Rearranged BMP reader to prevent incorrectly decoded images

Argent77 · Jan 24, 2015 · a6cc6a5 · a6cc6a5
1 parent b67d335
commit a6cc6a5
Showing 1 changed file with 45 additions and 44 deletions.
diff --git a/src/infinity/resource/graphics/BmpResource.java b/src/infinity/resource/graphics/BmpResource.java
@@ -37,51 +37,52 @@ public final class BmpResource implements Resource, ActionListener
   public BmpResource(ResourceEntry entry) throws Exception
   {
     this.entry = entry;
-    try {
-      image = ImageIO.read(entry.getResourceDataAsStream());
-    } catch (Exception e) {
-      image = null;
+    byte[] data = entry.getResourceData();
+    // Checking signature
+    if (!"BM".equals(new String(data, 0, 2))) {
+      throw new Exception("Invalid BMP resource");
     }
-    if (image == null) {
-      byte[] data = entry.getResourceData();
-      new String(data, 0, 2); // Signature
-      DynamicArray.getInt(data, 2); // Size
-      DynamicArray.getInt(data, 6); // Reserved
-      int rasteroff = DynamicArray.getInt(data, 10);
-
-      DynamicArray.getInt(data, 14); // Headersize
-      int width = DynamicArray.getInt(data, 18);
-      int height = DynamicArray.getInt(data, 22);
-      DynamicArray.getShort(data, 26); // Planes
-      int bitcount = (int)DynamicArray.getShort(data, 28);
-      int compression = DynamicArray.getInt(data, 30);
-      if ((compression == 0 || compression == 3) && bitcount <= 32) {
-        DynamicArray.getInt(data, 34); // Comprsize
-        DynamicArray.getInt(data, 38); // Xpixprm
-        DynamicArray.getInt(data, 42); // Ypixprm
-        int colsUsed = DynamicArray.getInt(data, 46); // Colorsused
-        DynamicArray.getInt(data, 50); // Colorsimp
-
-        if (bitcount <= 8) {
-          if (colsUsed == 0)
-            colsUsed = 1 << bitcount;
-          int palSize = 4 * colsUsed;
-          palette = new Palette(data, rasteroff - palSize, palSize);
-        }
-
-        int bytesprline = bitcount * width / 8;
-        int padded = 4 - bytesprline % 4;
-        if (padded == 4)
-          padded = 0;
-
-        image = ColorConvert.createCompatibleImage(width, height, bitcount >= 32);
-        int offset = rasteroff;
-        for (int y = height - 1; y >= 0; y--) {
-          setPixels(data, offset, bitcount, bytesprline, y, palette);
-          offset += bytesprline + padded;
-        }
-      } else {
-        throw new Exception(String.format("%1$s: Unsupported BMP format", entry.getResourceName()));
+    DynamicArray.getInt(data, 2); // Size
+    DynamicArray.getInt(data, 6); // Reserved
+    int rasteroff = DynamicArray.getInt(data, 10);
+
+    DynamicArray.getInt(data, 14); // Headersize
+    int width = DynamicArray.getInt(data, 18);
+    int height = DynamicArray.getInt(data, 22);
+    DynamicArray.getShort(data, 26); // Planes
+    int bitcount = (int)DynamicArray.getShort(data, 28);
+    int compression = DynamicArray.getInt(data, 30);
+    if ((compression == 0 || compression == 3) && bitcount <= 32) {
+      DynamicArray.getInt(data, 34); // Comprsize
+      DynamicArray.getInt(data, 38); // Xpixprm
+      DynamicArray.getInt(data, 42); // Ypixprm
+      int colsUsed = DynamicArray.getInt(data, 46); // Colorsused
+      DynamicArray.getInt(data, 50); // Colorsimp
+
+      if (bitcount <= 8) {
+        if (colsUsed == 0)
+          colsUsed = 1 << bitcount;
+        int palSize = 4 * colsUsed;
+        palette = new Palette(data, rasteroff - palSize, palSize);
+      }
+
+      int bytesprline = bitcount * width / 8;
+      int padded = 4 - bytesprline % 4;
+      if (padded == 4)
+        padded = 0;
+
+      image = ColorConvert.createCompatibleImage(width, height, bitcount >= 32);
+      int offset = rasteroff;
+      for (int y = height - 1; y >= 0; y--) {
+        setPixels(data, offset, bitcount, bytesprline, y, palette);
+        offset += bytesprline + padded;
+      }
+    } else {
+      try {
+        image = ImageIO.read(entry.getResourceDataAsStream());
+      } catch (Exception e) {
+        image = null;
+        throw new Exception("Unsupported BMP format");
       }
     }
   }