[gnome-games] sega-saturn: Use StringInputStream in SegaSaturnHeader

[Adrien Plazas <aplazas src gnome org>]

commit dfb065183a0405e044dc8fdf988f1f9976e8d4bb
Author: Adrien Plazas <kekun plazas laposte net>
Date:   Thu Jul 28 17:19:26 2016 +0200

    sega-saturn: Use StringInputStream in SegaSaturnHeader
    
    This makes the code easier to read and avoid duplication.
    
    Fixes #319

 plugins/sega-saturn/src/sega-saturn-error.vala  |    3 -
 plugins/sega-saturn/src/sega-saturn-header.vala |   69 +++-------------------
 2 files changed, 10 insertions(+), 62 deletions(-)
---
diff --git a/plugins/sega-saturn/src/sega-saturn-error.vala b/plugins/sega-saturn/src/sega-saturn-error.vala
index 5bbb490..be7b853 100644
--- a/plugins/sega-saturn/src/sega-saturn-error.vala
+++ b/plugins/sega-saturn/src/sega-saturn-error.vala
@@ -4,8 +4,5 @@ errordomain Games.SegaSaturnError {
        INVALID_CUE_SHEET,
        INVALID_FILE_TYPE,
        CANT_READ_FILE,
-       INVALID_SIZE,
        INVALID_HEADER,
-       INVALID_DATE,
-       INVALID_DISK_INFO,
 }
diff --git a/plugins/sega-saturn/src/sega-saturn-header.vala b/plugins/sega-saturn/src/sega-saturn-header.vala
index 8d4558d..ea965ee 100644
--- a/plugins/sega-saturn/src/sega-saturn-header.vala
+++ b/plugins/sega-saturn/src/sega-saturn-header.vala
@@ -21,30 +21,33 @@ private class Games.SegaSaturnHeader : Object {
                this.file = file;
        }
 
-       public void check_validity () throws SegaSaturnError {
+       public void check_validity () throws Error {
                // Getting the header offset needs to look for the header, and hence
                // check the validity of the file.
                get_header_offset ();
        }
 
-       public string get_product_number () throws SegaSaturnError {
-               var product_number = get_string_at_offset (PRODUCT_NUMBER_OFFSET, PRODUCT_NUMBER_SIZE);
+       public string get_product_number () throws Error {
+               var stream = new StringInputStream (file);
+               var product_number = stream.read_string_for_size (PRODUCT_NUMBER_OFFSET, PRODUCT_NUMBER_SIZE);
 
                return product_number.strip ();
        }
 
-       public string get_areas () throws SegaSaturnError {
-               var areas = get_string_at_offset (AREAS_OFFSET, AREAS_SIZE);
+       public string get_areas () throws Error {
+               var stream = new StringInputStream (file);
+               var areas = stream.read_string_for_size (AREAS_OFFSET, AREAS_SIZE);
 
                return areas.strip ();
        }
 
-       private size_t get_header_offset () throws SegaSaturnError {
+       private size_t get_header_offset () throws Error {
                if (header_offset != null)
                        return header_offset;
 
+               var stream = new StringInputStream (file);
                foreach (var offset in HEADER_OFFSETS)
-                       if (lookup_header_offset (offset))
+                       if (stream.has_string (offset, MAGIC_VALUE))
                                header_offset = offset;
 
                if (header_offset == null)
@@ -52,56 +55,4 @@ private class Games.SegaSaturnHeader : Object {
 
                return header_offset;
        }
-
-       private bool lookup_header_offset (size_t offset) throws SegaSaturnError {
-               var stream = get_stream ();
-               try {
-                       stream.seek (offset + MAGIC_OFFSET, SeekType.SET);
-               }
-               catch (Error e) {
-                       throw new SegaSaturnError.INVALID_SIZE (_("Invalid Sega Saturn header size: %s"), 
e.message);
-               }
-
-               var buffer = new uint8[MAGIC_VALUE.length];
-               try {
-                       stream.read (buffer);
-               }
-               catch (Error e) {
-                       throw new SegaSaturnError.INVALID_SIZE (e.message);
-               }
-
-               var magic = (string) buffer;
-
-               return magic == MAGIC_VALUE;
-       }
-
-       private string get_string_at_offset (size_t offset, size_t size) throws SegaSaturnError {
-               var header_offset = get_header_offset ();
-               var stream = get_stream ();
-               try {
-                       stream.seek (header_offset + offset, SeekType.SET);
-               }
-               catch (Error e) {
-                       throw new SegaSaturnError.INVALID_SIZE (_("Invalid Sega Saturn header size: %s"), 
e.message);
-               }
-
-               var buffer = new uint8[size];
-               try {
-                       stream.read (buffer);
-               }
-               catch (Error e) {
-                       throw new SegaSaturnError.INVALID_HEADER (_("The file doesn't have a Sega Saturn 
header."));
-               }
-
-               return (string) buffer;
-       }
-
-       private FileInputStream get_stream () throws SegaSaturnError {
-               try {
-                       return file.read ();
-               }
-               catch (Error e) {
-                       throw new SegaSaturnError.CANT_READ_FILE (_("Couldn't read file: %s"), e.message);
-               }
-       }
 }