Re: [PATCH] Cygwin: chown: make sure ctime gets updated when necessary

[Corinna Vinschen <corinna-cygwin@cygwin.com>]

On Jan 25 12:24, Ken Brown via Cygwin-patches wrote:
> Following POSIX, ensure that ctime is updated if chown succeeds,
> unless the new owner is specified as (uid_t)-1 and the new group is
> specified as (gid_t)-1.  Previously, ctime was unchanged whenever the
> owner and group were both unchanged.
> 
> Aside from POSIX compliance, this fix makes gnulib report that chown
> works on Cygwin.  This improves the efficiency of packages like GNU
> tar that use gnulib's chown module.  Previously such packages would
> use a gnulib replacement for chown on Cygwin.
> ---
>  winsup/cygwin/fhandler_disk_file.cc | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/winsup/cygwin/fhandler_disk_file.cc b/winsup/cygwin/fhandler_disk_file.cc
> index 07f9c513a..72d259579 100644
> --- a/winsup/cygwin/fhandler_disk_file.cc
> +++ b/winsup/cygwin/fhandler_disk_file.cc
> @@ -863,6 +863,7 @@ fhandler_disk_file::fchown (uid_t uid, gid_t gid)
>    tmp_pathbuf tp;
>    aclent_t *aclp;
>    int nentries;
> +  bool noop = true;
>  
>    if (!pc.has_acls ())
>      {
> @@ -887,11 +888,18 @@ fhandler_disk_file::fchown (uid_t uid, gid_t gid)
>  				    aclp, MAX_ACL_ENTRIES)) < 0)
>      goto out;
>  
> +  /* According to POSIX, chown can be a no-op if uid is (uid_t)-1 and
> +     gid is (gid_t)-1.  Otherwise, even if uid and gid are unchanged,
> +     we must ensure that ctime is updated. */
>    if (uid == ILLEGAL_UID)
>      uid = old_uid;
> +  else
> +    noop = false;
>    if (gid == ILLEGAL_GID)
>      gid = old_gid;
> -  if (uid == old_uid && gid == old_gid)

Basically ok, but why not just

     if (uid == ILLEGAL_UID && gid == ILLEGAL_GID)

instead of the noop var?


Corinna