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From: Jeff King <peff@peff.net>
To: git@vger.kernel.org
Cc: Hamza Mahfooz <someguy@effective-light.com>
Subject: [PATCH 1/5] grep: stop modifying buffer in strip_timestamp
Date: Mon, 20 Sep 2021 23:46:56 -0400	[thread overview]
Message-ID: <YUlVsLkFGRfRqpKG@coredump.intra.peff.net> (raw)
In-Reply-To: <YUlVZk1xXulAqdef@coredump.intra.peff.net>

When grepping for headers in commit objects, we receive individual
lines (e.g., "author Name <email> 1234 -0000"), and then strip off the
timestamp to do our match. We do so by writing a NUL byte over the
whitespace separator, and then remembering to restore it later.

We had to do it this way when this was added back in a4d7d2c6db (log
--author/--committer: really match only with name part, 2008-09-04),
because we fed the result directly to regexec(), which expects a
NUL-terminated string. But since b7d36ffca0 (regex: use regexec_buf(),
2016-09-21), we have a function which can match part of a buffer.

So instead of modifying the string, we can instead just move the "eol"
pointer, and the rest of the code will do the right thing. This will let
further patches mark more buffers as "const".

Signed-off-by: Jeff King <peff@peff.net>
---
 grep.c | 13 +++----------
 1 file changed, 3 insertions(+), 10 deletions(-)

diff --git a/grep.c b/grep.c
index 79598f245f..5b1f2da4d3 100644
--- a/grep.c
+++ b/grep.c
@@ -922,20 +922,16 @@ static int patmatch(struct grep_pat *p, char *line, char *eol,
 	return hit;
 }
 
-static int strip_timestamp(char *bol, char **eol_p)
+static void strip_timestamp(char *bol, char **eol_p)
 {
 	char *eol = *eol_p;
-	int ch;
 
 	while (bol < --eol) {
 		if (*eol != '>')
 			continue;
 		*eol_p = ++eol;
-		ch = *eol;
-		*eol = '\0';
-		return ch;
+		break;
 	}
-	return 0;
 }
 
 static struct {
@@ -952,7 +948,6 @@ static int match_one_pattern(struct grep_pat *p, char *bol, char *eol,
 			     regmatch_t *pmatch, int eflags)
 {
 	int hit = 0;
-	int saved_ch = 0;
 	const char *start = bol;
 
 	if ((p->token != GREP_PATTERN) &&
@@ -971,7 +966,7 @@ static int match_one_pattern(struct grep_pat *p, char *bol, char *eol,
 		switch (p->field) {
 		case GREP_HEADER_AUTHOR:
 		case GREP_HEADER_COMMITTER:
-			saved_ch = strip_timestamp(bol, &eol);
+			strip_timestamp(bol, &eol);
 			break;
 		default:
 			break;
@@ -1021,8 +1016,6 @@ static int match_one_pattern(struct grep_pat *p, char *bol, char *eol,
 				goto again;
 		}
 	}
-	if (p->token == GREP_PATTERN_HEAD && saved_ch)
-		*eol = saved_ch;
 	if (hit) {
 		pmatch[0].rm_so += bol - start;
 		pmatch[0].rm_eo += bol - start;
-- 
2.33.0.1023.gc687d0d3c8


  reply	other threads:[~2021-09-21  3:46 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-21  3:45 [PATCH 0/5] const-correctness in grep.c Jeff King
2021-09-21  3:46 ` Jeff King [this message]
2021-09-21  5:18   ` [PATCH 1/5] grep: stop modifying buffer in strip_timestamp Carlo Arenas
2021-09-21  5:24     ` Eric Sunshine
2021-09-21  5:40       ` Carlo Arenas
2021-09-21  5:43       ` Jeff King
2021-09-21  6:42         ` Carlo Marcelo Arenas Belón
2021-09-21  7:37           ` René Scharfe
2021-09-21 14:24             ` Jeff King
2021-09-21 21:02               ` Ævar Arnfjörð Bjarmason
2021-09-22 20:20                 ` Jeff King
2021-09-23  0:53                   ` Ævar Arnfjörð Bjarmason
2021-09-21  3:48 ` [PATCH 2/5] grep: stop modifying buffer in show_line() Jeff King
2021-09-21  4:22   ` Taylor Blau
2021-09-21  4:42     ` Jeff King
2021-09-21  4:45       ` Taylor Blau
2021-09-21  3:48 ` [PATCH 3/5] grep: stop modifying buffer in grep_source_1() Jeff King
2021-09-21  3:49 ` [PATCH 4/5] grep: mark "haystack" buffers as const Jeff King
2021-09-21 12:04   ` Ævar Arnfjörð Bjarmason
2021-09-21 14:27     ` Jeff King
2021-09-21  3:51 ` [PATCH 5/5] grep: store grep_source buffer " Jeff King
2021-09-21  4:30 ` [PATCH 0/5] const-correctness in grep.c Taylor Blau
2021-09-21 12:07 ` Ævar Arnfjörð Bjarmason
2021-09-21 14:49   ` Jeff King
2021-09-21 12:45 ` [PATCH 6/5] grep.c: mark eol/bol and derived as "const char * const" Ævar Arnfjörð Bjarmason
2021-09-21 14:53   ` Jeff King
2021-09-21 15:17     ` Ævar Arnfjörð Bjarmason
2021-09-21 19:18       ` Jeff King
2021-09-23 13:56         ` Ævar Arnfjörð Bjarmason
2021-09-24  4:22           ` Junio C Hamano
2021-09-22 19:02     ` Junio C Hamano
2021-09-22 18:57 ` [PATCH 0/5] const-correctness in grep.c Junio C Hamano

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