Switch-Toolbox/Switch_Toolbox_Library/IO/Extensions/IOExtensions.cs

using System;
using System.Collections.Generic;
using System.Text;
using System.IO;
using System.Threading.Tasks;
using System.Text.RegularExpressions;
using Toolbox.Library.Security.Cryptography;
using System.Runtime.InteropServices;
using Syroot.BinaryData;
using System.Linq;

namespace Toolbox.Library.IO
{
    public static class IOExtensions
    {
        //From https://github.com/IcySon55/Kuriimu/blob/master/src/Kontract/IO/Extensions.cs
        //Read
        public static unsafe T BytesToStruct<T>(this byte[] buffer, bool isBigEndian = false, int offset = 0)
        {
            if (offset < 0) throw new ArgumentOutOfRangeException(nameof(offset));

            AdjustBigEndianByteOrder(typeof(T), buffer, isBigEndian);

            fixed (byte* pBuffer = buffer) 
                return Marshal.PtrToStructure<T>((IntPtr)pBuffer + offset);
        }

        // Write
        public static unsafe byte[] StructToBytes<T>(this T item, bool isBigEndian)
        {
            var buffer = new byte[Marshal.SizeOf(typeof(T))];

            fixed (byte* pBuffer = buffer)
                Marshal.StructureToPtr(item, (IntPtr)pBuffer, false);

            AdjustBigEndianByteOrder(typeof(T), buffer, isBigEndian);

            return buffer;
        }

        //Adjust byte order for big endian
        private static void AdjustBigEndianByteOrder(Type type, byte[] buffer, bool isBigEndian, int startOffset = 0)
        {
            if (!isBigEndian)
                return;

            if (type.IsPrimitive)
            {
                if (type == typeof(short) || type == typeof(ushort) ||
                 type == typeof(int) || type == typeof(uint) ||
                 type == typeof(long) || type == typeof(ulong))
                {
                    Array.Reverse(buffer);
                    return;
                }
            }

            foreach (var field in type.GetFields())
            {
                var fieldType = field.FieldType;

                // Ignore static fields
                if (field.IsStatic) continue;

                if (fieldType.BaseType == typeof(Enum) && fieldType != typeof(ByteOrder))
                    fieldType = fieldType.GetFields()[0].FieldType;

                // Swap bytes only for the following types (incomplete just like BinaryReaderX is)
                if (fieldType == typeof(short) || fieldType == typeof(ushort) ||
                    fieldType == typeof(int) || fieldType == typeof(uint) ||
                    fieldType == typeof(long) || fieldType == typeof(ulong))
                {
                    var offset = Marshal.OffsetOf(type, field.Name).ToInt32();

                    // Enums
                    if (fieldType.IsEnum)
                        fieldType = Enum.GetUnderlyingType(fieldType);

                    // Check for sub-fields to recurse if necessary
                    var subFields = fieldType.GetFields().Where(subField => subField.IsStatic == false).ToArray();
                    var effectiveOffset = startOffset + offset;

                    if (subFields.Length == 0)
                        Array.Reverse(buffer, effectiveOffset, Marshal.SizeOf(fieldType));
                    else
                        AdjustBigEndianByteOrder(fieldType, buffer, isBigEndian, effectiveOffset);
                }
            }
        }

        //https://github.com/exelix11/EditorCore/blob/872d210f85ec0409f8a6ac3a12fc162aaf4cd90c/EditorCoreCommon/CustomClasses.cs#L367
        public static bool Matches(this byte[] arr, string magic) =>
                    arr.Matches(0, magic.ToCharArray());
        public static bool Matches(this byte[] arr, uint magic) =>
            arr.Matches(0, BitConverter.GetBytes(magic));

        public static bool Matches(this byte[] arr, uint startIndex, params byte[] magic)
        {
            if (arr.Length < magic.Length + startIndex) return false;
            for (uint i = 0; i < magic.Length; i++)
            {
                if (arr[i + startIndex] != magic[i]) return false;
            }
            return true;
        }

        public static byte[] ToByteArray(this string str, int length)
        {
            return Encoding.ASCII.GetBytes(str.PadRight(length, ' '));
        }

        public static uint EncodeCrc32(this string str)
        {
            return Crc32.Compute(str);
        }

        public static bool Matches(this byte[] arr, uint startIndex, params char[] magic)
        {
            if (arr.Length < magic.Length + startIndex) return false;
            for (uint i = 0; i < magic.Length; i++)
            {
                if (arr[i + startIndex] != magic[i]) return false;
            }
            return true;
        }

        public static uint Reverse(this uint x)
        {
            // swap adjacent 16-bit blocks
            x = (x >> 16) | (x << 16);
            // swap adjacent 8-bit blocks
            return ((x & 0xFF00FF00) >> 8) | ((x & 0x00FF00FF) << 8);
        }

        //https://stackoverflow.com/questions/2230826/remove-invalid-disallowed-bad-characters-from-filename-or-directory-folder/12800424#12800424
        public static string RemoveIllegaleFileNameCharacters(this string str)
        {
            return string.Join("_", str.Split(Path.GetInvalidFileNameChars()));
        }

        public static string RemoveIllegaleFolderNameCharacters(this string str)
        {
            return string.Join("_", str.Split(Path.GetInvalidPathChars()));
        }

    }
}