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author | Florian Zumbiehl <florz@florz.de> | 2007-12-11 09:39:39 +0800 |
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committer | Greg Kroah-Hartman <gregkh@suse.de> | 2007-12-14 10:31:59 -0800 |
commit | 528555127d861e3470ea63b883da672cb0257f78 (patch) | |
tree | b54151bbbf3a670380aca8281c9c3c09740b8b40 | |
parent | 08a8ddbdcfe03832f7a09967752e6820bbb13a8e (diff) | |
download | lwn-528555127d861e3470ea63b883da672cb0257f78.tar.gz lwn-528555127d861e3470ea63b883da672cb0257f78.zip |
UNIX: EOF on non-blocking SOCK_SEQPACKET
[UNIX]: EOF on non-blocking SOCK_SEQPACKET
[ Upstream commit: 0a11225887fe6cbccd882404dc36ddc50f47daf9 ]
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 <sys/types.h>
| #include <unistd.h>
| #include <sys/socket.h>
| #include <sys/un.h>
| #include <fcntl.h>
| #include <string.h>
| #include <stdlib.h>
|
| 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 <florz@florz.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-rw-r--r-- | net/unix/af_unix.c | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index d70fa30d4294..ae80150233b4 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -1608,8 +1608,15 @@ 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(&u->peer_wait); |