitecture().GetArchitectureName());
+
+  return std::unique_ptr<NativeProcessAIX>(new NativeProcessAIX(
+      pid, launch_info.GetPTY().ReleasePrimaryFileDescriptor(), native_delegate,
+      Info.GetArchitecture(), *this, {pid}));
+}
+
+llvm::Expected<std::unique_ptr<NativeProcessProtocol>>
+NativeProcessAIX::Manager::Attach(
+    lldb::pid_t pid, NativeProcessProtocol::NativeDelegate &native_delegate) {
+  Log *log = GetLog(POSIXLog::Process);
+  LLDB_LOG(log, "pid = {0:x}", pid);
+
+  ProcessInstanceInfo Info;
+  if (!Host::GetProcessInfo(pid, Info)) {
+    return llvm::make_error<StringError>("Cannot get process architectrue",
+                                         llvm::inconvertibleErrorCode());
+  }
+  auto tids_or = NativeProcessAIX::Attach(pid);
+  if (!tids_or)
+    return tids_or.takeError();
+
+  return std::unique_ptr<NativeProcessAIX>(new NativeProcessAIX(
+      pid, -1, native_delegate, Info.GetArchitecture(), *this, *tids_or));
+}
+
+NativeProcessAIX::Extension
+NativeProcessAIX::Manager::GetSupportedExtensions() const {
+  NativeProcessAIX::Extension supported = {};
+
+  return supported;
+}
+
+void NativeProcessAIX::Manager::SigchldHandler() {}
+
+void NativeProcessAIX::Manager::CollectThread(::pid_t tid) {}
+
+// Public Instance Methods
+
+NativeProcessAIX::NativeProcessAIX(::pid_t pid, int terminal_fd,
+                                   NativeDelegate &delegate,
+                                   const ArchSpec &arch, Manager &manager,
+                                   llvm::ArrayRef<::pid_t> tids)
+    : NativeProcessProtocol(pid, terminal_fd, delegate), m_manager(manager),
+      m_arch(arch) {
+  manager.AddProcess(*this);
+  if (m_terminal_fd != -1) {
+    Status status = EnsureFDFlags(m_terminal_fd, O_NONBLOCK);
+    assert(status.Success());
+  }
+
+  // Let our process instance know the thread has stopped.
+  SetCurrentThreadID(tids[0]);
+  SetState(StateType::eStateStopped, false);
+}
+
+llvm::Expected<std::vector<::pid_t>> NativeProcessAIX::Attach(::pid_t pid) {
+
+  Error status;
+  if ((status = PtraceWrapper(PT_ATTACH, pid)).Fail()) {
+    return errorCodeToError(errnoAsErrorCode());
+  }
+
+  int wpid = llvm::sys::RetryAfterSignal(-1, ::waitpid, pid, nullptr, WNOHANG);
+  if (wpid <= 0) {
+    return llvm::errorCodeToError(
+        std::error_code(errno, std::generic_category()));
+  }
+  LLDB_LOG(log, "adding pid = {0}", pid);
+
+  std::vector<::pid_t> tids;
+  tids.push_back(pid);
+  return std::move(tids);
+}
+
+void NativeProcessAIX::MonitorSIGTRAP(const WaitStatus status,
+                                      NativeThreadAIX &thread) {}
+
+void NativeProcessAIX::MonitorBreakpoint(NativeThreadAIX &thread) {}
+
+bool NativeProcessAIX::SupportHardwareSingleStepping() const { return false; }
+
+Status NativeProcessAIX::Resume(const ResumeActionList &resume_actions) {
+  return Status();
+}
+
+Error NativeProcessAIX::Halt() {
+  Error error;
+  return error;
+}
+
+Error NativeProcessAIX::Detach() {
+  Error error;
+  return error;
+}
+
+Error NativeProcessAIX::Signal(int signo) {
+  Error error;
+  return error;
+}
+
+Error NativeProcessAIX::Interrupt() { return Status(); }
+
+Error NativeProcessAIX::Kill() {
+  Error error;
+  return error;
+}
+
+Error NativeProcessAIX::SetBreakpoint(lldb::addr_t addr, uint32_t size,
+                                      bool hardware) {
+  if (hardware)
+    return SetHardwareBreakpoint(addr, size);
+  else
+    return SetSoftwareBreakpoint(addr, size);
+}
+
+Error NativeProcessAIX::RemoveBreakpoint(lldb::addr_t addr, bool hardware) {
+  if (hardware)
+    return RemoveHardwareBreakpoint(addr);
+  else
+    return NativeProcessProtocol::RemoveBreakpoint(addr);
+}
+
+int8_t NativeProcessAIX::GetSignalInfo(WaitStatus wstatus) const {
+  return wstatus.status;
+}
+
+Error NativeProcessAIX::Detach(lldb::tid_t tid) {
+  if (tid == LLDB_INVALID_THREAD_ID)
+    return Status();
+
+  return PtraceWrapper(PT_DETACH, tid);
+}
+
+// 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*)
+Error NativeProcessAIX::PtraceWrapper(int req, lldb::pid_t pid, void *addr,
+                                      void *data, size_t data_size,
+                                      long *result) {
+  Error error;
+  long int ret;
+
+  Log *log = GetLog(POSIXLog::Ptrace);
+  errno = 0;
+  if (req < PT_COMMAND_MAX) {
+    if (req == PT_ATTACH) {
+      ptrace64(req, pid, 0, 0, nullptr);
+    } else if (req == PT_DETACH) {
+      ptrace64(req, pid, 0, 0, nullptr);
+    }
+  } else {
+    assert(0 && "Not supported yet.");
+  }
----------------
DavidSpickett wrote:

On the subject of removing braces, I would write this as:
```
  if (req < PT_COMMAND_MAX) {
    if (req == PT_ATTACH)
      ptrace64(req, pid, 0, 0, nullptr);
    else if (req == PT_DETACH)
      ptrace64(req, pid, 0, 0, nullptr);
  } else
    assert(0 && "Not supported yet.");
```
But, I think you are missing an else here. Perhaps you are going to expand this to recognise more PT_ constants later, and that's why it looks incomplete right now?

As far as I can tell right now it's:
```
switch (req) {
  case PT_ATTACH:
  case PT_DETATCH:
    ptrace64(req, pid, 0, 0, nullptr);
    break;
  default:
    assert(0 && "PT_ request not supported yet.");
}
```
But if that's not going to scale as you add more PT_ values, I suppose we can take this as is knowing that it will make sense later.

https://github.com/llvm/llvm-project/pull/118160