[gnome-games] master-system: Use StringInputStream in MasterSystemHeader

[Adrien Plazas <aplazas src gnome org>]

commit 93cd92994979fdf02364377a7c0880dd77abb611
Author: Adrien Plazas <kekun plazas laposte net>
Date:   Thu Jul 28 17:06:52 2016 +0200

    master-system: Use StringInputStream in MasterSystemHeader
    
    This makes the code easier to read and avoid duplication.

 .../master-system/src/master-system-header.vala    |   40 ++++++++------------
 1 files changed, 16 insertions(+), 24 deletions(-)
---
diff --git a/plugins/master-system/src/master-system-header.vala 
b/plugins/master-system/src/master-system-header.vala
index 08cf5da..ded175f 100644
--- a/plugins/master-system/src/master-system-header.vala
+++ b/plugins/master-system/src/master-system-header.vala
@@ -14,6 +14,16 @@ private class Games.MasterSystemHeader : Object {
                        if (_region_code != null)
                                return _region_code;
 
+                       FileInputStream stream;
+                       try {
+                               stream = file.read ();
+                       }
+                       catch (Error e) {
+                               _region_code = MasterSystemRegion.INVALID;
+
+                               return _region_code;
+                       }
+
                        try {
                                stream.seek (REGION_CODE_OFFSET, SeekType.SET);
                        }
@@ -47,32 +57,15 @@ private class Games.MasterSystemHeader : Object {
                }
        }
 
-       private FileInputStream stream;
+       private File file;
 
-       public MasterSystemHeader (File file) throws Error {
-               stream = file.read ();
-
-               check_validity ();
+       public MasterSystemHeader (File file) {
+               this.file = file;
        }
 
-       public void check_validity () throws MasterSystemError {
-               try {
-                       stream.seek (MAGIC_OFFSET, SeekType.SET);
-               }
-               catch (Error e) {
-                       throw new MasterSystemError.INVALID_SIZE (_("Invalid Master System header size: %s"), 
e.message);
-               }
-
-               var buffer = new uint8[MAGIC_VALUE.length];
-               try {
-                       stream.read (buffer);
-               }
-               catch (Error e) {
-                       throw new MasterSystemError.INVALID_SIZE (e.message);
-               }
-
-               var magic = (string) buffer;
-               if (magic != MAGIC_VALUE)
+       public void check_validity () throws Error {
+               var stream = new StringInputStream (file);
+               if (!stream.has_string (MAGIC_OFFSET, MAGIC_VALUE))
                        throw new MasterSystemError.INVALID_HEADER (_("The file doesn't have a Master System 
header."));
        }
 }
@@ -87,6 +80,5 @@ private enum Games.MasterSystemRegion {
 }
 
 errordomain Games.MasterSystemError {
-       INVALID_SIZE,
        INVALID_HEADER,
 }