Fix bug #80866

Closes GH-6774.

Author: kamil-tekiela

NEWS

@@ -23,6 +23,10 @@ PHP                                                                        NEWS
 - opcache:
   . Fixed bug #80805 (create simple class and get error in opcache.so). (Nikita)
 
+- PCRE:
+  . Fixed bug #80866 (preg_split ignores limit flag when pattern with \K has
+    0-width fullstring match). (Kamil Tekiela)
+
 - phpdbg:
   . Fixed bug #80757 (Exit code is 0 when could not open file). (Felipe)
 

ext/pcre/php_pcre.c

@@ -2644,6 +2644,10 @@ PHPAPI void php_pcre_split_impl(pcre_cache_entry *pce, zend_string *subject_str,
 			   the match again at the same point. If this fails (picked up above) we
 			   advance to the next character. */
 			if (start_offset == offsets[0]) {
+				/* Get next piece if no limit or limit not yet reached and something matched*/
+				if (limit_val != -1 && limit_val <= 1) {
+					break;
+				}
 				count = pcre2_match(pce->re, (PCRE2_SPTR)subject, ZSTR_LEN(subject_str), start_offset,
 					PCRE2_NO_UTF_CHECK | PCRE2_NOTEMPTY_ATSTART | PCRE2_ANCHORED, match_data, mctx);
 				if (count >= 0) {

ext/pcre/tests/bug80866.phpt

@@ -0,0 +1,12 @@
+--TEST--
+Bug #80866 preg_split ignores limit flag when pattern with \K has 0-width fullstring match
+--FILE--
+<?php
+var_export(preg_split('~.{3}\K~', 'abcdefghijklm', 3));
+?>
+--EXPECT--
+array (
+  0 => 'abc',
+  1 => 'def',
+  2 => 'ghijklm',
+)