Don't call exit() from atexit handlers on Darwin

Summary:
Calling exit() from an atexit handler is undefined behavior.
On Linux, it's unavoidable, since we cannot intercept exit (_exit isn't called
if a user program uses return instead of exit()), and I haven't
seen it cause issues regardless.

However, on Darwin, I have a fairly complex internal test that hangs roughly
once in every 300 runs after leak reporting finishes, which is resolved with
this patch, and is presumably due to the undefined behavior (since the Die() is
the only thing that happens after the end of leak reporting).

In addition, this is the way TSan works as well, where an atexit handler+Die()
is used on Linux, and an _exit() interceptor is used on Darwin. I'm not sure if it's
intentionally structured that way in TSan, since TSan sets up the atexit handler and the
_exit() interceptor on both platforms, but I have observed that on Darwin, only the
_exit() interceptor is used, and on Linux the atexit handler is used.

There is some additional related discussion here: https://reviews.llvm.org/D35085

Reviewers: alekseyshl, kubamracek

Subscribers: eugenis, vsk, llvm-commits

Differential Revision: https://reviews.llvm.org/D35513

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@308353 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 4 insertions, 0 deletions

diff --git a/lib/asan/asan_interceptors.cc b/lib/asan/asan_interceptors.cc
index ed12a9ac9..34ca22b86 100644
--- a/lib/asan/asan_interceptors.cc
+++ b/lib/asan/asan_interceptors.cc
@@ -178,6 +178,10 @@ void SetThreadName(const char *name) {
 }
 
 int OnExit() {
+  if (CAN_SANITIZE_LEAKS && common_flags()->detect_leaks &&
+      __lsan::HasReportedLeaks()) {
+    return common_flags()->exitcode;
+  }
   // FIXME: ask frontend whether we need to return failure.
   return 0;
 }