Re: [PATCH] grep: do not do external grep on skip-worktree entries

Linus Torvalds [off-list ref] writes:

The bad news is that you broke multi-line greps:

	git grep --no-ext-grep -2 qwerty.*as

results in:

	drivers/char/keyboard.c-unsigned char kbd_sysrq_xlate[KEY_MAX + 1] =
	drivers/char/keyboard.c-        "\000\0331234567890-=\177\t"                    /* 0x00 - 0x0f */
	drivers/char/keyboard.c:        "qwertyuiop[]\r\000as"                          /* 0x10 - 0x1f */

Meh.  I checked pre-context codepath before sending the patch and was very
satisfied that René did the right thing in 49de321 (grep: handle pre
context lines on demand, 2009-07-02), but somehow forgot about the post
context codepath.

An ObviouslyRightThing fix is this two-liner.  We shouldn't lookahead if
we want to do something more than just skipping when we see an unmatch for
the line we are currently looking at.

 grep.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/grep.c b/grep.c
index 940e200..ac0ce0b 100644
--- a/grep.c
+++ b/grep.c

@@ -719,6 +719,8 @@ static int grep_buffer_1(struct grep_opt *opt, const char *name,
 		int hit;
 
 		if (try_lookahead
+		    && !(last_hit
+			 && lno <= last_hit + opt->post_context)
 		    && look_ahead(opt, &left, &lno, &bol))
 			break;
 		eol = end_of_line(bol, &left);