[scudo][standalone] Fix Android logging

[cryptoad]

Summary

Zygote & children's stderr is lost, so use Bionic's provided allocation
free syslog function for outputRaw. Get rid of the mutex as it's not
vital and could cause issues with fork.

[merge_guards_bot]

Unit tests: fail. 62268 tests passed, 3 failed and 827 were skipped.

failed: Clang.CodeGenOpenCL/amdgpu-features.cl
failed: Clang.CodeGenOpenCL/builtins-amdgcn-mfma.cl
failed: Clang.SemaOpenCL/builtins-amdgcn-error-gfx908-param.cl

clang-tidy: fail. clang-tidy found 0 errors and 4 warnings. 0 of them are added as review comments below (why?).

clang-format: pass.

Build artifacts: diff.json, clang-tidy.txt, clang-format.patch, CMakeCache.txt, console-log.txt, test-results.xml

Pre-merge checks is in beta. Report issue. Please join beta or enable it for your project.

[hctim]

compiler-rt/lib/scudo/standalone/linux.cpp

173

nit: constexpr

[cryptoad]

constexpr-ing.

[eugenis]

LGTM

[merge_guards_bot]

Unit tests: fail. 62268 tests passed, 3 failed and 827 were skipped.

failed: Clang.CodeGenOpenCL/amdgpu-features.cl
failed: Clang.CodeGenOpenCL/builtins-amdgcn-mfma.cl
failed: Clang.SemaOpenCL/builtins-amdgcn-error-gfx908-param.cl

clang-tidy: fail. clang-tidy found 0 errors and 4 warnings. 0 of them are added as review comments below (why?).

clang-format: pass.

Build artifacts: diff.json, clang-tidy.txt, clang-format.patch, CMakeCache.txt, console-log.txt, test-results.xml

Pre-merge checks is in beta. Report issue. Please join beta or enable it for your project.

compiler-rt/lib/scudo/standalone/linux.cpp

#endif // defined(SYS_getrandom)
   const int FileDesc = open("/dev/urandom", O_RDONLY);
   if (FileDesc == -1)
     return false;
   ReadBytes = read(FileDesc, Buffer, Length);
   close(FileDesc);
   return (ReadBytes == static_cast<ssize_t>(Length));
 }
 
+// Allocation free syslog-like API.
+extern "C" WEAK int async_safe_write_log(int pri, const char *tag,
+                                         const char *msg);
+
 void outputRaw(const char *Buffer) {
-  static HybridMutex Mutex;
-  ScopedLock L(Mutex);
+  if (&async_safe_write_log) {
+    constexpr s32 AndroidLogInfo = 4;
+    async_safe_write_log(AndroidLogInfo, "scudo", Buffer);
+  } else {
     write(2, Buffer, strlen(Buffer));
   }
+}
 
 extern "C" WEAK void android_set_abort_message(const char *);
 
 void setAbortMessage(const char *Message) {
   if (&android_set_abort_message)
     android_set_abort_message(Message);
 }
 
 } // namespace scudo
 
 #endif // SCUDO_LINUX