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From: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
To: git@vger.kernel.org
Cc: "Junio C Hamano" <gitster@pobox.com>, "Jeff King" <peff@peff.net>,
	"Han-Wen Nienhuys" <hanwen@google.com>,
	"Michael Haggerty" <mhagger@alum.mit.edu>,
	"Jonathan Tan" <jonathantanmy@google.com>,
	"Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
Subject: [PATCH v10 3/8] refs/files-backend: stop setting errno from lock_ref_oid_basic
Date: Mon, 23 Aug 2021 13:52:39 +0200	[thread overview]
Message-ID: <patch-v10-3.8-2c4c30e8e06-20210823T114712Z-avarab@gmail.com> (raw)
In-Reply-To: <cover-v10-0.8-00000000000-20210823T114712Z-avarab@gmail.com>

From: Han-Wen Nienhuys <hanwen@google.com>

refs/files-backend.c::lock_ref_oid_basic() tries to signal how it failed
to its callers using errno.

It is safe to stop setting errno here, because the callers of this
file-scope static function are

* files_copy_or_rename_ref()
* files_create_symref()
* files_reflog_expire()

None of them looks at errno after seeing a negative return from
lock_ref_oid_basic() to make any decision, and no caller of these three
functions looks at errno after they signal a failure by returning a
negative value. In particular,

* files_copy_or_rename_ref() - here, calls are followed by error()
(which performs I/O) or write_ref_to_lockfile() (which calls
parse_object() which may perform I/O)

* files_create_symref() - here, calls are followed by error() or
create_symref_locked() (which performs I/O and does not inspect
errno)

* files_reflog_expire() - here, calls are followed by error() or
refs_reflog_exists() (which calls a function in a vtable that is not
documented to use and/or preserve errno)

Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 refs/files-backend.c | 11 ++---------
 1 file changed, 2 insertions(+), 9 deletions(-)

diff --git a/refs/files-backend.c b/refs/files-backend.c
index 950f9738ae0..c1794dcd295 100644
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -982,7 +982,6 @@ 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, int *type,
@@ -990,7 +989,6 @@ 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;
 
 	files_assert_main_repository(refs, "lock_ref_oid_basic");
 	assert(err);
@@ -1001,11 +999,10 @@ static struct ref_lock *lock_ref_oid_basic(struct files_ref_store *refs,
 	if (!refs_resolve_ref_unsafe(&refs->base, refname,
 				     RESOLVE_REF_NO_RECURSE,
 				     &lock->old_oid, type)) {
-		last_errno = errno;
 		if (!refs_verify_refname_available(&refs->base, refname,
 						   NULL, NULL, err))
 			strbuf_addf(err, "unable to resolve reference '%s': %s",
-				    refname, strerror(last_errno));
+				    refname, strerror(errno));
 
 		goto error_return;
 	}
@@ -1018,15 +1015,12 @@ 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,
-					  NULL, NULL, err)) {
-		last_errno = ENOTDIR;
+					  NULL, NULL, err))
 		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;
 	}
@@ -1043,7 +1037,6 @@ static struct ref_lock *lock_ref_oid_basic(struct files_ref_store *refs,
 
  out:
 	strbuf_release(&ref_file);
-	errno = last_errno;
 	return lock;
 }
 
-- 
2.33.0.662.g438caf9576d


  parent reply	other threads:[~2021-08-23 11:53 UTC|newest]

