[compiler-rt] Don't reset non-default user handler if allow_user_segv_handler is true.

Reviewers: eugenis, kcc

Subscribers: kubamracek, llvm-commits

Differential Revision: https://reviews.llvm.org/D32457

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@304039 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 19 insertions, 1 deletions

diff --git a/lib/sanitizer_common/sanitizer_posix_libcdep.cc b/lib/sanitizer_common/sanitizer_posix_libcdep.cc
index 21178c46a..791ff4481 100644
--- a/lib/sanitizer_common/sanitizer_posix_libcdep.cc
+++ b/lib/sanitizer_common/sanitizer_posix_libcdep.cc
@@ -189,7 +189,25 @@ void UnsetAlternateSignalStack() {
 
 static void MaybeInstallSigaction(int signum,
                                   SignalHandlerType handler) {
-  if (GetHandleSignalMode(signum) == kHandleSignalNo) return;
+  switch (GetHandleSignalMode(signum)) {
+    case kHandleSignalNo:
+      return;
+    case kHandleSignalYes: {
+      struct sigaction sigact;
+      internal_memset(&sigact, 0, sizeof(sigact));
+      CHECK_EQ(0, internal_sigaction(signum, nullptr, &sigact));
+      if (sigact.sa_flags & SA_SIGINFO) {
+        if (sigact.sa_sigaction) return;
+      } else {
+        if (sigact.sa_handler != SIG_DFL && sigact.sa_handler != SIG_IGN &&
+            sigact.sa_handler != SIG_ERR)
+          return;
+      }
+      break;
+    }
+    case kHandleSignalExclusive:
+      break;
+  }
 
   struct sigaction sigact;
   internal_memset(&sigact, 0, sizeof(sigact));