Ticket #37111: 37111.diff

src/wp-includes/formatting.php

@@ -1725 +1725 @@
  * operating systems and special characters requiring special escaping
  * to manipulate at the command line. Replaces spaces and consecutive
  * dashes with a single dash. Trims period, dash and underscore from beginning
- * and end of filename.
+ * and end of filename. It is not guaranteed that this function will return a
+ * filename that is allowed to be uploaded.
  *
  * @since 2.1.0
  *
@@ -1750 +1751 @@
         $filename = preg_replace( '/[\r\n\t -]+/', '-', $filename );
         $filename = trim( $filename, '.-_' );
 
+        if ( false === strpos( $filename, '.' ) ) {
+                $filetype = wp_check_filetype( 'test.' . $filename );
+                if ( $filetype['ext'] === $filename ) {
+                        $filename = 'unnamed-file.' . $filetype['ext'];
+                } else {
+                        $filename .= $filetype['ext'];
+                }
+        }
+
         // Split the filename into a base and extension[s]
         $parts = explode('.', $filename);
 

tests/phpunit/tests/formatting/SanitizeFileName.php

@@ -56 +56 @@
         function test_replaces_percent_sign() {
                 $this->assertEquals( 'a22b.jpg', sanitize_file_name( 'a%22b.jpg' ) );
         }
+
+        function test_replaces_unnammed_file_extentions() {
+                // Test filenames with both supported and unsupported extensions.
+                $this->assertEquals( 'unnamed-file.exe', sanitize_file_name( '_.exe' ) );
+                $this->assertEquals( 'unnamed-file.jpg', sanitize_file_name( '_.jpg' ) );
+        }
+
+        function test_replaces_unnammed_file_extentionless() {
+                // Test a filenames that becomes extentionless.
+                $this->assertEquals( 'no-extention', sanitize_file_name( '_.no-extention' ) );
+        }
 }