Fixed bug #77853

Author: nikic

NEWS

@@ -32,6 +32,8 @@ PHP                                                                        NEWS
     (Vlad Temian)
   . Fixed bug #77844 (Crash due to null pointer in parse_ini_string with
     INI_SCANNER_TYPED). (Nikita)
+  . Fixed bug #77853 (Inconsistent substr_compare behaviour with empty
+    haystack). (Nikita)
 
 04 Apr 2019, PHP 7.2.17
 

ext/standard/string.c

@@ -5739,7 +5739,7 @@ PHP_FUNCTION(substr_compare)
 		offset = (offset < 0) ? 0 : offset;
 	}
 
-	if ((size_t)offset >= ZSTR_LEN(s1)) {
+	if ((size_t)offset > ZSTR_LEN(s1)) {
 		php_error_docref(NULL, E_WARNING, "The start position cannot exceed initial string length");
 		RETURN_FALSE;
 	}

ext/standard/tests/strings/bug77853.phpt

@@ -0,0 +1,20 @@
+--TEST--
+Bug #77853: Inconsistent substr_compare behaviour with empty haystack
+--FILE--
+<?php
+
+var_dump(substr_compare('', '', 0, 0));
+var_dump(substr_compare('', '', 0));
+
+var_dump(substr_compare('abc', '', 3, 0));
+var_dump(substr_compare('abc', '', 3));
+
+var_dump(substr_compare('abc', "\0", 3));
+
+?>
+--EXPECT--
+int(0)
+int(0)
+int(0)
+int(0)
+int(-1)

ext/standard/tests/strings/substr_compare.phpt

@@ -27,9 +27,7 @@ int(0)
 int(0)
 bool(true)
 bool(true)
-
-Warning: substr_compare(): The start position cannot exceed initial string length in %s on line %d
-bool(false)
+int(-1)
 bool(true)
 int(0)