[ASan] Add stress test for asynch signals in nonhalting mode.

[ygribov]

Summary

This patch adds a stress test for asynch signals in nonhalting ASan. This is an addition to http://reviews.llvm.org/D12318

[kcc]

LGTM

compiler-rt/trunk/test/asan/TestCases/Linux/halt_on_error-signals.c

+// Test interaction of Asan recovery mode with asynch signals.
+//
+// RUN: %clang_asan -fsanitize-recover=address %s -o %t
+//
+// RUN: rm -f %t.log
+// RUN: env ASAN_OPTIONS=halt_on_error=false %run %t 1000 >%t.log 2>&1 || true
+// RUN: FileCheck %s < %t.log
+// Collision will almost always get triggered but we still need to check the unlikely case:
+// RUN: FileCheck --check-prefix=CHECK-COLLISION %s < %t.log || FileCheck --check-prefix=CHECK-NO-COLLISION %s < %t.log
+//
+// REQUIRES: stable-runtime
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <pthread.h>
+#include <time.h>
+#include <signal.h>
+
+#include <sanitizer/asan_interface.h>
+
+void random_sleep(unsigned *seed) {
+  struct timespec delay = { 0, rand_r(seed) * 1000000 };
+  nanosleep(&delay, 0);
+}
+
+volatile char bad[2] = {1, };
+
+void error() {
+  // CHECK-COLLISION: AddressSanitizer: nested bug in the same thread, aborting
+  // CHECK: AddressSanitizer: use-after-poison
+  volatile int idx = 0;
+  bad[idx] = 0;
+}
+
+size_t niter = 10;
+pthread_t sender_tid, receiver_tid;
+
+void *sender(void *arg) {
+  unsigned seed = 0;
+  for (size_t i = 0; i < niter; ++i) {
+    random_sleep(&seed);
+    pthread_kill(receiver_tid, SIGUSR1);
+  }
+  return 0;
+}
+
+void handler(int sig) {
+  // Expect error collisions here
+  error();
+}
+
+void *receiver(void *arg) {
+  unsigned seed = 1;
+  for (size_t i = 0; i < niter; ++i) {
+    random_sleep(&seed);
+    // And here
+    error();
+  }
+  return 0;
+}
+
+int main(int argc, char **argv) {
+  if (argc != 2) {
+    fprintf(stderr, "Syntax: %s niter\n", argv[0]);
+    exit(1);
+  }
+
+  niter = (size_t)strtoul(argv[1], 0, 0);
+
+  struct sigaction sa;
+  memset(&sa, 0, sizeof(sa));
+  sa.sa_handler = handler;
+  sa.sa_flags = SA_NODEFER; // Enable nested handlers to add more stress
+  if (0 != sigaction(SIGUSR1, &sa, 0)) {
+    fprintf(stderr, "Failed to set sighandler\n");
+    exit(1);
+  }
+
+  __asan_poison_memory_region(&bad, sizeof(bad)); 
+
+  if (0 != pthread_create(&receiver_tid, 0, receiver, 0)) {
+    fprintf(stderr, "Failed to start receiver thread\n");
+    exit(1);
+  }
+
+  if (0 != pthread_create(&sender_tid, 0, sender, 0)) {
+    fprintf(stderr, "Failed to start sender thread\n");
+    exit(1);
+  }
+
+  if (0 != pthread_join(receiver_tid, 0)) {
+    fprintf(stderr, "Failed to wait receiver thread\n");
+    exit(1);
+  }
+
+  if (0 != pthread_join(sender_tid, 0)) {
+    fprintf(stderr, "Failed to wait sender thread\n");
+    exit(1);
+  }
+
+  // CHECK-NO-COLLISION: All threads terminated
+  printf("All threads terminated\n");
+
+  return 0;
+}