From mboxrd@z Thu Jan  1 00:00:00 1970
From: Junio C Hamano <gitster@pobox.com>
Subject: Re: [PATCH v2 05/19] pull: implement fetch + merge
Date: Tue, 09 Jun 2015 16:27:50 -0700
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References: <1433314143-4478-1-git-send-email-pyokagan@gmail.com>
	<1433314143-4478-6-git-send-email-pyokagan@gmail.com>
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Cc: git@vger.kernel.org, Stefan Beller <sbeller@google.com>,
	Johannes Schindelin <johannes.schindelin@gmx.de>,
	Stephen Robin <stephen.robin@gmail.com>
To: Paul Tan <pyokagan@gmail.com>
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In-Reply-To: <1433314143-4478-6-git-send-email-pyokagan@gmail.com> (Paul Tan's
	message of "Wed, 3 Jun 2015 14:48:49 +0800")
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Paul Tan <pyokagan@gmail.com> writes:

> +/**
> + * Parses argv into [<repo> [<refspecs>...]], returning their values in `repo`
> + * as a string and `refspecs` as a null-terminated array of strings. If `repo`
> + * is not provided in argv, it is set to NULL.
> + */
> +static void parse_repo_refspecs(int argc, const char **argv, const char **repo,
> +		const char ***refspecs)
> +{
> +	if (argc > 0) {
> +		*repo = *argv++;
> +		argc--;
> +	} else
> +		*repo = NULL;
> +	*refspecs = argv;
> +}
> +
> +/**
> + * Runs git-fetch, returning its exit status. `repo` and `refspecs` are the
> + * repository and refspecs to fetch, or NULL if they are not provided.
> + */
> +static int run_fetch(const char *repo, const char **refspecs)
> +{
> +	struct argv_array args = ARGV_ARRAY_INIT;
> +	int ret;
> +
> +	argv_array_pushl(&args, "fetch", "--update-head-ok", NULL);
> +	if (repo)
> +		argv_array_push(&args, repo);
> +	while (*refspecs)
> +		argv_array_push(&args, *refspecs++);

As you cannot say "git pull refspecs...", the above might be more
clear if you spelled it like this instead:

	if (repo) {
		argv_array_push(&args, repo);
		argv_array_pushv(&args, refspecs);
	} else if (*refspecs) {
        	die("BUG: refspec without repo?");
	}

> +/**
> + * Runs git-merge, returning its exit status.
> + */
> +static int run_merge(void)
> +{
> +	int ret;
> +	struct argv_array args = ARGV_ARRAY_INIT;
> +
> +	argv_array_pushl(&args, "merge", NULL);
> +	argv_array_push(&args, "FETCH_HEAD");
> +	ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
> +	argv_array_clear(&args);
> +	return ret;
> +}

No frills yet, which is a good way to start with and show the
overall structure.