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From: Johannes Schindelin <Johannes.Schindelin@gmx.de>
To: Eric Sunshine <sunshine@sunshineco.com>
Cc: Pranit Bauva <pranit.bauva@gmail.com>,
	Git List <git@vger.kernel.org>,
	Christian Couder <christian.couder@gmail.com>,
	Christian Couder <chriscool@tuxfamily.org>,
	Lars Schneider <larsxschneider@gmail.com>,
	Junio C Hamano <gitster@pobox.com>
Subject: Re: [PATCH v6 3/3] bisect--helper: `write_terms` shell function in C
Date: Mon, 16 May 2016 18:45:42 +0200 (CEST)	[thread overview]
Message-ID: <alpine.DEB.2.20.1605161830200.3303@virtualbox> (raw)
In-Reply-To: <CAPig+cQ=Gche_uO840wF6qE4WD-ZNZj1HFzNNgaBi_UjG1sjEg@mail.gmail.com>

Hi Eric,

On Mon, 16 May 2016, Eric Sunshine wrote:

> On Mon, May 16, 2016 at 9:16 AM, Johannes Schindelin
> <Johannes.Schindelin@gmx.de> wrote:
> > On Mon, 16 May 2016, Eric Sunshine wrote:
> >> On Thu, May 12, 2016 at 1:32 AM, Pranit Bauva <pranit.bauva@gmail.com> wrote:
> >> > +       fp = fopen(".git/BISECT_TERMS", "w");
> >>
> >> Hardcoding ".git/" is wrong for a variety of reasons: It won't be correct
> >> with linked worktrees, or when GIT_DIR is pointing elsewhere, or when ".git"
> >> is a symbolic link, etc. Check out the get_git_dir(), get_git_common_dir(),
> >> etc. functions in cache.h instead.
> >
> > Maybe in this case, `git_path("BISECT_TERMS")` would be a good idea. Or even
> > better: follow the example of bisect.c and use
> > `GIT_PATH_FUNC(bisect_terms_path, "BISECT_TERMS")`.
> 
> Thanks for pointing this out. My review time is severely limited these
> days so I didn't go the distance of re-studying and re-digesting which
> function was the correct one to use.

I am constantly amazed how much you manage to review, and how helpful your
comments are. I am glad if I could contribute a little.

> >> > +               strbuf_release(&content);
> >> > +               die_errno(_("could not open the file to read terms"));
> >>
> >> Is dying here correct? I thought we established previously that you
> >> should be reporting failure via normal -1 return value rather than
> >> dying. Indeed, you're doing so below when strbuf_write() fails.
> >
> > The rule of thumb seems to be that die()ing is okay in builtin/*.c, but not
> > in *.c. So technically, it would be okay here, too. However, I think that
> > this code should be written with libification in mind, so I would also
> > prefer it to error() and return, to give the caller a chance to do other
> > things after an error occurred.
> 
> Agreed. Specific to the "established previously" I wrote above, I was
> referring to [1] from just a few days ago which explained why 'return
> -1' was preferable to die() in a similar case that had an odd mix of
> 'return -1' and die() in the same function.
> 
> [1]: http://thread.gmane.org/gmane.comp.version-control.git/289476/focus=293556

Yes, this is an excellent link. Maybe we would want something like this,
too?

-- snipsnap --
(From: Eric Sunshine <sunshine@sunshineco.com>)
CodingGuidelines: mention that die() is for fatal errors only

Let's formalize the rule when to use die() and when to use error().

diff --git a/Documentation/CodingGuidelines
b/Documentation/CodingGuidelines
index 0ddd368..5d2d65f 100644
--- a/Documentation/CodingGuidelines
+++ b/Documentation/CodingGuidelines
@@ -333,6 +333,10 @@ For C programs:
 
  - When you come up with an API, document it.
 
