From a8f901f22954028f995b3f21712aaa54e603fdb1 Mon Sep 17 00:00:00 2001 From: Greg Burd Date: Sun, 18 Oct 2026 07:52:08 -0400 Subject: [PATCH v1] Fix ILIKE '%' followed by a non-ASCII byte in single-byte C-ctype databases MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Since 1e493158d3d, C_IMatchText (the ILIKE path for a single-byte encoding with a C ctype) lowercases with pg_ascii_tolower(), which returns unsigned char. MatchText stores the first pattern byte after a '%' in a char and compares it with GETCHAR(*t); on platforms where char is signed, a byte >= 0x80 is negative in firstpat but positive on the other side, so the comparison never succeeds and the '%' never finds a match. 'xÆy' ILIKE '%Æ%' in a LATIN1 database with LOCALE 'C' returns false, where 18 returns true. Declare firstpat as int. The regression database is normally UTF-8, which never takes this path, so add a TAP test that creates a LATIN1 database. Backpatch-through: 19 --- src/backend/utils/adt/like_match.c | 7 ++- src/test/modules/test_misc/meson.build | 1 + .../test_misc/t/016_ilike_single_byte.pl | 43 +++++++++++++++++++ 3 files changed, 50 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/test_misc/t/016_ilike_single_byte.pl diff --git a/src/backend/utils/adt/like_match.c b/src/backend/utils/adt/like_match.c index defcaa96fb5..830d2b98653 100644 --- a/src/backend/utils/adt/like_match.c +++ b/src/backend/utils/adt/like_match.c @@ -109,7 +109,12 @@ MatchText(const char *t, int tlen, const char *p, int plen, pg_locale_t locale) */ if (*p == '%') { - char firstpat; + /* + * int, not char: under MATCH_LOWER, GETCHAR() yields an unsigned + * char, which a signed char would not compare equal to for bytes + * >= 0x80. + */ + int firstpat; /* * % processing is essentially a search for a text position at diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 5d81f5b13be..1b6ffc3a185 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -24,6 +24,7 @@ tests += { 't/013_temp_obj_multisession.pl', 't/014_log_statement_max_length.pl', 't/015_temp_schema_exit_deferrable.pl', + 't/016_ilike_single_byte.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/016_ilike_single_byte.pl b/src/test/modules/test_misc/t/016_ilike_single_byte.pl new file mode 100644 index 00000000000..f01c40cc565 --- /dev/null +++ b/src/test/modules/test_misc/t/016_ilike_single_byte.pl @@ -0,0 +1,43 @@ +# Copyright (c) 2026, PostgreSQL Global Development Group + +# ILIKE in a single-byte encoding with a C ctype matches via C_IMatchText +# (like.c), which folds bytes with pg_ascii_tolower(). A '%' followed by a +# non-ASCII byte must still find it. The main regression database is +# usually UTF-8, which never takes this path, so use a LATIN1 database. + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +my $node = PostgreSQL::Test::Cluster->new('ilike_single_byte'); +$node->init; +$node->start; + +$node->safe_psql('postgres', + q{CREATE DATABASE latin1 TEMPLATE template0 ENCODING 'LATIN1' LOCALE 'C'}); + +# Build every string from bytes, so the test does not depend on the client +# encoding: \xc6 is LATIN1 'Æ', \xe6 is 'æ', \xe9 is 'é'. +my $result = $node->safe_psql( + 'latin1', q{ +SELECT string_agg(r::text, ',' ORDER BY n) + FROM (VALUES + (1, convert_from('\x78c679', 'LATIN1') ILIKE convert_from('\x25c625', 'LATIN1')), + (2, convert_from('\x6162c6', 'LATIN1') ILIKE convert_from('\x25c6', 'LATIN1')), + (3, convert_from('\x786579', 'LATIN1') ILIKE convert_from('\x25e925', 'LATIN1')), + (4, convert_from('\x78c6e679', 'LATIN1') ILIKE convert_from('\x25e625', 'LATIN1')), + (5, convert_from('\xc66364', 'LATIN1') ILIKE convert_from('\xc625', 'LATIN1')), + (6, convert_from('\x78c679', 'LATIN1') NOT ILIKE convert_from('\x25c625', 'LATIN1')), + (7, convert_from('\x78e679', 'LATIN1') ILIKE convert_from('\x25c625', 'LATIN1')) + ) AS v(n, r)}); + +# 1: '%Æ%' finds Æ mid-string; 2: at the end; 3: '%é%' does not match 'xey'; +# 4: '%æ%' finds æ after Æ; 5: no leading '%' (always worked); +# 6: the NOT ILIKE counterpart of 1; 7: Æ and æ are different bytes and the +# C ctype folds ASCII only, so '%Æ%' does not match 'xæy'. +is($result, 'true,true,false,true,true,false,false', + 'ILIKE with % before a non-ASCII byte, LATIN1 / C'); + +done_testing(); -- 2.54.0