On Sun, Jul 11, 2021 at 1:48 PM Ævar Arnfjörð Bjarmason
<avarab@xxxxxxxxx> wrote:
>
>
> On Wed, Jul 07 2021, Han-Wen Nienhuys via GitGitGadget wrote:
>
> > /*
> > * 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@xxxxxxxxxxxxxx/
> 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.
I disagree. In your suggested change
> + 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;
the refs_verify_refname_available() call happens only if
errno==ENOTDIR. The call might clobber the ENOTDIR errno and then
fail. Then we'd be printing the last errno that
refs_verify_refname_available() saw, which may be different from
ENOTDIR.
Other than that, for clarity's sake, it's always better to avoid the
use of global errno if we can.
--
Han-Wen Nienhuys - Google Munich
I work 80%. Don't expect answers from me on Fridays.
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