move to own files and refactor UTF8 usage

src/SharpCompress/Common/ArchiveEncoding.cs

@@ -11,55 +11,3 @@ public class ArchiveEncoding : IArchiveEncoding
     public Encoding? Forced { get; set; }
     public Func<byte[], int, int, string>? CustomDecoder { get; set; }
 }
-
-public interface IArchiveEncoding
-{
-    /// <summary>
-    /// Default encoding to use when archive format doesn't specify one.
-    /// </summary>
-    public Encoding Default { get; set; }
-
-    /// <summary>
-    /// ArchiveEncoding used by encryption schemes which don't comply with RFC 2898.
-    /// </summary>
-    public Encoding Password { get; set; }
-
-    /// <summary>
-    /// Default encoding to use when archive format specifies UTF-8 encoding.
-    /// </summary>
-    public Encoding UTF8 { get; set; }
-
-    /// <summary>
-    /// Set this encoding when you want to force it for all encoding operations.
-    /// </summary>
-    public Encoding? Forced { get; set; }
-
-    /// <summary>
-    /// Set this when you want to use a custom method for all decoding operations.
-    /// </summary>
-    /// <returns>string Func(bytes, index, length)</returns>
-    public Func<byte[], int, int, string>? CustomDecoder { get; set; }
-}
-
-public static class ArchiveEncodingExtensions
-{
-    public static Encoding GetEncoding(this IArchiveEncoding encoding) =>
-        encoding.Forced ?? encoding.Default;
-
-    public static Func<byte[], int, int, string> GetDecoder(this IArchiveEncoding encoding) =>
-        encoding.CustomDecoder
-        ?? ((bytes, index, count) => encoding.GetEncoding().GetString(bytes, index, count));
-
-    public static byte[] Encode(this IArchiveEncoding encoding, string str) =>
-        encoding.Default.GetBytes(str);
-
-    public static string Decode(this IArchiveEncoding encoding, byte[] bytes) =>
-        encoding.Decode(bytes, 0, bytes.Length);
-
-    public static string Decode(
-        this IArchiveEncoding encoding,
-        byte[] bytes,
-        int start,
-        int length
-    ) => encoding.GetDecoder()(bytes, start, length);
-}

src/SharpCompress/Common/ArchiveEncodingExtensions.cs

@@ -0,0 +1,28 @@
+using System;
+using System.Text;
+
+namespace SharpCompress.Common;
+
+public static class ArchiveEncodingExtensions
+{
+    extension(IArchiveEncoding encoding)
+    {
+        public Encoding GetEncoding(bool useUtf8 = false) =>
+            encoding.Forced ?? (useUtf8 ? encoding.UTF8 : encoding.Default);
+
+        public Func<byte[], int, int, string> GetDecoder(bool useUtf8) =>
+            encoding.CustomDecoder
+            ?? (
+                (bytes, index, count) =>
+                    encoding.GetEncoding(useUtf8).GetString(bytes, index, count)
+            );
+
+        public byte[] Encode(string str) => encoding.Default.GetBytes(str);
+
+        public string Decode(byte[] bytes, bool useUtf8 = false) =>
+            encoding.Decode(bytes, 0, bytes.Length, useUtf8);
+
+        public string Decode(byte[] bytes, int start, int length, bool useUtf8 = false) =>
+            encoding.GetDecoder(useUtf8)(bytes, start, length);
+    }
+}

src/SharpCompress/Common/IArchiveEncoding.cs

@@ -0,0 +1,33 @@
+using System;
+using System.Text;
+
+namespace SharpCompress.Common;
+
+public interface IArchiveEncoding
+{
+    /// <summary>
+    /// Default encoding to use when archive format doesn't specify one.
+    /// </summary>
+    public Encoding Default { get; set; }
+
+    /// <summary>
+    /// ArchiveEncoding used by encryption schemes which don't comply with RFC 2898.
+    /// </summary>
+    public Encoding Password { get; set; }
+
+    /// <summary>
+    /// Default encoding to use when archive format specifies UTF-8 encoding.
+    /// </summary>
+    public Encoding UTF8 { get; set; }
+
+    /// <summary>
+    /// Set this encoding when you want to force it for all encoding operations.
+    /// </summary>
+    public Encoding? Forced { get; set; }
+
+    /// <summary>
+    /// Set this when you want to use a custom method for all decoding operations.
+    /// </summary>
+    /// <returns>string Func(bytes, index, length)</returns>
+    public Func<byte[], int, int, string>? CustomDecoder { get; set; }
+}

src/SharpCompress/Common/Zip/Headers/DirectoryEntryHeader.cs

@@ -41,8 +41,8 @@ internal class DirectoryEntryHeader : ZipFileEntry
 
         if (Flags.HasFlag(HeaderFlags.Efs))
         {
-            Name = ArchiveEncoding.DecodeUTF8(name);
-            Comment = ArchiveEncoding.DecodeUTF8(comment);
+            Name = ArchiveEncoding.Decode(name, true);
+            Comment = ArchiveEncoding.Decode(comment, true);
         }
         else
         {

src/SharpCompress/Common/Zip/Headers/LocalEntryHeader.cs

@@ -33,7 +33,7 @@ internal class LocalEntryHeader : ZipFileEntry
 
         if (Flags.HasFlag(HeaderFlags.Efs))
         {
-            Name = ArchiveEncoding.DecodeUTF8(name);
+            Name = ArchiveEncoding.Decode(name, true);
         }
         else
         {