On Jan 25 14:16, Ken Brown via Cygwin-patches wrote:
> On 1/25/2021 1:57 PM, Corinna Vinschen via Cygwin-patches wrote:
> > 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?
>
> I went back and forth on that. Following your suggestion, the code looks
> like this:
>
> if (uid == ILLEGAL_UID && gid == ILLEGAL_GID)
> {
> ret = 0;
> goto out;
> }
> if (uid == ILLEGAL_UID)
> uid = old_uid;
> if (gid == ILLEGAL_GID)
> gid = old_gid;
>
> I was trying to avoid checking uid == ILLEGAL_UID and gid == ILLEGAL_GID
> twice. But on second thought, it's probably silly to worry about that. The
> code is cleaner without the noop variable.
Both is ok with me, whatever you think more spiffy here.
Thanks,
Corinna
