linux/net/unix
Florian Zumbiehl 0a11225887 [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 <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>
2007-11-29 23:19:23 +11:00
..
af_unix.c [UNIX]: EOF on non-blocking SOCK_SEQPACKET 2007-11-29 23:19:23 +11:00
garbage.c [AF_UNIX]: Convert socks to unix_socks in scan_inflight, not in callbacks 2007-11-10 22:07:13 -08:00
Kconfig
Makefile
sysctl_net_unix.c