From 7149ca04ad8cce1171ec99e78db40d4b84d655bd Mon Sep 17 00:00:00 2001
From: Kuba Mracek <mracek@apple.com>
Date: Wed, 5 Jul 2017 22:17:44 +0000
Subject: [PATCH] [tsan] Use pthread_sigmask instead of sigprocmask to block
 signals in a thread on Darwin

On Darwin, sigprocmask changes the signal mask for the entire process. This has some unwanted consequences, because e.g. internal_start_thread wants to disable signals only in the current thread (to make the new thread inherit the signal mask), which is currently broken on Darwin. This patch switches to pthread_sigmask.

Differential Revision: https://reviews.llvm.org/D35016

llvm-svn: 307212
---
 .../lib/sanitizer_common/sanitizer_mac.cc     |  3 +-
 .../test/tsan/Darwin/signals-blocked.cc       | 75 +++++++++++++++++++
 2 files changed, 77 insertions(+), 1 deletion(-)
 create mode 100644 compiler-rt/test/tsan/Darwin/signals-blocked.cc

diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_mac.cc b/compiler-rt/lib/sanitizer_common/sanitizer_mac.cc
index b48238106dd9..2a13fee0518f 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_mac.cc
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_mac.cc
@@ -191,7 +191,8 @@ void internal_sigfillset(__sanitizer_sigset_t *set) { sigfillset(set); }
 
 uptr internal_sigprocmask(int how, __sanitizer_sigset_t *set,
                           __sanitizer_sigset_t *oldset) {
-  return sigprocmask(how, set, oldset);
+  // Don't use sigprocmask here, because it affects all threads.
+  return pthread_sigmask(how, set, oldset);
 }
 
 // Doesn't call pthread_atfork() handlers (but not available on 10.6).
diff --git a/compiler-rt/test/tsan/Darwin/signals-blocked.cc b/compiler-rt/test/tsan/Darwin/signals-blocked.cc
new file mode 100644
index 000000000000..209dc2229ff6
--- /dev/null
+++ b/compiler-rt/test/tsan/Darwin/signals-blocked.cc
@@ -0,0 +1,75 @@
+// RUN: %clangxx_tsan %s -o %t && %run %t 2>&1 | FileCheck %s
+
+#include <pthread.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <signal.h>
+#include <sys/types.h>
+#include <sys/time.h>
+#include <unistd.h>
+#include <errno.h>
+
+volatile bool signal_delivered;
+
+static void handler(int sig) {
+  if (sig == SIGALRM)
+    signal_delivered = true;
+}
+
+static void* thr(void *p) {
+  sigset_t sigset;
+  sigemptyset(&sigset);
+  sigaddset(&sigset, SIGALRM);
+  int ret = pthread_sigmask(SIG_UNBLOCK, &sigset, NULL);
+  if (ret) abort();
+
+  struct sigaction act = {};
+  act.sa_handler = &handler;
+  if (sigaction(SIGALRM, &act, 0)) {
+    perror("sigaction");
+    exit(1);
+  }
+
+  itimerval t;
+  t.it_value.tv_sec = 0;
+  t.it_value.tv_usec = 10000;
+  t.it_interval = t.it_value;
+  if (setitimer(ITIMER_REAL, &t, 0)) {
+    perror("setitimer");
+    exit(1);
+  }
+
+  while (!signal_delivered) {
+    usleep(1000);
+  }
+
+  t.it_value.tv_usec = 0;
+  if (setitimer(ITIMER_REAL, &t, 0)) {
+    perror("setitimer");
+    exit(1);
+  }
+
+  fprintf(stderr, "SIGNAL DELIVERED\n");
+
+  return 0;
+}
+
+int main() {
+  sigset_t sigset;
+  sigemptyset(&sigset);
+  sigaddset(&sigset, SIGALRM);
+  int ret = pthread_sigmask(SIG_BLOCK, &sigset, NULL);
+  if (ret) abort();
+
+  pthread_t th;
+  pthread_create(&th, 0, thr, 0);
+  pthread_join(th, 0);
+
+  fprintf(stderr, "DONE\n");
+  return 0;
+}
+
+// CHECK-NOT: WARNING: ThreadSanitizer:
+// CHECK: SIGNAL DELIVERED
+// CHECK: DONE
+// CHECK-NOT: WARNING: ThreadSanitizer: