Subject: Re: [PATCH] submodule-config: use explicit empty string instead of strbuf in config_from()

From: René Scharfe <[email-masked]>
Date: Thu, 21 Jul 2016 20:57:03 +0200

Am 20.07.2016 um 10:25 schrieb Heiko Voigt:
> Hi,
>
> On Tue, Jul 19, 2016 at 09:05:43PM +0200, René Scharfe wrote:
>> Use a string constant instead of an empty strbuf to shorten the code
>> and make it easier to read.
>
> This must have been some oversight from my original code. I also can not
> see any purpose.
>
>> Signed-off-by: Rene Scharfe <[email-masked]>
>> ---
>> ... unless someone can come up with a suitable non-empty string to feed
>> to git_config_from_mem() as its name parameter.
>
> If we would want to be absolutely correct we could use something like
> "SHA1:.gitmodules". E.g. like we use to lookup the blob in
> gitmodule_sha1_from_commit():
>
> 	strbuf_addf(&rev, "%s:.gitmodules", sha1_to_hex(commit_sha1));
>
> And now I see where this was leftover from... before extracting this
> function this code was filling the strbuf.
>
> How about this instead?

I like it.

> ---8<------
> Subject: [PATCH] fix passing a name for config from submodules
>
> In commit 959b5455 we implemented the initial version of the submodule
> config cache. During development of that initial version we extracted
> the function gitmodule_sha1_from_commit(). During that process we missed
> that the strbuf rev was still used in config_from() and now is left
> empty. Lets fix this by also returning this string.
>
> Signed-off-by: Heiko Voigt <[email-masked]>
> ---
>
> Its not exactly pretty with all the releases before the returns but
> this is what I could quickly come up with...

Indeed.

>   submodule-config.c | 23 +++++++++++++++--------
>   1 file changed, 15 insertions(+), 8 deletions(-)
>
> diff --git a/submodule-config.c b/submodule-config.c
> index 077db40..dccea59 100644
> --- a/submodule-config.c
> +++ b/submodule-config.c
> @@ -371,9 +371,9 @@ static int parse_config(const char *var, const char *value, void *data)
>   }
>
>   static int gitmodule_sha1_from_commit(const unsigned char *commit_sha1,
> -				      unsigned char *gitmodules_sha1)
> +				      unsigned char *gitmodules_sha1,
> +				      struct strbuf *rev)
>   {
> -	struct strbuf rev = STRBUF_INIT;
>   	int ret = 0;
>
>   	if (is_null_sha1(commit_sha1)) {
> @@ -381,11 +381,10 @@ static int gitmodule_sha1_from_commit(const unsigned char *commit_sha1,
>   		return 1;
>   	}
>
> -	strbuf_addf(&rev, "%s:.gitmodules", sha1_to_hex(commit_sha1));
> -	if (get_sha1(rev.buf, gitmodules_sha1) >= 0)
> +	strbuf_addf(rev, "%s:.gitmodules", sha1_to_hex(commit_sha1));
> +	if (get_sha1(rev->buf, gitmodules_sha1) >= 0)
>   		ret = 1;
>
> -	strbuf_release(&rev);
>   	return ret;
>   }
>
> @@ -420,8 +419,10 @@ static const struct submodule *config_from(struct submodule_cache *cache,
>   		return entry->config;
>   	}
>
> -	if (!gitmodule_sha1_from_commit(commit_sha1, sha1))
> +	if (!gitmodule_sha1_from_commit(commit_sha1, sha1, &rev)) {
> +		strbuf_release(&rev);
>   		return NULL;
> +	}
>
>   	switch (lookup_type) {
>   	case lookup_name:
> @@ -431,14 +432,19 @@ static const struct submodule *config_from(struct submodule_cache *cache,
>   		submodule = cache_lookup_path(cache, sha1, key);
>   		break;
>   	}
> -	if (submodule)
> +	if (submodule) {
> +		strbuf_release(&rev);
>   		return submodule;
> +	}
>
>   	config = read_sha1_file(sha1, &type, &config_size);
> -	if (!config)
> +	if (!config) {
> +		strbuf_release(&rev);
>   		return NULL;
> +	}
>
>   	if (type != OBJ_BLOB) {
> +		strbuf_release(&rev);
>   		free(config);
>   		return NULL;
>   	}

A separate patch could combine the previous two conditionals; free(NULL) 
is allowed.

> @@ -450,6 +456,7 @@ static const struct submodule *config_from(struct submodule_cache *cache,
>   	parameter.overwrite = 0;
>   	git_config_from_mem(parse_config, "submodule-blob", rev.buf,
>   			config, config_size, &parameter);
> +	strbuf_release(&rev);
>   	free(config);
>
>   	switch (lookup_type) {
>