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.
Thanks.
Ken
