grep/pcre2: better support invalid UTF-8 haystacks

Improve the support for invalid UTF-8 haystacks given a non-ASCII
needle when using the PCREv2 backend.

This is a more complete fix for a bug I started to fix in
870eea8166 (grep: do not enter PCRE2_UTF mode on fixed matching,
2019-07-26), now that PCREv2 has the PCRE2_MATCH_INVALID_UTF mode we
can make use of it.

This fixes the sort of case described in 8a5999838e (grep: stess test
PCRE v2 on invalid UTF-8 data, 2019-07-26), i.e.:

    - The subject string is non-ASCII (e.g. "ævar")
    - We're under a is_utf8_locale(), e.g. "en_US.UTF-8", not "C"
    - We are using --ignore-case, or we're a non-fixed pattern

If those conditions were satisfied and we matched found non-valid
UTF-8 data PCREv2 might bark on it, in practice this only happened
under the JIT backend (turned on by default on most platforms).

Ultimately this fixes a "regression" in b65abcafc7 ("grep: use PCRE v2
for optimized fixed-string search", 2019-07-01), I'm putting that in
scare-quotes because before then we wouldn't properly support these
complex case-folding, locale etc. cases either, it just broke in
different ways.

There was a bug related to this the PCRE2_NO_START_OPTIMIZE flag fixed
in PCREv2 10.36. It can be worked around by setting the
PCRE2_NO_START_OPTIMIZE flag. Let's do that in those cases, and add
tests for the bug.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 45 insertions, 1 deletions

diff --git a/t/t7812-grep-icase-non-ascii.sh b/t/t7812-grep-icase-non-ascii.sh
index 38457c2e4f..e5d1e4ea68 100755
--- a/t/t7812-grep-icase-non-ascii.sh
+++ b/t/t7812-grep-icase-non-ascii.sh
@@ -57,7 +57,12 @@ test_expect_success GETTEXT_LOCALE,LIBPCRE2 'PCRE v2: setup invalid UTF-8 data'
 	printf "\\200\\n" >invalid-0x80 &&
 	echo "ævar" >expected &&
 	cat expected >>invalid-0x80 &&
-	git add invalid-0x80
+	git add invalid-0x80 &&
+
+	# Test for PCRE2_MATCH_INVALID_UTF bug
+	# https://bugs.exim.org/show_bug.cgi?id=2642
+	printf "\\345Aæ\\n" >invalid-0xe5 &&
+	git add invalid-0xe5
 '
 
 test_expect_success GETTEXT_LOCALE,LIBPCRE2 'PCRE v2: grep ASCII from invalid UTF-8 data' '
@@ -67,6 +72,13 @@ test_expect_success GETTEXT_LOCALE,LIBPCRE2 'PCRE v2: grep ASCII from invalid UT
 	test_cmp expected actual
 '
 
+test_expect_success GETTEXT_LOCALE,LIBPCRE2 'PCRE v2: grep ASCII from invalid UTF-8 data (PCRE2 bug #2642)' '
+	git grep -h "Aæ" invalid-0xe5 >actual &&
+	test_cmp invalid-0xe5 actual &&
+	git grep -h "(*NO_JIT)Aæ" invalid-0xe5 >actual &&
+	test_cmp invalid-0xe5 actual
+'
+
 test_expect_success GETTEXT_LOCALE,LIBPCRE2 'PCRE v2: grep non-ASCII from invalid UTF-8 data' '
 	git grep -h "æ" invalid-0x80 >actual &&
 	test_cmp expected actual &&
@@ -74,9 +86,41 @@ test_expect_success GETTEXT_LOCALE,LIBPCRE2 'PCRE v2: grep non-ASCII from invali
 	test_cmp expected actual
 '
 
+test_expect_success GETTEXT_LOCALE,LIBPCRE2 'PCRE v2: grep non-ASCII from invalid UTF-8 data (PCRE2 bug #2642)' '
+	git grep -h "Aæ" invalid-0xe5 >actual &&
+	test_cmp invalid-0xe5 actual &&
+	git grep -h "(*NO_JIT)Aæ" invalid-0xe5 >actual &&
+	test_cmp invalid-0xe5 actual
+'
+
+test_lazy_prereq PCRE2_MATCH_INVALID_UTF '
+	test-tool pcre2-config has-PCRE2_MATCH_INVALID_UTF
+'
+
 test_expect_success GETTEXT_LOCALE,LIBPCRE2 'PCRE v2: grep non-ASCII from invalid UTF-8 data with -i' '
 	test_might_fail git grep -hi "Æ" invalid-0x80 >actual &&
 	test_might_fail git grep -hi "(*NO_JIT)Æ" invalid-0x80 >actual
 '
 
+test_expect_success GETTEXT_LOCALE,LIBPCRE2,PCRE2_MATCH_INVALID_UTF 'PCRE v2: grep non-ASCII from invalid UTF-8 data with -i' '
+	git grep -hi "Æ" invalid-0x80 >actual &&
+	test_cmp expected actual &&
+	git grep -hi "(*NO_JIT)Æ" invalid-0x80 >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success GETTEXT_LOCALE,LIBPCRE2,PCRE2_MATCH_INVALID_UTF 'PCRE v2: grep non-ASCII from invalid UTF-8 data with -i (PCRE2 bug #2642)' '
+	git grep -hi "Æ" invalid-0xe5 >actual &&
+	test_cmp invalid-0xe5 actual &&
+	git grep -hi "(*NO_JIT)Æ" invalid-0xe5 >actual &&
+	test_cmp invalid-0xe5 actual &&
+
+	# Only the case of grepping the ASCII part in a way that
+	# relies on -i fails
+	git grep -hi "aÆ" invalid-0xe5 >actual &&
+	test_cmp invalid-0xe5 actual &&
+	git grep -hi "(*NO_JIT)aÆ" invalid-0xe5 >actual &&
+	test_cmp invalid-0xe5 actual
+'
+
 test_done