Re: [PATCH 4/6] revert: Make commit descriptions in insn sheet optional

[Junio C Hamano <gitster@pobox.com>]

Ramkumar Ramachandra <artagnon@gmail.com> writes:

> Change the instruction sheet format subtly so that a description of
> the commit after the object name is optional.  As a result, an
> instruction sheet like this is now perfectly valid:
>
>   pick 35b0426
>   pick fbd5bbcbc2e
>   pick 7362160f
>
> Suggested-by: Jonathan Nieder <jrnieder@gmail.com>
> Acked-by: Jonathan Nieder <jrnieder@gmail.com>
> Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
> ---
>  builtin/revert.c                |   19 ++++++++-----------
>  t/t3510-cherry-pick-sequence.sh |   14 ++++++++++++++
>  2 files changed, 22 insertions(+), 11 deletions(-)
>
> diff --git a/builtin/revert.c b/builtin/revert.c
> index 6451089..aa6c34e 100644
> --- a/builtin/revert.c
> +++ b/builtin/revert.c
> @@ -692,26 +692,23 @@ static struct commit *parse_insn_line(char *start, struct replay_opts *opts)
>  	unsigned char commit_sha1[20];
>  	char sha1_abbrev[40];
>  	enum replay_action action;
> -	int insn_len = 0;
> -	char *p, *q;
> +	const char *p, *q;
>  
> +	p = start;
>  	if (!prefixcmp(start, "pick ")) {
>  		action = CHERRY_PICK;
> -		insn_len = strlen("pick");
> -		p = start + insn_len + 1;
> +		p += strlen("pick ");
>  	} else if (!prefixcmp(start, "revert ")) {
>  		action = REVERT;
> -		insn_len = strlen("revert");
> -		p = start + insn_len + 1;
> +		p += strlen("revert ");
>  	} else
>  		return NULL;
>  
> -	q = strchr(p, ' ');
> -	if (!q || q - p + 1 > sizeof(sha1_abbrev))
> +	q = p + strcspn(p, " \n");
> +	if (q - p + 1 > sizeof(sha1_abbrev))
>  		return NULL;
> -	q++;
> -
> -	strlcpy(sha1_abbrev, p, q - p);
> +	memcpy(sha1_abbrev, p, q - p);
> +	sha1_abbrev[q - p] = '\0';

Since this is a part of clean-up series...

Do you even need to have a sha1_abbrev[] local array that is limited to 40
bytes here? The incoming _line_ is not "const char *start", so you should
at least be able to temporarily terminate the commit object name with NUL
(while remembering what byte there was before), give it to get_sha1(), and
then restore the byte at the end before returning from this function.

A bonus point would be to introduce a variant of get_sha1() that can take
(a pointer + len) not (a pointer to NUL terminated string). While I think
that would be a right thing to do in the longer term, it is outside of the
scope of this series.