git-remote-fd problem

Hi! I have problem with using git-remote-fd function. I create two local pipes for communication for locally running process git pull. Then I start git-upload-pack on remote side (this process is started in different part of my code and it works correctly). Communication runs successfully and when remote side finish, I want to close local pipes to finish local process. I call close function to all of these pipes, but unfortunatelly local process doesnt finish (in this moment transfered data aresaved in /.git/object/pack folder in .pack files) and hanging on. But if I kill child of this local process, downloaded files are unpacked and files are created sucessfully. I think this way is not so correct. Can someone help me and tell me what am I doing wrong? Thank You. Code is in an attachement (its part of big system).

    #create local pipes for cimmunication
    local_r, local_w = os.pipe()
    remote_r, remote_w = os.pipe()

    #start local git process
    client_process = subprocess.Popen("/usr/bin/git pull fd::{0},{1}".format(remote_r, local_w,), shell=True)
    
    #start git process on remote side 
    remoteGit = proc.runDaemon("sudo git-upload-pack /tmp/testGit")

    #set
    epoll = select.epoll()

    epoll.register(local_r, select.EPOLLIN)
    #register from remote side
    epoll.register(proc.fd, select.EPOLLIN)

    while True:
        events = epoll.poll(1)

        for fd, event in events:
            if fd == local_r:
                #event on local process
                if event & select.EPOLLIN:
                    rd = os.read(local_r, 5000)

                    if rd:
                        #write data to remote side
                        remoteGit.writeToChannel(rd)
                    else:
                        proc.writeError("Local socket write error")
                        client_process.kill()
                        return 1
                else:
                    proc.writeError("Local socket error")
                    client_process.kill()
                    return 1

            else:
                if event & select.EPOLLIN:
                    #get all data from remote side
                    data = remoteGit.getAll()
                    remoteGit.stderrWrite()

                    if not data:
                        #remote side finished - close local pipes - local process wouldnt finish 
                        os.close(local_r) 
                        os.close(local_w)
                        os.close(remote_r)
                        os.close(remote_w)

                        #get local process pid and kill his child to finish git-remote-fd
                        gitPid = psutil.Process(client_process.pid).children()[0].pid
                        os.kill(gitPid, signal.SIGTERM)

                        return 0

                    want = len(data)
                    writed = 0
                    offset = 0

                    while(writed != want):
                        #write data from remote side to local process
                        wr = os.write(remote_w, data[offset:])

                        if(wr < 0):
                            proc.writeError("Local socket write error")

                            return 1

                        writed += wr
                        offset += wr

                else:
                    proc.writeError("Remote socket error")
                    client_process.kill()
                    return -1

On Wed, Sep 10, 2014 at 03:29:00PM +0200, Jiri Sevcik wrote:

The remote-fd expects the transport to pass half-closes. So you can't close all at once.

Let there be pipes W and R and transport connection C.

- W-read should be closed after being passed to remote-fd.
- R-write should be closed after being passed to remote-fd.
- Upon receiving "no more data" from C, close W-write.
- Upon receiving EOF from R-read, close it and signal "no more data"
  to C.

If you have server end, the same applies, but with remote-fd replaced by upload-pack/upload-archive/receive-pack.

-Ilari

Hi, I followed your advices, correctly close pipes but git clone still doesnt finish and hanging on. Code is in an attachement (its part of big system).

    #create pipes
    w_pipe = os.pipe()
    r_pipe = os.pipe()

    client_process = subprocess.Popen("/usr/bin/git clone fd::{0},{1} /tmp/gittest".format(r_pipe[0], w_pipe[1]), shell=True)
    #closing pipes
    os.close(r_pipe[0]) 
    os.close(w_pipe[1])

    epoll = select.epoll()
    epoll.register(w_pipe[0], select.EPOLLIN)
    epoll.register(proc.fd, select.EPOLLIN)

    remoteGit = proc.runDaemon("git-upload-pack /tmp/testgit")
    
    while True:
        events = epoll.poll(1)

        for fd, event in events:
            if fd == w_pipe[0]:
                if event & select.EPOLLIN:
                    rd = os.read(w_pipe[0], 10000)
                    if rd:
                        #write data to remove git server
                        remoteGit.writeToChannel(rd)
                    else:
                        proc.writeError("Local socket write error")
                        return 1
                else:
                    proc.writeError("Local socket error")
                    return 1

            elif fd == proc.fd:
                if event & select.EPOLLIN:
                    #read data from remote git server
                    data = remoteGit.getAll()
                    remoteGit.stderrWrite()

                    if not data:
                        #remote server send EOF, close local pipe
                        #but git clone is still running
                        os.close(r_pipe[1])
                        return 0
                    
                    want = len(data)

                    writed = 0
                    offset = 0
                    
                    while(writed != want):
                        #write data from remote git server to local pipe
                        wr = os.write(r_pipe[1], data[offset:])

                        if(wr < 0):
                            return 1

                        writed += wr
                        offset += wr

                else:
                    return -1              

On Mon, Dec 29, 2014 at 10:47:58AM +0100, Jiri Sevcik wrote:

Few ideas:
- Check that git clone (and its subprocesses) don't inherit
w_pipe[0] (/proc/<pid>/fd on Linux might be handy). If they do, that
prevents this program from closing the pipe.

- Setting environment variable GIT_TRANSLOOP_DEBUG to 1 might make
  git spew lots of messages to stderr about reads, writes and closes.

-Ilari