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From: Emily Shaffer <emilyshaffer@google.com>
To: Junio C Hamano <gitster@pobox.com>
Cc: git@vger.kernel.org
Subject: Re: [PATCH v8 03/15] bugreport: add tool to generate debugging info
Date: Thu, 20 Feb 2020 14:33:23 -0800	[thread overview]
Message-ID: <20200220223323.GD2447@google.com> (raw)
In-Reply-To: <xmqq8skxawah.fsf@gitster-ct.c.googlers.com>

On Thu, Feb 20, 2020 at 11:33:26AM -0800, Junio C Hamano wrote:
> Emily Shaffer <emilyshaffer@google.com> writes:
> 
> > +	argc = parse_options(argc, argv, "", bugreport_options,
> > +			     bugreport_usage, 0);
> 
> Which one between an empty string and NULL is more appropriate to be
> passed as "prefix" here?  I assume that this is *not* really a git
> program, and no repository/working-tree discovery is involved, and
> you won't be using OPT_FILENAME, so it would probably be OK.
> 
> > +
> > +	if (option_output) {
> > +		strbuf_addstr(&report_path, option_output);
> > +		strbuf_complete(&report_path, '/');
> > +	}
> > +
> > +
> > +	strbuf_addstr(&report_path, "git-bugreport-");
> > +	strbuf_addftime(&report_path, option_suffix, localtime(&now), 0, 0);
> > +	strbuf_addstr(&report_path, ".txt");
> > +
> > +	if (!stat(report_path.buf, &statbuf))
> > +		die("'%s' already exists", report_path.buf);
> 
> Missed i18n/l10n, but I do not think it is a useful thing for this
> check to be here in the first place.
> 
> > +	switch (safe_create_leading_directories(report_path.buf)) {
> > +	case SCLD_OK:
> > +	case SCLD_EXISTS:
> > +		break;
> > +	default:
> > +		die(_("could not create leading directories for '%s'"),
> > +		    report_path.buf);
> > +	}
> > +
> > +	get_bug_template(&buffer);
> > +
> > +	report = fopen_for_writing(report_path.buf);
> 
> fopen_for_writing() does not give good semantics for what you seem
> to want to do here (i.e. to make sure you do not overwrite an
> existing one).  It even has "if we cannot open it, retry after
> unlinking" logic in it, which screams "this function is designed for
> those who want to overwrite the file", and if you look at its
> callers, they are _all_ about opening a file for writing with a well
> known name like FETCH_HEAD, COMMIT_EDITMSG, etc.
> 
> Besides, a stat() that dies when a file exists would not
> help---since that check, you've spent non-zero time, creating
> leading directories and preparing boilerplate in the buffer,
> and there is no guarantee somebody else used the same filename
> in the meantime.

Good point. Ouch.

> 
> If you want to avoid overwriting an existing file (which I think is
> a good idea---I just do not think the earlier "if (!stat()) die()"
> is a good way to do so), the only sensible way to do so is to ask
> your open/creat to fail if there already is a file---that is how
> you'd avoid racing with another process that may be creating such a
> file.  Grep for O_EXCL to find where the flag is used with O_CREAT
> to see how it is done.

Sure. Thanks, I reworked it to use open().

By the way, I noticed reading the GNU manual that file descriptors may
not be supported outside of GNU environments; but I also noticed that 1)
Git uses open() lots of places to use O_EXCL, and 2) fopen() doesn't
support exclusive opens (except in glibc, and nobody is using that
particular option in the Git codebase now). So I guess it's safe to use
open()...

> 
> > +	if (report == NULL) {
> 
> Style. "if (!report)"

The type of 'report' changes using open(), so this check changes too.
Now it says "if (report < 0)" - per the open() doc, it returns a
positive fd or -1.

> 
> > +		strbuf_release(&report_path);
> > +		die("couldn't open '%s' for writing", report_path.buf);
> 
> Do we see a use-after-free here?  Also missed i18n/l10n.

Hm. I suppose it's OK to UNLEAK() like we do at the successful exit
since the die() will end the process. Added i18n too.

> It is embarrassing on the reviewers' side that this (which is not
> new in this round at all and hasn't changed since v6) hasn't been
> caught for a few rounds X-<.

