From mboxrd@z Thu Jan 1 00:00:00 1970 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=-12.7 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 B2E01C433B4 for ; Thu, 29 Apr 2021 15:32:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7AF686141E for ; Thu, 29 Apr 2021 15:32:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240603AbhD2PdB (ORCPT ); Thu, 29 Apr 2021 11:33:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54624 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234590AbhD2PdA (ORCPT ); Thu, 29 Apr 2021 11:33:00 -0400 Received: from mail-wr1-x42a.google.com (mail-wr1-x42a.google.com [IPv6:2a00:1450:4864:20::42a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D8DC3C06138C for ; Thu, 29 Apr 2021 08:32:12 -0700 (PDT) Received: by mail-wr1-x42a.google.com with SMTP id h4so58326575wrt.12 for ; Thu, 29 Apr 2021 08:32:12 -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:fcc :content-transfer-encoding:mime-version:to:cc; bh=dAjq7gpUAKf+nhWN3RaxzK79Jrd7riKdpJvlhkjm5+k=; b=gH/+OlwVSZ2bxMcvQv7424w6GAjswnpuGix9kPLxxmtRzkEKiqOXCCioilID2ad69n NnXdtYubl4yoRNP0VyoIuOqNro+TBmGkYgI9U+99Eh1B77ZcbKiqXkbGEZ/NZ9jI5njR yTdxR1HfjUHXYIg/Q8OPcoMIFCojKOHMznYwkhqTipIS3qoIQUIrf3ns5rppsdZ4Y+sA 5zlp3UwOnFJ6er9AwotIK6nVK56yWiiXm/ac5bdgRspSHMTf7jJ689a2P1HCDzXUEkVL kUIQ+yY1bhUBa4lzjbDLUYZXNFNTLxMBZYPdecbeSna7CGGD/tRtXLXAwj/9X/Z6e+Q4 PI3g== 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:fcc:content-transfer-encoding:mime-version:to:cc; bh=dAjq7gpUAKf+nhWN3RaxzK79Jrd7riKdpJvlhkjm5+k=; b=C5sWeXLd+3ECm1tPzf1Uhk393oXQ58WYq7D7mTJKDmwniqxd839utCWjk7fffeSTAR 350lgctO3T0zr8dedHi6cZgJuzfGVXHaTZ138ShBRDEBWNbo+deoFmwPTy8KLK/+tQ8X VY8htAEBJVJvWmZRHOqf/9OMJ/krwuuQOBabrNIILwHpVS5D/iDTwHYGR+qQRylqCNZr PAP7rFSdar5QrkQXGEJmO/o1qIoaWgncLAwLlR/swSU79IAeH6RLPpKz6ZG0fLl6oq9s 43wPzOPbaNwf3tC0eSoH7GRKhZfgoKBoN8i15EOaWP90Ufz8WS4UkhSZRp6Y3hZ/uylr rUYg== X-Gm-Message-State: AOAM531JjoRh6dvBh7T7ogxWlpF3jsXSOdMt4+CscJlk87xOlw+TN6MX fS8IpMm+UYwbZuEgHTbNNNV4nGRaeT0= X-Google-Smtp-Source: ABdhPJzkh1k6KRNpcDHgL/1/SsAhCwHzzYSDLMQ/Gt3VwLCz7Cj+YYOllWaQJzIoEx0vODhDTntuHQ== X-Received: by 2002:a05:6000:1843:: with SMTP id c3mr368437wri.361.1619710331646; Thu, 29 Apr 2021 08:32:11 -0700 (PDT) Received: from [127.0.0.1] ([13.74.141.28]) by smtp.gmail.com with ESMTPSA id t7sm5447099wrw.60.2021.04.29.08.32.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 29 Apr 2021 08:32:11 -0700 (PDT) Message-Id: In-Reply-To: References: From: "Han-Wen Nienhuys via GitGitGadget" Date: Thu, 29 Apr 2021 15:32:02 +0000 Subject: [PATCH 2/8] refs/files-backend: stop setting errno from lock_ref_oid_basic Fcc: Sent Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit MIME-Version: 1.0 To: git@vger.kernel.org Cc: Han-Wen Nienhuys , Han-Wen Nienhuys Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org From: Han-Wen Nienhuys Errno is a global variable written by almost all system calls, and therefore it is hard to reason about its state. It's also useless for user-visible errors, as it leaves no place to report the offending file and/or syscall. For the copy/rename support, calls to lock_ref_oid_basic() in this file are followed by: * lock_ref_oid_basic (copy/rename rollback error path) * write_ref_to_lockfile (both in the rollback path and the success path of copy/rename) These calls do not inspect the incoming errno. As they perform I/O, they can clobber errno. For this reason, callers cannot reliably observe the errno that lock_ref_oid_basic() generated, so it is unsound for programmatic use. For files_create_symref() and files_reflog_expire(), grepping over callers showed no callers inspecting errno. Signed-off-by: Han-Wen Nienhuys --- refs/files-backend.c | 9 +-------- 1 file changed, 1 insertion(+), 8 deletions(-) diff --git a/refs/files-backend.c b/refs/files-backend.c index 119972ee16f8..c9511da1d387 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)) @@ -962,7 +959,7 @@ 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)) @@ -981,20 +978,17 @@ 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 +999,6 @@ static struct ref_lock *lock_ref_oid_basic(struct files_ref_store *refs, out: strbuf_release(&ref_file); - errno = last_errno; return lock; } -- gitgitgadget