Re: [PATCH 1/3] grep: prepare for new header field filter

[Jeff King <peff@peff.net>]

On Sat, Sep 29, 2012 at 11:41:27AM +0700, Nguyen Thai Ngoc Duy wrote:

> diff --git a/grep.c b/grep.c
> index 898be6e..8d73995 100644
> --- a/grep.c
> +++ b/grep.c
> @@ -720,7 +720,14 @@ static int match_one_pattern(struct grep_pat *p, char *bol, char *eol,
>  		if (strncmp(bol, field, len))
>  			return 0;
>  		bol += len;
> -		saved_ch = strip_timestamp(bol, &eol);
> +		switch (p->field) {
> +		case GREP_HEADER_AUTHOR:
> +		case GREP_HEADER_COMMITTER:
> +			saved_ch = strip_timestamp(bol, &eol);
> +			break;
> +		default:
> +			break;
> +		}

Reading this hunk, I wondered what happens to saved_ch if we do not set
it here. Fortunately it is initialized to 0, as we already have to
handle the non-header case. Then later we do this, which does introduce
a new condition (saved_ch was not set, but we trigger the first half of
the conditional):

      if (p->token == GREP_PATTERN_HEAD && saved_ch)
                *eol = saved_ch;

However, the second half of that conditional (which previously was only
triggered when we tried to split the timestamp, but there was a bogus
line with no ">" on it) prevents us from overwriting *eol.

So I think it is good, but it was non-obvious enough that I wanted to
save other reviewers from investigating it.  The rest of the patch looks
good to me, as well.

-Peff