From Colin McDonald, fixed image size calculation in getTotalSizeInBytesIncludingMipmaps(),

added checks on success of opening files for writing in the .ive plugin.

src/osg/Image.cpp

@@ -308,9 +308,11 @@ unsigned int Image::getTotalSizeInBytesIncludingMipmaps() const
         case(GL_COMPRESSED_RGB_S3TC_DXT1_EXT):
         case(GL_COMPRESSED_RGBA_S3TC_DXT1_EXT):
            sizeOfLastMipMap = maximum(sizeOfLastMipMap, 8u); // block size of 8
+	   break;
         case(GL_COMPRESSED_RGBA_S3TC_DXT3_EXT):
         case(GL_COMPRESSED_RGBA_S3TC_DXT5_EXT):
            sizeOfLastMipMap = maximum(sizeOfLastMipMap, 16u); // block size of 16
+	   break;
         default: break;
    }