Fix #78346: strip_tags no longer handling nested php tags

When the strip tags state machine has been flattened, an if statement
has mistakenly been treated as else if.  We fix this, and also simplify
a bit right away.

Author: cmb69

NEWS

@@ -33,6 +33,7 @@ PHP                                                                        NEWS
     with invalid length). (Nikita)
   . Fixed bug #78326 (improper memory deallocation on stream_get_contents()
     with fixed length buffer). (Albert Casademont)
+  . Fixed bug #78346 (strip_tags no longer handling nested php tags). (cmb)
 
 01 Aug 2019, PHP 7.3.8
 

ext/standard/string.c

@@ -5271,8 +5271,7 @@ PHPAPI size_t php_strip_tags_ex(char *rbuf, size_t len, uint8_t *stateptr, const
 				} else if (lc != '\\') {
 					lc = c;
 				}
-			} else {
-				if (p != buf && *(p-1) != '\\' && (!in_q || *p == in_q)) {
+				if (p != buf && (!in_q || *p == in_q)) {
 					if (in_q) {
 						in_q = 0;
 					} else {

ext/standard/tests/strings/bug78346.phpt

@@ -0,0 +1,9 @@
+--TEST--
+Bug #78346 (strip_tags no longer handling nested php tags)
+--FILE--
+<?php
+$str = '<?= \'<?= 1 ?>\' ?>2';
+var_dump(strip_tags($str));
+?>
+--EXPECT--
+string(1) "2"