[Lldb-commits] [lldb] r149280 - in /lldb/trunk: source/Breakpoint/Watchpoint.cpp source/Commands/CommandObjectWatchpoint.cpp source/Commands/CommandObjectWatchpoint.h test/functionalities/watchpoint/hello_watchpoint/TestMyFirstWatchpoint.py test/functionalities/watchpoint/watchpoint_set_command/ test/functionalities/watchpoint/watchpoint_set_command/Makefile test/functionalities/watchpoint/watchpoint_set_command/TestWatchLocationWithWatchSet.py test/functionalities/watchpoint/watchpoint_set_command/main.cpp
Johnny Chen
johnny.chen at apple.com
Mon Jan 30 13:46:17 PST 2012
Author: johnny
Date: Mon Jan 30 15:46:17 2012
New Revision: 149280
URL: http://llvm.org/viewvc/llvm-project?rev=149280&view=rev
Log:
Add "watch set" command as a more general interface in conjunction with "frame var -w".
Also add test cases for watching a variable as well as a location expressed as an expression.
o TestMyFirstWatchpoint.py:
Modified to test "watchpoint set -w write global".
o TestWatchLocationWithWatchSet.py:
Added to test "watchpoint set -w write -x 1 g_char_ptr + 7" where a contrived example program
with several threads is supposed to only access the array index within the range [0..6], but
there's some misbehaving thread writing past the range.
rdar://problem/10701761
Added:
lldb/trunk/test/functionalities/watchpoint/watchpoint_set_command/
lldb/trunk/test/functionalities/watchpoint/watchpoint_set_command/Makefile
lldb/trunk/test/functionalities/watchpoint/watchpoint_set_command/TestWatchLocationWithWatchSet.py
lldb/trunk/test/functionalities/watchpoint/watchpoint_set_command/main.cpp
Modified:
lldb/trunk/source/Breakpoint/Watchpoint.cpp
lldb/trunk/source/Commands/CommandObjectWatchpoint.cpp
lldb/trunk/source/Commands/CommandObjectWatchpoint.h
lldb/trunk/test/functionalities/watchpoint/hello_watchpoint/TestMyFirstWatchpoint.py
Modified: lldb/trunk/source/Breakpoint/Watchpoint.cpp
URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/source/Breakpoint/Watchpoint.cpp?rev=149280&r1=149279&r2=149280&view=diff
==============================================================================
--- lldb/trunk/source/Breakpoint/Watchpoint.cpp (original)
+++ lldb/trunk/source/Breakpoint/Watchpoint.cpp Mon Jan 30 15:46:17 2012
@@ -122,7 +122,7 @@
m_watch_write ? "w" : "");
if (description_level >= lldb::eDescriptionLevelFull) {
- if (m_decl_str.c_str())
+ if (!m_decl_str.empty())
s->Printf("\n declare @ '%s'", m_decl_str.c_str());
if (GetConditionText())
s->Printf("\n condition = '%s'", GetConditionText());
Modified: lldb/trunk/source/Commands/CommandObjectWatchpoint.cpp
URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/source/Commands/CommandObjectWatchpoint.cpp?rev=149280&r1=149279&r2=149280&view=diff
==============================================================================
--- lldb/trunk/source/Commands/CommandObjectWatchpoint.cpp (original)
+++ lldb/trunk/source/Commands/CommandObjectWatchpoint.cpp Mon Jan 30 15:46:17 2012
@@ -16,10 +16,14 @@
#include "lldb/Breakpoint/Watchpoint.h"
#include "lldb/Breakpoint/WatchpointList.h"
#include "lldb/Core/StreamString.h"
+#include "lldb/Core/ValueObject.h"
+#include "lldb/Core/ValueObjectVariable.h"
#include "lldb/Interpreter/CommandInterpreter.h"
#include "lldb/Interpreter/CommandReturnObject.h"
-#include "lldb/Target/Target.h"
#include "lldb/Interpreter/CommandCompletions.h"
+#include "lldb/Symbol/Variable.h"
+#include "lldb/Symbol/VariableList.h"
+#include "lldb/Target/Target.h"
#include <vector>
@@ -157,6 +161,7 @@
CommandObjectSP delete_command_object (new CommandObjectWatchpointDelete (interpreter));
CommandObjectSP ignore_command_object (new CommandObjectWatchpointIgnore (interpreter));