Well, I'm embarrassed to have written it in the first place.

 - Emily

  reply	other threads:[~2020-02-20 22:33 UTC|newest]

Thread overview: 273+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-13  0:42 [PATCH v4 00/15] add git-bugreport tool Emily Shaffer
2019-12-13  0:42 ` [PATCH v4 01/15] bugreport: add tool to generate debugging info Emily Shaffer
2019-12-13  0:42 ` [PATCH v4 02/15] help: move list_config_help to builtin/help Emily Shaffer
2019-12-13 20:51   ` Junio C Hamano
2019-12-16 21:36     ` Emily Shaffer
2019-12-16 22:19       ` Junio C Hamano
2019-12-16 22:34         ` Emily Shaffer
2019-12-13  0:43 ` [PATCH v4 03/15] bugreport: gather git version and build info Emily Shaffer
2019-12-13 21:06   ` Junio C Hamano
2019-12-20  1:46     ` Emily Shaffer
2019-12-17 18:45   ` Johannes Schindelin
2019-12-17 20:34     ` Junio C Hamano
2019-12-20  1:25       ` Emily Shaffer
2019-12-13  0:43 ` [PATCH v4 04/15] help: add shell-path to --build-options Emily Shaffer
2019-12-13  0:43 ` [PATCH v4 05/15] bugreport: add uname info Emily Shaffer
2019-12-13 21:12   ` Junio C Hamano
2020-01-10  2:05   ` Aaron Schrab
2019-12-13  0:43 ` [PATCH v4 06/15] bugreport: add glibc version Emily Shaffer
2019-12-13 21:18   ` Junio C Hamano
2019-12-16 22:39     ` Emily Shaffer
2019-12-13  0:43 ` [PATCH v4 07/15] bugreport: add curl version Emily Shaffer
2019-12-13 21:27   ` Junio C Hamano
2019-12-16 22:49     ` Emily Shaffer
2019-12-17 18:47   ` Johannes Schindelin
2019-12-13  0:43 ` [PATCH v4 08/15] bugreport: include user interactive shell Emily Shaffer
2019-12-13 21:38   ` Junio C Hamano
2019-12-13  0:43 ` [PATCH v4 09/15] bugreport: generate config safelist based on docs Emily Shaffer
2019-12-13 22:57   ` Junio C Hamano
2019-12-16 23:01     ` Emily Shaffer
2019-12-17  0:41       ` Emily Shaffer
2019-12-15 20:17   ` Johannes Schindelin
2019-12-16 22:52     ` Emily Shaffer
2019-12-17 18:38   ` Johannes Schindelin
2019-12-13  0:43 ` [PATCH v4 10/15] bugreport: add config values from safelist Emily Shaffer
2019-12-13 21:45   ` Junio C Hamano
2019-12-16 23:40     ` Emily Shaffer
2019-12-17 17:43       ` Junio C Hamano
2020-01-24  3:29         ` Emily Shaffer
2019-12-29 20:17   ` Johannes Schindelin
2019-12-13  0:43 ` [PATCH v4 11/15] bugreport: collect list of populated hooks Emily Shaffer
2019-12-13 21:47   ` Junio C Hamano
2019-12-16 23:51     ` Emily Shaffer
2019-12-13  0:43 ` [PATCH v4 12/15] bugreport: count loose objects Emily Shaffer
2019-12-13 21:51   ` Junio C Hamano
2019-12-16 23:54     ` Emily Shaffer
2019-12-13  0:43 ` [PATCH v4 13/15] bugreport: add packed object summary Emily Shaffer
2019-12-13 21:56   ` Junio C Hamano
2019-12-16 23:56     ` Emily Shaffer
2019-12-13  0:43 ` [PATCH v4 14/15] bugreport: list contents of $OBJDIR/info Emily Shaffer
2019-12-13  0:43 ` [PATCH v4 15/15] bugreport: summarize contents of alternates file Emily Shaffer
2020-01-24  3:34 ` [PATCH v5 00/15] add git-bugreport tool emilyshaffer
2020-01-24  3:34   ` [PATCH v5 01/15] bugreport: add tool to generate debugging info emilyshaffer
2020-01-30 22:18     ` Martin Ågren
2020-02-04 22:00       ` Emily Shaffer
2020-01-24  3:34   ` [PATCH v5 02/15] help: move list_config_help to builtin/help emilyshaffer
2020-01-30 22:19     ` Martin Ågren
