Commit 3c333937 authored Jul 25, 2008 by Ulrich Drepper Committed by Al Viro Jul 26, 2008

[PATCH] dup3 fix



Al Viro notice one cornercase that the new dup3() code.  The dup2()
function, as a special case, handles dup-ing to the same file
descriptor.  In this case the current dup3() code does nothing at
all.  I.e., it ingnores the flags parameter.  This shouldn't happen,
the close-on-exec flag should be set if requested.

In case the O_CLOEXEC bit in the flags parameter is not set the
dup3() function should behave in this respect identical to dup2().
This means dup3(fd, fd, 0) should not actively reset the c-o-e
flag.

The patch below implements this minor change.

[AV: credits to Artur Grabowski for bringing that up as potential subtle point
in dup2() behaviour]

Signed-off-by: Ulrich Drepper <drepper@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

parent 58ec42b0

fs/fcntl.c

+6 −1

Original line number	Original line	Diff line number	Diff line
	@@ -139,8 +139,13 @@ asmlinkage long sys_dup3(unsigned int oldfd, unsigned int newfd, int flags)
	if (!(file = fcheck(oldfd)))		if (!(file = fcheck(oldfd)))
	goto out_unlock;		goto out_unlock;
	err = newfd;		err = newfd;
	if (newfd == oldfd)		if (unlikely(newfd == oldfd)) {
			if (flags & O_CLOEXEC) {
			fdt = files_fdtable(files);
			FD_SET(newfd, fdt->close_on_exec);
			}
	goto out_unlock;		goto out_unlock;
			}
	err = -EBADF;		err = -EBADF;
	if (newfd >= current->signal->rlim[RLIMIT_NOFILE].rlim_cur)		if (newfd >= current->signal->rlim[RLIMIT_NOFILE].rlim_cur)
	goto out_unlock;		goto out_unlock;