Thanks for the bug report. I installed the attached patch; please give
it a try.From b9a8047099d2388c15e6ad39e7b8c91c6633096c Mon Sep 17 00:00:00 2001
From: Paul Eggert <egg...@cs.ucla.edu>
Date: Fri, 9 Feb 2024 01:06:49 -0800
Subject: [PATCH] =?UTF-8?q?grep:=20fix=20=E2=80=98grep=20-m2=20pattern=20<?=
=?UTF-8?q?file=20>/dev/null=E2=80=99?=
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Problem reported by Grisha Levit <https://bugs.gnu.org/68989>.
* src/grep.c (grep, main): Don’t set done_on_match if -m is used.
* tests/max-count-overread: Add a test case.
---
NEWS | 3 +++
src/grep.c | 9 +++++++--
tests/max-count-overread | 6 ++++++
3 files changed, 16 insertions(+), 2 deletions(-)
diff --git a/NEWS b/NEWS
index bc487ce..4294fc6 100644
--- a/NEWS
+++ b/NEWS
@@ -11,6 +11,9 @@ GNU grep NEWS -*- outline -*-
1
[bug introduced in grep 3.11]
+ -mN where 1 < N no longer mistakenly lseeks to end of input merely
+ because standard output is /dev/null.
+
** Changes in behavior
On Windows platforms and on AIX in 32-bit mode, grep now supports
diff --git a/src/grep.c b/src/grep.c
index dab3be7..1256dfd 100644
--- a/src/grep.c
+++ b/src/grep.c
@@ -1558,7 +1558,11 @@ grep (int fd, struct stat const *st, bool *ineof)
if (binary_files == WITHOUT_MATCH_BINARY_FILES)
return 0;
if (!count_matches)
- done_on_match = out_quiet = true;
+ {
+ out_quiet = true;
+ if (max_count == INTMAX_MAX)
+ done_on_match = true;
+ }
nlines_first_null = nlines;
nul_zapper = eol;
skip_nuls = skip_empty_lines;
@@ -2897,7 +2901,8 @@ main (int argc, char **argv)
if ((exit_on_match | dev_null_output) || list_files != LISTFILES_NONE)
{
count_matches = false;
- done_on_match = true;
+ if (max_count == INTMAX_MAX)
+ done_on_match = true;
}
out_quiet = count_matches | done_on_match;
diff --git a/tests/max-count-overread b/tests/max-count-overread
index 23c45cb..f829cc5 100755
--- a/tests/max-count-overread
+++ b/tests/max-count-overread
@@ -12,4 +12,10 @@ echo x > exp || framework_failure_
yes x | timeout 10 grep -m1 x > out || fail=1
compare exp out || fail=1
+# Make sure -m2 stops reading even when output is /dev/null.
+# In grep 3.11, it would continue reading.
+printf 'x\nx\nx\n' >in || framework_failure
+(grep -m2 x >/dev/null && head -n1) <in >out || fail=1
+compare exp out || fail=1
+
Exit $fail
--
2.40.1
