Subject: Re: [PATCH v2 01/94] builtin/apply: make gitdiff_verify_name() return void

From: Junio C Hamano <[email-masked]>
Date: Thu, 12 May 2016 12:06:07 -0700

Christian Couder <[email-masked]> writes:

> As the value returned by gitdiff_verify_name() is put into the
> same variable that is passed as a parameter to this function,
> it is simpler to pass the address of the variable and have
> gitdiff_verify_name() change the variable itself.
>
> This also makes it possible to later have this function return
> -1 instead of die()ing in case of error.
>
> Reviewed-by: Stefan Beller <[email-masked]>
> Signed-off-by: Christian Couder <[email-masked]>
> ---

While I do not agree with "it is simpler" at all (it makes it harder
for callers if they ever want to use different variables--they would
need to invent a temporary variable just for that, and it makes it
no difference for existing callers that happen to use the same
variable), I like the way the real reason why we want to do this is
mentioned in the proposed log message.

Will queue.

>  builtin/apply.c | 26 +++++++++++++-------------
>  1 file changed, 13 insertions(+), 13 deletions(-)
>
> diff --git a/builtin/apply.c b/builtin/apply.c
> index 8e4da2e..fe5aebd 100644
> --- a/builtin/apply.c
> +++ b/builtin/apply.c
> @@ -925,43 +925,43 @@ static int gitdiff_hdrend(const char *line, struct patch *patch)
>  #define DIFF_OLD_NAME 0
>  #define DIFF_NEW_NAME 1
>  
> -static char *gitdiff_verify_name(const char *line, int isnull, char *orig_name, int side)
> +static void gitdiff_verify_name(const char *line, int isnull, char **name, int side)
>  {
> -	if (!orig_name && !isnull)
> -		return find_name(line, NULL, p_value, TERM_TAB);
> +	if (!*name && !isnull) {
> +		*name = find_name(line, NULL, p_value, TERM_TAB);
> +		return;
> +	}
>  
> -	if (orig_name) {
> -		int len = strlen(orig_name);
> +	if (*name) {
> +		int len = strlen(*name);
>  		char *another;
>  		if (isnull)
>  			die(_("git apply: bad git-diff - expected /dev/null, got %s on line %d"),
> -			    orig_name, linenr);
> +			    *name, linenr);
>  		another = find_name(line, NULL, p_value, TERM_TAB);
> -		if (!another || memcmp(another, orig_name, len + 1))
> +		if (!another || memcmp(another, *name, len + 1))
>  			die((side == DIFF_NEW_NAME) ?
>  			    _("git apply: bad git-diff - inconsistent new filename on line %d") :
>  			    _("git apply: bad git-diff - inconsistent old filename on line %d"), linenr);
>  		free(another);
> -		return orig_name;
>  	} else {
>  		/* expect "/dev/null" */
>  		if (memcmp("/dev/null", line, 9) || line[9] != '\n')
>  			die(_("git apply: bad git-diff - expected /dev/null on line %d"), linenr);
> -		return NULL;
>  	}
>  }
>  
>  static int gitdiff_oldname(const char *line, struct patch *patch)
>  {
> -	patch->old_name = gitdiff_verify_name(line, patch->is_new, patch->old_name,
> -					      DIFF_OLD_NAME);
> +	gitdiff_verify_name(line, patch->is_new, &patch->old_name,
> +			    DIFF_OLD_NAME);
>  	return 0;
>  }
>  
>  static int gitdiff_newname(const char *line, struct patch *patch)
>  {
> -	patch->new_name = gitdiff_verify_name(line, patch->is_delete, patch->new_name,
> -					      DIFF_NEW_NAME);
> +	gitdiff_verify_name(line, patch->is_delete, &patch->new_name,
> +			    DIFF_NEW_NAME);
>  	return 0;
>  }