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Commit acda4251 authored by Tom Cherry's avatar Tom Cherry Committed by Automerger Merge Worker
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Merge "Ueventd: Fix a corner case in ReadUevent() that triggers duplicate... 

Merge "Ueventd: Fix a corner case in ReadUevent() that triggers duplicate firmware loading." am: e1227011 am: 578bfe94

Original change: https://android-review.googlesource.com/c/platform/system/core/+/1366617

Change-Id: Ib5c868d1da20fdcb8b0b0642eba7c707abb1ea1e
parents 5c9dbc71 578bfe94

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_;