Thread overview: 148+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-29 15:32 [PATCH 0/8] refs: cleanup errno sideband ref related functions Han-Wen Nienhuys via GitGitGadget
2021-04-29 15:32 ` [PATCH 1/8] refs: remove EINVAL specification from the errno sideband in read_raw_ref_fn Han-Wen Nienhuys via GitGitGadget
2021-04-30  2:38   ` Junio C Hamano
2021-05-19 12:25     ` Han-Wen Nienhuys
2021-06-03  2:19   ` Jonathan Tan
2021-06-09 11:28     ` Han-Wen Nienhuys
2021-04-29 15:32 ` [PATCH 2/8] refs/files-backend: stop setting errno from lock_ref_oid_basic Han-Wen Nienhuys via GitGitGadget
2021-04-30  3:10   ` Junio C Hamano
2021-05-19 12:29     ` Han-Wen Nienhuys
2021-06-03  2:33   ` Jonathan Tan
2021-06-10 10:02     ` Han-Wen Nienhuys
2021-04-29 15:32 ` [PATCH 3/8] refs: make errno output explicit for read_raw_ref_fn Han-Wen Nienhuys via GitGitGadget
2021-04-30  3:34   ` Junio C Hamano
2021-04-30  6:02     ` Junio C Hamano
2021-05-19 12:33       ` Han-Wen Nienhuys
2021-06-03  2:37   ` Jonathan Tan
2021-06-10 10:05     ` Han-Wen Nienhuys
2021-04-29 15:32 ` [PATCH 4/8] refs: make errno output explicit for refs_resolve_ref_unsafe Han-Wen Nienhuys via GitGitGadget
2021-06-03  2:51   ` Jonathan Tan
2021-06-10 11:27     ` Han-Wen Nienhuys
2021-04-29 15:32 ` [PATCH 5/8] refs: add failure_errno to refs_read_raw_ref() signature Han-Wen Nienhuys via GitGitGadget
2021-04-29 15:32 ` [PATCH 6/8] refs: clear errno return in refs_resolve_ref_unsafe() Han-Wen Nienhuys via GitGitGadget
2021-06-03  2:53   ` Jonathan Tan
2021-06-10 11:45     ` Han-Wen Nienhuys
2021-04-29 15:32 ` [PATCH 7/8] refs: stop setting EINVAL and ELOOP in symref resolution Han-Wen Nienhuys via GitGitGadget
2021-06-03  2:55   ` Jonathan Tan
2021-06-10 11:58     ` Han-Wen Nienhuys
2021-04-29 15:32 ` [PATCH 8/8] refs: explicitly propagate errno from refs_read_raw_ref Han-Wen Nienhuys via GitGitGadget
2021-06-03  2:13 ` [PATCH 0/8] refs: cleanup errno sideband ref related functions Jonathan Tan
2021-06-09 11:29   ` Han-Wen Nienhuys
2021-06-10 12:57 ` [PATCH v2 " Han-Wen Nienhuys via GitGitGadget
2021-06-10 12:57   ` [PATCH v2 1/8] refs: remove EINVAL errno output from specification of read_raw_ref_fn Han-Wen Nienhuys via GitGitGadget
2021-06-10 12:57   ` [PATCH v2 2/8] refs/files-backend: stop setting errno from lock_ref_oid_basic Han-Wen Nienhuys via GitGitGadget
2021-07-01 11:13     ` Ævar Arnfjörð Bjarmason
2021-07-05 14:16       ` Han-Wen Nienhuys
2021-06-10 12:57   ` [PATCH v2 3/8] refs: make errno output explicit for read_raw_ref_fn Han-Wen Nienhuys via GitGitGadget
2021-07-01 11:34     ` Ævar Arnfjörð Bjarmason
2021-07-05 14:34       ` Han-Wen Nienhuys
2021-06-10 12:57   ` [PATCH v2 4/8] refs: make errno output explicit for refs_resolve_ref_unsafe Han-Wen Nienhuys via GitGitGadget
2021-07-01 11:56     ` Ævar Arnfjörð Bjarmason
2021-06-10 12:57   ` [PATCH v2 5/8] refs: use refs_resolve_ref_unsafe_with_errno() where needed Han-Wen Nienhuys via GitGitGadget
2021-07-01 11:58     ` Ævar Arnfjörð Bjarmason
2021-06-10 12:57   ` [PATCH v2 6/8] refs: add failure_errno to refs_read_raw_ref() signature Han-Wen Nienhuys via GitGitGadget
2021-07-01 12:06     ` Ævar Arnfjörð Bjarmason
2021-06-10 12:57   ` [PATCH v2 7/8] refs: clear errno return in refs_resolve_ref_unsafe() Han-Wen Nienhuys via GitGitGadget
2021-07-01 12:19     ` Ævar Arnfjörð Bjarmason
2021-06-10 12:57   ` [PATCH v2 8/8] refs: explicitly propagate errno from refs_read_raw_ref Han-Wen Nienhuys via GitGitGadget
2021-07-01 12:26     ` Ævar Arnfjörð Bjarmason
2021-07-05 16:09       ` Han-Wen Nienhuys
