public override Stream OpenEntry(ArcFile arc, Entry entry)
{
ushort signature = arc.File.View.ReadUInt16(entry.Offset);
// C1/D1/E1/F1
if (0x3146 != signature && 0x3143 != signature && 0x3144 != signature && 0x3145 != signature)
{
return(base.OpenEntry(arc, entry));
}
var mkarc = arc as MkArchive;
ScrambleScheme scheme = mkarc != null ? mkarc.Scheme : DefaultScheme;
uint packed_size = arc.File.View.ReadUInt32(entry.Offset + 2);
if (packed_size < scheme.ScrambledSize || packed_size > entry.Size - 10)
{
return(base.OpenEntry(arc, entry));
}
Stream input;
// XXX scrambling might be applicable for 'E1' signatures only
if (scheme.ScrambledSize > 0)
{
var prefix = arc.File.View.ReadBytes(entry.Offset + 10, scheme.ScrambledSize);
foreach (var pair in scheme.ScrambleMap)
{
byte t = prefix[pair.Item1];
prefix[pair.Item1] = prefix[pair.Item2];
prefix[pair.Item2] = t;
}
input = arc.File.CreateStream(entry.Offset + 10 + scheme.ScrambledSize, packed_size - scheme.ScrambledSize);
input = new PrefixStream(prefix, input);
}
else
{
input = arc.File.CreateStream(entry.Offset + 10, packed_size);
}
input = new LzssStream(input);
var header = new byte[5];
input.Read(header, 0, 5);
if (Binary.AsciiEqual(header, "BPR02"))
{
return(new PackedStream <Bpr02Decompressor> (input));
}
if (Binary.AsciiEqual(header, "BPR01"))
{
return(new PackedStream <Bpr01Decompressor> (input));
}
return(new PrefixStream(header, input));
}
public MkArchive(ArcView arc, ArchiveFormat impl, ICollection <Entry> dir, ScrambleScheme scheme)
: base(arc, impl, dir)
{
Scheme = scheme;
}