Make logger thread safe (#885)

libsrc/utils/DefaultSignalHandler.cpp

@@ -16,6 +16,35 @@
 
 namespace DefaultSignalHandler
 {
+struct Signal
+{
+	int          number;
+	const char * name;
+};
+
+const Signal ALL_SIGNALS[] = {
+	{ SIGABRT, "SIGABRT" },
+	{ SIGBUS,  "SIGBUS"  },
+	{ SIGFPE,  "SIGFPE"  },
+	{ SIGILL,  "SIGILL"  },
+	{ SIGSEGV, "SIGSEGV" },
+	{ SIGTERM, "SIGTERM" },
+	{ SIGHUP,  "SIGHUP"  },
+	{ SIGINT,  "SIGINT"  },
+	{ SIGPIPE, "SIGPIPE" },
+};
+
+void write_to_stderr(const char* data, size_t size)
+{
+	int res = write(STDERR_FILENO, data, size);
+
+	Q_UNUSED(res);
+}
+
+void write_to_stderr(const char* data)
+{
+	write_to_stderr(data, strlen(data));
+}
 
 std::string decipher_trace(const std::string &trace)
 {
@@ -70,26 +99,48 @@ void print_trace()
 	free(symbols);
 }
 
+void install_default_handler(int signum)
+{
+	struct sigaction action{};
+	sigemptyset(&action.sa_mask);
+	action.sa_handler = SIG_DFL;
+	(void)sigaction(signum, &action, nullptr);
+}
+
 /* Note that this signal handler is not async signal safe !
  * Ideally a signal handler should only flip a bit and defer
  * heavy work to some kind of bottom-half processing. */
 void signal_handler(int signum, siginfo_t * /*info*/, void * /*context*/)
 {
-	Logger* log = Logger::getInstance("SIGNAL");
+	const char * name = "UNKNOWN SIGNAL";
 
-	char *name = strsignal(signum);
-	if (name)
-	{
-		Info(log, "Signal received : %s", name);
+	for (const auto& s : ALL_SIGNALS) {
+		if (s.number == signum) {
+			name = s.name;
+			break;
+		}
 	}
 
+	write_to_stderr("\n");
+	write_to_stderr("Hyperion caught signal :");
+	write_to_stderr(name);
+	write_to_stderr("\n");
+
+	/* Anything below here is unsafe ! */
+
 	switch(signum)
 	{
+	case SIGBUS:
 	case SIGSEGV:
 	case SIGABRT:
 	case SIGFPE :
 		print_trace();
-		exit(1);
+
+		/* Don't catch our own signal */
+		install_default_handler(signum);
+
+		kill(getpid(), signum);
+		return;
 	case SIGINT :
 	case SIGTERM:
 	case SIGPIPE:
@@ -101,10 +152,7 @@ void signal_handler(int signum, siginfo_t * /*info*/, void * /*context*/)
 		QMetaObject::invokeMethod(qApp, "quit", Qt::QueuedConnection);
 
 		// Reset signal handler to default (in case this handler is not capable of stopping)
-		struct sigaction action{};
-		action.sa_handler = SIG_DFL;
-		sigaction(signum, &action, nullptr);
-
+		install_default_handler(signum);
 	}
 }
 
@@ -116,17 +164,20 @@ namespace DefaultSignalHandler
 void install()
 {
 #ifndef _WIN32
-	struct sigaction action{};
-	action.sa_sigaction = signal_handler;
-	action.sa_flags = SA_RESTART | SA_SIGINFO;
+	Logger* log = Logger::getInstance("CORE");
 
-	sigaction(SIGHUP , &action, nullptr);
-	sigaction(SIGFPE , &action, nullptr);
-	sigaction(SIGINT , &action, nullptr);
-	sigaction(SIGTERM, &action, nullptr);
-	sigaction(SIGABRT, &action, nullptr);
-	sigaction(SIGSEGV, &action, nullptr);
-	sigaction(SIGPIPE, &action, nullptr);
+	struct sigaction action{};
+	sigemptyset(&action.sa_mask);
+	action.sa_sigaction = signal_handler;
+	action.sa_flags |= SA_SIGINFO;
+
+	for (const auto& s : ALL_SIGNALS)
+	{
+		if (sigaction(s.number, &action, nullptr)!= 0)
+		{
+			Error(log, "Failed to install handler for %s]\n", s.name);
+		}
+	}
 #endif // _WIN32
 }
 } // namespace DefaultSignalHandler