Message ID | 95025080c16f535599826ed4f013845d712b0e8d.1625684869.git.gitgitgadget@gmail.com (mailing list archive) |
---|---|
State | New, archived |
Headers | show |
Series | refs: cleanup errno sideband ref related functions | expand |
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@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; }
On Sun, Jul 11, 2021 at 1:48 PM Ævar Arnfjörð Bjarmason <avarab@gmail.com> 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@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. 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. -- Google Germany GmbH, Erika-Mann-Strasse 33, 80636 Munich Registergericht und -nummer: Hamburg, HRB 86891 Sitz der Gesellschaft: Hamburg Geschäftsführer: Paul Manicle, Halimah DeLaine Prado
diff --git a/refs/files-backend.c b/refs/files-backend.c index 677b7e4cdd2..83ddfb3b627 100644 --- a/refs/files-backend.c +++ b/refs/files-backend.c @@ -910,7 +910,6 @@ static int create_reflock(const char *path, void *cb) /* * 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)); @@ -981,20 +981,17 @@ static struct ref_lock *lock_ref_oid_basic(struct files_ref_store *refs, if (is_null_oid(&lock->old_oid) && refs_verify_refname_available(refs->packed_ref_store, refname, extras, skip, err)) { - last_errno = ENOTDIR; goto error_return; } lock->ref_name = xstrdup(refname); if (raceproof_create_file(ref_file.buf, create_reflock, &lock->lk)) { - last_errno = errno; unable_to_lock_message(ref_file.buf, errno, err); goto error_return; } if (verify_lock(&refs->base, lock, old_oid, mustexist, err)) { - last_errno = errno; goto error_return; } goto out; @@ -1005,7 +1002,6 @@ static struct ref_lock *lock_ref_oid_basic(struct files_ref_store *refs, out: strbuf_release(&ref_file); - errno = last_errno; return lock; }