Fix test bug60120.phpt

The process cmd was broken. We're now also checking that the process output is
actually what we expect.

Author: iluuu1994

ext/standard/tests/file/bug60120.phpt

@@ -16,7 +16,7 @@ $php = getenv('TEST_PHP_EXECUTABLE');
 if (!$php) {
     die("No php executable defined\n");
 }
-$cmd = 'php -r "fwrite(STDOUT, $in = file_get_contents(\'php://stdin\')); fwrite(STDERR, $in);"';
+$cmd = 'php -r "\$in = file_get_contents(\'php://stdin\'); fwrite(STDOUT, \$in); fwrite(STDERR, \$in);"';
 $descriptors = array(array('pipe', 'r'), array('pipe', 'w'), array('pipe', 'w'));
 $stdin = str_repeat('*', 2049 );
 
@@ -32,6 +32,7 @@ $stdinOffset = 0;
 
 unset($pipes[0]);
 
+$procOutput = [];
 while ($pipes || $writePipes) {
     $r = $pipes;
     $w = $writePipes;
@@ -48,6 +49,8 @@ while ($pipes || $writePipes) {
         $written = fwrite($writePipes[0], substr($stdin, $stdinOffset), 8192);
         if (false !== $written) {
             $stdinOffset += $written;
+        } else {
+            die('Failed to write to pipe');
         }
         if ($stdinOffset >= $stdinLen) {
             fclose($writePipes[0]);
@@ -61,9 +64,17 @@ while ($pipes || $writePipes) {
         if (false === $data || feof($pipe)) {
             fclose($pipe);
             unset($pipes[$type]);
+        } else {
+            $resourceId = get_resource_id($pipe);
+            $procOutput[$resourceId] = ($procOutput[$resourceId] ?? '') . $data;
         }
     }
 }
+foreach ($procOutput as $output) {
+    if ($output !== $stdin) {
+        die('Output does not match input');
+    }
+}
 echo "OK.";
 ?>
 --EXPECT--