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Commit 8a74190b authored by David Brazdil's avatar David Brazdil
Browse files

rpc_binder: Properly shut down on socketpair() EOF 

FdTrigger::triggerablePoll returns OK on POLLIN (higher priority)
and DEAD_OBJECT on POLLHUP (lower priority). Unlike INET or vsock,
socketpair() sockets trigger POLLIN|POLLHUP on EOF and EOF is detected
by recvmsg() returning zero bytes.

Adjust the server accept loop to take this into account and correctly
break out of the loop.

Bug: 250685929
Test: cleanly shut down UDS bootstrap RpcServer
Change-Id: I56d6a67373f16b5b1bdc167de94a7252bedca8e2
parent 8a1a5f8d

libs/binder/RpcServer.cpp

+10 −3
Original line number Diff line number Diff line
@@ -204,11 +204,15 @@ status_t RpcServer::recvmsgSocketConnection(const RpcServer& server, RpcTranspor 
    iovec iov{&zero, sizeof(zero)};

    std::vector<std::variant<base::unique_fd, base::borrowed_fd>> fds;



    if (receiveMessageFromSocket(server.mServer, &iov, 1, &fds) < 0) {

    ssize_t num_bytes = receiveMessageFromSocket(server.mServer, &iov, 1, &fds);

    if (num_bytes < 0) {

        int savedErrno = errno;

        ALOGE("Failed recvmsg: %s", strerror(savedErrno));

        return -savedErrno;

    }

    if (num_bytes == 0) {

        return DEAD_OBJECT;

    }

    if (fds.size() != 1) {

        ALOGE("Expected exactly one fd from recvmsg, got %zu", fds.size());

        return -EINVAL;
@@ -243,7 +247,10 @@ void RpcServer::join() { 
        socklen_t addrLen = addr.size();



        RpcTransportFd clientSocket;

        if (mAcceptFn(*this, &clientSocket) != OK) {

        if ((status = mAcceptFn(*this, &clientSocket)) != OK) {

            if (status == DEAD_OBJECT)

                break;

            else

                continue;

        }