2021-07-05 19:08         ` Ævar Arnfjörð Bjarmason
2021-07-05 19:39           ` Han-Wen Nienhuys
2021-06-14 10:10   ` [PATCH v2 0/8] refs: cleanup errno sideband ref related functions Han-Wen Nienhuys
2021-07-05 20:56   ` [PATCH v3 0/5] " Han-Wen Nienhuys via GitGitGadget
2021-07-05 20:56     ` [PATCH v3 1/5] refs: remove EINVAL errno output from specification of read_raw_ref_fn Han-Wen Nienhuys via GitGitGadget
2021-07-05 20:56     ` [PATCH v3 2/5] refs/files-backend: stop setting errno from lock_ref_oid_basic Han-Wen Nienhuys via GitGitGadget
2021-07-05 20:56     ` [PATCH v3 3/5] refs: make errno output explicit for read_raw_ref_fn Han-Wen Nienhuys via GitGitGadget
2021-07-05 20:56     ` [PATCH v3 4/5] refs: add failure_errno to refs_read_raw_ref() signature Han-Wen Nienhuys via GitGitGadget
2021-07-06 19:28       ` Junio C Hamano
2021-07-05 20:56     ` [PATCH v3 5/5] refs: make errno output explicit for refs_resolve_ref_unsafe Han-Wen Nienhuys via GitGitGadget
2021-07-06  0:38     ` [PATCH v3 0/5] refs: cleanup errno sideband ref related functions Ævar Arnfjörð Bjarmason
2021-07-06  9:53       ` Han-Wen Nienhuys
2021-07-06 14:27         ` Ævar Arnfjörð Bjarmason
2021-07-06 18:36           ` Han-Wen Nienhuys
2021-07-06 18:55     ` [PATCH v4 0/6] " Han-Wen Nienhuys via GitGitGadget
2021-07-06 18:55       ` [PATCH v4 1/6] refs: remove EINVAL errno output from specification of read_raw_ref_fn Han-Wen Nienhuys via GitGitGadget
2021-07-06 18:55       ` [PATCH v4 2/6] refs/files-backend: stop setting errno from lock_ref_oid_basic Han-Wen Nienhuys via GitGitGadget
2021-07-06 18:55       ` [PATCH v4 3/6] refs: make errno output explicit for read_raw_ref_fn Han-Wen Nienhuys via GitGitGadget
2021-07-06 18:55       ` [PATCH v4 4/6] refs: add failure_errno to refs_read_raw_ref() signature Han-Wen Nienhuys via GitGitGadget
2021-07-06 19:39         ` Junio C Hamano
2021-07-06 18:55       ` [PATCH v4 5/6] refs: explicitly return failure_errno from parse_loose_ref_contents Han-Wen Nienhuys via GitGitGadget
2021-07-06 19:37         ` Junio C Hamano
2021-07-07  8:20           ` Han-Wen Nienhuys
2021-07-06 18:55       ` [PATCH v4 6/6] refs: make errno output explicit for refs_resolve_ref_unsafe Han-Wen Nienhuys via GitGitGadget
2021-07-07 19:07       ` [PATCH v5 0/6] refs: cleanup errno sideband ref related functions Han-Wen Nienhuys via GitGitGadget
2021-07-07 19:07         ` [PATCH v5 1/6] refs: remove EINVAL errno output from specification of read_raw_ref_fn Han-Wen Nienhuys via GitGitGadget
2021-07-07 19:07         ` [PATCH v5 2/6] refs/files-backend: stop setting errno from lock_ref_oid_basic Han-Wen Nienhuys via GitGitGadget
2021-07-11 11:38           ` Ævar Arnfjörð Bjarmason
2021-07-13  8:00             ` Han-Wen Nienhuys
2021-07-07 19:07         ` [PATCH v5 3/6] refs: make errno output explicit for read_raw_ref_fn Han-Wen Nienhuys via GitGitGadget
2021-07-11 11:52           ` Ævar Arnfjörð Bjarmason
2021-07-07 19:07         ` [PATCH v5 4/6] refs: add failure_errno to refs_read_raw_ref() signature Han-Wen Nienhuys via GitGitGadget
2021-07-11 11:59           ` Ævar Arnfjörð Bjarmason
2021-07-13  8:02             ` Han-Wen Nienhuys
2021-07-07 19:07         ` [PATCH v5 5/6] refs: explicitly return failure_errno from parse_loose_ref_contents Han-Wen Nienhuys via GitGitGadget
2021-07-11 12:41           ` Ævar Arnfjörð Bjarmason
2021-07-07 19:07         ` [PATCH v5 6/6] refs: make errno output explicit for refs_resolve_ref_unsafe Han-Wen Nienhuys via GitGitGadget
2021-07-07 20:44         ` [PATCH v5 0/6] refs: cleanup errno sideband ref related functions Junio C Hamano
