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From: Jeff King <peff@peff.net>
To: Junio C Hamano <gitster@pobox.com>
Cc: Brandon Williams <bmwill@google.com>,
	git@vger.kernel.org, j6t@kdbg.org, sbeller@google.com,
	e@80x24.org, jrnieder@gmail.com
Subject: Re: [PATCH v6 04/11] run-command: use the async-signal-safe execv instead of execvp
Date: Tue, 16 May 2017 22:28:34 -0400	[thread overview]
Message-ID: <20170517022834.on2h4n535eidaxal@sigill.intra.peff.net> (raw)
In-Reply-To: <20170517022602.jj26pf7eypxp2fjm@sigill.intra.peff.net>

On Tue, May 16, 2017 at 10:26:02PM -0400, Jeff King wrote:

> On Wed, May 17, 2017 at 11:15:43AM +0900, Junio C Hamano wrote:
> 
> > > +		if (errno == ENOEXEC)
> > > +			execv(argv.argv[0], (char *const *) argv.argv);
> > 
> > "/bin/sh" tries to run "/usr/bin/git" that was not executable (well,
> > the one in "usr/bin/" would have +x bit, but let's pretend that we
> > are trying to run one from bin-wrappers/ and somehow forgot +x bit)?
> > 
> > I think all of that is sensible, but there is one "huh?" I can't
> > figure out.  Typically we do "sh -c git cat-file -t HEAD" but this
> > lacks the "-c" (cf. the original prepare_shell_cmd()); why do we not
> > need it in this case?
> 
> I think this is the same case we were discussing over in the "rebase"
> thread. This isn't about running the user's command as a shell command.
> Note that this kicks in even when cmd->shell_cmd isn't set.
> 
> This is about finding "/usr/bin/foo", realizing it cannot be exec'd
> because it lacks a shebang line, and then pretending that it did have
> "#!/bin/sh". IOW, maintaining compatibility with execvp().
> 
> So the command itself isn't a shell command, but it may execute a shell
> script. If that makes sense.

And note that this isn't about the "+x" bit. That would result in
EACCES.  Getting ENOEXEC means that the contents of the binary are not
something execv thought it could run.

-Peff

  reply	other threads:[~2017-05-17  2:28 UTC|newest]

