[compiler-rt] [sanitizer-common] [Darwin] Provide warnings for common sandbox issues (PR #165907)

[Dan Blackwell via llvm-commits]

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@@ -960,7 +960,18 @@ static void DisableMmapExcGuardExceptions() {
       RTLD_DEFAULT, "task_set_exc_guard_behavior");
   if (set_behavior == nullptr) return;
   const task_exc_guard_behavior_t task_exc_guard_none = 0;
-  set_behavior(mach_task_self(), task_exc_guard_none);
+  kern_return_t res = set_behavior(mach_task_self(), task_exc_guard_none);
+  if (res != KERN_SUCCESS) {
+    Report(
+        "WARN: task_set_exc_guard_behavior returned %d (%s), "
+        "mmap may fail unexpectedly.\n",
+        res, mach_error_string(res));
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DanBlackwell wrote:

Thanks for adding the mach_error_string call here

https://github.com/llvm/llvm-project/pull/165907