JDevlieghere created this revision.
JDevlieghere added reviewers: labath, jingham.
Herald added a subscriber: kristof.beyls.
Herald added a project: All.
JDevlieghere requested review of this revision.
This patch introduces a small utility called `LockableStream` to protect the
debugger's output and error stream. Nothing prevents someone from bypassing
this and going straight through the debugger's `Get{Output,Error}File`. I don't
think we want to get rid of that, but at least now we have something that
allows us to access these streams in a safe way.
This fixes a real world race between the main thread and the default event
handler thread:
Write of size 8 at 0x000106c01bc0 by thread T1 (mutexes: write M4069, write
M2753):
#0 lldb_private::IOHandlerEditline::PrintAsync(lldb_private::Stream*, char
const*, unsigned long) IOHandler.cpp:636
(liblldb.15.0.0git.dylib:arm64+0x3ef4a4)
#1 lldb_private::IOHandlerStack::PrintAsync(lldb_private::Stream*, char
const*, unsigned long) IOHandler.cpp:129
(liblldb.15.0.0git.dylib:arm64+0x3ec84c)
#2 lldb_private::Debugger::PrintAsync(char const*, unsigned long, bool)
Debugger.cpp:1074 (liblldb.15.0.0git.dylib:arm64+0x3cb03c)
#3 lldb_private::StreamAsynchronousIO::~StreamAsynchronousIO()
StreamAsynchronousIO.cpp:21 (liblldb.15.0.0git.dylib:arm64+0x44749c)
#4 std::__1::__shared_ptr_emplace<lldb_private::StreamAsynchronousIO,
std::__1::allocator<lldb_private::StreamAsynchronousIO> >::__on_zero_shared()
shared_ptr.h:315 (liblldb.15.0.0git.dylib:arm64+0x3d0f80)
#5
lldb_private::Debugger::HandleThreadEvent(std::__1::shared_ptr<lldb_private::Event>
const&) Debugger.cpp:1591 (liblldb.15.0.0git.dylib:arm64+0x3ce2cc)
#6 lldb_private::Debugger::DefaultEventHandler() Debugger.cpp:1659
(liblldb.15.0.0git.dylib:arm64+0x3ce720)
#7
std::__1::__function::__func<lldb_private::Debugger::StartEventHandlerThread()::$_2,
std::__1::allocator<lldb_private::Debugger::StartEventHandlerThread()::$_2>,
void* ()>::operator()() function.h:352 (liblldb.15.0.0git.dylib:arm64+0x3d145c)
#8 lldb_private::HostNativeThreadBase::ThreadCreateTrampoline(void*)
HostNativeThreadBase.cpp:62 (liblldb.15.0.0git.dylib:arm64+0x4c67a4)
#9 lldb_private::HostThreadMacOSX::ThreadCreateTrampoline(void*)
HostThreadMacOSX.mm:18 (liblldb.15.0.0git.dylib:arm64+0x29cebac)
Previous write of size 8 at 0x000106c01bc0 by main thread (mutexes: write
M2754):
#0
lldb_private::CommandInterpreter::PrintCommandOutput(lldb_private::Stream&,
llvm::StringRef) CommandInterpreter.cpp:2992
(liblldb.15.0.0git.dylib:arm64+0x502888)
#1
lldb_private::CommandInterpreter::IOHandlerInputComplete(lldb_private::IOHandler&,
std::__1::basic_string<char, std::__1::char_traits<char>,
std::__1::allocator<char> >&) CommandInterpreter.cpp:3060
(liblldb.15.0.0git.dylib:arm64+0x502fec)
#2 non-virtual thunk to
lldb_private::CommandInterpreter::IOHandlerInputComplete(lldb_private::IOHandler&,
std::__1::basic_string<char, std::__1::char_traits<char>,
std::__1::allocator<char> >&) CommandInterpreter.cpp
(liblldb.15.0.0git.dylib:arm64+0x503410)
#3 lldb_private::IOHandlerEditline::Run() IOHandler.cpp
(liblldb.15.0.0git.dylib:arm64+0x3ef2f4)
#4
lldb_private::Debugger::RunIOHandlerSync(std::__1::shared_ptr<lldb_private::IOHandler>
const&) Debugger.cpp:1037 (liblldb.15.0.0git.dylib:arm64+0x3cabc0)