CommandObjectSP modify_command_object (new CommandObjectWatchpointModify (interpreter));
+ CommandObjectSP set_command_object (new CommandObjectWatchpointSet (interpreter));
list_command_object->SetCommandName ("watchpoint list");
enable_command_object->SetCommandName("watchpoint enable");
@@ -164,6 +169,7 @@
delete_command_object->SetCommandName("watchpoint delete");
ignore_command_object->SetCommandName("watchpoint ignore");
modify_command_object->SetCommandName("watchpoint modify");
+ set_command_object->SetCommandName("watchpoint set");
status = LoadSubCommand ("list", list_command_object);
status = LoadSubCommand ("enable", enable_command_object);
@@ -171,6 +177,7 @@
status = LoadSubCommand ("delete", delete_command_object);
status = LoadSubCommand ("ignore", ignore_command_object);
status = LoadSubCommand ("modify", modify_command_object);
+ status = LoadSubCommand ("set", set_command_object);
}
CommandObjectMultiwordWatchpoint::~CommandObjectMultiwordWatchpoint()
@@ -844,3 +851,202 @@
return result.Succeeded();
}
+
+//-------------------------------------------------------------------------
+// CommandObjectWatchpointSet
+//-------------------------------------------------------------------------
+#pragma mark Set
+
+CommandObjectWatchpointSet::CommandObjectWatchpointSet (CommandInterpreter &interpreter) :
+ CommandObject (interpreter,
+ "watchpoint set",
+ "Set a watchpoint. "
+ "You can choose to watch a variable in scope with just the '-w' option. "
+ "If you use the '-x' option to specify the byte size, it is implied "
+ "that the remaining string is evaluated as an expression with the result "
+ "interpreted as an address to watch for, i.e., the pointee is watched. "
+ "If no '-w' option is specified, it defaults to read_write. "
+ "Note that hardware resources for watching are often limited.",
+ NULL,
+ eFlagProcessMustBeLaunched | eFlagProcessMustBePaused),
+ m_option_group (interpreter),
+ m_option_watchpoint()
+{
+ SetHelpLong(
+"Examples: \n\
+\n\
+ watchpoint set -w read_wriate my_global_var \n\
+ # Watch my_global_var for read/write access.\n\
+\n\
+ watchpoint set -w write -x 1 foo + 32\n\
+ # Watch write access for the 1-byte region pointed to by the address 'foo + 32'.\n");
+
+ CommandArgumentEntry arg;
+ CommandArgumentData var_name_arg, expression_arg;
+
+ // Define the first variant of this arg.
+ var_name_arg.arg_type = eArgTypeVarName;
+ var_name_arg.arg_repetition = eArgRepeatPlain;
+
+ // Define the second variant of this arg.
+ expression_arg.arg_type = eArgTypeExpression;
+ expression_arg.arg_repetition = eArgRepeatPlain;
+
+ // Push the two variants into the argument entry.
+ arg.push_back (var_name_arg);
+ arg.push_back (expression_arg);
+
+ // Push the data for the first argument into the m_arguments vector.
+ m_arguments.push_back (arg);
+
+ m_option_group.Append (&m_option_watchpoint, LLDB_OPT_SET_ALL, LLDB_OPT_SET_1);
+ m_option_group.Finalize();
+}
+
+CommandObjectWatchpointSet::~CommandObjectWatchpointSet ()
+{
+}
+
+Options *
+CommandObjectWatchpointSet::GetOptions ()
+{
+ return &m_option_group;
+}
+
+bool
+CommandObjectWatchpointSet::Execute
+(
+ Args& command,
+ CommandReturnObject &result
+)
+{
+ Target *target = m_interpreter.GetDebugger().GetSelectedTarget().get();
+ ExecutionContext exe_ctx(m_interpreter.GetExecutionContext());
+ StackFrame *frame = exe_ctx.GetFramePtr();
+ if (frame == NULL)
+ {
+ result.AppendError ("you must be stopped in a valid stack frame to set a watchpoint.");
+ result.SetStatus (eReturnStatusFailed);
+ return false;
+ }
+
+ // Be careful about the stack frame, if any summary formatter runs code, it might clear the StackFrameList
+ // for the thread. So hold onto a shared pointer to the frame so it stays alive.
