Mac: Ensure signal handlers run on the sigaltstack() stack

This is generally safer.  Using SA_ONSTACK for signal handlers
whenever possible is good practice and can't hurt.

BUG=https://code.google.com/p/nativeclient/issues/detail?id=3265
TEST=none

Review URL: https://codereview.chromium.org/12047034

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@178706 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 14 insertions, 2 deletions

diff --git a/base/mac/os_crash_dumps.cc b/base/mac/os_crash_dumps.cc
index e82fd73..e6b0996 100644
--- a/base/mac/os_crash_dumps.cc
+++ b/base/mac/os_crash_dumps.cc
@@ -8,6 +8,7 @@
 #include <unistd.h>
 
 #include "base/basictypes.h"
+#include "base/logging.h"
 
 namespace base {
 namespace mac {
@@ -37,8 +38,19 @@ void DisableOSCrashDumps() {
   };
 
   // For all these signals, just wire things up so we exit immediately.
-  for (size_t i = 0; i < arraysize(signals_to_intercept); ++i)
-    signal(signals_to_intercept[i], ExitSignalHandler);
+  for (size_t i = 0; i < arraysize(signals_to_intercept); ++i) {
+    struct sigaction act = {};
+    act.sa_handler = ExitSignalHandler;
+
+    // It is better to allow the signal handler to run on the stack
+    // registered with sigaltstack(), if one is present.
+    act.sa_flags = SA_ONSTACK;
+
+    if (sigemptyset(&act.sa_mask) != 0)
+      DLOG_ERRNO(FATAL) << "sigemptyset() failed";
+    if (sigaction(signals_to_intercept[i], &act, NULL) != 0)
+      DLOG_ERRNO(FATAL) << "sigaction() failed";
+  }
 }
 
 }  // namespace mac