Thread overview: 140+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-04-10 23:49 [PATCH 0/5] forking and threading Brandon Williams
2017-04-10 23:49 ` [PATCH 1/5] run-command: convert sane_execvp to sane_execvpe Brandon Williams
2017-04-12 19:22   ` Brandon Williams
2017-04-10 23:49 ` [PATCH 2/5] run-command: prepare argv before forking Brandon Williams
2017-04-10 23:49 ` [PATCH 3/5] run-command: allocate child_err " Brandon Williams
2017-04-10 23:49 ` [PATCH 4/5] run-command: prepare child environment " Brandon Williams
2017-04-11  0:58   ` Jonathan Nieder
2017-04-11 17:27     ` Brandon Williams
2017-04-11 17:30       ` Jonathan Nieder
2017-04-10 23:49 ` [PATCH 5/5] run-command: add note about forking and threading Brandon Williams
2017-04-11  0:26   ` Jonathan Nieder
2017-04-11  0:53     ` Eric Wong
2017-04-11 17:33       ` Jonathan Nieder
2017-04-11 17:34       ` Brandon Williams
2017-04-11 17:40         ` Eric Wong
2017-04-11  7:05 ` [PATCH 6/5] run-command: avoid potential dangers in forked child Eric Wong
2017-04-11 16:29   ` Brandon Williams
2017-04-11 16:59     ` Eric Wong
2017-04-11 17:17       ` Brandon Williams
2017-04-11 17:37 ` [PATCH 0/5] forking and threading Jonathan Nieder
2017-04-11 17:54   ` Brandon Williams
2017-04-13 18:32 ` [PATCH v2 0/6] " Brandon Williams
2017-04-13 18:32   ` [PATCH v2 1/6] t5550: use write_script to generate post-update hook Brandon Williams
2017-04-13 20:43     ` Jonathan Nieder
2017-04-13 20:59       ` Eric Wong
2017-04-13 21:35         ` Brandon Williams
2017-04-13 21:39           ` Eric Wong
2017-04-13 18:32   ` [PATCH v2 2/6] run-command: prepare command before forking Brandon Williams
2017-04-13 21:14     ` Jonathan Nieder
2017-04-13 22:41       ` Brandon Williams
2017-04-13 18:32   ` [PATCH v2 3/6] run-command: prepare child environment " Brandon Williams
2017-04-13 18:32   ` [PATCH v2 4/6] run-command: don't die in child when duping /dev/null Brandon Williams
2017-04-13 19:29     ` Eric Wong
2017-04-13 19:43       ` Brandon Williams
2017-04-13 18:32   ` [PATCH v2 5/6] run-command: eliminate calls to error handling functions in child Brandon Williams
2017-04-13 18:32   ` [PATCH v2 6/6] run-command: add note about forking and threading Brandon Williams
2017-04-13 20:50   ` [PATCH v2 0/6] " Jonathan Nieder
2017-04-13 23:44     ` Brandon Williams
2017-04-13 21:14   ` [PATCH 7/6] run-command: block signals between fork and execve Eric Wong
2017-04-13 23:37     ` Brandon Williams
2017-04-14  2:42     ` Brandon Williams
2017-04-14  5:26       ` Eric Wong
2017-04-14  5:35         ` Eric Wong
2017-04-14 16:58   ` [PATCH v3 00/10] forking and threading Brandon Williams
2017-04-14 16:58     ` [PATCH v3 01/10] t5550: use write_script to generate post-update hook Brandon Williams
2017-04-14 16:58     ` [PATCH v3 02/10] t0061: run_command executes scripts without a #! line Brandon Williams
2017-04-14 16:58     ` [PATCH v3 03/10] run-command: prepare command before forking Brandon Williams
2017-04-14 16:58     ` [PATCH v3 04/10] run-command: use the async-signal-safe execv instead of execvp Brandon Williams
2017-04-14 16:58     ` [PATCH v3 05/10] run-command: prepare child environment before forking Brandon Williams
2017-04-14 16:58     ` [PATCH v3 06/10] run-command: don't die in child when duping /dev/null Brandon Williams
2017-04-14 19:38       ` Eric Wong
2017-04-14 20:19         ` Brandon Williams
2017-04-14 16:58     ` [PATCH v3 07/10] run-command: eliminate calls to error handling functions in child Brandon Williams
2017-04-14 18:50       ` Eric Wong
2017-04-14 20:22         ` Brandon Williams
2017-04-14 16:59     ` [PATCH v3 08/10] run-command: handle dup2 and close errors " Brandon Williams
2017-04-14 16:59     ` [PATCH v3 09/10] run-command: add note about forking and threading Brandon Williams
2017-04-14 16:59     ` [PATCH v3 10/10] run-command: block signals between fork and execve Brandon Williams
2017-04-14 20:24       ` Brandon Williams
2017-04-14 21:35         ` Eric Wong
2017-04-17 22:08     ` [PATCH v4 00/10] forking and threading Brandon Williams
2017-04-17 22:08       ` [PATCH v4 01/10] t5550: use write_script to generate post-update hook Brandon Williams
2017-04-17 22:08       ` [PATCH v4 02/10] t0061: run_command executes scripts without a #! line Brandon Williams
2017-04-17 22:08       ` [PATCH v4 03/10] run-command: prepare command before forking Brandon Williams
2017-04-17 22:08       ` [PATCH v4 04/10] run-command: use the async-signal-safe execv instead of execvp Brandon Williams
2017-04-17 22:08       ` [PATCH v4 05/10] run-command: prepare child environment before forking Brandon Williams
2017-04-18  0:26         ` Eric Wong
2017-04-18 21:02           ` Brandon Williams
2017-04-17 22:08       ` [PATCH v4 06/10] run-command: don't die in child when duping /dev/null Brandon Williams
2017-04-17 22:08       ` [PATCH v4 07/10] run-command: eliminate calls to error handling functions in child Brandon Williams
2017-04-17 22:08       ` [PATCH v4 08/10] run-command: handle dup2 and close errors " Brandon Williams
2017-04-17 22:08       ` [PATCH v4 09/10] run-command: add note about forking and threading Brandon Williams
2017-04-17 22:08       ` [PATCH v4 10/10] run-command: block signals between fork and execve Brandon Williams
