diff options
authorKyle Evans <kevans@FreeBSD.org>2021-02-08 18:31:17 +0000
committerKyle Evans <kevans@FreeBSD.org>2021-02-08 18:41:22 +0000
commit3e2d96ac974db823255a6f40b90eeffa6e38d022 (patch)
parent32bf05ad89aaa93f4dd27e3721f4cb52cf57fa03 (diff)
grep: fix -A handling in conjunction with -m match limitation
The basic issue here is that grep, when given -m 1, would stop all line processing once it hit the match count and exit immediately. The problem with exiting immediately is that -A processing only happens when subsequent lines are processed and do not match. The fix here is relatively easy; when bsdgrep matches a line, it resets the 'tail' of the matching context to the value supplied to -A and dumps anything that's been queued up for -B. After the current line has been printed and tail is reset, we check our mcount and do what's needed. Therefore, at the time that we decide we're doing nothing, we know that 'tail' of the context is correct and we can simply continue on if there's still more to pick up. With this change, we still bail out immediately if there's been no -A flag. If -A was supplied, we signal that we should continue on. However, subsequent lines will not even bothere to try and process the line. We have reached the match count, so even if the next line would match then we must process it if it hadn't. Thus, the loop in procfile() can short-circuit and just process the line as a non-match until procmatches() indicates that it's safe to stop. A test has been added to reflect both that we should be picking up the next line and that the next line should be considered a non-match even if it should have been. PR: 253350 MFC-after: 3 days
2 files changed, 37 insertions, 1 deletions
diff --git a/contrib/netbsd-tests/usr.bin/grep/t_grep.sh b/contrib/netbsd-tests/usr.bin/grep/t_grep.sh
index ef3f0617465e..d2539a8250de 100755
--- a/contrib/netbsd-tests/usr.bin/grep/t_grep.sh
+++ b/contrib/netbsd-tests/usr.bin/grep/t_grep.sh
@@ -907,6 +907,22 @@ mflag_body()
atf_check -o inline:"test1:2\n" grep -m 2 -EHc "a|b|e|f" test1
+atf_test_case mflag_trail_ctx
+ atf_set "descr" "Check proper handling of -m with trailing context (PR 253350)"
+ printf "foo\nfoo\nbar\nfoo\nbar\nfoo\nbar\n" > test1
+ # Should pick up the next line after matching the first.
+ atf_check -o inline:"foo\nfoo\n" grep -A1 -m1 foo test1
+ # Make sure the trailer is picked up as a non-match!
+ atf_check -o inline:"1:foo\n2-foo\n" grep -A1 -nm1 foo test1
atf_test_case zgrep_multiple_files
@@ -978,6 +994,7 @@ atf_init_test_cases()
atf_add_test_case fgrep_oflag
atf_add_test_case cflag
atf_add_test_case mflag
+ atf_add_test_case mflag_trail_ctx
atf_add_test_case zgrep_multiple_files
# End FreeBSD
diff --git a/usr.bin/grep/util.c b/usr.bin/grep/util.c
index f22b7abd79ef..a2520e24de8e 100644
--- a/usr.bin/grep/util.c
+++ b/usr.bin/grep/util.c
@@ -252,6 +252,16 @@ static bool
procmatches(struct mprintc *mc, struct parsec *pc, bool matched)
+ if (mflag && mcount <= 0) {
+ /*
+ * We already hit our match count, but we need to keep dumping
+ * lines until we've lost our tail.
+ */
+ grep_printline(&pc->ln, '-');
+ mc->tail--;
+ return (mc->tail != 0);
+ }
* XXX TODO: This should loop over pc->matches and handle things on a
* line-by-line basis, setting up a `struct str` as needed.
@@ -265,7 +275,7 @@ procmatches(struct mprintc *mc, struct parsec *pc, bool matched)
/* XXX TODO: Decrement by number of matched lines */
mcount -= 1;
if (mcount <= 0)
- return (false);
+ return (mc->tail != 0);
} else if (mc->doctx)
procmatch_nomatch(mc, pc);
@@ -357,6 +367,15 @@ procfile(const char *fn)
return (0);
+ if (mflag && mcount <= 0) {
+ /*
+ * Short-circuit, already hit match count and now we're
+ * just picking up any remaining pieces.
+ */
+ if (!procmatches(&mc, &pc, false))
+ break;
+ continue;
+ }
line_matched = procline(&pc) == !vflag;
if (line_matched)