https://github.com/JDevlieghere updated
https://github.com/llvm/llvm-project/pull/134956
>From 390942ce3a1cf6c51f95e8e2893f88807a48e745 Mon Sep 17 00:00:00 2001
From: Jonas Devlieghere <jo...@devlieghere.com>
Date: Tue, 8 Apr 2025 17:33:41 -0700
Subject: [PATCH 1/2] [lldb] Handle signals in a separate thread in the driver
Handle signals in a separate thread in the driver so that we can stop
worrying about signal safety of functions in libLLDB that may get called
from a signal handler.
---
lldb/tools/driver/CMakeLists.txt | 2 +
lldb/tools/driver/Driver.cpp | 96 +++++++++++++++++++++-----------
2 files changed, 64 insertions(+), 34 deletions(-)
diff --git a/lldb/tools/driver/CMakeLists.txt b/lldb/tools/driver/CMakeLists.txt
index 89884ecd0601b..8b4aa92f96f0d 100644
--- a/lldb/tools/driver/CMakeLists.txt
+++ b/lldb/tools/driver/CMakeLists.txt
@@ -22,6 +22,8 @@ add_lldb_tool(lldb
LINK_LIBS
liblldb
+ lldbHost
+ lldbUtility
LINK_COMPONENTS
Option
diff --git a/lldb/tools/driver/Driver.cpp b/lldb/tools/driver/Driver.cpp
index 15cb0134fec8e..fb051f198381f 100644
--- a/lldb/tools/driver/Driver.cpp
+++ b/lldb/tools/driver/Driver.cpp
@@ -19,7 +19,9 @@
#include "lldb/API/SBStringList.h"
#include "lldb/API/SBStructuredData.h"
#include "lldb/Host/Config.h"
-
+#include "lldb/Host/MainLoop.h"
+#include "lldb/Host/MainLoopBase.h"
+#include "lldb/Utility/Status.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/Format.h"
#include "llvm/Support/InitLLVM.h"
@@ -50,6 +52,9 @@
using namespace lldb;
using namespace llvm;
+using lldb_private::MainLoop;
+using lldb_private::MainLoopBase;
+using lldb_private::Status;
namespace {
using namespace llvm::opt;
@@ -636,15 +641,12 @@ void Driver::UpdateWindowSize() {
}
}
-void sigwinch_handler(int signo) {
- if (g_driver != nullptr)
- g_driver->UpdateWindowSize();
-}
-
void sigint_handler(int signo) {
-#ifdef _WIN32 // Restore handler as it is not persistent on Windows
+#ifdef _WIN32
+ // Restore handler as it is not persistent on Windows.
signal(SIGINT, sigint_handler);
#endif
+
static std::atomic_flag g_interrupt_sent = ATOMIC_FLAG_INIT;
if (g_driver != nullptr) {
if (!g_interrupt_sent.test_and_set()) {
@@ -657,31 +659,6 @@ void sigint_handler(int signo) {
_exit(signo);
}
-#ifndef _WIN32
-static void sigtstp_handler(int signo) {
- if (g_driver != nullptr)
- g_driver->GetDebugger().SaveInputTerminalState();
-
- // Unblock the signal and remove our handler.
- sigset_t set;
- sigemptyset(&set);
- sigaddset(&set, signo);
- pthread_sigmask(SIG_UNBLOCK, &set, nullptr);
- signal(signo, SIG_DFL);
-
- // Now re-raise the signal. We will immediately suspend...
- raise(signo);
- // ... and resume after a SIGCONT.
-
- // Now undo the modifications.
- pthread_sigmask(SIG_BLOCK, &set, nullptr);
- signal(signo, sigtstp_handler);
-
- if (g_driver != nullptr)
- g_driver->GetDebugger().RestoreInputTerminalState();
-}
-#endif
-
static void printHelp(LLDBOptTable &table, llvm::StringRef tool_name) {
std::string usage_str = tool_name.str() + " [options]";
table.printHelp(llvm::outs(), usage_str.c_str(), "LLDB", false);
@@ -787,11 +764,56 @@ int main(int argc, char const *argv[]) {
// Setup LLDB signal handlers once the debugger has been initialized.
