Mac: Enable Mach exception handler by default

src/trusted/service_runtime/osx/mach_exception_handler.c

Index: src/trusted/service_runtime/osx/mach_exception_handler.c
diff --git a/src/trusted/service_runtime/osx/mach_exception_handler.c b/src/trusted/service_runtime/osx/mach_exception_handler.c
index 3cbab30aea467c029509466bb7d90d74162ca2cb..2c0c7d0d46636bf3b43c6dda67c01cadc5af8023 100644
--- a/src/trusted/service_runtime/osx/mach_exception_handler.c
+++ b/src/trusted/service_runtime/osx/mach_exception_handler.c
@@ -44,7 +44,7 @@ boolean_t nacl_exc_server(
     mach_msg_header_t *OutHeadP);
 
 
-/* Exception types to intercept. */
+/* Exception types to intercept.  This should be a superset of what Breakpad handles... */
 #define NACL_MACH_EXCEPTION_MASK \
     (EXC_MASK_BAD_ACCESS | \
      EXC_MASK_BAD_INSTRUCTION | \
@@ -406,6 +406,16 @@ static kern_return_t ForwardException(
 }
 
 
+static void ReportCrash(int exception_type, int is_untrusted) {
+  char buf[128];
+  int len = snprintf(buf, sizeof(buf),
+                     "\n** Mach exception %d from %s code\n",
+                     exception_type,
+                     is_untrusted ? "untrusted" : "trusted");
+  write(2, buf, len);
+}
+
+
 kern_return_t nacl_catch_exception_raise(
     mach_port_t exception_port,
     mach_port_t thread,
@@ -498,6 +508,8 @@ kern_return_t nacl_catch_exception_raise_state_identity (
     return MACH_RCV_PORT_DIED;
   }
 
+  ReportCrash(exception, is_untrusted);
+
   /*
    * Don't forward if the crash is untrusted, but unhandled.
    * (As we don't want things like Breakpad handling the crash.)