log: let --invert-grep only invert --grep

The option --invert-grep is documented to filter out commits whose
messages match the --grep filters.  However, it also affects the
header matches (--author, --committer), which is not intended.

Move the handling of that option to grep.c, as only the code there can
distinguish between matches in the header from those in the message
body.  If --invert-grep is given then enable extended expressions (not
the regex type, we just need git grep's --not to work), negate the body
patterns and check if any of them match by piggy-backing on the
collect_hits mechanism of grep_source_1().

Collecting the matches in struct grep_opt is a bit iffy, but with
"last_shown" we have a precedent for writing state information to that
struct.

Reported-by: Dotan Cohen <dotancohen@gmail.com>
Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/grep.h b/grep.h
index 3e8815c347..6a1f0ab017 100644
--- a/grep.h
+++ b/grep.h
@@ -148,6 +148,8 @@ struct grep_opt {
 	int word_regexp;
 	int fixed;
 	int all_match;
+	int no_body_match;
+	int body_hit;
 #define GREP_BINARY_DEFAULT	0
 #define GREP_BINARY_NOMATCH	1
 #define GREP_BINARY_TEXT	2