accept() doesn't block as it should in 2.3.x kernels

David Dyck (dcd@tc.fluke.com)
Sat, 11 Dec 1999 22:59:17 -0800 (PST)

The following demo code should block on the call to accept
but it doesn't in 2.3.x, (where x is 24,27,28,30,31, and 32pre2)

2.2.5, 2.2.13, and 2.2.14pre9 block as expected in accept()

I'm getting
ENOTCONN "Transport endpoint is not connected"

The man page for accept(2) leads me to believe that it should block

If no pending connections are present on the queue, and the
socket is not marked as non- blocking, accept blocks the
caller until a connection is present.

I discovered this when attempting to build perl for 2.3.32pre2
(I'm using libc5.4.44 if that matters)
and it failed in when testing lib/io_unix

I will appreciate your comments

Thanks again,
David Dyck

#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/un.h>

#define PATH "/tmp/sock-test"
int main()
{
int s;
pid_t pid;
struct sockaddr_un sa = { AF_UNIX, PATH };
char *buf[1024];

unlink(PATH); /* just in case */

s = socket(AF_UNIX, SOCK_STREAM, 0);
if (s == -1) { perror("socket"); exit(1); }

if (bind(s, (struct sockaddr *)&sa,
strlen(sa.sun_path) + sizeof (sa.sun_family)) == -1)
{ perror("bind"); exit(1); }

if (listen(s, 5) == -1) { perror("listen"); exit(1); }

{
int s2;
int sa2_len;
struct sockaddr_un sa2;

if ((s2=accept(s, (struct sockaddr *)&sa2, &sa2_len)) == -1)
{perror("accept didn't block"); exit(1); }
}

return 0;
}

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