using System; using System.Collections.Generic; using System.Text; namespace DSDecmp.Formats.Nitro { /// /// Base class for Nitro-based decompressors. Uses the 1-byte magic and 3-byte decompression /// size format. /// public abstract class NitroCFormat : CompressionFormat { /// /// If true, Nitro Decompressors will not decompress files that have a decompressed /// size (plaintext size) larger than MaxPlaintextSize. /// public static bool SkipLargePlaintexts = true; /// /// The maximum allowed size of the decompressed file (plaintext size) allowed for Nitro /// Decompressors. Only used when SkipLargePlaintexts = true. /// public static int MaxPlaintextSize = 0x180000; /// /// The first byte of every file compressed with the format for this particular /// Nitro Dcompressor instance. /// protected byte magicByte; public NitroCFormat(byte magicByte) { this.magicByte = magicByte; } public override bool Supports(System.IO.Stream stream, long inLength) { long startPosition = stream.Position; try { int firstByte = stream.ReadByte(); if (firstByte != this.magicByte) return false; // no need to read the size info as well if it's used anyway. if (!SkipLargePlaintexts) return true; byte[] sizeBytes = new byte[3]; stream.Read(sizeBytes, 0, 3); int outSize = IOUtils.ToNDSu24(sizeBytes, 0); if (outSize == 0) { sizeBytes = new byte[4]; stream.Read(sizeBytes, 0, 4); outSize = (int)IOUtils.ToNDSu32(sizeBytes, 0); } return outSize <= MaxPlaintextSize; } finally { stream.Position = startPosition; } } } }