+ bool get_file_globals = true;
+ VariableList *variable_list = frame->GetVariableList (get_file_globals);
+
+ bool watch_address = (m_option_watchpoint.watch_size > 0);
+
+ // If no '-w' is specified, default to '-w read_write'.
+ if (!m_option_watchpoint.watch_variable)
+ {
+ m_option_watchpoint.watch_variable = true;
+ m_option_watchpoint.watch_type = OptionGroupWatchpoint::eWatchReadWrite;
+ }
+ // It's possible to specify an address to watch for with the '-x' option.
+ if (!variable_list && !watch_address)
+ {
+ result.GetErrorStream().Printf("error: no variables found, did you forget to use '-x' option to watch an address?\n");
+ result.SetStatus(eReturnStatusFailed);
+ return false;
+ }
+ // If thre's no argument, it is an error.
+ if (command.GetArgumentCount() <= 0) {
+ result.GetErrorStream().Printf("error: specify your target variable (no '-x') or expression (with '-x') to watch for\n");
+ result.SetStatus(eReturnStatusFailed);
+ return false;
+ }
+
+ // We passed the sanity check for the options.
+ // Proceed to set the watchpoint now.
+ lldb::addr_t addr = 0;
+ size_t size = 0;
+
+ VariableSP var_sp;
+ ValueObjectSP valobj_sp;
+ Stream &output_stream = result.GetOutputStream();
+
+ if (watch_address) {
+ std::string expr_str;
+ command.GetQuotedCommandString(expr_str);
+ const bool coerce_to_id = true;
+ const bool unwind_on_error = true;
+ const bool keep_in_memory = false;
+ ExecutionResults expr_result = target->EvaluateExpression (expr_str.c_str(),
+ frame,
+ eExecutionPolicyOnlyWhenNeeded,
+ coerce_to_id,
+ unwind_on_error,
+ keep_in_memory,
+ eNoDynamicValues,
+ valobj_sp);
+ if (expr_result != eExecutionCompleted) {
+ result.GetErrorStream().Printf("error: expression evaluation of address to watch failed\n");
+ result.SetStatus(eReturnStatusFailed);
+ }
+
+ // Get the address to watch.
+ addr = valobj_sp->GetValueAsUnsigned(0);
+ if (!addr) {
+ result.GetErrorStream().Printf("error: expression did not evaluate to an address\n");
+ result.SetStatus(eReturnStatusFailed);
+ return false;
+ }
+ size = m_option_watchpoint.watch_size;
+ } else {
+ // A simple watch variable gesture allows only one argument.
+ if (m_option_watchpoint.watch_size == 0 && command.GetArgumentCount() != 1) {
+ result.GetErrorStream().Printf("error: specify exactly one variable with the '-w' option, i.e., no '-x'\n");
+ result.SetStatus(eReturnStatusFailed);
+ return false;
+ }
+
+ // Things have checked out ok...
+ Error error;
+ uint32_t expr_path_options = StackFrame::eExpressionPathOptionCheckPtrVsMember;
+ valobj_sp = frame->GetValueForVariableExpressionPath (command.GetArgumentAtIndex(0),
+ eNoDynamicValues,
+ expr_path_options,
+ var_sp,
+ error);
+ if (valobj_sp) {
+ AddressType addr_type;
+ addr = valobj_sp->GetAddressOf(false, &addr_type);
+ if (addr_type == eAddressTypeLoad) {
+ // We're in business.
+ // Find out the size of this variable.