#5
lldb_private::CommandInterpreter::HandleCommandsFromFile(lldb_private::FileSpec&,
lldb_private::CommandInterpreterRunOptions const&,
lldb_private::CommandReturnObject&) CommandInterpreter.cpp:2748
(liblldb.15.0.0git.dylib:arm64+0x5000d4)
#6 CommandObjectCommandsSource::DoExecute(lldb_private::Args&,
lldb_private::CommandReturnObject&) CommandObjectCommands.cpp:187
(liblldb.15.0.0git.dylib:arm64+0x284d0b4)
#7 lldb_private::CommandObjectParsed::Execute(char const*,
lldb_private::CommandReturnObject&) CommandObject.cpp:998
(liblldb.15.0.0git.dylib:arm64+0x50bf04)
#8 lldb_private::CommandInterpreter::HandleCommand(char const*,
lldb_private::LazyBool, lldb_private::CommandReturnObject&)
CommandInterpreter.cpp:1981 (liblldb.15.0.0git.dylib:arm64+0x4feaf0)
#9
lldb_private::CommandInterpreter::IOHandlerInputComplete(lldb_private::IOHandler&,
std::__1::basic_string<char, std::__1::char_traits<char>,
std::__1::allocator<char> >&) CommandInterpreter.cpp:3049
(liblldb.15.0.0git.dylib:arm64+0x502ee0)
#10 non-virtual thunk to
lldb_private::CommandInterpreter::IOHandlerInputComplete(lldb_private::IOHandler&,
std::__1::basic_string<char, std::__1::char_traits<char>,
std::__1::allocator<char> >&) CommandInterpreter.cpp
(liblldb.15.0.0git.dylib:arm64+0x503410)
#11 lldb_private::IOHandlerEditline::Run() IOHandler.cpp
(liblldb.15.0.0git.dylib:arm64+0x3ef2f4)
#12 lldb_private::Debugger::RunIOHandlers() Debugger.cpp:1008
(liblldb.15.0.0git.dylib:arm64+0x3ca8f8)
#13
lldb_private::CommandInterpreter::RunCommandInterpreter(lldb_private::CommandInterpreterRunOptions&)
CommandInterpreter.cpp:3299 (liblldb.15.0.0git.dylib:arm64+0x5048a4)
#14
lldb::SBDebugger::RunCommandInterpreter(lldb::SBCommandInterpreterRunOptions
const&) SBDebugger.cpp:1203 (liblldb.15.0.0git.dylib:arm64+0x523f8)
#15 Driver::MainLoop() Driver.cpp:575 (lldb:arm64+0x10000606c)
#16 main Driver.cpp:851 (lldb:arm64+0x100007388)
https://reviews.llvm.org/D121500
Files:
lldb/include/lldb/Utility/Stream.h
lldb/source/Core/Debugger.cpp
Index: lldb/source/Core/Debugger.cpp
===================================================================
--- lldb/source/Core/Debugger.cpp
+++ lldb/source/Core/Debugger.cpp
@@ -733,8 +733,10 @@
: UserID(g_unique_id++),
Properties(std::make_shared<OptionValueProperties>()),
m_input_file_sp(std::make_shared<NativeFile>(stdin, false)),
- m_output_stream_sp(std::make_shared<StreamFile>(stdout, false)),
- m_error_stream_sp(std::make_shared<StreamFile>(stderr, false)),
+ m_output_stream_sp(
+ std::make_shared<LockableStream<StreamFile>>(stdout, false)),
+ m_error_stream_sp(
+ std::make_shared<LockableStream<StreamFile>>(stderr, false)),
m_input_recorder(nullptr),
m_broadcaster_manager_sp(BroadcasterManager::MakeBroadcasterManager()),
m_terminal_state(), m_target_list(*this), m_platform_list(),
Index: lldb/include/lldb/Utility/Stream.h
===================================================================
--- lldb/include/lldb/Utility/Stream.h
+++ lldb/include/lldb/Utility/Stream.h
@@ -19,6 +19,7 @@
#include <cstdarg>
#include <cstddef>
#include <cstdint>
+#include <mutex>
#include <type_traits>
namespace lldb_private {
@@ -44,7 +45,6 @@
Stream *m_stream;
/// Bytes we have written so far when ByteDelta was created.
