From mboxrd@z Thu Jan  1 00:00:00 1970
From: Junio C Hamano <gitster@pobox.com>
Subject: Re: segmentation fault (nullpointer) with git log --submodule -p
Date: Thu, 24 Jan 2013 23:27:17 -0800
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Cc: Jeff King <peff@peff.net>, Duy Nguyen <pclouds@gmail.com>,
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To: Jonathan Nieder <jrnieder@gmail.com>
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In-Reply-To: <20130125055331.GC26524@elie.Belkin> (Jonathan Nieder's message
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Jonathan Nieder <jrnieder@gmail.com> writes:

> Hi,
>
> Junio C Hamano wrote:
>
>> I've been toying with an idea along this line.
>
> Heh.  Just for fun, here's an uglier version:

Much nicer, though.

>
> 	struct wcb_data {
> 		int had_buffer;
> 		int using_buffer;
> 	};
> 	#define WITH_COMMIT_BUFFER_DATA_INIT { 0, 0 }
>
> 	extern void acquire_commit_buffer(struct commit *, struct wcb_data *);
> 	extern void done_with_commit_buffer(struct commit *, struct wcb_data *);
>
> 	/*
> 	 * usage:
> 	 *	struct wcb_data buf = WITH_COMMIT_BUFFER_INIT;
> 	 *
> 	 *	with_commit_buffer(commit, buf) {
> 	 *		...
> 	 *	}
> 	 */
> 	#define with_commit_buffer(commit, i) \
> 		for (acquire_commit_buffer(commit, &i); \
> 		     i.using_buffer; \
> 		     done_with_commit_buffer(commit, &i))
>
> 	void acquire_commit_buffer(struct commit *commit, struct wcb_data *i)
> 	{
> 		enum object_type type;
> 		unsigned long size;
>
> 		assert(!i->using_buffer);
> 		i->using_buffer = 1;
> 		i->had_buffer = !!commit->buffer;
>
> 		if (i->had_buffer)
> 			return;
> 		commit->buffer = read_sha1_file(commit->object.sha1, &type, &size);
> 		if (!commit->buffer)
> 			die("unable to read commit %s", sha1_to_hex(commit->object.sha1));
> 	}
>
> 	void done_with_commit_buffer(struct commit *commit, struct wcb_data *i)
> 	{
> 		assert(i->using_buffer);
> 		i->using_buffer = 0;
>
> 		if (!i->had_buffer) {
> 			free(commit->buffer);
> 			commit->buffer = NULL;
> 		}
> 	}