+ size = valobj_sp->GetByteSize();
+ }
+ } else {
+ const char *error_cstr = error.AsCString(NULL);
+ if (error_cstr)
+ result.GetErrorStream().Printf("error: %s\n", error_cstr);
+ else
+ result.GetErrorStream().Printf ("error: unable to find any variable expression path that matches '%s'\n",
+ command.GetArgumentAtIndex(0));
+ return false;
+ }
+ }
+
+ // Now it's time to create the watchpoint.
+ uint32_t watch_type = m_option_watchpoint.watch_type;
+ Watchpoint *wp = exe_ctx.GetTargetRef().CreateWatchpoint(addr, size, watch_type).get();
+ if (wp) {
+ if (var_sp && var_sp->GetDeclaration().GetFile()) {
+ StreamString ss;
+ // True to show fullpath for declaration file.
+ var_sp->GetDeclaration().DumpStopContext(&ss, true);
+ wp->SetDeclInfo(ss.GetString());
+ }
+ StreamString ss;
+ output_stream.Printf("Watchpoint created: ");
+ wp->GetDescription(&output_stream, lldb::eDescriptionLevelFull);
+ output_stream.EOL();
+ result.SetStatus(eReturnStatusSuccessFinishResult);
+ } else {
+ result.AppendErrorWithFormat("Watchpoint creation failed.\n");
+ result.SetStatus(eReturnStatusFailed);
+ }
+
+ return result.Succeeded();
+}
Modified: lldb/trunk/source/Commands/CommandObjectWatchpoint.h
URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/source/Commands/CommandObjectWatchpoint.h?rev=149280&r1=149279&r2=149280&view=diff
==============================================================================
--- lldb/trunk/source/Commands/CommandObjectWatchpoint.h (original)
+++ lldb/trunk/source/Commands/CommandObjectWatchpoint.h Mon Jan 30 15:46:17 2012
@@ -17,6 +17,7 @@
// Project includes
#include "lldb/Interpreter/CommandObjectMultiword.h"
#include "lldb/Interpreter/Options.h"
+#include "lldb/Interpreter/OptionGroupWatchpoint.h"
namespace lldb_private {
@@ -242,6 +243,31 @@
CommandOptions m_options;
};
+//-------------------------------------------------------------------------
+// CommandObjectWatchpointSet
+//-------------------------------------------------------------------------
+
+class CommandObjectWatchpointSet : public CommandObject
+{
+public:
+
+ CommandObjectWatchpointSet (CommandInterpreter &interpreter);
+
+ virtual
+ ~CommandObjectWatchpointSet ();
+
+ virtual bool
+ Execute (Args& command,
+ CommandReturnObject &result);
+
+ virtual Options *
+ GetOptions ();
+
+private:
+ OptionGroupOptions m_option_group;
+ OptionGroupWatchpoint m_option_watchpoint;
+};
+
} // namespace lldb_private
#endif // liblldb_CommandObjectWatchpoint_h_
Modified: lldb/trunk/test/functionalities/watchpoint/hello_watchpoint/TestMyFirstWatchpoint.py
URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/test/functionalities/watchpoint/hello_watchpoint/TestMyFirstWatchpoint.py?rev=149280&r1=149279&r2=149280&view=diff
==============================================================================
--- lldb/trunk/test/functionalities/watchpoint/hello_watchpoint/TestMyFirstWatchpoint.py (original)
+++ lldb/trunk/test/functionalities/watchpoint/hello_watchpoint/TestMyFirstWatchpoint.py Mon Jan 30 15:46:17 2012
@@ -12,18 +12,30 @@
mydir = os.path.join("functionalities", "watchpoint", "hello_watchpoint")
@unittest2.skipUnless(sys.platform.startswith("darwin"), "requires Darwin")
- def test_hello_watchpoint_with_dsym(self):
+ def test_hello_watchpoint_with_dsym_using_frame_var(self):
"""Test a simple sequence of watchpoint creation and watchpoint hit."""
self.buildDsym(dictionary=self.d)
self.setTearDownCleanup(dictionary=self.d)
self.hello_watchpoint()
- def test_hello_watchpoint_with_dwarf(self):
+ def test_hello_watchpoint_with_dwarf_using_frame_var(self):
"""Test a simple sequence of watchpoint creation and watchpoint hit."""
self.buildDwarf(dictionary=self.d)
self.setTearDownCleanup(dictionary=self.d)
self.hello_watchpoint()
+ def test_hello_watchpoint_with_dsym_using_watchpoint_set(self):
+ """Test a simple sequence of watchpoint creation and watchpoint hit."""