+ - Use die() only to signal an exceptional conditions which should
+   abort the program. All other error conditions should instead
+   return e.g. using "return error(...)".
+
  - The first #include in C files, except in platform specific compat/
    implementations, must be either "git-compat-util.h", "cache.h" or
    "builtin.h".  You do not have to include more than one of these.

  reply	other threads:[~2016-05-16 16:47 UTC|newest]

Thread overview: 114+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-03-21 19:00 [PATCH] bisect--helper: convert a function in shell to C Pranit Bauva
2016-03-22  0:28 ` Stefan Beller
2016-03-22  6:10   ` Christian Couder
2016-03-22  6:13     ` Pranit Bauva
2016-03-22  6:13   ` Pranit Bauva
2016-03-22  8:01 ` [PATCH v2] " Pranit Bauva
2016-03-22 15:09   ` Johannes Schindelin
2016-03-22 15:11     ` Johannes Schindelin
2016-03-22 17:46       ` Pranit Bauva
2016-03-23 11:23         ` Johannes Schindelin
2016-03-22 16:03     ` Junio C Hamano
2016-03-22 16:49       ` Johannes Schindelin
2016-03-22 17:52       ` Pranit Bauva
2016-03-22 17:59         ` Stefan Beller
2016-03-23 11:24           ` Johannes Schindelin
2016-03-22 17:45     ` Pranit Bauva
2016-03-23 11:22       ` Johannes Schindelin
2016-03-23 13:53         ` Pranit Bauva
2016-03-23  7:16   ` [PATCH v3] " Pranit Bauva
2016-03-23 11:57     ` Johannes Schindelin
2016-03-23 13:16       ` Pranit Bauva
2016-03-23 16:24         ` Junio C Hamano
2016-03-23 18:38           ` Pranit Bauva
2016-03-23 16:15       ` Junio C Hamano
2016-03-23 18:46         ` Pranit Bauva
2016-05-04  5:07     ` [PATCH 0/2] bisect--helper: rewrite of check_term_format() Pranit Bauva
2016-05-04  5:07       ` [PATCH 1/2] bisect--helper: use OPT_CMDMODE instead of OPT_BOOL Pranit Bauva
2016-05-04  5:34         ` Pranit Bauva
2016-05-04  6:07         ` Eric Sunshine
2016-05-04  6:50           ` Christian Couder
2016-05-04 11:05             ` Johannes Schindelin
2016-05-04 12:04               ` Pranit Bauva
2016-05-04 12:05               ` Christian Couder
2016-05-04 12:21                 ` Johannes Schindelin
2016-05-04 12:41                   ` Christian Couder
2016-05-04 14:56                     ` Johannes Schindelin
2016-05-04 19:07                       ` Christian Couder
2016-05-08  6:54                         ` Johannes Schindelin
2016-05-04  7:28           ` Junio C Hamano
2016-05-04 11:02         ` Johannes Schindelin
2016-05-04  5:07       ` [PATCH 2/2] bisect: rewrite `check_term_format` shell function in C Pranit Bauva
2016-05-04  6:52         ` Eric Sunshine
2016-05-04  7:36           ` Pranit Bauva
2016-05-04  7:40             ` Pranit Bauva
2016-05-04  8:28             ` Eric Sunshine
2016-05-04  8:54               ` Christian Couder
2016-05-04 11:58               ` Pranit Bauva
2016-05-04 17:49                 ` Eric Sunshine
2016-05-04 18:08                   ` Pranit Bauva
2016-05-04 11:13             ` Johannes Schindelin
2016-05-04 12:00               ` Pranit Bauva
2016-05-04 12:21               ` Christian Couder
2016-05-04 19:10               ` Junio C Hamano
2016-05-04  5:22       ` [PATCH 0/2] bisect--helper: rewrite of check_term_format() Christian Couder
2016-05-04  5:25         ` Pranit Bauva
2016-05-06 14:49       ` [PATCH v5 0/2] bisect--helper: rewrite of check-term-format() Pranit Bauva
2016-05-06 14:49         ` [PATCH v5 1/2] bisect--helper: use OPT_CMDMODE instead of OPT_BOOL Pranit Bauva
2016-05-08  7:04           ` Johannes Schindelin
2016-05-08  7:17             ` Pranit Bauva
2016-05-08 15:30               ` Christian Couder
2016-05-08 15:33                 ` Pranit Bauva
2016-05-09 14:59               ` Johannes Schindelin
