Subject: Re: [PATCH v5] commit.c: use skip_prefix() instead of starts_with()

From: Michael Haggerty <[email-masked]>
Date: Fri, 21 Mar 2014 16:48:23 +0100

On 03/04/2014 11:07 PM, Tanay Abhra wrote:
> In record_author_date() & parse_gpg_output(), the callers of
> starts_with() not just want to know if the string starts with the
> prefix, but also can benefit from knowing the string that follows
> the prefix.
> 
> By using skip_prefix(), we can do both at the same time.
> 
> Helped-by: Max Horn <[email-masked]>
> Helped-by: Junio C Hamano <[email-masked]>
> Helped-by: Michael Haggerty <[email-masked]>
> Signed-off-by: Tanay Abhra <[email-masked]>
> ---
> Patch V5 Minor revision of indentation
> Patch V4  Identation improved, removed useless comment. [1]
> 		Thanks to Junio C Hamano and Max Horn.
> [1] http://article.gmane.org/gmane.comp.version-control.git/243388
> 
> Patch V3 Variable naming improved, removed assignments inside conditionals.
>         Thanks to Junio C Hamano and Max Horn.
> 
> Patch V2 Corrected email formatting ,reapplied the implementation according to suggestions.
>         Thanks to Michael Haggerty.
> 
> This is in respect to GSoC microproject #10.
> 
> In record_author_date(), extra and useless calls to strlen due to using starts_with()
> were removed by using skip_prefix(). Extra variable "ident_line" was used as "buf" is used in
> for loop update check.
> 
> Other usages of starts_with() in the same file can be found with,
> 
> $ grep -n starts_with commit.c
> 
> 1116:           else if (starts_with(line, gpg_sig_header) &&
> 1196:           if (starts_with(buf, sigcheck_gpg_status[i].check + 1)) {
> 
> The starts_with() in line 1116 was left as it is, as strlen values were pre computed as
> global variables, and replacing may hamper the clarity.
> The starts_with() in line 1196 was replaced as it abstracts way the skip_prefix part by
> directly using the function.
> Also skip_prefix() is inline when compared to starts_with().
> 
> ---
>  commit.c | 14 ++++++--------
>  1 file changed, 6 insertions(+), 8 deletions(-)
> 
> diff --git a/commit.c b/commit.c
> index 6bf4fe0..d37675c 100644
> --- a/commit.c
> +++ b/commit.c
> @@ -548,7 +548,7 @@ define_commit_slab(author_date_slab, unsigned long);
>  static void record_author_date(struct author_date_slab *author_date,
>  			       struct commit *commit)
>  {
> -	const char *buf, *line_end;
> +	const char *buf, *line_end, *ident_line;
>  	char *buffer = NULL;
>  	struct ident_split ident;
>  	char *date_end;
> @@ -566,14 +566,14 @@ static void record_author_date(struct author_date_slab *author_date,
>  	     buf;
>  	     buf = line_end + 1) {
>  		line_end = strchrnul(buf, '\n');
> -		if (!starts_with(buf, "author ")) {
> +		ident_line = skip_prefix(buf, "author ");
> +		if (!ident_line) {
>  			if (!line_end[0] || line_end[1] == '\n')
>  				return; /* end of header */
>  			continue;
>  		}
>  		if (split_ident_line(&ident,
> -				     buf + strlen("author "),
> -				     line_end - (buf + strlen("author "))) ||
> +				     ident_line, line_end - ident_line) ||
>  		    !ident.date_begin || !ident.date_end)
>  			goto fail_exit; /* malformed "author" line */
>  		break;
> @@ -1193,10 +1193,8 @@ static void parse_gpg_output(struct signature_check *sigc)
>  	for (i = 0; i < ARRAY_SIZE(sigcheck_gpg_status); i++) {
>  		const char *found, *next;
>  
> -		if (starts_with(buf, sigcheck_gpg_status[i].check + 1)) {
> -			/* At the very beginning of the buffer */
> -			found = buf + strlen(sigcheck_gpg_status[i].check + 1);
> -		} else {
> +		found = skip_prefix(buf, sigcheck_gpg_status[i].check + 1);
> +		if(!found) {

Nit: There should be a space between "if" and the opening parenthesis.

>  			found = strstr(buf, sigcheck_gpg_status[i].check);
>  			if (!found)
>  				continue;
> 

Michael

-- 
Michael Haggerty
[email-masked]
http://softwareswirl.blogspot.com/