From: Jonathan Nieder <jrnieder@gmail.com>
Date: Fri, 25 Jan 2013 05:53:31 GMT
Subject: Re: segmentation fault (nullpointer) with git log --submodule -p
Message-ID: <20130125055331.GC26524@elie.Belkin>
In-Reply-To: <7vzjzx7w01.fsf@alter.siamese.dyndns.org>

Hi,

Junio C Hamano wrote:

> I've been toying with an idea along this line.

Heh.  Just for fun, here's an uglier version:

	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;
		}
	}