size_t m_start;
-
public:
ByteDelta(Stream &s) : m_stream(&s), m_start(s.GetWrittenBytes()) {}
/// Returns the number of bytes written to the given Stream since this
@@ -412,6 +412,26 @@
RawOstreamForward m_forwarder;
};
+template <typename T, typename M = std::mutex> class LockableStream : public T
{
+public:
+ using T::T;
+ ~LockableStream() = default;
+
+ void Flush() override {
+ std::lock_guard<M> guard(m_mutex);
+ T::Flush();
+ }
+
+protected:
+ size_t WriteImpl(const void *s, size_t length) override {
+ std::lock_guard<M> guard(m_mutex);
+ return T::WriteImpl(s, length);
+ }
+
+private:
+ M m_mutex;
+};
+
/// Output an address value to this stream.
///
/// Put an address \a addr out to the stream with optional \a prefix and \a
Index: lldb/source/Core/Debugger.cpp
===================================================================
--- lldb/source/Core/Debugger.cpp
+++ lldb/source/Core/Debugger.cpp
@@ -733,8 +733,10 @@
: UserID(g_unique_id++),
Properties(std::make_shared<OptionValueProperties>()),
m_input_file_sp(std::make_shared<NativeFile>(stdin, false)),
- m_output_stream_sp(std::make_shared<StreamFile>(stdout, false)),
- m_error_stream_sp(std::make_shared<StreamFile>(stderr, false)),
+ m_output_stream_sp(
+ std::make_shared<LockableStream<StreamFile>>(stdout, false)),
+ m_error_stream_sp(
+ std::make_shared<LockableStream<StreamFile>>(stderr, false)),
m_input_recorder(nullptr),
m_broadcaster_manager_sp(BroadcasterManager::MakeBroadcasterManager()),
m_terminal_state(), m_target_list(*this), m_platform_list(),
Index: lldb/include/lldb/Utility/Stream.h
===================================================================
--- lldb/include/lldb/Utility/Stream.h
+++ lldb/include/lldb/Utility/Stream.h
@@ -19,6 +19,7 @@
#include <cstdarg>
#include <cstddef>
#include <cstdint>
+#include <mutex>
#include <type_traits>
namespace lldb_private {
@@ -44,7 +45,6 @@
Stream *m_stream;
/// Bytes we have written so far when ByteDelta was created.
size_t m_start;
-
public:
ByteDelta(Stream &s) : m_stream(&s), m_start(s.GetWrittenBytes()) {}
/// Returns the number of bytes written to the given Stream since this
@@ -412,6 +412,26 @@
RawOstreamForward m_forwarder;
};
+template <typename T, typename M = std::mutex> class LockableStream : public T {
+public:
+ using T::T;
+ ~LockableStream() = default;
+
+ void Flush() override {
+ std::lock_guard<M> guard(m_mutex);
+ T::Flush();
+ }
+
+protected:
+ size_t WriteImpl(const void *s, size_t length) override {
+ std::lock_guard<M> guard(m_mutex);
+ return T::WriteImpl(s, length);
+ }
+
+private:
+ M m_mutex;
+};
+
/// Output an address value to this stream.
///
/// Put an address \a addr out to the stream with optional \a prefix and \a
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