dup3: Return an error when oldfd == newfd.
authorRichard W.M. Jones <rjones@redhat.com>
Tue, 9 Oct 2012 14:27:43 +0000 (15:27 +0100)
committerAl Viro <viro@zeniv.linux.org.uk>
Wed, 10 Oct 2012 03:33:38 +0000 (23:33 -0400)
commitaed976475bff939672b0e21595839c445dcec0fa
treea260411639546dad441bf6060be123ca0842a31c
parentd1c7d97ad58836affde6e39980b96527510b572e
dup3: Return an error when oldfd == newfd.

I have tested the attached patch to fix the dup3 regression.

Rich.

From 0944e30e12dec6544b3602626b60ff412375c78f Mon Sep 17 00:00:00 2001
From: "Richard W.M. Jones" <rjones@redhat.com>
Date: Tue, 9 Oct 2012 14:42:45 +0100
Subject: [PATCH] dup3: Return an error when oldfd == newfd.

The following commit:

  commit fe17f22d7fd0e344ef6447238f799bb49f670c6f
  Author: Al Viro <viro@zeniv.linux.org.uk>
  Date:   Tue Aug 21 11:48:11 2012 -0400

    take purely descriptor-related stuff from fcntl.c to file.c

was supposed to be just code motion, but it dropped the following two
lines:

  if (unlikely(oldfd == newfd))
          return -EINVAL;

from the dup3 system call.  dup3 is not specified by POSIX, so Linux
can do what it likes.  However the POSIX proposal for dup3 [1] states
that it should return an error if oldfd == newfd.

[1] http://austingroupbugs.net/view.php?id=411

Signed-off-by: Richard W.M. Jones <rjones@redhat.com>
Tested-by: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
fs/file.c