+ self.buildDsym(dictionary=self.d)
+ self.setTearDownCleanup(dictionary=self.d)
+ self.hello_watchpoint(use_frame_var=False)
+
+ def test_hello_watchpoint_with_dwarf_using_watchpoint_set(self):
+ """Test a simple sequence of watchpoint creation and watchpoint hit."""
+ self.buildDwarf(dictionary=self.d)
+ self.setTearDownCleanup(dictionary=self.d)
+ self.hello_watchpoint(use_frame_var=False)
+
def setUp(self):
# Call super's setUp().
TestBase.setUp(self)
@@ -37,7 +49,7 @@
self.exe_name = self.testMethodName
self.d = {'C_SOURCES': self.source, 'EXE': self.exe_name}
- def hello_watchpoint(self):
+ def hello_watchpoint(self, use_frame_var=True):
"""Test a simple sequence of watchpoint creation and watchpoint hit."""
exe = os.path.join(os.getcwd(), self.exe_name)
self.runCmd("file " + exe, CURRENT_EXECUTABLE_SET)
@@ -58,9 +70,14 @@
# Now let's set a write-type watchpoint for 'global'.
# There should be only one watchpoint hit (see main.c).
- self.expect("frame variable -w write -g -L global", WATCHPOINT_CREATED,
- substrs = ['Watchpoint created', 'size = 4', 'type = w',
- '%s:%d' % (self.source, self.decl)])
+ if use_frame_var:
+ self.expect("frame variable -w write -g -L global", WATCHPOINT_CREATED,
+ substrs = ['Watchpoint created', 'size = 4', 'type = w',
+ '%s:%d' % (self.source, self.decl)])
+ else:
+ self.expect("watchpoint set -w write global", WATCHPOINT_CREATED,
+ substrs = ['Watchpoint created', 'size = 4', 'type = w',
+ '%s:%d' % (self.source, self.decl)])
# Use the '-v' option to do verbose listing of the watchpoint.
# The hit count should be 0 initially.
Added: lldb/trunk/test/functionalities/watchpoint/watchpoint_set_command/Makefile
URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/test/functionalities/watchpoint/watchpoint_set_command/Makefile?rev=149280&view=auto
==============================================================================
--- lldb/trunk/test/functionalities/watchpoint/watchpoint_set_command/Makefile (added)
+++ lldb/trunk/test/functionalities/watchpoint/watchpoint_set_command/Makefile Mon Jan 30 15:46:17 2012
@@ -0,0 +1,5 @@
+LEVEL = ../../../make
+
+CXX_SOURCES := main.cpp
+
+include $(LEVEL)/Makefile.rules
Added: lldb/trunk/test/functionalities/watchpoint/watchpoint_set_command/TestWatchLocationWithWatchSet.py
URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/test/functionalities/watchpoint/watchpoint_set_command/TestWatchLocationWithWatchSet.py?rev=149280&view=auto
==============================================================================
--- lldb/trunk/test/functionalities/watchpoint/watchpoint_set_command/TestWatchLocationWithWatchSet.py (added)
+++ lldb/trunk/test/functionalities/watchpoint/watchpoint_set_command/TestWatchLocationWithWatchSet.py Mon Jan 30 15:46:17 2012
@@ -0,0 +1,102 @@
+"""
+Test lldb watchpoint that uses '-x size' to watch a pointed location with size.
+"""
+
+import os, time
+import unittest2
+import lldb
+from lldbtest import *
+
+class WatchLocationUsingWatchpointSetTestCase(TestBase):
+
+ mydir = os.path.join("functionalities", "watchpoint", "watchpoint_set_command")
+
+ @unittest2.skipUnless(sys.platform.startswith("darwin"), "requires Darwin")
+ def test_watchlocation_with_dsym_using_watchpoint_set(self):
+ """Test watching a location with 'watchpoint set -w write -x size' option."""
