[gnome-games] playstation: Add PlayStationHeader.search_id_in_header()

[Adrien Plazas <aplazas src gnome org>]

commit 78eeb73564237e601babd556829a1ef6d717875f
Author: Adrien Plazas <kekun plazas laposte net>
Date:   Sun Aug 28 09:30:23 2016 +0200

    playstation: Add PlayStationHeader.search_id_in_header()
    
    Look for IDs in the 'PLAYSTATION' header.
    
    This allows to support games having no 'BOOT' header but containing the
    disc's ID in the 'PLAYSTATION' header.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=770470

 plugins/playstation/src/playstation-header.vala |   43 +++++++++++++++++++++++
 1 files changed, 43 insertions(+), 0 deletions(-)
---
diff --git a/plugins/playstation/src/playstation-header.vala b/plugins/playstation/src/playstation-header.vala
index 762b824..289c863 100644
--- a/plugins/playstation/src/playstation-header.vala
+++ b/plugins/playstation/src/playstation-header.vala
@@ -1,6 +1,13 @@
 // This file is part of GNOME Games. License: GPLv3
 
 private class Games.PlayStationHeader : Object {
+       private const size_t[] HEADER_OFFSETS = {
+               0x9320, // .bin
+               0x9360, // .iso 
+       };
+       private const size_t HEADER_TITLE_OFFSET = 0x20;
+       private const string HEADER_MAGIC_VALUE = "PLAYSTATION";
+
        private const size_t[] BOOT_OFFSETS = {
                0xD368, // .bin
                0xD3A8, // .iso
@@ -31,9 +38,45 @@ private class Games.PlayStationHeader : Object {
                if (_disc_id != null)
                        return;
 
+               _disc_id = search_id_in_header ();
+               if (_disc_id != null)
+                       return;
+
                throw new PlayStationError.INVALID_HEADER (_("Invalid PlayStation header: disc ID not found 
in '%s'."), file.get_uri ());
        }
 
+       private string? search_id_in_header () throws Error {
+               var offset = get_header_offset ();
+               if (offset == null)
+                       return null;
+
+               var stream = new StringInputStream (file);
+               var header = stream.read_string_for_size (offset + HEADER_TITLE_OFFSET, DISC_ID_SIZE);
+
+               var raw_id = header.up ();
+               raw_id = raw_id.replace ("_", "-");
+
+               foreach (var id in IDS) {
+                       if (!(id in header))
+                               continue;
+
+                       if (is_a_disc_id (raw_id))
+                               return raw_id;
+               }
+
+               return null;
+       }
+
+       private size_t? get_header_offset () throws Error {
+               var stream = new StringInputStream (file);
+
+               foreach (var offset in HEADER_OFFSETS)
+                       if (stream.has_string (offset, HEADER_MAGIC_VALUE))
+                               return offset;
+
+               return null;
+       }
+
        private string? get_id_from_boot () throws Error {
                var offset = get_boot_offset ();
                if (offset == null)