Re: [PATCH v5 2/6] refs/files-backend: stop setting errno from lock_ref_oid_basic
- From
Ævar Arnfjörð Bjarmason <avarab@gmail.com>
- Date
- Jul 11, 2021, 11:38 UTC
- Message-ID
- <87lf6d3wbz.fsf@evledraar.gmail.com>
- In-Reply-To
- <95025080c16f535599826ed4f013845d712b0e8d.1625684869.git.gitgitgadget@gmail.com>
On Wed, Jul 07 2021, Han-Wen Nienhuys via GitGitGadget wrote:
Show 38 quoted lines
> /*
> * Locks a ref returning the lock on success and NULL on failure.
> - * On failure errno is set to something meaningful.
> */
> static struct ref_lock *lock_ref_oid_basic(struct files_ref_store *refs,
> const char *refname,
> @@ -922,7 +921,6 @@ static struct ref_lock *lock_ref_oid_basic(struct files_ref_store *refs,
> {
> struct strbuf ref_file = STRBUF_INIT;
> struct ref_lock *lock;
> - int last_errno = 0;
> int mustexist = (old_oid && !is_null_oid(old_oid));
> int resolve_flags = RESOLVE_REF_NO_RECURSE;
> int resolved;
> @@ -949,7 +947,6 @@ static struct ref_lock *lock_ref_oid_basic(struct files_ref_store *refs,
> * to remain.
> */
> if (remove_empty_directories(&ref_file)) {
> - last_errno = errno;
> if (!refs_verify_refname_available(
> &refs->base,
> refname, extras, skip, err))
> @@ -962,10 +959,13 @@ static struct ref_lock *lock_ref_oid_basic(struct files_ref_store *refs,
> &lock->old_oid, type);
> }
> if (!resolved) {
> - last_errno = errno;
> + int last_errno = errno;
> if (last_errno != ENOTDIR ||
> - !refs_verify_refname_available(&refs->base, refname,
> - extras, skip, err))
> + /* in case of D/F conflict, try to generate a better error
> + * message. If that fails, fall back to strerror(ENOTDIR).
> + */
> + !refs_verify_refname_available(&refs->base, refname, extras,
> + skip, err))
> strbuf_addf(err, "unable to resolve reference '%s': %s",
> refname, strerror(last_errno));I don't think it's some dealbreaker and we can move on, but just FWIW I think what I mentioned ending in your https://lore.kernel.org/git/CAFQ2z_NpyJQLuM70MhJ8K1h2v3QXFuAZRjN=SvSsjnukNRJ8pw@mail.gmail.com/ is still outstanding.
I.e. you added the comment, which is just says what the error emitting looks like, that's all well & good.
But what I was pointing out that it didn't make sense to do any "last_errno" here at all anymore. You pointed to 5b2d8d6f218 (lock_ref_sha1_basic(): improve diagnostics for ref D/F conflicts, 2015-05-11), we started setting "last_errno" there, but that was *not* to avoid clobbering between the !resolved and the strbuf_add(strerror(last_errno)) here, but rather to carry the "last_errno" forward to the end of this lock_ref_oid_basic(), because other things (after this hunk) might reset/clear errno.
Anyway, as noted there it doesn't actually matter, just reviewing & looking if there's any loose ends, and for future source spelunking for anyone reading this thread.
I.e. something like what I mentioned in https://lore.kernel.org/git/87k0mae0ga.fsf@evledraar.gmail.com/ could be squashed in, or better yet (probably) this:
diff --git a/refs/files-backend.c b/refs/files-backend.c index 83ddfb3b627..f0ce0aac857 100644 --- a/refs/files-backend.c +++ b/refs/files-backend.c @@ -958,17 +958,15 @@ static struct ref_lock *lock_ref_oid_basic(struct files_ref_store *refs, refname, resolve_flags, &lock->old_oid, type); } - if (!resolved) { - int last_errno = errno; - if (last_errno != ENOTDIR || - /* in case of D/F conflict, try to generate a better error - * message. If that fails, fall back to strerror(ENOTDIR). - */ - !refs_verify_refname_available(&refs->base, refname, extras, - skip, err)) - strbuf_addf(err, "unable to resolve reference '%s': %s", - refname, strerror(last_errno)); - + if (!resolved && + (errno != ENOTDIR || + /* in case of D/F conflict, try to generate a better error + * message. If that fails, fall back to strerror(ENOTDIR). + */ + !refs_verify_refname_available(&refs->base, refname, extras, + skip, err))) { + strbuf_addf(err, "unable to resolve reference '%s': %s", + refname, strerror(errno)); goto error_return; }