Don't leak memory if wrong resource type is passed to proc_open

proc_open can accept stream resources in the descriptorspec, like this:

    proc_open("command", array(0 => $resource), $pipes);

Previously, if a resource which was *not* of type "stream" was passed, proc_open would
return without freeing dynamically allocated memory. It's fixed now.

Author: alexdowad

ext/standard/proc_open.c

@@ -933,12 +933,14 @@ PHP_FUNCTION(proc_open)
 
 		if (Z_TYPE_P(descitem) == IS_RESOURCE) {
 			/* should be a stream - try and dup the descriptor */
-			php_stream *stream;
+			php_stream *stream = (php_stream*)zend_fetch_resource(Z_RES_P(descitem), "stream", php_file_le_stream());
+			if (stream == NULL) {
+				goto exit_fail;
+			}
+
 			php_socket_t fd;
 			php_file_descriptor_t desc;
 
-			php_stream_from_zval(stream, descitem);
-
 			if (FAILURE == php_stream_cast(stream, PHP_STREAM_AS_FD, (void **)&fd, REPORT_ERRORS)) {
 				goto exit_fail;
 			}

ext/standard/tests/file/proc_open_with_wrong_resource_type.phpt

@@ -0,0 +1,13 @@
+--TEST--
+proc_open does not leak memory when called with wrong resource type in descriptorspec
+--FILE--
+<?php
+    $context = stream_context_create();
+    $child   = proc_open('not_a_real_command_but_I_dont_care', array(0 => $context), $pipes);
+    echo "Not reached\n";
+--EXPECTF--
+Fatal error: Uncaught TypeError: proc_open(): supplied resource is not a valid stream resource in %s:3
+Stack trace:
+#0 %s(3): proc_open('not_a_real_comm...', Array, NULL)
+#1 {main}
+  thrown in %s on line 3