[PATCH] log: require --grep for --invert-grep and --all-match, fix segfault

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

Neither the "--invert-grep" option added in [1] nor the earlier
"--all-match" option added in [2] were intended to be used
stand-alone.

But due to how the built-in and the revision API interacted those
options without the corresponding --grep would be ignored.

Then in f41fb662f57 (revisions API: have release_revisions() release
"grep_filter", 2022-04-13) this turned into a segfault, as we'd
attempt to free() the non-existing --grep patterns.

Arguably it makes more sense to add this check to
compile_grep_patterns(), since it's possible to use the C API in the
same way and trigger this segfault. But in practice the revision.c API
is the only user of "no_body_match", and by placing the check here we
can more sensibly emit a message that assumes that the user used
"--invert-grep" without "--grep".

1. 22dfa8a23de (log: teach --invert-grep option, 2015-01-12)
2. 0ab7befa31d (grep --all-match, 2006-09-27)

Reported-by: orygaw <orygaw@protonmail.com>
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 revision.c      | 6 ++++++
 t/t4202-log.sh  | 4 ++++
 t/t7810-grep.sh | 4 ++++
 3 files changed, 14 insertions(+)

diff --git a/revision.c b/revision.c
index 36e31942cee..a55ead48448 100644
--- a/revision.c
+++ b/revision.c
@@ -2986,6 +2986,12 @@ int setup_revisions(int argc, const char **argv, struct rev_info *revs, struct s
 		die(_("options '%s' and '%s' cannot be used together"), "--no-walk", "--graph");
 	if (!revs->reflog_info && revs->grep_filter.use_reflog_filter)
 		die(_("the option '%s' requires '%s'"), "--grep-reflog", "--walk-reflogs");
+	if (!revs->grep_filter.pattern_expression) {
+		if (revs->grep_filter.no_body_match)
+			die(_("the option '%s' requires '%s'"), "--invert-grep", "--grep");
+		if (revs->grep_filter.all_match)
+			die(_("the option '%s' requires '%s'"), "--all-match", "--grep");
+	}
 
 	if (revs->line_level_traverse &&
 	    (revs->diffopt.output_format & ~(DIFF_FORMAT_PATCH | DIFF_FORMAT_NO_OUTPUT)))
diff --git a/t/t4202-log.sh b/t/t4202-log.sh
index cc15cb4ff62..298678fb7c8 100755
--- a/t/t4202-log.sh
+++ b/t/t4202-log.sh
@@ -249,6 +249,10 @@ test_expect_success 'log --grep' '
 	test_cmp expect actual
 '
 
+test_expect_success 'log --invert-grep usage' '
+	test_expect_code 128 git log --invert-grep
+'
+
 cat > expect << EOF
 second
 initial
diff --git a/t/t7810-grep.sh b/t/t7810-grep.sh
index 8eded6ab274..6dd750349e1 100755
--- a/t/t7810-grep.sh
+++ b/t/t7810-grep.sh
@@ -914,6 +914,10 @@ test_expect_success 'log with multiple --grep uses union' '
 	test_cmp expect actual
 '
 
+test_expect_success 'log --all-match usage' '
+	test_expect_code 128 git log --all-match
+'
+
 test_expect_success 'log --all-match with multiple --grep uses intersection' '
 	git log --all-match --grep=i --grep=r --format=%s >actual &&
 	{
-- 
2.38.0.971.ge79ff6d20e7