/// <summary>
/// Apply patch data from given <see cref="Stream"/> to the ROM.
/// </summary>
/// <param name="inStream">Input stream.</param>
/// <returns><see cref="SHA256"/> hash of the patch.</returns>
public static byte[] ApplyPatch(Stream inStream)
{
try
{
var aes = Aes.Create();
var hashAlg = new SHA256Managed();
using (var cryptoStream = new CryptoStream(inStream, aes.CreateDecryptor(key, iv), CryptoStreamMode.Read))
using (var hashStream = new CryptoStream(cryptoStream, hashAlg, CryptoStreamMode.Read))
using (var decompressStream = new GZipStream(hashStream, CompressionMode.Decompress))
using (var memoryStream = new MemoryStream())
{
// Fully decompress into MemoryStream so that we can access Position to check for end of Stream.
decompressStream.CopyTo(memoryStream);
memoryStream.Seek(0, SeekOrigin.Begin);
using var reader = new BeBinaryReader(memoryStream);
// Validate patch magic.
var magic = reader.ReadUInt32();
ValidateMagic(magic);
Span <byte> headerBytes = stackalloc byte[PatchHeader.Size];
while (reader.BaseStream.Position != reader.BaseStream.Length)
{
// Read header bytes into stack buffer to prevent allocation.
reader.ReadExact(headerBytes);
var header = PatchHeader.Read(headerBytes);
var data = reader.ReadBytes(header.Length);
ApplyPatchEntry(header, data);
}
}
return(hashAlg.Hash);
}
catch
{
throw new IOException("Failed to apply patch. Patch may be invalid.");
}
}
