Add new ASAN_OPTION: sleep_after_init.

Summary: As mentioned in google/sanitizers#834, suggested option can be handy for debugging.

Reviewers: kcc

Reviewed By: kcc

Subscribers: llvm-commits, kubamracek

Differential Revision: https://reviews.llvm.org/D35409

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@309854 91177308-0d34-0410-b5e6-96231b3b80d8

Author: kcc

lib/asan/asan_flags.inc

@@ -79,6 +79,10 @@ ASAN_FLAG(
     "Number of seconds to sleep between printing an error report and "
     "terminating the program. Useful for debugging purposes (e.g. when one "
     "needs to attach gdb).")
+ASAN_FLAG(
+    int, sleep_after_init, 0,
+    "Number of seconds to sleep after AddressSanitizer is initialized. "
+    "Useful for debugging purposes (e.g. when one needs to attach gdb).")
 ASAN_FLAG(bool, check_malloc_usable_size, true,
           "Allows the users to work around the bug in Nvidia drivers prior to "
           "295.*.")

lib/asan/asan_rtl.cc

@@ -484,6 +484,11 @@ static void AsanInitInternal() {
   }
 
   VReport(1, "AddressSanitizer Init done\n");
+
+  if (flags()->sleep_after_init) {
+    Report("Sleeping for %d second(s)\n", flags()->sleep_after_init);
+    SleepForSeconds(flags()->sleep_after_init);
+  }
 }
 
 // Initialize as requested from some part of ASan runtime library (interceptors,

test/asan/TestCases/sleep_after_init.c

@@ -0,0 +1,10 @@
+// RUN: %clang_asan -O2 %s -o %t
+// RUN: %env_asan_opts=sleep_after_init=1 not %run %t 2>&1 | FileCheck %s
+
+#include <stdlib.h>
+int main() {
+  // CHECK: Sleeping for 1 second
+  char *x = (char*)malloc(10 * sizeof(char));
+  free(x);
+  return x[5];
+}