2021-07-11 16:30         ` [PATCH v6? 00/17] refs API: get rid of errno setting entirely Ævar Arnfjörð Bjarmason
2021-07-11 16:30           ` [PATCH v6? 01/17] refs: remove EINVAL errno output from specification of read_raw_ref_fn Ævar Arnfjörð Bjarmason
2021-07-11 16:30           ` [PATCH v6? 02/17] refs/files-backend: stop setting errno from lock_ref_oid_basic Ævar Arnfjörð Bjarmason
2021-07-11 16:30           ` [PATCH v6? 03/17] refs: make errno output explicit for read_raw_ref_fn Ævar Arnfjörð Bjarmason
2021-07-11 16:30           ` [PATCH v6? 04/17] refs: add failure_errno to refs_read_raw_ref() signature Ævar Arnfjörð Bjarmason
2021-07-11 16:30           ` [PATCH v6? 05/17] refs: explicitly return failure_errno from parse_loose_ref_contents Ævar Arnfjörð Bjarmason
2021-07-11 16:30           ` [PATCH v6? 06/17] refs: make errno output explicit for refs_resolve_ref_unsafe Ævar Arnfjörð Bjarmason
2021-07-11 16:30           ` [PATCH v6? 07/17] refs: make errno ignoring explicit in lock_ref_oid_basic() Ævar Arnfjörð Bjarmason
2021-07-11 16:30           ` [PATCH v6? 08/17] refs file-backend.c: stop setting "EBUSY" in verify_lock() Ævar Arnfjörð Bjarmason
2021-07-13  8:08             ` Han-Wen Nienhuys
2021-07-11 16:30           ` [PATCH v6? 09/17] refs file-backend.c: deal with errno directly " Ævar Arnfjörð Bjarmason
2021-07-11 16:30           ` [PATCH v6? 10/17] refs API: remove refs_read_ref_full() wrapper Ævar Arnfjörð Bjarmason
2021-07-11 16:30           ` [PATCH v6? 11/17] refs API: make resolve_gitlink_ref() not set errno Ævar Arnfjörð Bjarmason
2021-07-11 16:30           ` [PATCH v6? 12/17] refs API: make refs_resolve_ref_unsafe() static Ævar Arnfjörð Bjarmason
2021-07-11 16:30           ` [PATCH v6? 13/17] refs API: make refs_resolve_refdup() not set errno Ævar Arnfjörð Bjarmason
2021-07-11 16:30           ` [PATCH v6? 14/17] refs API: make refs_ref_exists() " Ævar Arnfjörð Bjarmason
2021-07-11 16:30           ` [PATCH v6? 15/17] refs API: make resolve_ref_unsafe() " Ævar Arnfjörð Bjarmason
2021-07-13  8:13             ` Han-Wen Nienhuys
2021-07-14  8:32               ` Ævar Arnfjörð Bjarmason
2021-07-11 16:30           ` [PATCH v6? 16/17] refs API: make expand_ref() and repo_dwim_log() " Ævar Arnfjörð Bjarmason
2021-07-11 16:30           ` [PATCH v6? 17/17] refs API: don't leak "errno" in run_transaction_hook() Ævar Arnfjörð Bjarmason
2021-07-13  8:28           ` [PATCH v6? 00/17] refs API: get rid of errno setting entirely Han-Wen Nienhuys
2021-07-13 18:26             ` Ævar Arnfjörð Bjarmason
2021-07-14  8:38               ` Ævar Arnfjörð Bjarmason
2021-07-14  8:43                 ` Han-Wen Nienhuys
2021-07-14 11:43           ` [PATCH v7 0/6] refs: cleanup errno sideband ref related functions Ævar Arnfjörð Bjarmason
2021-07-14 11:43             ` [PATCH v7 1/6] refs: remove EINVAL errno output from specification of read_raw_ref_fn Ævar Arnfjörð Bjarmason
2021-07-14 11:43             ` [PATCH v7 2/6] refs/files-backend: stop setting errno from lock_ref_oid_basic Ævar Arnfjörð Bjarmason
2021-07-14 11:43             ` [PATCH v7 3/6] refs: make errno output explicit for read_raw_ref_fn Ævar Arnfjörð Bjarmason
2021-07-14 11:43             ` [PATCH v7 4/6] refs: add failure_errno to refs_read_raw_ref() signature Ævar Arnfjörð Bjarmason
2021-07-14 11:43             ` [PATCH v7 5/6] refs: explicitly return failure_errno from parse_loose_ref_contents Ævar Arnfjörð Bjarmason
2021-07-14 11:43             ` [PATCH v7 6/6] refs: make errno output explicit for refs_resolve_ref_unsafe Ævar Arnfjörð Bjarmason
