On Wed, Jul 05, 2023 at 08:04:41PM -0400, Jeff Layton wrote: > > I don't believe it's an issue. I've seen nothing in the POSIX spec that > mandates that timestamp updates to different inodes involved in an > operation be set to the _same_ value. It just says they must be updated. > > It's also hard to believe that any software would depend on this either, > given that it's very inconsistent across filesystems today. AFAICT, this > was mostly done in the past just as a matter of convenience. I've seen this assumption in several programs: mutt buffy.c https://sources.debian.org/src/mutt/2.2.9-1/buffy.c/?hl=625#L625 if (mailbox->newly_created && (sb->st_ctime != sb->st_mtime || sb->st_ctime != sb->st_atime)) mailbox->newly_created = 0; neomutt mbox/mbox.c https://sources.debian.org/src/neomutt/20220429+dfsg1-4.1/mbox/mbox.c/?hl=1820#L1820 if (m->newly_created && ((st.st_ctime != st.st_mtime) || (st.st_ctime != st.st_atime))) m->newly_created = false; screen logfile.c https://sources.debian.org/src/screen/4.9.0-4/logfile.c/?hl=130#L130 if ((!s->st_dev && !s->st_ino) || /* stat failed, that's new! */ !s->st_nlink || /* red alert: file unlinked */ (s->st_size < o.st_size) || /* file truncated */ (s->st_mtime != o.st_mtime) || /* file modified */ ((s->st_ctime != o.st_ctime) && /* file changed (moved) */ !(s->st_mtime == s->st_ctime && /* and it was not a change */ o.st_ctime < s->st_ctime))) /* due to delayed nfs write */ { nemo libnemo-private/nemo-vfs-file.c https://sources.debian.org/src/nemo/5.6.5-1/libnemo-private/nemo-vfs-file.c/?hl=344#L344 /* mtime is when the contents changed; ctime is when the * contents or the permissions (inc. owner/group) changed. * So we can only know when the permissions changed if mtime * and ctime are different. */ if (file->details->mtime == file->details->ctime) { return FALSE; } While looking for more examples, I found a perl test that seems to suggest that at least Solaris, AFS, AmigaOS, DragonFly BSD do as you suggest: https://sources.debian.org/src/perl/5.36.0-7/t/op/stat.t/?hl=158#L140 Thanks
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