Save and modify functionality

IPFBrowser/Extensions.cs

@@ -0,0 +1,139 @@
+using System;
+using System.IO;
+using System.Text;
+
+namespace IPFBrowser
+{
+    /// <summary>
+    /// Extensions for BinaryReader and BinaryWriter to make working with
+    /// IES files easier.
+    /// </summary>
+    public static class BinaryReaderWriterExtensions
+    {
+        private const int XorKey = 1;
+
+        /// <summary>
+        /// XORs buffer and returns it as a string in the given encoding.
+        /// </summary>
+        /// <param name="buffer">Buffer to XOR.</param>
+        private static void XorBuffer(ref byte[] buffer)
+        {
+            for (var i = 0; i < buffer.Length; ++i)
+            {
+                if (buffer[i] == 0)
+                    break;
+
+                buffer[i] = (byte)(buffer[i] ^ XorKey);
+            }
+        }
+
+        /// <summary>
+        /// Reads ushort-length-prefixed, XORed UTF8 string from reader and
+        /// returns it.
+        /// </summary>
+        /// <param name="reader"></param>
+        /// <returns></returns>
+        public static string ReadXoredLpString(this BinaryReader reader)
+        {
+            var length = reader.ReadUInt16();
+            return ReadXoredFixedString(reader, length);
+        }
+
+        /// <summary>
+        /// Reads XORed UTF8 string with given length from reader and
+        /// returns it.
+        /// </summary>
+        /// <param name="reader"></param>
+        /// <param name="length"></param>
+        /// <returns></returns>
+        public static string ReadXoredFixedString(this BinaryReader reader, int length)
+        {
+            if (length <= 0)
+                return "";
+
+            var buffer = reader.ReadBytes(length);
+            XorBuffer(ref buffer);
+            var index = Array.IndexOf(buffer, (byte)0);
+
+            if (index != -1)
+                length = index;
+
+            return Encoding.UTF8.GetString(buffer, 0, length);
+        }
+
+        /// <summary>
+        /// Reads XORed UTF8 string with given length from reader and
+        /// returns it.
+        /// </summary>
+        /// <param name="reader"></param>
+        /// <param name="length"></param>
+        /// <returns></returns>
+        public static string ReadFixedString(this BinaryReader reader, int length)
+        {
+            if (length <= 0)
+                return "";
+
+            var buffer = reader.ReadBytes(length);
+            var index = Array.IndexOf(buffer, (byte)0);
+
+            if (index != -1)
+                length = index;
+
+            return Encoding.UTF8.GetString(buffer, 0, length);
+        }
+
+        /// <summary>
+        /// Writes UTF8 string to the writer, prefixed with a length.
+        /// The string is XORed.
+        /// </summary>
+        /// <param name="writer"></param>
+        /// <param name="value"></param>
+        /// <param name="length"></param>
+        public static void WriteXoredLpString(this BinaryWriter writer, string value)
+        {
+            var length = Encoding.UTF8.GetByteCount(value);
+            writer.Write((ushort)length);
+            WriteXoredFixedString(writer, value, length);
+        }
+
+        /// <summary>
+        /// Writes UTF8 string with a fixed length to the writer. String
+        /// is cut off if it's to long and extended with null bytes if
+        /// too short. The actual string is XORed.
+        /// </summary>
+        /// <param name="writer"></param>
+        /// <param name="value"></param>
+        /// <param name="length"></param>
+        public static void WriteXoredFixedString(this BinaryWriter writer, string value, int length)
+        {
+            var buffer = Encoding.UTF8.GetBytes(value);
+            var writeLength = (buffer.Length > length ? length : buffer.Length);
+
+            XorBuffer(ref buffer);
+
+            writer.Write(buffer, 0, writeLength);
+
+            for (; writeLength < length; ++writeLength)
+                writer.Write((byte)0);
+        }
+
+        /// <summary>
+        /// Writes UTF8 string with a fixed length to the writer. String
+        /// is cut off if it's to long and extended with null bytes if
+        /// too short.
+        /// </summary>
+        /// <param name="writer"></param>
+        /// <param name="value"></param>
+        /// <param name="length"></param>
+        public static void WriteFixedString(this BinaryWriter writer, string value, int length)
+        {
+            var buffer = Encoding.UTF8.GetBytes(value);
+            var writeLength = (buffer.Length > length ? length : buffer.Length);
+
+            writer.Write(buffer, 0, writeLength);
+
+            for (; writeLength < length; ++writeLength)
+                writer.Write((byte)0);
+        }
+    }
+}