2020-02-04  0:53       ` Emily Shaffer
2020-01-24  3:34   ` [PATCH v5 03/15] bugreport: gather git version and build info emilyshaffer
2020-01-30 22:19     ` Martin Ågren
2020-02-04 22:21       ` Emily Shaffer
2020-01-24  3:34   ` [PATCH v5 04/15] help: add shell-path to --build-options emilyshaffer
2020-01-30 22:21     ` Martin Ågren
2020-01-24  3:34   ` [PATCH v5 05/15] bugreport: add uname info emilyshaffer
2020-01-24  3:34   ` [PATCH v5 06/15] bugreport: add compiler info emilyshaffer
2020-01-30 22:21     ` Martin Ågren
2020-02-04 22:51       ` Emily Shaffer
2020-02-05 19:47         ` Martin Ågren
2020-01-24  3:34   ` [PATCH v5 07/15] bugreport: add curl version emilyshaffer
2020-01-30 22:27     ` Martin Ågren
2020-02-04 22:54       ` Emily Shaffer
2020-01-24  3:34   ` [PATCH v5 08/15] bugreport: include user interactive shell emilyshaffer
2020-01-30 22:28     ` Martin Ågren
2020-02-04 23:16       ` Emily Shaffer
2020-02-05 20:06       ` Junio C Hamano
2020-02-05 20:14         ` Martin Ågren
2020-01-24  3:34   ` [PATCH v5 09/15] bugreport: generate config safelist based on docs emilyshaffer
2020-01-30 22:34     ` Martin Ågren
2020-02-05  0:44       ` Emily Shaffer
2020-02-05 19:53         ` Martin Ågren
2020-01-31 21:20     ` Martin Ågren
2020-02-05  0:30       ` Emily Shaffer
2020-02-05  0:52         ` Emily Shaffer
2020-01-24  3:34   ` [PATCH v5 10/15] bugreport: add config values from safelist emilyshaffer
2020-01-30 22:36     ` Martin Ågren
2020-02-05  1:34       ` Emily Shaffer
2020-01-31 21:25     ` Martin Ågren
2020-02-05  2:31       ` Emily Shaffer
2020-02-05 20:12         ` Martin Ågren
2020-01-24  3:34   ` [PATCH v5 11/15] bugreport: collect list of populated hooks emilyshaffer
2020-02-04 18:44     ` Junio C Hamano
2020-02-05  2:48       ` Emily Shaffer
2020-02-05  3:00         ` Emily Shaffer
2020-01-24  3:34   ` [PATCH v5 12/15] bugreport: count loose objects emilyshaffer
2020-02-04 18:48     ` Junio C Hamano
2020-02-05  2:50       ` Emily Shaffer
2020-01-24  3:34   ` [PATCH v5 13/15] bugreport: add packed object summary emilyshaffer
2020-02-04 19:00     ` Junio C Hamano
2020-02-05  3:15       ` Emily Shaffer
2020-02-04 19:03     ` Junio C Hamano
2020-02-05  3:09       ` Emily Shaffer
2020-01-24  3:34   ` [PATCH v5 14/15] bugreport: list contents of $OBJDIR/info emilyshaffer
2020-01-24  3:34   ` [PATCH v5 15/15] bugreport: summarize contents of alternates file emilyshaffer
2020-01-24  3:38   ` [PATCH v5 00/15] add git-bugreport tool Emily Shaffer
2020-01-28 23:04   ` Jonathan Tan
2020-01-28 23:26     ` Emily Shaffer
2020-01-30 22:15   ` Martin Ågren
2020-02-04  0:07     ` Emily Shaffer
2020-02-06  0:40   ` [PATCH v6 " Emily Shaffer
2020-02-06  0:40     ` [PATCH v6 01/15] help: move list_config_help to builtin/help Emily Shaffer
2020-02-06  1:35       ` Danh Doan
2020-02-13 22:58         ` Emily Shaffer
2020-02-13 23:07           ` Eric Sunshine
2020-02-13 23:24             ` Junio C Hamano
2020-02-13 23:29               ` Eric Sunshine
2020-02-14  1:20                 ` Emily Shaffer
2020-02-06  0:40     ` [PATCH v6 02/15] help: add shell-path to --build-options Emily Shaffer
2020-02-06  0:40     ` [PATCH v6 03/15] bugreport: add tool to generate debugging info Emily Shaffer
2020-02-07 14:18       ` SZEDER Gábor
