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List:       linux-fsdevel
Subject:    Another bug, in dup3
From:       "Richard W.M. Jones" <rjones () redhat ! com>
Date:       2012-10-09 9:15:21
Message-ID: 20121009091521.GM24071 () rhmail ! home ! annexia ! org
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Al:

A second problem we noticed from the gnulib test is that this
assertion fails with the latest upstream kernel:

      /* Assigning to self is invalid.  */
      errno = 0;
      ASSERT (dup3 (fd, fd, o_flags) == -1);   <--- fails
      ASSERT (errno == EINVAL);

dup3 is not currently specified by POSIX, so technically it is fine
for dup3 on Linux to do anything it likes.

*However* the proposal for dup3 in POSIX:

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

says:

  "The dup3( ) function shall be equivalent to the dup2( ) function if
  the flag argument is 0, except that it shall be an error if fildes
  is equal to fildes2."

So it's probably a good idea for Linux not to regress here.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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