[libcxx-commits] [libcxx] [libc++][hardening] Introduce a dylib function to log hardening errors. (PR #148266)

[Konstantin Varlamov via libcxx-commits]

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@@ -0,0 +1,61 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <__config>
+#include <__log_error>
+#include <cstdio>
+
+#ifdef __BIONIC__
+#  include <syslog.h>
+extern "C" void android_set_abort_message(const char* msg);
+#endif // __BIONIC__
+
+#if defined(__APPLE__) && __has_include(<os/reason_private.h>)
+#  include <os/reason_private.h>
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+namespace {
+
+void log_security_failure(const char* message) noexcept {
+  // On Apple platforms, use the `os_fault_with_payload` OS function that simulates a crash.
+#if defined(__APPLE__) && __has_include(<os/reason_private.h>)
+  os_fault_with_payload(
+      /*reason_namespace=*/OS_REASON_SECURITY,
+      /*reason_code=*/0,
+      /*payload=*/nullptr,
+      /*payload_size=*/0,
+      /*reason_string=*/message,
+      /*reason_flags=*/0);
+
+#elif defined(__BIONIC__)
+  // Show error in tombstone.
+  android_set_abort_message(message);
+
+  // Show error in logcat.
+  openlog("libc++", 0, 0);
+  syslog(LOG_CRIT, "%s", message);
+  closelog();
+
+#else
+  fprintf(stderr, "%s", message);
+#endif
+}
+
+} // namespace
+
+void __log_error(_LogErrorReason reason, const char* message) noexcept {
+  switch (reason) {
+  case _LogErrorReason::_HardeningFailure:
+  default:
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var-const wrote:

@ldionne We need to make sure the default is reasonable and backward-compatible (IIUC, we will have the situation where the enum is newer than the dylib and the dylib has to handle a value it doesn't understand).

https://github.com/llvm/llvm-project/pull/148266