2017-04-18 23:17       ` [PATCH v5 00/11] forking and threading Brandon Williams
2017-04-18 23:17         ` [PATCH v5 01/11] t5550: use write_script to generate post-update hook Brandon Williams
2017-04-18 23:17         ` [PATCH v5 02/11] t0061: run_command executes scripts without a #! line Brandon Williams
2017-04-19  5:43           ` Johannes Sixt
2017-04-19  6:21             ` Johannes Sixt
2017-04-19 15:56               ` Brandon Williams
2017-04-19 18:18                 ` Johannes Sixt
2017-04-20 10:47                 ` Johannes Schindelin
2017-04-20 17:02                   ` Brandon Williams
2017-04-20 20:24                     ` Johannes Schindelin
2017-04-20 20:49                       ` Brandon Williams
2017-04-18 23:17         ` [PATCH v5 03/11] run-command: prepare command before forking Brandon Williams
2017-04-18 23:17         ` [PATCH v5 04/11] run-command: use the async-signal-safe execv instead of execvp Brandon Williams
2017-04-18 23:17         ` [PATCH v5 05/11] string-list: add string_list_remove function Brandon Williams
2017-04-18 23:31           ` Stefan Beller
2017-04-18 23:36             ` Brandon Williams
2017-04-18 23:40               ` Stefan Beller
2017-04-18 23:18         ` [PATCH v5 06/11] run-command: prepare child environment before forking Brandon Williams
2017-04-18 23:18         ` [PATCH v5 07/11] run-command: don't die in child when duping /dev/null Brandon Williams
2017-04-18 23:18         ` [PATCH v5 08/11] run-command: eliminate calls to error handling functions in child Brandon Williams
2017-04-18 23:18         ` [PATCH v5 09/11] run-command: handle dup2 and close errors " Brandon Williams
2017-04-18 23:18         ` [PATCH v5 10/11] run-command: add note about forking and threading Brandon Williams
2017-04-18 23:18         ` [PATCH v5 11/11] run-command: block signals between fork and execve Brandon Williams
2017-04-19  6:00           ` Johannes Sixt
2017-04-19  7:48             ` Eric Wong
2017-04-19 16:10               ` Brandon Williams
2017-04-19 23:13         ` [PATCH v6 00/11] forking and threading Brandon Williams
2017-04-19 23:13           ` [PATCH v6 01/11] t5550: use write_script to generate post-update hook Brandon Williams
2017-04-19 23:13           ` [PATCH v6 02/11] t0061: run_command executes scripts without a #! line Brandon Williams
2017-04-20 10:49             ` Johannes Schindelin
2017-04-20 16:58               ` Brandon Williams
2017-04-19 23:13           ` [PATCH v6 03/11] run-command: prepare command before forking Brandon Williams
2017-04-19 23:13           ` [PATCH v6 04/11] run-command: use the async-signal-safe execv instead of execvp Brandon Williams
2017-05-17  2:15             ` Junio C Hamano
2017-05-17  2:26               ` Jeff King
2017-05-17  2:28                 ` Jeff King [this message]
2017-05-17  3:41                 ` Junio C Hamano
2017-05-17 14:52                 ` Brandon Williams
2017-04-19 23:13           ` [PATCH v6 05/11] string-list: add string_list_remove function Brandon Williams
2017-04-19 23:13           ` [PATCH v6 06/11] run-command: prepare child environment before forking Brandon Williams
2017-04-19 23:13           ` [PATCH v6 07/11] run-command: don't die in child when duping /dev/null Brandon Williams
2017-04-19 23:13           ` [PATCH v6 08/11] run-command: eliminate calls to error handling functions in child Brandon Williams
2017-04-19 23:13           ` [PATCH v6 09/11] run-command: handle dup2 and close errors " Brandon Williams
2017-04-19 23:13           ` [PATCH v6 10/11] run-command: add note about forking and threading Brandon Williams
2017-04-19 23:13           ` [PATCH v6 11/11] run-command: block signals between fork and execve Brandon Williams
2017-04-24 22:37           ` [PATCH v6 00/11] forking and threading Brandon Williams
2017-04-24 23:50             ` [PATCH v6 12/11] run-command: don't try to execute directories Brandon Williams
2017-04-25  0:17               ` Jonathan Nieder
2017-04-25  1:58                 ` Junio C Hamano
2017-04-25  2:51                   ` Jonathan Nieder
2017-04-25  2:56                 ` Jeff King
2017-04-25  1:47               ` Junio C Hamano
2017-04-25  2:57               ` Jonathan Nieder
2017-04-25 17:54               ` [PATCH v7 1/2] exec_cmd: expose is_executable function Brandon Williams
2017-04-25 17:54                 ` [PATCH v7 2/2] run-command: don't try to execute directories Brandon Williams
2017-04-25 18:51                   ` Jonathan Nieder
2017-04-25 19:32                     ` Brandon Williams
2017-04-25 18:04                 ` [PATCH v7 1/2] exec_cmd: expose is_executable function Jonathan Nieder
2017-04-25 18:18                 ` Johannes Sixt
2017-04-25 18:38                   ` Brandon Williams
2017-04-25 23:46                 ` [PATCH v8 1/2] run-command: " Brandon Williams
2017-04-25 23:47                   ` [PATCH v8 2/2] run-command: restrict PATH search to executable files Brandon Williams
2017-04-25 23:50                     ` Jonathan Nieder
2017-04-26  1:44                     ` Junio C Hamano
2017-04-26 17:10                       ` [PATCH v9 " Brandon Williams
2017-04-27  0:33                         ` Junio C Hamano
2017-04-25 23:48                   ` [PATCH v8 1/2] run-command: expose is_executable function Jonathan Nieder

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