2020-02-07 18:51         ` Junio C Hamano
2020-02-11 22:40           ` Emily Shaffer
2020-02-07 14:54       ` SZEDER Gábor
2020-02-12 18:06       ` Junio C Hamano
2020-02-12 22:36         ` Emily Shaffer
2020-02-06  0:40     ` [PATCH v6 04/15] bugreport: gather git version and build info Emily Shaffer
2020-02-06  0:40     ` [PATCH v6 05/15] bugreport: add uname info Emily Shaffer
2020-02-06  0:40     ` [PATCH v6 06/15] bugreport: add compiler info Emily Shaffer
2020-02-06  0:41     ` [PATCH v6 07/15] bugreport: add git-remote-https version Emily Shaffer
2020-02-06  0:41     ` [PATCH v6 08/15] bugreport: include user interactive shell Emily Shaffer
2020-02-06  0:41     ` [PATCH v6 09/15] bugreport: generate config safelist based on docs Emily Shaffer
2020-02-07 15:30       ` SZEDER Gábor
2020-02-13 23:14         ` Emily Shaffer
2020-02-06  0:41     ` [PATCH v6 10/15] bugreport: add config values from safelist Emily Shaffer
2020-02-07 14:47       ` SZEDER Gábor
2020-02-07 15:08         ` SZEDER Gábor
2020-02-07 16:24           ` Eric Sunshine
2020-02-07 16:51             ` Andreas Schwab
2020-02-13 22:02               ` Emily Shaffer
2020-02-06  0:41     ` [PATCH v6 11/15] bugreport: collect list of populated hooks Emily Shaffer
2020-02-06  0:41     ` [PATCH v6 12/15] bugreport: count loose objects Emily Shaffer
2020-02-06  0:41     ` [PATCH v6 13/15] bugreport: add packed object summary Emily Shaffer
2020-02-06  0:41     ` [PATCH v6 14/15] bugreport: list contents of $OBJDIR/info Emily Shaffer
2020-02-06  0:41     ` [PATCH v6 15/15] bugreport: summarize contents of alternates file Emily Shaffer
2020-02-14  1:53     ` [PATCH v7 00/15] add git-bugreport tool Emily Shaffer
2020-02-14  1:53       ` [PATCH v7 01/15] help: move list_config_help to builtin/help Emily Shaffer
2020-02-14  1:53       ` [PATCH v7 02/15] help: add shell-path to --build-options Emily Shaffer
2020-02-14  1:53       ` [PATCH v7 03/15] bugreport: add tool to generate debugging info Emily Shaffer
2020-02-14 17:25         ` Junio C Hamano
2020-02-15  1:57           ` Emily Shaffer
2020-02-15 18:24             ` Junio C Hamano
2020-02-18 23:46               ` Emily Shaffer
2020-02-18 23:56                 ` Emily Shaffer
2020-02-19 23:15                   ` Emily Shaffer
2020-02-19 23:24                     ` Junio C Hamano
2020-02-19 14:18         ` Johannes Schindelin
2020-02-19 16:55           ` Junio C Hamano
2020-02-19 21:52             ` Emily Shaffer
2020-02-19 22:09               ` Junio C Hamano
2020-02-19 23:06                 ` Emily Shaffer
2020-02-14  1:53       ` [PATCH v7 04/15] bugreport: gather git version and build info Emily Shaffer
2020-02-14  1:53       ` [PATCH v7 05/15] bugreport: add uname info Emily Shaffer
2020-02-14  1:53       ` [PATCH v7 06/15] bugreport: add compiler info Emily Shaffer
2020-02-19 14:23         ` Johannes Schindelin
2020-02-19 22:45           ` Emily Shaffer
2020-02-20 22:33             ` Johannes Schindelin
2020-02-20 23:33               ` Emily Shaffer
2020-02-21 15:22                 ` Johannes Schindelin
2020-02-22  0:04                   ` Emily Shaffer
2020-02-24  2:55                     ` Junio C Hamano
2020-02-14  1:53       ` [PATCH v7 07/15] bugreport: add git-remote-https version Emily Shaffer