+ self.buildDsym(dictionary=self.d)
+ self.setTearDownCleanup(dictionary=self.d)
+ self.watchlocation_using_watchpoint_set()
+
+ def test_watchlocation_with_dwarf_using_watchpoint_set(self):
+ """Test watching a location with 'watchpoint set -w write -x size' option."""
+ self.buildDwarf(dictionary=self.d)
+ self.setTearDownCleanup(dictionary=self.d)
+ self.watchlocation_using_watchpoint_set()
+
+ def setUp(self):
+ # Call super's setUp().
+ TestBase.setUp(self)
+ # Our simple source filename.
+ self.source = 'main.cpp'
+ # Find the line number to break inside main().
+ self.line = line_number(self.source, '// Set break point at this line.')
+ # This is for verifying that watch location works.
+ self.violating_func = "do_bad_thing_with_location";
+ # Build dictionary to have unique executable names for each test method.
+ self.exe_name = self.testMethodName
+ self.d = {'CXX_SOURCES': self.source, 'EXE': self.exe_name}
+
+ def watchlocation_using_watchpoint_set(self):
+ """Test watching a location with '-x size' option."""
+ exe = os.path.join(os.getcwd(), self.exe_name)
+ self.runCmd("file " + exe, CURRENT_EXECUTABLE_SET)
+
+ # Add a breakpoint to set a watchpoint when stopped on the breakpoint.
+ self.expect("breakpoint set -l %d" % self.line, BREAKPOINT_CREATED,
+ startstr = "Breakpoint created: 1: file ='%s', line = %d, locations = 1" %
+ (self.source, self.line))
+
+ # Run the program.
+ self.runCmd("run", RUN_SUCCEEDED)
+
+ # We should be stopped again due to the breakpoint.
+ # The stop reason of the thread should be breakpoint.
+ self.expect("thread list", STOPPED_DUE_TO_BREAKPOINT,
+ substrs = ['stopped',
+ 'stop reason = breakpoint'])
+
+ # Now let's set a write-type watchpoint pointed to by 'g_char_ptr' and
+ # with offset as 7.
+ # The main.cpp, by design, misbehaves by not following the agreed upon
+ # protocol of only accessing the allowable index range of [0, 6].
+ self.expect("watchpoint set -w write -x 1 g_char_ptr + 7", WATCHPOINT_CREATED,
+ substrs = ['Watchpoint created', 'size = 1', 'type = w'])
+ self.runCmd("expr unsigned val = *g_char_ptr; val")
+ self.expect(self.res.GetOutput().splitlines()[0], exe=False,
+ endstr = ' = 0')
+
+ # Use the '-v' option to do verbose listing of the watchpoint.
+ # The hit count should be 0 initially.
+ self.expect("watchpoint list -v",
+ substrs = ['hit_count = 0'])
+
+ self.runCmd("process continue")
+
+ # We should be stopped again due to the watchpoint (write type), but
+ # only once. The stop reason of the thread should be watchpoint.
+ self.expect("thread list", STOPPED_DUE_TO_WATCHPOINT,
+ substrs = ['stopped',
+ 'stop reason = watchpoint',
+ self.violating_func])
+
+ # Switch to the thread stopped due to watchpoint and issue some commands.
+ self.switch_to_thread_with_stop_reason(lldb.eStopReasonWatchpoint)
+ self.runCmd("thread backtrace")
+ self.runCmd("expr unsigned val = g_char_ptr[7]; val")
+ self.expect(self.res.GetOutput().splitlines()[0], exe=False,
+ endstr = ' = 99')
+
+ # Use the '-v' option to do verbose listing of the watchpoint.
+ # The hit count should now be 1.
