From 0a11225887fe6cbccd882404dc36ddc50f47daf9 Mon Sep 17 00:00:00 2001 From: Florian Zumbiehl Date: Thu, 29 Nov 2007 23:19:23 +1100 Subject: [PATCH] [UNIX]: EOF on non-blocking SOCK_SEQPACKET I am not absolutely sure whether this actually is a bug (as in: I've got no clue what the standards say or what other implementations do), but at least I was pretty surprised when I noticed that a recv() on a non-blocking unix domain socket of type SOCK_SEQPACKET (which is connection oriented, after all) where the remote end has closed the connection returned -1 (EAGAIN) rather than 0 to indicate end of file. This is a test case: | #include | #include | #include | #include | #include | #include | #include | | int main(){ | int sock; | struct sockaddr_un addr; | char buf[4096]; | int pfds[2]; | | pipe(pfds); | sock=socket(PF_UNIX,SOCK_SEQPACKET,0); | addr.sun_family=AF_UNIX; | strcpy(addr.sun_path,"/tmp/foobar_testsock"); | bind(sock,(struct sockaddr *)&addr,sizeof(addr)); | listen(sock,1); | if(fork()){ | close(sock); | sock=socket(PF_UNIX,SOCK_SEQPACKET,0); | connect(sock,(struct sockaddr *)&addr,sizeof(addr)); | fcntl(sock,F_SETFL,fcntl(sock,F_GETFL)|O_NONBLOCK); | close(pfds[1]); | read(pfds[0],buf,sizeof(buf)); | recv(sock,buf,sizeof(buf),0); // <-- this one | }else accept(sock,NULL,NULL); | exit(0); | } If you try it, make sure /tmp/foobar_testsock doesn't exist. The marked recv() returns -1 (EAGAIN) on 2.6.23.9. Below you find a patch that fixes that. Signed-off-by: Florian Zumbiehl Signed-off-by: Herbert Xu --- net/unix/af_unix.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index e835da8fc091..060bba4567d2 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -1637,8 +1637,15 @@ static int unix_dgram_recvmsg(struct kiocb *iocb, struct socket *sock, mutex_lock(&u->readlock); skb = skb_recv_datagram(sk, flags, noblock, &err); - if (!skb) + if (!skb) { + unix_state_lock(sk); + /* Signal EOF on disconnected non-blocking SEQPACKET socket. */ + if (sk->sk_type == SOCK_SEQPACKET && err == -EAGAIN && + (sk->sk_shutdown & RCV_SHUTDOWN)) + err = 0; + unix_state_unlock(sk); goto out_unlock; + } wake_up_interruptible_sync(&u->peer_wait); -- 2.30.2