2020-02-19 14:28         ` Johannes Schindelin
2020-02-19 22:28           ` Emily Shaffer
2020-02-19 22:33             ` Junio C Hamano
2020-02-20 22:33               ` Johannes Schindelin
2020-02-14  1:53       ` [PATCH v7 08/15] bugreport: include user interactive shell Emily Shaffer
2020-02-14  1:53       ` [PATCH v7 09/15] bugreport: generate config safelist based on docs Emily Shaffer
2020-02-14  1:53       ` [PATCH v7 10/15] bugreport: add config values from safelist Emily Shaffer
2020-02-14  1:53       ` [PATCH v7 11/15] bugreport: collect list of populated hooks Emily Shaffer
2020-02-14  1:53       ` [PATCH v7 12/15] bugreport: count loose objects Emily Shaffer
2020-02-14  1:53       ` [PATCH v7 13/15] bugreport: add packed object summary Emily Shaffer
2020-02-14  1:53       ` [PATCH v7 14/15] bugreport: list contents of $OBJDIR/info Emily Shaffer
2020-02-14 17:04         ` Junio C Hamano
2020-02-18 23:59           ` Emily Shaffer
2020-02-14  1:53       ` [PATCH v7 15/15] bugreport: summarize contents of alternates file Emily Shaffer
2020-02-14 17:32       ` [PATCH v7 00/15] add git-bugreport tool Junio C Hamano
2020-02-14 22:00         ` Emily Shaffer
2020-02-14 22:30           ` Junio C Hamano
2020-02-20  1:58       ` [PATCH v8 " Emily Shaffer
2020-02-20  1:58         ` [PATCH v8 01/15] help: move list_config_help to builtin/help Emily Shaffer
2020-02-20  1:58         ` [PATCH v8 02/15] help: add shell-path to --build-options Emily Shaffer
2020-02-20 19:03           ` Junio C Hamano
2020-02-20 21:15             ` Emily Shaffer
2020-02-20  1:58         ` [PATCH v8 03/15] bugreport: add tool to generate debugging info Emily Shaffer
2020-02-20 19:33           ` Junio C Hamano
2020-02-20 22:33             ` Emily Shaffer [this message]
2020-02-26 16:12           ` Johannes Schindelin
2020-02-20  1:58         ` [PATCH v8 04/15] bugreport: gather git version and build info Emily Shaffer
2020-02-20 20:07           ` Junio C Hamano
2020-02-20 23:03             ` Emily Shaffer
2020-02-20 23:18               ` Junio C Hamano
2020-02-20  1:58         ` [PATCH v8 05/15] bugreport: add uname info Emily Shaffer
2020-02-20 20:12           ` Junio C Hamano
2020-02-20 23:20             ` Emily Shaffer
2020-02-20  1:58         ` [PATCH v8 06/15] bugreport: add compiler info Emily Shaffer
2020-02-20  2:49           ` Danh Doan
2020-02-20 23:23             ` Emily Shaffer
2020-02-20 20:23           ` Junio C Hamano
2020-02-21  0:26           ` Junio C Hamano
2020-02-20  1:58         ` [PATCH v8 07/15] bugreport: add git-remote-https version Emily Shaffer
2020-02-20 20:35           ` Junio C Hamano
2020-02-20 23:28             ` Emily Shaffer
2020-02-21  3:44               ` Junio C Hamano
2020-02-25 22:08                 ` Emily Shaffer
2020-02-25 22:26                   ` Junio C Hamano
2020-02-25 23:29                     ` Emily Shaffer
2020-02-25 23:29                   ` Junio C Hamano
2020-02-25 23:55                     ` Emily Shaffer
2020-02-20  1:58         ` [PATCH v8 08/15] bugreport: include user interactive shell Emily Shaffer
2020-02-20  1:58         ` [PATCH v8 09/15] bugreport: generate config safelist based on docs Emily Shaffer
2020-02-20 20:40           ` Junio C Hamano
2020-02-26 16:13           ` Johannes Schindelin
