[Patch] [v3] Add Comment to io/fcntl.h

[Patsy Franklin]

Thanks for the help Roland.



v1
- Initial submission.
v2
- Included missing ChangeLog.
- Adjusted wording.
- Two spaces after periods.
- Reflow text to 80 characters.
v3
- removed "()"
- changed the wording

2013-02-25  Patsy Franklin<pfrankli@redhat.com>

     * io/fcntl.h: Added a comment about AT_EACCESS and AT_REMOVEDIR.

diff --git a/io/fcntl.h b/io/fcntl.h
index 61834ce..fb46143 100644
--- a/io/fcntl.h
+++ b/io/fcntl.h
@@ -129,6 +129,12 @@ typedef __pid_t pid_t;
  # define SEEK_END      2       /* Seek from end of file.  */
  #endif /* XPG */

+/* The constants AT_REMOVEDIR and AT_EACCESS have the same value.  
AT_EACCESS
+   is meaningful only to faccessat, while AT_REMOVEDIR is meaningful 
only to
+   unlinkat.  The two functions do completely different things and 
therefore,
+   the flags can be allowed to overlap.  For example, passing 
AT_REMOVEDIR to
+   faccessat would be undefined behavior and thus treating it equivalent to
+   AT_EACCESS is valid undefined behavior.  */
  #ifdef __USE_ATFILE
  # define AT_FDCWD              -100    /* Special value used to indicate
                                            the *at functions should use the