2021-07-16 14:22             ` [PATCH v8 0/7] refs: cleanup errno sideband ref related functions Ævar Arnfjörð Bjarmason
2021-07-16 14:22               ` [PATCH v8 1/7] refs file backend: move raceproof_create_file() here Ævar Arnfjörð Bjarmason
2021-07-16 14:22               ` [PATCH v8 2/7] refs: remove EINVAL errno output from specification of read_raw_ref_fn Ævar Arnfjörð Bjarmason
2021-07-16 14:22               ` [PATCH v8 3/7] refs/files-backend: stop setting errno from lock_ref_oid_basic Ævar Arnfjörð Bjarmason
2021-07-16 14:22               ` [PATCH v8 4/7] refs: make errno output explicit for read_raw_ref_fn Ævar Arnfjörð Bjarmason
2021-07-16 14:22               ` [PATCH v8 5/7] refs: add failure_errno to refs_read_raw_ref() signature Ævar Arnfjörð Bjarmason
2021-07-16 14:22               ` [PATCH v8 6/7] refs: explicitly return failure_errno from parse_loose_ref_contents Ævar Arnfjörð Bjarmason
2021-07-16 14:22               ` [PATCH v8 7/7] refs: make errno output explicit for refs_resolve_ref_unsafe Ævar Arnfjörð Bjarmason
2021-07-20 10:33               ` [PATCH v9 0/7] refs: cleanup errno sideband ref related functions Ævar Arnfjörð Bjarmason
2021-07-20 10:33                 ` [PATCH v9 1/7] refs file backend: move raceproof_create_file() here Ævar Arnfjörð Bjarmason
2021-07-20 10:33                 ` [PATCH v9 2/7] refs: remove EINVAL errno output from specification of read_raw_ref_fn Ævar Arnfjörð Bjarmason
2021-07-20 10:33                 ` [PATCH v9 3/7] refs/files-backend: stop setting errno from lock_ref_oid_basic Ævar Arnfjörð Bjarmason
2021-07-20 10:33                 ` [PATCH v9 4/7] refs: make errno output explicit for read_raw_ref_fn Ævar Arnfjörð Bjarmason
2021-08-16 13:00                   ` Han-Wen Nienhuys
2021-07-20 10:33                 ` [PATCH v9 5/7] refs: add failure_errno to refs_read_raw_ref() signature Ævar Arnfjörð Bjarmason
2021-07-20 10:33                 ` [PATCH v9 6/7] refs: explicitly return failure_errno from parse_loose_ref_contents Ævar Arnfjörð Bjarmason
2021-08-13 20:54                   ` Jonathan Tan
2021-07-20 10:33                 ` [PATCH v9 7/7] refs: make errno output explicit for refs_resolve_ref_unsafe Ævar Arnfjörð Bjarmason
2021-07-26 23:49                 ` [PATCH v9 0/7] refs: cleanup errno sideband ref related functions Ævar Arnfjörð Bjarmason
2021-07-27  0:18                   ` Junio C Hamano
2021-08-23 11:52                 ` [PATCH v10 0/8] " Ævar Arnfjörð Bjarmason
2021-08-23 11:52                   ` [PATCH v10 1/8] refs file backend: move raceproof_create_file() here Ævar Arnfjörð Bjarmason
2021-08-23 11:52                   ` [PATCH v10 2/8] refs: remove EINVAL errno output from specification of read_raw_ref_fn Ævar Arnfjörð Bjarmason
2021-08-23 11:52                   ` Ævar Arnfjörð Bjarmason [this message]
2021-08-23 11:52                   ` [PATCH v10 4/8] refs: make errno output explicit for read_raw_ref_fn Ævar Arnfjörð Bjarmason
2021-08-23 11:52                   ` [PATCH v10 5/8] refs: add failure_errno to refs_read_raw_ref() signature Ævar Arnfjörð Bjarmason
2021-08-23 11:52                   ` [PATCH v10 6/8] branch tests: test for errno propagating on failing read Ævar Arnfjörð Bjarmason
2021-08-23 11:52                   ` [PATCH v10 7/8] refs: explicitly return failure_errno from parse_loose_ref_contents Ævar Arnfjörð Bjarmason
2021-08-23 11:52                   ` [PATCH v10 8/8] refs: make errno output explicit for refs_resolve_ref_unsafe Ævar Arnfjörð Bjarmason

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