From patchwork Mon Jul 5 20:56:03 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Han-Wen Nienhuys X-Patchwork-Id: 12359559 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-12.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E644CC07E9B for ; Mon, 5 Jul 2021 20:56:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CC91161205 for ; Mon, 5 Jul 2021 20:56:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230081AbhGEU7A (ORCPT ); Mon, 5 Jul 2021 16:59:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53336 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229939AbhGEU6s (ORCPT ); Mon, 5 Jul 2021 16:58:48 -0400 Received: from mail-wm1-x336.google.com (mail-wm1-x336.google.com [IPv6:2a00:1450:4864:20::336]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9EF68C061762 for ; Mon, 5 Jul 2021 13:56:10 -0700 (PDT) Received: by mail-wm1-x336.google.com with SMTP id h18-20020a05600c3512b029020e4ceb9588so261524wmq.5 for ; Mon, 05 Jul 2021 13:56:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=message-id:in-reply-to:references:from:date:subject:mime-version :content-transfer-encoding:fcc:to:cc; bh=fsoE1BEMrpOR5uMSEd0uJ2DQUGtfeXwz8ETqcDgZ1v4=; b=Wp/MO1cVTUbcikzn/mQuNEwFkBzgkOOn8v6CNzIhgniwWIlWmVdiKyGUWeMdgswKOH Sw3bDXftWw8sDLXmmPYpeKVhglILe2GgSjc9iVnejCa8eELkPtGz5wk4brpX3jjmsmEa o1Re7xlJhFD9iimhvLETr7iWWH+JgZjAqQl0U7eULL+kg8/yOwamq+Grc1x4OuWn8uME 7atZlfSlQvcm2RHAOvoFj93SdzPY/KwCSmi0kGaPyRv8d68NHhcxTjwurOmDva8WrDLF wb4z+r3p6bA2q9T5fzr65CHt1eDlAt9qNeY0ALm7Mk2SqFXtPDvVGJtjbzuLD9qTgc3r GPwA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:message-id:in-reply-to:references:from:date :subject:mime-version:content-transfer-encoding:fcc:to:cc; bh=fsoE1BEMrpOR5uMSEd0uJ2DQUGtfeXwz8ETqcDgZ1v4=; b=C1/pBRZi8drCpAqLEB612ODatAPRHXS0KKje53Sl9vgElBmpTwcvLIM6WqCHlMEN+h l681w26WfyfLskUA/8xFbSGIGAV6qBZhR/VsdRKadQqXzOsstt/0EoR4D+ZZlufcjnQM j93g+XoLJJaBrlIZA3AMrgKtKQGIuaXttKTuCp2dgB3cXG17fu4CjMNZNVo4PKl51i99 PgJhe5E+kRUp0PooYp8tnAM/FJah6qcPbIRni+paOM2B78hcYMujuYw9b9BjsWayD2uc 0YhbF28GjcodtkwkXIKC3RLSkPloUtid6EhPUUUSo9fU2LWcB/jcinnmDaCcM9AggF2F gseA== X-Gm-Message-State: AOAM5301uyKVyw/Bi7z7DNKlnSf1h+AhLhsNX5xNSFbPSV/yMXkfwiMS EqBET98yNquBR7islJDBKC8NuqfDRY0= X-Google-Smtp-Source: ABdhPJz2kiSksTneG22ajtik7i+06Cfn9Z1TM2YdGuY9J8lS4sqWg7cWgPtS+vBDvxXTzcZZoP/Dvw== X-Received: by 2002:a1c:730d:: with SMTP id d13mr929231wmb.129.1625518569183; Mon, 05 Jul 2021 13:56:09 -0700 (PDT) Received: from [127.0.0.1] ([13.74.141.28]) by smtp.gmail.com with ESMTPSA id c9sm7652806wrx.22.2021.07.05.13.56.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 05 Jul 2021 13:56:08 -0700 (PDT) Message-Id: In-Reply-To: References: Date: Mon, 05 Jul 2021 20:56:03 +0000 Subject: [PATCH v3 3/5] refs: make errno output explicit for read_raw_ref_fn MIME-Version: 1.0 Fcc: Sent To: git@vger.kernel.org Cc: Han-Wen Nienhuys , Jonathan Tan , =?utf-8?b?w4Z2YXIgQXJuZmrDtnLDsA==?= Bjarmason , Han-Wen Nienhuys , Han-Wen Nienhuys Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org From: Han-Wen Nienhuys 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 Reviewed-by: Jonathan Tan Reviewed-by: Ævar Arnfjörð Bjarmason --- refs.c | 10 ++++++++-- refs/debug.c | 4 ++-- refs/files-backend.c | 23 +++++++++++------------ refs/packed-backend.c | 8 ++++---- refs/refs-internal.h | 20 ++++++++++++-------- 5 files changed, 37 insertions(+), 28 deletions(-) diff --git a/refs.c b/refs.c index 8c9490235ea..5e5e3af8da0 100644 --- a/refs.c +++ b/refs.c @@ -1675,13 +1675,19 @@ int refs_read_raw_ref(struct ref_store *ref_store, const char *refname, struct object_id *oid, struct strbuf *referent, unsigned int *type) { + int result; + int failure_errno; if (!strcmp(refname, "FETCH_HEAD") || !strcmp(refname, "MERGE_HEAD")) { return refs_read_special_head(ref_store, refname, oid, referent, type); } - return ref_store->be->read_raw_ref(ref_store, refname, oid, referent, - type); + failure_errno = 0; + result = ref_store->be->read_raw_ref(ref_store, refname, oid, referent, + type, &failure_errno); + if (failure_errno) + errno = failure_errno; + return result; } /* This function needs to return a meaningful errno on failure */ diff --git a/refs/debug.c b/refs/debug.c index 7db4abccc34..f12413a9bc0 100644 --- a/refs/debug.c +++ b/refs/debug.c @@ -238,7 +238,7 @@ 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; @@ -246,7 +246,7 @@ static int debug_read_raw_ref(struct ref_store *ref_store, const char *refname, 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", diff --git a/refs/files-backend.c b/refs/files-backend.c index 83ddfb3b627..f98b1be9386 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 @@ stat_ref: 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; } @@ -541,6 +539,7 @@ 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 = 0; assert(err); files_assert_main_repository(refs, "lock_raw_ref"); @@ -629,9 +628,9 @@ retry: * 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'", @@ -655,7 +654,7 @@ retry: * 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 @@ -693,13 +692,13 @@ retry: 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 dfecdbc1db6..a457f18e93c 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 f4445e32904..79dfb3af484 100644 --- a/refs/refs-internal.h +++ b/refs/refs-internal.h @@ -617,11 +617,15 @@ 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. @@ -635,9 +639,9 @@ 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;