+ self.expect("watchpoint list -v",
+ substrs = ['hit_count = 1'])
+
+ self.runCmd("thread backtrace all")
+
+
+if __name__ == '__main__':
+ import atexit
+ lldb.SBDebugger.Initialize()
+ atexit.register(lambda: lldb.SBDebugger.Terminate())
+ unittest2.main()
Added: lldb/trunk/test/functionalities/watchpoint/watchpoint_set_command/main.cpp
URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/test/functionalities/watchpoint/watchpoint_set_command/main.cpp?rev=149280&view=auto
==============================================================================
--- lldb/trunk/test/functionalities/watchpoint/watchpoint_set_command/main.cpp (added)
+++ lldb/trunk/test/functionalities/watchpoint/watchpoint_set_command/main.cpp Mon Jan 30 15:46:17 2012
@@ -0,0 +1,109 @@
+//===-- main.cpp ------------------------------------------------*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// C includes
+#include <pthread.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+pthread_t g_thread_1 = NULL;
+pthread_t g_thread_2 = NULL;
+pthread_t g_thread_3 = NULL;
+
+char *g_char_ptr = NULL;
+
+void
+do_bad_thing_with_location(unsigned index, char *char_ptr, char new_val)
+{
+ unsigned what = new_val;
+ printf("new value written to array(%p) and index(%u) = %u\n", char_ptr, index, what);
+ char_ptr[index] = new_val;
+}
+
+uint32_t access_pool (uint32_t flag = 0);
+
+uint32_t
+access_pool (uint32_t flag)
+{
+ static pthread_mutex_t g_access_mutex = PTHREAD_MUTEX_INITIALIZER;
+ static unsigned idx = 0; // Well-behaving thread only writes into indexs from 0..6.
+ if (flag == 0)
+ ::pthread_mutex_lock (&g_access_mutex);
+
+ // idx valid range is [0, 6].
+ if (idx > 6)
+ idx = 0;
+
+ if (flag != 0) {
+ // Write into a forbidden area.
+ do_bad_thing_with_location(7, g_char_ptr, 99);
+ }
+
+ unsigned index = idx++;
+
+ if (flag == 0)
+ ::pthread_mutex_unlock (&g_access_mutex);
+ return g_char_ptr[index];
+}
+
+void *
+thread_func (void *arg)
+{
+ uint32_t thread_index = *((uint32_t *)arg);
+ printf ("%s (thread index = %u) startng...\n", __FUNCTION__, thread_index);
+
+ uint32_t count = 0;
+ uint32_t val;
+ while (count++ < 15)
+ {
+ // random micro second sleep from zero to 3 seconds
+ int usec = ::rand() % 3000000;
+ printf ("%s (thread = %u) doing a usleep (%d)...\n", __FUNCTION__, thread_index, usec);
+ ::usleep (usec);
+
+ if (count < 7)
+ val = access_pool ();
+ else
+ val = access_pool (1);
+
+ printf ("%s (thread = %u) after usleep access_pool returns %d (count=%d)...\n", __FUNCTION__, thread_index, val, count);
+ }
+ printf ("%s (thread index = %u) exiting...\n", __FUNCTION__, thread_index);
+ return NULL;
+}
+
+
+int main (int argc, char const *argv[])
+{
+ int err;
+ void *thread_result = NULL;
+ uint32_t thread_index_1 = 1;
+ uint32_t thread_index_2 = 2;
+ uint32_t thread_index_3 = 3;
+
+ g_char_ptr = (char *)malloc (10);
+ for (int i = 0; i < 10; ++i)
+ *g_char_ptr = 0;
+
+ // Create 3 threads
+ err = ::pthread_create (&g_thread_1, NULL, thread_func, &thread_index_1);
+ err = ::pthread_create (&g_thread_2, NULL, thread_func, &thread_index_2);
+ err = ::pthread_create (&g_thread_3, NULL, thread_func, &thread_index_3);
+
+ printf ("Before turning all three threads loose...\n"); // Set break point at this line.
+
+ // Join all of our threads
+ err = ::pthread_join (g_thread_1, &thread_result);
+ err = ::pthread_join (g_thread_2, &thread_result);
+ err = ::pthread_join (g_thread_3, &thread_result);
+
+ return 0;
+}
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