Merge "Ueventd: Fix a corner case in ReadUevent() that triggers duplicate firmware loading." (e1227011) · Commits · e / os / android_system_core

init/uevent_listener.cpp

+12 −8

Original line number	Diff line number	Diff line
		@@ -95,20 +95,18 @@ UeventListener::UeventListener(size_t uevent_socket_rcvbuf_size) {
		fcntl(device_fd_, F_SETFL, O_NONBLOCK);
		}

		bool UeventListener::ReadUevent(Uevent* uevent) const {
		ReadUeventResult UeventListener::ReadUevent(Uevent* uevent) const {
		char msg[UEVENT_MSG_LEN + 2];
		int n = uevent_kernel_multicast_recv(device_fd_, msg, UEVENT_MSG_LEN);
		if (n <= 0) {
		if (errno != EAGAIN && errno != EWOULDBLOCK) {
		PLOG(ERROR) << "Error reading from Uevent Fd";
		}
		return false;
		return ReadUeventResult::kFailed;
		}
		if (n >= UEVENT_MSG_LEN) {
		LOG(ERROR) << "Uevent overflowed buffer, discarding";
		// Return true here even if we discard as we may have more uevents pending and we
		// want to keep processing them.
		return true;
		return ReadUeventResult::kInvalid;
		}

		msg[n] = '\0';
		@@ -116,7 +114,7 @@ bool UeventListener::ReadUevent(Uevent* uevent) const {

		ParseEvent(msg, uevent);

		return true;
		return ReadUeventResult::kSuccess;
		}

		// RegenerateUevents*() walks parts of the /sys tree and pokes the uevent files to cause the kernel
		@@ -137,7 +135,10 @@ ListenerAction UeventListener::RegenerateUeventsForDir(DIR* d,
		close(fd);

		Uevent uevent;
		while (ReadUevent(&uevent)) {
		ReadUeventResult result;
		while ((result = ReadUevent(&uevent)) != ReadUeventResult::kFailed) {
		// Skip processing the uevent if it is invalid.
		if (result == ReadUeventResult::kInvalid) continue;
		if (callback(uevent) == ListenerAction::kStop) return ListenerAction::kStop;
		}
		}
		@@ -212,7 +213,10 @@ void UeventListener::Poll(const ListenerCallback& callback,
		// We're non-blocking, so if we receive a poll event keep processing until
		// we have exhausted all uevent messages.
		Uevent uevent;
		while (ReadUevent(&uevent)) {
		ReadUeventResult result;
		while ((result = ReadUevent(&uevent)) != ReadUeventResult::kFailed) {
		// Skip processing the uevent if it is invalid.
		if (result == ReadUeventResult::kInvalid) continue;
		if (callback(uevent) == ListenerAction::kStop) return;
		}
		}

init/uevent_listener.h

+7 −1

Original line number	Diff line number	Diff line
		@@ -37,6 +37,12 @@ enum class ListenerAction {
		kContinue, // Continue regenerating uevents as we haven't seen the one(s) we're interested in.
		};

		enum class ReadUeventResult {
		kSuccess = 0, // Uevent was successfully read.
		kFailed, // Uevent reading has failed.
		kInvalid, // An Invalid Uevent was read (like say, the msg received is >= UEVENT_MSG_LEN).
		};

		using ListenerCallback = std::function<ListenerAction(const Uevent&)>;

		class UeventListener {
		@@ -50,7 +56,7 @@ class UeventListener {
		const std::optional<std::chrono::milliseconds> relative_timeout = {}) const;

		private:
		bool ReadUevent(Uevent* uevent) const;
		ReadUeventResult ReadUevent(Uevent* uevent) const;
		ListenerAction RegenerateUeventsForDir(DIR* d, const ListenerCallback& callback) const;

		android::base::unique_fd device_fd_;