Re: [PATCH v2 1/2] patchbreak(), is_scissors_line(): work with a buf/len pair

[Phillip Wood <phillip.wood123@gmail.com>]

On 07/09/2022 15:44, Matheus Tavares wrote:
> From: René Scharfe <l.s.r@web.de>
> 
> The next patch will add calls to these two functions from code that
> works with a char */size_t pair. So let's adapt the functions in
> preparation.

Reading this I wonder if we should add a starts_with_mem() function, 
rather than having to pass pointers to buf and len to skip_prefix_mem().

Best Wishes

Phillip

> ---
>   mailinfo.c | 37 +++++++++++++++++++------------------
>   1 file changed, 19 insertions(+), 18 deletions(-)
> 
> diff --git a/mailinfo.c b/mailinfo.c
> index 9621ba62a3..f0a690b6e8 100644
> --- a/mailinfo.c
> +++ b/mailinfo.c
> @@ -646,32 +646,30 @@ static void decode_transfer_encoding(struct mailinfo *mi, struct strbuf *line)
>   	free(ret);
>   }
>   
> -static inline int patchbreak(const struct strbuf *line)
> +static inline int patchbreak(const char *buf, size_t len)
>   {
> -	size_t i;
> -
>   	/* Beginning of a "diff -" header? */
> -	if (starts_with(line->buf, "diff -"))
> +	if (skip_prefix_mem(buf, len, "diff -", &buf, &len))
>   		return 1;
>   
>   	/* CVS "Index: " line? */
> -	if (starts_with(line->buf, "Index: "))
> +	if (skip_prefix_mem(buf, len, "Index: ", &buf, &len))
>   		return 1;
>   
>   	/*
>   	 * "--- <filename>" starts patches without headers
>   	 * "---<sp>*" is a manual separator
>   	 */
> -	if (line->len < 4)
> +	if (len < 4)
>   		return 0;
>   
> -	if (starts_with(line->buf, "---")) {
> +	if (skip_prefix_mem(buf, len, "---", &buf, &len)) {
>   		/* space followed by a filename? */
> -		if (line->buf[3] == ' ' && !isspace(line->buf[4]))
> +		if (len > 1 && buf[0] == ' ' && !isspace(buf[1]))
>   			return 1;
>   		/* Just whitespace? */
> -		for (i = 3; i < line->len; i++) {
> -			unsigned char c = line->buf[i];
> +		for (; len; buf++, len--) {
> +			unsigned char c = buf[0];
>   			if (c == '\n')
>   				return 1;
>   			if (!isspace(c))
> @@ -682,14 +680,14 @@ static inline int patchbreak(const struct strbuf *line)
>   	return 0;
>   }
>   
> -static int is_scissors_line(const char *line)
> +static int is_scissors_line(const char *line, size_t len)
>   {
>   	const char *c;
>   	int scissors = 0, gap = 0;
>   	const char *first_nonblank = NULL, *last_nonblank = NULL;
>   	int visible, perforation = 0, in_perforation = 0;
>   
> -	for (c = line; *c; c++) {
> +	for (c = line; len; c++, len--) {
>   		if (isspace(*c)) {
>   			if (in_perforation) {
>   				perforation++;
> @@ -705,12 +703,14 @@ static int is_scissors_line(const char *line)
>   			perforation++;
>   			continue;
>   		}
> -		if (starts_with(c, ">8") || starts_with(c, "8<") ||
> -		    starts_with(c, ">%") || starts_with(c, "%<")) {
> +		if (skip_prefix_mem(c, len, ">8", &c, &len) ||
> +		    skip_prefix_mem(c, len, "8<", &c, &len) ||
> +		    skip_prefix_mem(c, len, ">%", &c, &len) ||
> +		    skip_prefix_mem(c, len, "%<", &c, &len)) {
>   			in_perforation = 1;
>   			perforation += 2;
>   			scissors += 2;
> -			c++;
> +			c--, len++;
>   			continue;
>   		}
>   		in_perforation = 0;
> @@ -747,7 +747,8 @@ static int check_inbody_header(struct mailinfo *mi, const struct strbuf *line)
>   {
>   	if (mi->inbody_header_accum.len &&
>   	    (line->buf[0] == ' ' || line->buf[0] == '\t')) {
> -		if (mi->use_scissors && is_scissors_line(line->buf)) {
> +		if (mi->use_scissors &&
> +		    is_scissors_line(line->buf, line->len)) {
>   			/*
>   			 * This is a scissors line; do not consider this line
>   			 * as a header continuation line.
> @@ -808,7 +809,7 @@ static int handle_commit_msg(struct mailinfo *mi, struct strbuf *line)
>   	if (convert_to_utf8(mi, line, mi->charset.buf))
>   		return 0; /* mi->input_error already set */
>   
> -	if (mi->use_scissors && is_scissors_line(line->buf)) {
> +	if (mi->use_scissors && is_scissors_line(line->buf, line->len)) {
>   		int i;
>   
>   		strbuf_setlen(&mi->log_message, 0);
> @@ -826,7 +827,7 @@ static int handle_commit_msg(struct mailinfo *mi, struct strbuf *line)
>   		return 0;
>   	}
>   
> -	if (patchbreak(line)) {
> +	if (patchbreak(line->buf, line->len)) {
>   		if (mi->message_id)
>   			strbuf_addf(&mi->log_message,
>   				    "Message-Id: %s\n", mi->message_id);