NDecrypt/NDecrypt.N3DS/Headers/ExeFSFileHeader.cs

using System.IO;
using System.Linq;
using System.Text;

namespace NDecrypt.N3DS.Headers
{
    internal class ExeFSFileHeader
    {
        // .code\0\0\0
        private readonly byte[] codeSegmentBytes = [0x2e, 0x63, 0x6f, 0x64, 0x65, 0x00, 0x00, 0x00];

        /// <summary>
        /// File name
        /// </summary>
        public byte[]? FileName { get; private set; }
        public string ReadableFileName { get { return Encoding.ASCII.GetString(FileName!); } }
        public bool IsCodeBinary { get { return Enumerable.SequenceEqual(FileName!, codeSegmentBytes); } }

        /// <summary>
        /// File offset
        /// </summary>
        public uint FileOffset { get; private set; }

        /// <summary>
        /// File size
        /// </summary>
        public uint FileSize { get; private set; }

        /// <summary>
        /// SHA256 hash calculated over the entire file contents
        /// </summary>
        public byte[]? FileHash { get; set; }

        /// <summary>
        /// Read from a stream and get an ExeFS file header, if possible
        /// </summary>
        /// <param name="reader">BinaryReader representing the input stream</param>
        /// <returns>ExeFS file header object, null on error</returns>
        public static ExeFSFileHeader? Read(BinaryReader reader)
        {
            var header = new ExeFSFileHeader();

            try
            {
                header.FileName = reader.ReadBytes(8);
                header.FileOffset = reader.ReadUInt32();
                header.FileSize = reader.ReadUInt32();
                return header;
            }
            catch
            {
                return null;
            }
        }
    }
}