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Fix GH-22779: mb_strrpos() wrong result in a non-UTF-8 encoding #22780

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Fix GH-22779: mb_strrpos() wrong result in a non-UTF-8 encoding #22780

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4 changes: 4 additions & 0 deletions NEWS
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,10 @@ PHP NEWS
- Date:
. Fixed leak on double DatePeriod::__construct() call. (ilutov)

- MBString:
. Fixed bug GH-22779 (mb_strrpos() returns the wrong position for a negative
offset in a non-UTF-8 encoding). (Eyüp Can Akman)

30 Jul 2026, PHP 8.4.24

- Calendar:
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2 changes: 1 addition & 1 deletion ext/mbstring/mbstring.c
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Expand Up @@ -1931,7 +1931,7 @@ static size_t mb_find_strpos(zend_string *haystack, zend_string *needle, const m
} else if (offset >= 0) {
found_pos = zend_memnrstr((const char*)offset_pointer, ZSTR_VAL(needle_u8), ZSTR_LEN(needle_u8), ZSTR_VAL(haystack_u8) + ZSTR_LEN(haystack_u8));
} else {
size_t needle_len = pointer_to_offset_utf8((unsigned char*)ZSTR_VAL(needle), (unsigned char*)ZSTR_VAL(needle) + ZSTR_LEN(needle));
size_t needle_len = pointer_to_offset_utf8((unsigned char*)ZSTR_VAL(needle_u8), (unsigned char*)ZSTR_VAL(needle_u8) + ZSTR_LEN(needle_u8));
offset_pointer = offset_to_pointer_utf8(offset_pointer, (unsigned char*)ZSTR_VAL(haystack_u8) + ZSTR_LEN(haystack_u8), needle_len);
if (!offset_pointer) {
offset_pointer = (unsigned char*)ZSTR_VAL(haystack_u8) + ZSTR_LEN(haystack_u8);
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34 changes: 34 additions & 0 deletions ext/mbstring/tests/gh22779.phpt
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@@ -0,0 +1,34 @@
--TEST--
GH-22779: mb_strrpos() wrong result for a negative offset in a non-UTF-8 encoding
--EXTENSIONS--
mbstring
--FILE--
<?php
/* mb_strrpos() with a negative offset must return the correct position in non-UTF-8 encodings. */
$haystack = "\xA9\xA9X";
$needle = "\xA9";
foreach ([-1, -2, -3] as $offset) {
var_dump(mb_strrpos($haystack, $needle, $offset, 'ISO-8859-1'));
}
var_dump(mb_strrpos("X\xA9", "\xA9", -1, 'ISO-8859-1'));
var_dump(mb_strrpos("\x95Z\x95Z", "\x95", -1, 'Windows-1252'));
var_dump(mb_strrpos("\x95Z\x95Z", "\x95", -2, 'Windows-1252'));
// Two-byte needle in a single-byte encoding.
var_dump(mb_strrpos("\xA9\xB0\xA9\xB0Z", "\xA9\xB0", -2, 'ISO-8859-1'));
// Multibyte: "ああA" in Shift_JIS, needle "あ" (\x82\xA0).
var_dump(mb_strrpos("\x82\xA0\x82\xA0A", "\x82\xA0", -2, 'SJIS'));
var_dump(mb_strrpos("\x82\xA0\x82\xA0A", "\x82\xA0", -3, 'SJIS'));
// UTF-16: an ASCII needle miscounts the other way.
var_dump(mb_strrpos("\x00A\x00X\x00A", "\x00A", -2, 'UTF-16BE'));
?>
--EXPECT--
int(1)
int(1)
int(0)
int(1)
int(2)
int(2)
int(2)
int(1)
int(0)
int(0)
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