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[2a01:4f8:120:2468::2]) by smtp.gmail.com with ESMTPSA id l2sm12350713wmi.1.2021.08.23.04.52.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 23 Aug 2021 04:52:54 -0700 (PDT) From: =?utf-8?b?w4Z2YXIgQXJuZmrDtnLDsCBCamFybWFzb24=?= To: git@vger.kernel.org Cc: Junio C Hamano , Jeff King , Han-Wen Nienhuys , Michael Haggerty , Jonathan Tan , =?utf-8?b?w4Z2YXIgQXJuZmrDtnLDsCBC?= =?utf-8?b?amFybWFzb24=?= Subject: [PATCH v10 4/8] refs: make errno output explicit for read_raw_ref_fn Date: Mon, 23 Aug 2021 13:52:40 +0200 Message-Id: X-Mailer: git-send-email 2.33.0.662.g438caf9576d In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org From: Han-Wen Nienhuys This makes it explicit how alternative ref backends should report errors in read_raw_ref_fn. read_raw_ref_fn needs to supply a credible errno for a number of cases. These are primarily: 1) The files backend calls read_raw_ref from lock_raw_ref, and uses the resulting error codes to create/remove directories as needed. 2) ENOENT should be translated in a zero OID, optionally with REF_ISBROKEN set, returning the last successfully resolved symref. This is necessary so read_raw_ref("HEAD") on an empty repo returns refs/heads/main (or the default branch du-jour), and we know on which branch to create the first commit. Make this information flow explicit by adding a failure_errno to the signature of read_raw_ref. All errnos from the files backend are still propagated unchanged, even though inspection suggests only ENOTDIR, EISDIR and ENOENT are relevant. Signed-off-by: Han-Wen Nienhuys Signed-off-by: Ævar Arnfjörð Bjarmason --- refs.c | 2 +- refs/debug.c | 7 +++---- refs/files-backend.c | 29 +++++++++++++++-------------- refs/packed-backend.c | 8 ++++---- refs/refs-internal.h | 20 ++++++++++++-------- 5 files changed, 35 insertions(+), 31 deletions(-) diff --git a/refs.c b/refs.c index 05944d8e725..da0cc82ca66 100644 --- a/refs.c +++ b/refs.c @@ -1682,7 +1682,7 @@ int refs_read_raw_ref(struct ref_store *ref_store, } return ref_store->be->read_raw_ref(ref_store, refname, oid, referent, - type); + type, &errno); } /* This function needs to return a meaningful errno on failure */ diff --git a/refs/debug.c b/refs/debug.c index bf4a82bccb6..8667c640237 100644 --- a/refs/debug.c +++ b/refs/debug.c @@ -239,15 +239,14 @@ debug_ref_iterator_begin(struct ref_store *ref_store, const char *prefix, static int debug_read_raw_ref(struct ref_store *ref_store, const char *refname, struct object_id *oid, struct strbuf *referent, - unsigned int *type) + unsigned int *type, int *failure_errno) { struct debug_ref_store *drefs = (struct debug_ref_store *)ref_store; int res = 0; oidcpy(oid, null_oid()); - errno = 0; res = drefs->refs->be->read_raw_ref(drefs->refs, refname, oid, referent, - type); + type, failure_errno); if (res == 0) { trace_printf_key(&trace_refs, "read_raw_ref: %s: %s (=> %s) type %x: %d\n", @@ -255,7 +254,7 @@ static int debug_read_raw_ref(struct ref_store *ref_store, const char *refname, } else { trace_printf_key(&trace_refs, "read_raw_ref: %s: %d (errno %d)\n", refname, - res, errno); + res, *failure_errno); } return res; } diff --git a/refs/files-backend.c b/refs/files-backend.c index c1794dcd295..b3de3633969 100644 --- a/refs/files-backend.c +++ b/refs/files-backend.c @@ -341,9 +341,9 @@ static struct ref_cache *get_loose_ref_cache(struct files_ref_store *refs) return refs->loose; } -static int files_read_raw_ref(struct ref_store *ref_store, - const char *refname, struct object_id *oid, - struct strbuf *referent, unsigned int *type) +static int files_read_raw_ref(struct ref_store *ref_store, const char *refname, + struct object_id *oid, struct strbuf *referent, + unsigned int *type, int *failure_errno) { struct files_ref_store *refs = files_downcast(ref_store, REF_STORE_READ, "read_raw_ref"); @@ -354,7 +354,6 @@ static int files_read_raw_ref(struct ref_store *ref_store, struct stat st; int fd; int ret = -1; - int save_errno; int remaining_retries = 3; *type = 0; @@ -459,10 +458,9 @@ static int files_read_raw_ref(struct ref_store *ref_store, ret = parse_loose_ref_contents(buf, oid, referent, type); out: - save_errno = errno; + *failure_errno = errno; strbuf_release(&sb_path); strbuf_release(&sb_contents); - errno = save_errno; return ret; } @@ -540,6 +538,7 @@ static int lock_raw_ref(struct files_ref_store *refs, struct strbuf ref_file = STRBUF_INIT; int attempts_remaining = 3; int ret = TRANSACTION_GENERIC_ERROR; + int failure_errno; assert(err); files_assert_main_repository(refs, "lock_raw_ref"); @@ -610,7 +609,9 @@ static int lock_raw_ref(struct files_ref_store *refs, if (hold_lock_file_for_update_timeout( &lock->lk, ref_file.buf, LOCK_NO_DEREF, get_files_ref_lock_timeout_ms()) < 0) { - if (errno == ENOENT && --attempts_remaining > 0) { + int myerr = errno; + errno = 0; + if (myerr == ENOENT && --attempts_remaining > 0) { /* * Maybe somebody just deleted one of the * directories leading to ref_file. Try @@ -618,7 +619,7 @@ static int lock_raw_ref(struct files_ref_store *refs, */ goto retry; } else { - unable_to_lock_message(ref_file.buf, errno, err); + unable_to_lock_message(ref_file.buf, myerr, err); goto error_return; } } @@ -628,9 +629,9 @@ static int lock_raw_ref(struct files_ref_store *refs, * fear that its value will change. */ - if (files_read_raw_ref(&refs->base, refname, - &lock->old_oid, referent, type)) { - if (errno == ENOENT) { + if (files_read_raw_ref(&refs->base, refname, &lock->old_oid, referent, + type, &failure_errno)) { + if (failure_errno == ENOENT) { if (mustexist) { /* Garden variety missing reference. */ strbuf_addf(err, "unable to resolve reference '%s'", @@ -654,7 +655,7 @@ static int lock_raw_ref(struct files_ref_store *refs, * reference named "refs/foo/bar/baz". */ } - } else if (errno == EISDIR) { + } else if (failure_errno == EISDIR) { /* * There is a directory in the way. It might have * contained references that have been deleted. If @@ -692,13 +693,13 @@ static int lock_raw_ref(struct files_ref_store *refs, goto error_return; } } - } else if (errno == EINVAL && (*type & REF_ISBROKEN)) { + } else if (failure_errno == EINVAL && (*type & REF_ISBROKEN)) { strbuf_addf(err, "unable to resolve reference '%s': " "reference broken", refname); goto error_return; } else { strbuf_addf(err, "unable to resolve reference '%s': %s", - refname, strerror(errno)); + refname, strerror(failure_errno)); goto error_return; } diff --git a/refs/packed-backend.c b/refs/packed-backend.c index 65ba4214b8d..47247a14917 100644 --- a/refs/packed-backend.c +++ b/refs/packed-backend.c @@ -724,9 +724,9 @@ static struct snapshot *get_snapshot(struct packed_ref_store *refs) return refs->snapshot; } -static int packed_read_raw_ref(struct ref_store *ref_store, - const char *refname, struct object_id *oid, - struct strbuf *referent, unsigned int *type) +static int packed_read_raw_ref(struct ref_store *ref_store, const char *refname, + struct object_id *oid, struct strbuf *referent, + unsigned int *type, int *failure_errno) { struct packed_ref_store *refs = packed_downcast(ref_store, REF_STORE_READ, "read_raw_ref"); @@ -739,7 +739,7 @@ static int packed_read_raw_ref(struct ref_store *ref_store, if (!rec) { /* refname is not a packed reference. */ - errno = ENOENT; + *failure_errno = ENOENT; return -1; } diff --git a/refs/refs-internal.h b/refs/refs-internal.h index 1c6e5ab51d7..ddd6d7f8ebd 100644 --- a/refs/refs-internal.h +++ b/refs/refs-internal.h @@ -620,11 +620,15 @@ typedef int reflog_expire_fn(struct ref_store *ref_store, * properly-formatted or even safe reference name. NEITHER INPUT NOR * OUTPUT REFERENCE NAMES ARE VALIDATED WITHIN THIS FUNCTION. * - * Return 0 on success. If the ref doesn't exist, set errno to ENOENT - * and return -1. If the ref exists but is neither a symbolic ref nor - * an object ID, it is broken; set REF_ISBROKEN in type, and return -1 - * (errno should not be ENOENT) If there is another error reading the - * ref, set errno appropriately and return -1. + * Return 0 on success, or -1 on failure. If the ref exists but is neither a + * symbolic ref nor an object ID, it is broken. In this case set REF_ISBROKEN in + * type, and return -1 (failure_errno should not be ENOENT) + * + * failure_errno provides errno codes that are interpreted beyond error + * reporting. The following error codes have special meaning: + * * ENOENT: the ref doesn't exist + * * EISDIR: ref name is a directory + * * ENOTDIR: ref prefix is not a directory * * Backend-specific flags might be set in type as well, regardless of * outcome. @@ -638,9 +642,9 @@ typedef int reflog_expire_fn(struct ref_store *ref_store, * - in all other cases, referent will be untouched, and therefore * refname will still be valid and unchanged. */ -typedef int read_raw_ref_fn(struct ref_store *ref_store, - const char *refname, struct object_id *oid, - struct strbuf *referent, unsigned int *type); +typedef int read_raw_ref_fn(struct ref_store *ref_store, const char *refname, + struct object_id *oid, struct strbuf *referent, + unsigned int *type, int *failure_errno); struct ref_storage_be { struct ref_storage_be *next;