Subject: Re: [PATCH v3 2/6] branch.c: replace `git_config()` with `git_config_get_string()`

From: Tanay Abhra <[email-masked]>
Date: Mon, 21 Jul 2014 23:41:15 +0530

On 7/21/2014 11:29 PM, Junio C Hamano wrote:
> Tanay Abhra <[email-masked]> writes:
> 
>> Use `git_config_get_string()` instead of `git_config()` to take advantage of
>> the config-set API which provides a cleaner control flow.
>>
>> Signed-off-by: Tanay Abhra <[email-masked]>
>> ---
>>  branch.c | 24 ++++--------------------
>>  1 file changed, 4 insertions(+), 20 deletions(-)
>>
>> diff --git a/branch.c b/branch.c
>> index 46e8aa8..827307f 100644
>> --- a/branch.c
>> +++ b/branch.c
>> @@ -140,33 +140,17 @@ static int setup_tracking(const char *new_ref, const char *orig_ref,
>>  	return 0;
>>  }
>>  
>> -struct branch_desc_cb {
>> -	const char *config_name;
>> -	const char *value;
>> -};
>> -
>> -static int read_branch_desc_cb(const char *var, const char *value, void *cb)
>> -{
>> -	struct branch_desc_cb *desc = cb;
>> -	if (strcmp(desc->config_name, var))
>> -		return 0;
>> -	free((char *)desc->value);
>> -	return git_config_string(&desc->value, var, value);
>> -}
>> -
>>  int read_branch_desc(struct strbuf *buf, const char *branch_name)
>>  {
>> -	struct branch_desc_cb cb;
>> +	const char *v = NULL;
>>  	struct strbuf name = STRBUF_INIT;
>>  	strbuf_addf(&name, "branch.%s.description", branch_name);
>> -	cb.config_name = name.buf;
>> -	cb.value = NULL;
>> -	if (git_config(read_branch_desc_cb, &cb) < 0) {
>> +	if (git_config_get_string(name.buf, &v)) {
>>  		strbuf_release(&name);
>>  		return -1;
>>  	}
>> -	if (cb.value)
>> -		strbuf_addstr(buf, cb.value);
>> +	strbuf_addstr(buf, v);
>> +	free((char*)v);
> 
> In this cast, I smell an API mistake to insist an extra constness to
> the output parameter of git_config_get_string() in [3/4] of the
> previous series.  Unlike the underlying git_config_get_value(),
> which lets the caller peek into the internal cached copy, the caller
> of git_config_get_string() is given its own copy, and I do not
> offhand see a good reason to forbid the caller from modifying it.
>

I modeled git_config_get_string() on the previously existing API function
git_config_string() with the signature,
int git_config_string(const char **dest, const char *var, const char *value).

But after writing this series I do think there isn't a good reason to
keep the constness in the new function also since the dest is given
its own copy.

>>  	strbuf_release(&name);
>>  	return 0;
>>  }