bug in pipe() and pipe2()
Eric Blake
eblake@redhat.com
Wed Jun 29 21:30:00 GMT 2011
I was testing the behavior when pipe() fails, in order to propose an
update to POSIX wording: http://austingroupbugs.net/view.php?id=467
However, cygwin's pipe implementation dumps core when it runs out of
fds, so I could not definitively state whether cygwin properly leaves
the fd array unchanged on error, the way Linux does. According to a gdb
run and while using stock 1.7.9 cygwin1.dll, the crash is in
fhandler_pipe::create().
#define _POSIX_C_SOURCE 200811L
#include <unistd.h>
#include <string.h>
#include <stdio.h>
#include <errno.h>
int
main (int argc, char **argv)
{
int i = 0;
while (1) {
int fd[2] = {-2,-3};
int err = pipe(fd);
if (err) {
printf ("iteration %d, pipe returned %d errno %d %s, fds %d %d\n",
i, err, errno, strerror(errno), fd[0], fd[1]);
break;
}
i++;
}
return 0;
}
Expected behavior is EMFILE and fd unchanged, after however many
iterations it takes to reach the ulimit on max fd.
--
Eric Blake eblake@redhat.com +1-801-349-2682
Libvirt virtualization library http://libvirt.org
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