Fix the SIGINT handlers

1. Fix a data race (g_interrupt_sent flag usage was not thread safe, signals
can be handled on arbitrary threads)

2. exit() is not signal-safe, replaced it with the signal-safe equivalent
_exit()

(This differs from the patch on Phabrictor because I had to add
`#include <atomic>` to get the definition of `std::atomic_flag`.)

patch by lemo

Differential Revision: https://reviews.llvm.org/D37926

llvm-svn: 313785

1 files changed, 4 insertions, 4 deletions

diff --git a/lldb/tools/lldb-mi/MIDriverMain.cpp b/lldb/tools/lldb-mi/MIDriverMain.cpp
index be01f1d9779..eda67782ad6 100644
--- a/lldb/tools/lldb-mi/MIDriverMain.cpp
+++ b/lldb/tools/lldb-mi/MIDriverMain.cpp
@@ -33,6 +33,7 @@
 
 // Third party headers:
 #include "lldb/API/SBHostOS.h"
+#include <atomic>
 #include <csignal>
 #include <stdio.h>
 
@@ -72,14 +73,13 @@ void sigint_handler(int vSigno) {
 #ifdef _WIN32 // Restore handler as it is not persistent on Windows
   signal(SIGINT, sigint_handler);
 #endif
-  static bool g_interrupt_sent = false;
+  static std::atomic_flag g_interrupt_sent = ATOMIC_FLAG_INIT;
   CMIDriverMgr &rDriverMgr = CMIDriverMgr::Instance();
   lldb::SBDebugger *pDebugger = rDriverMgr.DriverGetTheDebugger();
   if (pDebugger != nullptr) {
-    if (!g_interrupt_sent) {
-      g_interrupt_sent = true;
+    if (!g_interrupt_sent.test_and_set()) {
       pDebugger->DispatchInputInterrupt();
-      g_interrupt_sent = false;
+      g_interrupt_sent.clear();
     }
   }