Base: Add AbortFunction for logging

Add a hook to modify FATAL behavior. Add a test.

Bug: 31338270
Test: m
Test: mmma system/core/base && $ANDROID_HOST_OUT/nativetest64/libbase_test/libbase_test64
Change-Id: I966da319cda613738b3f2ccdac8c21900d6a5c72

base/include/android-base/logging.h

@@ -51,12 +51,15 @@ enum LogId {
   SYSTEM,
 };
 
-typedef std::function<void(LogId, LogSeverity, const char*, const char*,
-                           unsigned int, const char*)> LogFunction;
+using LogFunction = std::function<void(LogId, LogSeverity, const char*, const char*,
+                                       unsigned int, const char*)>;
+using AbortFunction = std::function<void(const char*)>;
 
 void KernelLogger(LogId, LogSeverity, const char*, const char*, unsigned int, const char*);
 void StderrLogger(LogId, LogSeverity, const char*, const char*, unsigned int, const char*);
 
+void DefaultAborter(const char* abort_message);
+
 #ifdef __ANDROID__
 // We expose this even though it is the default because a user that wants to
 // override the default log buffer will have to construct this themselves.
@@ -80,15 +83,22 @@ class LogdLogger {
 // The tag (or '*' for the global level) comes first, followed by a colon and a
 // letter indicating the minimum priority level we're expected to log.  This can
 // be used to reveal or conceal logs with specific tags.
-void InitLogging(char* argv[], LogFunction&& logger);
-
-// Configures logging using the default logger (logd for the device, stderr for
-// the host).
-void InitLogging(char* argv[]);
+#ifdef __ANDROID__
+#define INIT_LOGGING_DEFAULT_LOGGER LogdLogger()
+#else
+#define INIT_LOGGING_DEFAULT_LOGGER StderrLogger
+#endif
+void InitLogging(char* argv[],
+                 LogFunction&& logger = INIT_LOGGING_DEFAULT_LOGGER,
+                 AbortFunction&& aborter = DefaultAborter);
+#undef INIT_LOGGING_DEFAULT_LOGGER
 
 // Replace the current logger.
 void SetLogger(LogFunction&& logger);
 
+// Replace the current aborter.
+void SetAborter(AbortFunction&& aborter);
+
 class ErrnoRestorer {
  public:
   ErrnoRestorer()

base/logging.cpp

@@ -173,6 +173,8 @@ static auto& gLogger = *new LogFunction(LogdLogger());
 static auto& gLogger = *new LogFunction(StderrLogger);
 #endif
 
+static auto& gAborter = *new AbortFunction(DefaultAborter);
+
 static bool gInitialized = false;
 static LogSeverity gMinimumLogSeverity = INFO;
 static auto& gProgramInvocationName = *new std::unique_ptr<std::string>();
@@ -247,6 +249,15 @@ void StderrLogger(LogId, LogSeverity severity, const char*, const char* file,
           severity_char, timestamp, getpid(), GetThreadId(), file, line, message);
 }
 
+void DefaultAborter(const char* abort_message) {
+#ifdef __ANDROID__
+  android_set_abort_message(abort_message);
+#else
+  UNUSED(abort_message);
+#endif
+  abort();
+}
+
 
 #ifdef __ANDROID__
 LogdLogger::LogdLogger(LogId default_log_id) : default_log_id_(default_log_id) {
@@ -284,12 +295,10 @@ void LogdLogger::operator()(LogId id, LogSeverity severity, const char* tag,
 }
 #endif
 
-void InitLogging(char* argv[], LogFunction&& logger) {
+void InitLogging(char* argv[], LogFunction&& logger, AbortFunction&& aborter) {
   SetLogger(std::forward<LogFunction>(logger));
-  InitLogging(argv);
-}
+  SetAborter(std::forward<AbortFunction>(aborter));
 
-void InitLogging(char* argv[]) {
   if (gInitialized) {
     return;
   }
@@ -349,6 +358,11 @@ void SetLogger(LogFunction&& logger) {
   gLogger = std::move(logger);
 }
 
+void SetAborter(AbortFunction&& aborter) {
+  lock_guard<mutex> lock(logging_lock);
+  gAborter = std::move(aborter);
+}
+
 static const char* GetFileBasename(const char* file) {
   // We can't use basename(3) even on Unix because the Mac doesn't
   // have a non-modifying basename.
@@ -450,10 +464,7 @@ LogMessage::~LogMessage() {
 
   // Abort if necessary.
   if (data_->GetSeverity() == FATAL) {
-#ifdef __ANDROID__
-    android_set_abort_message(msg.c_str());
-#endif
-    abort();
+    gAborter(msg.c_str());
   }
 }
 

base/logging_test.cpp

@@ -330,3 +330,23 @@ TEST(logging, UNIMPLEMENTED) {
   UNIMPLEMENTED(ERROR);
   CheckMessage(cap, android::base::ERROR, expected.c_str());
 }
+
+static void NoopAborter(const char* msg ATTRIBUTE_UNUSED) {
+  LOG(ERROR) << "called noop";
+}
+
+TEST(logging, LOG_FATAL_NOOP_ABORTER) {
+  {
+    android::base::SetAborter(NoopAborter);
+
+    android::base::ScopedLogSeverity sls(android::base::ERROR);
+    CapturedStderr cap;
+    LOG(FATAL) << "foobar";
+    CheckMessage(cap, android::base::FATAL, "foobar");
+    CheckMessage(cap, android::base::ERROR, "called noop");
+
+    android::base::SetAborter(android::base::DefaultAborter);
+  }
+
+  ASSERT_DEATH({SuppressAbortUI(); LOG(FATAL) << "foobar";}, "foobar");
+}