2020-02-26 16:49             ` Junio C Hamano
2020-02-20  1:58         ` [PATCH v8 10/15] bugreport: add config values from safelist Emily Shaffer
2020-02-20 20:47           ` Junio C Hamano
2020-02-20  1:58         ` [PATCH v8 11/15] bugreport: collect list of populated hooks Emily Shaffer
2020-02-20 20:58           ` Junio C Hamano
2020-02-25 23:19             ` Emily Shaffer
2020-02-20  1:58         ` [PATCH v8 12/15] bugreport: count loose objects Emily Shaffer
2020-02-20 21:04           ` Junio C Hamano
2020-02-25 23:22             ` Emily Shaffer
2020-02-25 23:26               ` Emily Shaffer
2020-02-20  1:58         ` [PATCH v8 13/15] bugreport: add packed object summary Emily Shaffer
2020-02-20 22:04           ` Junio C Hamano
2020-02-25 23:58             ` Emily Shaffer
2020-02-20  1:58         ` [PATCH v8 14/15] bugreport: list contents of $OBJDIR/info Emily Shaffer
2020-02-20 22:18           ` Junio C Hamano
2020-02-20  1:58         ` [PATCH v8 15/15] bugreport: summarize contents of alternates file Emily Shaffer
2020-02-20 14:08           ` Johannes Schindelin
2020-02-20 22:22           ` Junio C Hamano
2020-03-02 23:03         ` [PATCH v9 0/5] add git-bugreport tool Emily Shaffer
2020-03-02 23:03           ` [PATCH v9 1/5] help: move list_config_help to builtin/help Emily Shaffer
2020-03-02 23:03           ` [PATCH v9 2/5] bugreport: add tool to generate debugging info Emily Shaffer
2020-03-03 14:18             ` Johannes Schindelin
2020-03-04 21:35             ` Johannes Schindelin
2020-03-05 23:34               ` Jeff Hostetler
2020-03-06 13:57                 ` Johannes Schindelin
2020-03-06 18:25                   ` Junio C Hamano
2020-03-06 18:08                 ` Junio C Hamano
2020-03-06 18:58                   ` Jeff Hostetler
2020-03-08 22:24                   ` Johannes Schindelin
2020-03-09 14:59                     ` Junio C Hamano
2020-03-09 19:17                       ` Johannes Schindelin
2020-03-09 19:47                         ` Junio C Hamano
2020-03-10 11:42                           ` Johannes Schindelin
2020-03-10 18:37                             ` Junio C Hamano
2020-03-10 22:08                               ` Johannes Schindelin
2020-03-19 21:39               ` Emily Shaffer
2020-03-20  0:28                 ` Junio C Hamano
2020-03-20 15:35                   ` Johannes Schindelin
2020-03-23 18:52                     ` Emily Shaffer
2020-03-20 15:42                 ` Johannes Schindelin
2020-03-23 18:50                   ` Emily Shaffer
2020-03-20 17:43                 ` Junio C Hamano
2020-03-20 22:38                   ` Johannes Schindelin
2020-03-20 22:47                     ` Junio C Hamano
2020-03-21 10:53                       ` Johannes Schindelin
2020-03-02 23:03           ` [PATCH v9 3/5] bugreport: gather git version and build info Emily Shaffer
2020-03-23 21:20             ` Junio C Hamano
2020-03-02 23:03           ` [PATCH v9 4/5] bugreport: add uname info Emily Shaffer
2020-03-02 23:04           ` [PATCH v9 5/5] bugreport: add compiler info Emily Shaffer
2020-03-03 11:46             ` Danh Doan
2020-03-03 14:07             ` Junio C Hamano
2020-03-04 21:39             ` Johannes Schindelin
2020-03-23 21:27               ` Emily Shaffer

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