From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff King Subject: Re: [PATCH v2 0/3] nd/clear-gitenv-upon-use-of-alias Date: Wed, 23 Dec 2015 04:37:00 -0500 Message-ID: <20151223093700.GA13386@sigill.intra.peff.net> References: <1449166676-30845-1-git-send-email-pclouds@gmail.com> <1450597819-26278-1-git-send-email-pclouds@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Cc: Duy Nguyen , Git Mailing List , Stefan Beller , Anthony Sottile To: Junio C Hamano X-From: git-owner@vger.kernel.org Wed Dec 23 10:37:43 2015 Return-path: Envelope-to: gcvg-git-2@plane.gmane.org Received: from vger.kernel.org ([209.132.180.67]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1aBfrZ-0005Oa-MD for gcvg-git-2@plane.gmane.org; Wed, 23 Dec 2015 10:37:42 +0100 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755032AbbLWJhJ (ORCPT ); Wed, 23 Dec 2015 04:37:09 -0500 Received: from cloud.peff.net ([50.56.180.127]:45538 "HELO cloud.peff.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1752773AbbLWJhD (ORCPT ); Wed, 23 Dec 2015 04:37:03 -0500 Received: (qmail 1654 invoked by uid 102); 23 Dec 2015 09:37:03 -0000 Received: from Unknown (HELO peff.net) (10.0.1.1) by cloud.peff.net (qpsmtpd/0.84) with SMTP; Wed, 23 Dec 2015 03:37:03 -0600 Received: (qmail 6371 invoked by uid 107); 23 Dec 2015 09:37:12 -0000 Received: from sigill.intra.peff.net (HELO sigill.intra.peff.net) (10.0.0.7) by peff.net (qpsmtpd/0.84) with SMTP; Wed, 23 Dec 2015 04:37:12 -0500 Received: by sigill.intra.peff.net (sSMTP sendmail emulation); Wed, 23 Dec 2015 04:37:00 -0500 Content-Disposition: inline In-Reply-To: Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Archived-At: On Tue, Dec 22, 2015 at 10:13:03AM -0800, Junio C Hamano wrote: > > Another by the way, this "forcing aliases as external commands" now > > shows something like "error: git-log died of signal 13" when the pager > > exits early, for an alias like "l1 = log --oneline". > > ... and we do not show that when we directly call "git log" is...? > > We do signal this with non-zero exit status like so: > > $ GIT_PAGER=true git log --oneline ; echo $? > 141 > > and it is not surprising that the one that is catching the exit > status of what was spawned and reporting "signal 13". This sounded very familiar. Apparently I've been running with the patch below for almost 3 years and never got around to re-examining it. The original discussion is in: http://thread.gmane.org/gmane.comp.version-control.git/212630 Having skimmed through the arguments there, and given that we applied the patch from the middle of the thread, I think this is a good change. -- >8 -- Date: Fri, 4 Jan 2013 07:19:35 -0500 Subject: [PATCH] avoid SIGPIPE warnings for aliases When git executes an alias that specifies an external command, it will complain if the alias dies due to a signal. This is usually a good thing, as signal deaths are unexpected. However, SIGPIPE is not unexpected for many commands which produce a lot of output; it is intended that the user closing the pager would kill them them via SIGPIPE. As a result, the user might see annoying messages in a scenario like this: $ cat ~/.gitconfig [alias] lgbase = log --some-options lg = !git lgbase --more-options lg2 = !git lgbase --other-options $ git lg -p [user hits 'q' to exit pager] error: git lgbase --more-options died of signal 13 fatal: While expanding alias 'lg': 'git lgbase --more-options': Success Many users won't see this, because we execute the external command with the shell, and a POSIX shell will silently rewrite the signal-death exit code into 128+signal, and we will treat it like a normal exit code. However, this does not always happen: 1. If the sub-command does not have shell metacharacters, we will skip the shell and exec it directly, getting the signal code. 2. Some shells do not do this rewriting; for example, setting SHELL_PATH set to zsh will reveal this problem. This patch squelches the message, and lets git exit silently (with the same exit code that a shell would use in case of a signal). The first line of the message comes from run-command's wait_or_whine. To silence that message, we remain quiet anytime we see SIGPIPE. The second line comes from handle_alias itself. It calls die_errno whenever run_command returns a negative value. However, only -1 indicates a syscall error where errno has something useful (note that it says the useless "success" above). Instead, we treat negative returns from run_command (except for -1) as a normal code to be passed to exit. Signed-off-by: Jeff King --- git.c | 2 +- run-command.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/git.c b/git.c index 6ed824c..34a18a3 100644 --- a/git.c +++ b/git.c @@ -252,7 +252,7 @@ static int handle_alias(int *argcp, const char ***argv) alias_argv[argc] = NULL; ret = run_command_v_opt(alias_argv, RUN_USING_SHELL); - if (ret >= 0) /* normal exit */ + if (ret != -1) /* normal exit */ exit(ret); die_errno("While expanding alias '%s': '%s'", diff --git a/run-command.c b/run-command.c index 13fa452..694a6ff 100644 --- a/run-command.c +++ b/run-command.c @@ -245,7 +245,7 @@ static int wait_or_whine(pid_t pid, const char *argv0, int in_signal) error("waitpid is confused (%s)", argv0); } else if (WIFSIGNALED(status)) { code = WTERMSIG(status); - if (code != SIGINT && code != SIGQUIT) + if (code != SIGINT && code != SIGQUIT && code != SIGPIPE) error("%s died of signal %d", argv0, code); /* * This return value is chosen so that code & 0xff -- 2.7.0.rc2.368.g1cbb535