SBDebugger::PrintDiagnosticsOnError();
+ // FIXME: Migrate the SIGINT handler to be handled by the signal loop below.
signal(SIGINT, sigint_handler);
#if !defined(_WIN32)
signal(SIGPIPE, SIG_IGN);
- signal(SIGWINCH, sigwinch_handler);
- signal(SIGTSTP, sigtstp_handler);
+
+ // Handle signals in a MainLoop running on a separate thread.
+ MainLoop signal_loop;
+ Status signal_status;
+
+ auto sigwinch_handler = signal_loop.RegisterSignal(
+ SIGWINCH,
+ [&](MainLoopBase &) {
+ if (g_driver)
+ g_driver->UpdateWindowSize();
+ },
+ signal_status);
+ assert(sigwinch_handler && signal_status.Success());
+
+ auto sigtstp_handler = signal_loop.RegisterSignal(
+ SIGTSTP,
+ [&](MainLoopBase &) {
+ if (g_driver)
+ g_driver->GetDebugger().SaveInputTerminalState();
+
+ struct sigaction old_action;
+ struct sigaction new_action;
+
+ memset(&new_action, 0, sizeof(new_action));
+ new_action.sa_handler = SIG_DFL;
+ new_action.sa_flags = SA_SIGINFO;
+ sigemptyset(&new_action.sa_mask);
+ sigaddset(&new_action.sa_mask, SIGTSTP);
+
+ int ret = sigaction(SIGTSTP, &new_action, &old_action);
+ UNUSED_IF_ASSERT_DISABLED(ret);
+ assert(ret == 0 && "sigaction failed");
+
+ raise(SIGTSTP);
+
+ ret = sigaction(SIGTSTP, &old_action, nullptr);
+ UNUSED_IF_ASSERT_DISABLED(ret);
+ assert(ret == 0 && "sigaction failed");
+
+ if (g_driver)
+ g_driver->GetDebugger().RestoreInputTerminalState();
+ },
+ signal_status);
+ assert(sigtstp_handler && signal_status.Success());
+
+ std::thread signal_thread([&] { signal_loop.Run(); });
#endif
int exit_code = 0;
@@ -824,5 +846,11 @@ int main(int argc, char const *argv[]) {
future.wait();
}
+#if !defined(_WIN32)
+ signal_loop.AddPendingCallback(
+ [](MainLoopBase &loop) { loop.RequestTermination(); });
+ signal_thread.join();
+#endif
+
return exit_code;
}
>From a2fae8be8a0f3cfc9b9bc36704c32c3f1bc640c9 Mon Sep 17 00:00:00 2001
From: Jonas Devlieghere <jo...@devlieghere.com>
Date: Thu, 10 Apr 2025 08:38:20 -0700
Subject: [PATCH 2/2] Address Pavel's feedback
---
lldb/tools/driver/Driver.cpp | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)
diff --git a/lldb/tools/driver/Driver.cpp b/lldb/tools/driver/Driver.cpp
index fb051f198381f..e19fded051941 100644
--- a/lldb/tools/driver/Driver.cpp
+++ b/lldb/tools/driver/Driver.cpp
@@ -789,11 +789,8 @@ int main(int argc, char const *argv[]) {
g_driver->GetDebugger().SaveInputTerminalState();
struct sigaction old_action;
- struct sigaction new_action;
-
- memset(&new_action, 0, sizeof(new_action));
+ struct sigaction new_action = {};
new_action.sa_handler = SIG_DFL;
- new_action.sa_flags = SA_SIGINFO;
sigemptyset(&new_action.sa_mask);
sigaddset(&new_action.sa_mask, SIGTSTP);
_______________________________________________
lldb-commits mailing list
lldb-commits@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits
