Support CompressionType.None for uncompressed 7z files

src/SharpCompress/Common/SevenZip/SevenZipFilePart.cs

@@ -67,6 +67,7 @@ public CompressionType CompressionType
         }
     }
 
+    private const uint K_COPY = 0x0;
     private const uint K_LZMA2 = 0x21;
     private const uint K_LZMA = 0x030101;
     private const uint K_PPMD = 0x030401;
@@ -82,6 +83,7 @@ private CompressionType GetCompression()
         var coder = Folder.NotNull()._coders.First();
         return coder._methodId._id switch
         {
+            K_COPY => CompressionType.None,
             K_LZMA or K_LZMA2 => CompressionType.LZMA,
             K_PPMD => CompressionType.PPMd,
             K_B_ZIP2 => CompressionType.BZip2,

src/SharpCompress/packages.lock.json

@@ -335,9 +335,9 @@
     "net8.0": {
       "Microsoft.NET.ILLink.Tasks": {
         "type": "Direct",
-        "requested": "[8.0.17, )",
-        "resolved": "8.0.17",
-        "contentHash": "x5/y4l8AtshpBOrCZdlE4txw8K3e3s9meBFeZeR3l8hbbku2V7kK6ojhXvrbjg1rk3G+JqL1BI26gtgc1ZrdUw=="
+        "requested": "[8.0.0, )",
+        "resolved": "8.0.0",
+        "contentHash": "B3etT5XQ2nlWkZGO2m/ytDYrOmSsQG1XNBaM6ZYlX5Ch/tDrMFadr0/mK6gjZwaQc55g+5+WZMw4Cz3m8VEF7g=="
       },
       "Microsoft.SourceLink.GitHub": {
         "type": "Direct",

tests/SharpCompress.Test/SevenZip/SevenZipArchiveTests.cs

@@ -122,6 +122,25 @@ public void SevenZipArchive_BZip2_Split_FirstFileRead() =>
     //"7Zip.BZip2.split.006",
     //"7Zip.BZip2.split.007"
 
+    [Fact]
+    public void SevenZipArchive_Copy_StreamRead() => ArchiveStreamRead("7Zip.Copy.7z");
+
+    [Fact]
+    public void SevenZipArchive_Copy_PathRead() => ArchiveFileRead("7Zip.Copy.7z");
+
+    [Fact]
+    public void SevenZipArchive_Copy_CompressionType()
+    {
+        using (Stream stream = File.OpenRead(Path.Combine(TEST_ARCHIVES_PATH, "7Zip.Copy.7z")))
+        using (var archive = SevenZipArchive.Open(stream))
+        {
+            foreach (var entry in archive.Entries.Where(e => !e.IsDirectory))
+            {
+                Assert.Equal(CompressionType.None, entry.CompressionType);
+            }
+        }
+    }
+
     [Fact]
     public void SevenZipArchive_ZSTD_StreamRead() => ArchiveStreamRead("7Zip.ZSTD.7z");