2016-05-09 15:33                 ` Pranit Bauva
2016-05-06 14:49         ` [PATCH v5 2/2] bisect: rewrite `check_term_format` shell function in C Pranit Bauva
2016-05-07  0:05           ` Eric Sunshine
2016-05-06 22:15         ` [PATCH v5 0/2] bisect--helper: rewrite of check-term-format() Junio C Hamano
2016-05-07 13:07           ` Pranit Bauva
2016-05-08  2:25             ` Junio C Hamano
2016-05-08  6:23               ` Pranit Bauva
2016-05-08 13:34                 ` Pranit Bauva
2016-05-16  0:35                   ` Eric Sunshine
2016-05-16 17:07                     ` Christian Couder
2016-05-20  6:59                     ` Pranit Bauva
2016-05-12  5:32         ` [PATCH v6 0/3] bisect--helper: check_term_format() & write_terms() Pranit Bauva
2016-05-12  5:32           ` [PATCH v6 1/3] bisect--helper: use OPT_CMDMODE instead of OPT_BOOL Pranit Bauva
2016-05-16  7:07             ` Eric Sunshine
2016-05-20  7:17               ` Pranit Bauva
2016-05-12  5:32           ` [PATCH v6 2/3] bisect: rewrite `check_term_format` shell function in C Pranit Bauva
2016-05-12 22:36             ` Junio C Hamano
2016-05-13  6:59               ` Pranit Bauva
2016-05-13 18:01                 ` Junio C Hamano
2016-05-12  5:32           ` [PATCH v6 3/3] bisect--helper: `write_terms` " Pranit Bauva
2016-05-16  7:28             ` Eric Sunshine
2016-05-16 13:16               ` Johannes Schindelin
2016-05-16 15:42                 ` Eric Sunshine
2016-05-16 16:45                   ` Johannes Schindelin [this message]
2016-05-16 16:59                     ` Eric Sunshine
2016-05-20  7:45                 ` Pranit Bauva
2016-05-23 11:07                   ` Johannes Schindelin
2016-05-23 13:58                     ` Christian Couder
2016-05-23 15:10                       ` Johannes Schindelin
2016-05-23 14:33                     ` Pranit Bauva
2016-05-20  7:42               ` Pranit Bauva
2016-05-23 14:48           ` [PATCH v7 0/3] bisect--helper: check_term_format() & write_terms() Pranit Bauva
2016-05-23 14:48             ` [PATCH v7 1/3] bisect--helper: use OPT_CMDMODE instead of OPT_BOOL Pranit Bauva
2016-05-23 14:48             ` [PATCH v7 2/3] bisect: rewrite `check_term_format` shell function in C Pranit Bauva
2016-05-23 14:48             ` [PATCH v7 3/3] bisect--helper: `write_terms` " Pranit Bauva
2016-05-23 16:01               ` Eric Sunshine
2016-05-23 17:59                 ` Pranit Bauva
2016-05-24  7:21             ` [PATCH v8 0/3] bisect--helper: check-term-format() & write_terms() Pranit Bauva
2016-05-24 18:42               ` [PATCH v9 0/3] bisect--helper: check_term_format() and write_terms() Pranit Bauva
2016-05-24 18:42               ` [PATCH v9 1/3] bisect--helper: use OPT_CMDMODE instead of OPT_BOOL Pranit Bauva
2016-05-24 18:42               ` [PATCH v9 2/3] bisect: rewrite `check_term_format` shell function in C Pranit Bauva
2016-05-24 18:42               ` [PATCH v9 3/3] bisect--helper: `write_terms` " Pranit Bauva
2016-05-24  7:21             ` [PATCH v8 1/3] bisect--helper: use OPT_CMDMODE instead of OPT_BOOL Pranit Bauva
2016-05-24  7:21             ` [PATCH v8 2/3] bisect: rewrite `check_term_format` shell function in C Pranit Bauva
2016-05-25  5:04               ` Johannes Schindelin
2016-05-25  5:13                 ` Pranit Bauva
2016-06-16  7:10               ` Lars Schneider
2016-06-17 12:48                 ` Pranit Bauva
2016-05-24  7:21             ` [PATCH v8 3/3] bisect--helper: `write_terms` " Pranit Bauva
2016-05-24  7:33               ` Christian Couder
2016-05-24 17:39                 ` Junio C Hamano
2016-05-24 18:31                 ` Pranit Bauva

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