From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS31976 209.132.180.0/23 X-Spam-Status: No, score=-4.0 required=3.0 tests=AWL,BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,RCVD_IN_DNSWL_HI, RCVD_IN_SORBS_SPAM,RP_MATCHES_RCVD shortcircuit=no autolearn=no autolearn_force=no version=3.4.0 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by dcvr.yhbt.net (Postfix) with ESMTP id 65DC11FE90 for ; Wed, 19 Apr 2017 23:13:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S940297AbdDSXNs (ORCPT ); Wed, 19 Apr 2017 19:13:48 -0400 Received: from mail-io0-f179.google.com ([209.85.223.179]:33881 "EHLO mail-io0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S940290AbdDSXNp (ORCPT ); Wed, 19 Apr 2017 19:13:45 -0400 Received: by mail-io0-f179.google.com with SMTP id a103so42686900ioj.1 for ; Wed, 19 Apr 2017 16:13:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=jUTzvKrg09pN7ttMYVm0n5+31dEWfeSY/yGxX35Gwlw=; b=BMYd0wsfrInulbY1d6wROsN1f/kdFDhbMpQJvHbHNnqSLraO/nUQ5oTOITeLEGaFGF N1gVQdingPtiv0Jt4D0/jMMcDY4aFwTaSMcd/9qZrnRJ80T0hvdbnEwSERbOyLsJNRuh r1rVU8zd4NdoeBV+IoXC4xwa0tOtOyi8y4CP62MRzq/q0PJ6XJRI8PMkcB2wfUeoZC5S 18uzD/BuvBivh8hSdwqVtu+Jai/7N7vaBaaGKlCAkiLytROj34jgRF5hI2ZLr06YX1Zf /0MgxwweQgOvxPEo/jRcPSrWOS7vncVh/KwJErB+E2gwVI6ULh12rexsxfoS+H4fx0t/ sTtA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=jUTzvKrg09pN7ttMYVm0n5+31dEWfeSY/yGxX35Gwlw=; b=t65fbtjzEZbHkMV48I/2NDpLDgGdQcWRR02QEhGfbmJRJ7fCO7Na2OWVc407ubENFW ARsIxjoW9jGVBJdFm6kQJzLtembmWxN+lo4NySMAvVRef/rrkQ0FGUf3S6iocyHup+pp wAvJo9ftfouZxUQQ4e2PRUZ37YvyeEt4UfvkuclrhzpiR3KgE1m7EWSekB0uvIfLlMCV PXqKq/QX35/oCwgwRY2Pp53UzC9cHf/6Epb9G0Awjxy2DdRRkqlat8w4TPmtITGVemAP DslvtWZiNdcnrTk59VyNWbPYvMyYx4Y0gVJH2FO2xcwAZYTlIx9Ks+DSJNThUJV4kUAE ragQ== X-Gm-Message-State: AN3rC/7KtN2x7mspBYIwb+AEU7eCe+wilkL/nSjlItIgrapwq+gSe129 TNoKJn30/MIMr4+P X-Received: by 10.84.174.131 with SMTP id r3mr6775093plb.136.1492643620841; Wed, 19 Apr 2017 16:13:40 -0700 (PDT) Received: from roshar.svl.corp.google.com ([100.96.218.30]) by smtp.gmail.com with ESMTPSA id s10sm6433798pfe.28.2017.04.19.16.13.39 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Wed, 19 Apr 2017 16:13:39 -0700 (PDT) From: Brandon Williams To: git@vger.kernel.org Cc: Brandon Williams , j6t@kdbg.org, sbeller@google.com, e@80x24.org, jrnieder@gmail.com Subject: [PATCH v6 04/11] run-command: use the async-signal-safe execv instead of execvp Date: Wed, 19 Apr 2017 16:13:20 -0700 Message-Id: <20170419231327.49895-5-bmwill@google.com> X-Mailer: git-send-email 2.12.2.816.g2cccc81164-goog In-Reply-To: <20170419231327.49895-1-bmwill@google.com> References: <20170418231805.61835-1-bmwill@google.com> <20170419231327.49895-1-bmwill@google.com> Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Convert the function used to exec from 'execvp()' to 'execv()' as the (p) variant of exec isn't async-signal-safe and has the potential to call malloc during the path resolution it performs. Instead we simply do the path resolution ourselves during the preparation stage prior to forking. There also don't exist any portable (p) variants which also take in an environment to use in the exec'd process. This allows easy migration to using 'execve()' in a future patch. Also, as noted in [1], in the event of an ENOEXEC the (p) variants of exec will attempt to execute the command by interpreting it with the 'sh' utility. To maintain this functionality, if 'execv()' fails with ENOEXEC, start_command will atempt to execute the command by interpreting it with 'sh'. [1] http://pubs.opengroup.org/onlinepubs/009695399/functions/exec.html Signed-off-by: Brandon Williams --- run-command.c | 30 +++++++++++++++++++++++++++++- 1 file changed, 29 insertions(+), 1 deletion(-) diff --git a/run-command.c b/run-command.c index d8d143795..1c7a3b611 100644 --- a/run-command.c +++ b/run-command.c @@ -238,6 +238,12 @@ static void prepare_cmd(struct argv_array *out, const struct child_process *cmd) if (!cmd->argv[0]) die("BUG: command is empty"); + /* + * Add SHELL_PATH so in the event exec fails with ENOEXEC we can + * attempt to interpret the command with 'sh'. + */ + argv_array_push(out, SHELL_PATH); + if (cmd->git_cmd) { argv_array_push(out, "git"); argv_array_pushv(out, cmd->argv); @@ -246,6 +252,20 @@ static void prepare_cmd(struct argv_array *out, const struct child_process *cmd) } else { argv_array_pushv(out, cmd->argv); } + + /* + * If there are no '/' characters in the command then perform a path + * lookup and use the resolved path as the command to exec. If there + * are no '/' characters or if the command wasn't found in the path, + * have exec attempt to invoke the command directly. + */ + if (!strchr(out->argv[1], '/')) { + char *program = locate_in_PATH(out->argv[1]); + if (program) { + free((char *)out->argv[1]); + out->argv[1] = program; + } + } } #endif @@ -445,7 +465,15 @@ int start_command(struct child_process *cmd) } } - sane_execvp(argv.argv[0], (char *const *) argv.argv); + /* + * Attempt to exec using the command and arguments starting at + * argv.argv[1]. argv.argv[0] contains SHELL_PATH which will + * be used in the event exec failed with ENOEXEC at which point + * we will try to interpret the command using 'sh'. + */ + execv(argv.argv[1], (char *const *) argv.argv + 1); + if (errno == ENOEXEC) + execv(argv.argv[0], (char *const *) argv.argv); if (errno == ENOENT) { if (!cmd->silent_exec_failure) -- 2.12.2.816.g2cccc81164-goog