Re: [PATCH 1/2] object-name: detect and report empty reflogs
- From
Jeff King <peff@peff.net>
- Date
- Feb 21, 2024, 17:31 UTC
- Message-ID
- <20240221173121.GA634809@coredump.intra.peff.net>
- In-Reply-To
- <0fac6ebb098c7e8cdc87cb75f2dcffdc4b1ccfaa.1708509190.git.ps@pks.im>
On Wed, Feb 21, 2024 at 10:56:36AM +0100, Patrick Steinhardt wrote:
Show 7 quoted lines
> This behaviour goes back to 6436a20284 (refs: allow @{n} to work with
> n-sized reflog, 2021-01-07), which fixed a bug that wouldn't allow a
> user to return the n'th reflog entry with an n-sized reflog. With this
> commit, `read_ref_at()` started to special case reading the first entry
> of the reflog via a separate `read_ref_at_ent_newest()` function. The
> problem here is that we forgot to check whether the callback was invoked
> at all, and thus we don't notice empty reflogs.I'm on the fence no whether the current @{0} behavior is sensible and should be preserved. I agree it mostly worked by luck, but the presence of the test makes me think at least the intention was there.
But assuming that is a good direction, there's one thing that puzzles me about your patch:
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> @@ -1084,6 +1084,7 @@ static int read_ref_at_ent_newest(struct object_id *ooid UNUSED, > struct read_ref_at_cb *cb = cb_data; > > set_read_ref_cutoffs(cb, timestamp, tz, message); > + cb->found_it = 1; > oidcpy(cb->oid, noid); > /* We just want the first entry */ > return 1;
OK, so we note whether the callback was invoked, which is good...
Show 7 quoted lines
> @@ -1123,7 +1124,7 @@ int read_ref_at(struct ref_store *refs, const char *refname,
>
> if (cb.cnt == 0) {
> refs_for_each_reflog_ent_reverse(refs, refname, read_ref_at_ent_newest, &cb);
> - return 0;
> + return !cb.found_it;
> }...but here we just return without an error message. Whereas later in the function, we have logic to produce the "log for %s is empty" message. So now we will produce a message if you ask for branch@{1} in an empty reflog, but not for branch@{0}, and the caller is responsible for printing an error in the latter case.
If we instead set reccnt for branch@{0} as we would for branch@{1}, then we can fall through and share the error handling (like it was before 6436a20284, when they used the same callback):
diff --git a/refs.c b/refs.c index c633abf284..7d5e7a9ba6 100644 --- a/refs.c +++ b/refs.c @@ -1084,6 +1084,8 @@ static int read_ref_at_ent_newest(struct object_id *ooid UNUSED, struct read_ref_at_cb *cb = cb_data; set_read_ref_cutoffs(cb, timestamp, tz, message); + cb->reccnt++; + cb->found_it = 1; oidcpy(cb->oid, noid); /* We just want the first entry */ return 1; @@ -1121,12 +1123,10 @@ int read_ref_at(struct ref_store *refs, const char *refname, cb.cutoff_cnt = cutoff_cnt; cb.oid = oid; - if (cb.cnt == 0) { + if (cb.cnt == 0) refs_for_each_reflog_ent_reverse(refs, refname, read_ref_at_ent_newest, &cb); - return 0; - } - - refs_for_each_reflog_ent_reverse(refs, refname, read_ref_at_ent, &cb); + else + refs_for_each_reflog_ent_reverse(refs, refname, read_ref_at_ent, &cb); if (!cb.reccnt) { if (flags & GET_OID_QUIETLY) And it all just works without having to touch get_oid_basic() or cmd_show_branch() at all. Do note that one of the tests needs to be updated to account for the slightly different format of the error message; but again, I think that is showing off the inconsistency in having the error message in two places. -Peff