Dont crash on reading rar5 comment #783

src/SharpCompress/Common/Rar/Headers/RarHeaderFactory.cs

@@ -105,7 +105,14 @@ public IEnumerable<IRarHeader> ReadHeaders(Stream stream)
             case HeaderCodeV.RAR5_SERVICE_HEADER:
             {
                 var fh = new FileHeader(header, reader, HeaderType.Service);
-                SkipData(fh, reader);
+                if (fh.FileName == "CMT")
+                {
+                    fh.PackedStream = new ReadOnlySubStream(reader.BaseStream, fh.CompressedSize);
+                }
+                else
+                {
+                    SkipData(fh, reader);
+                }
                 return fh;
             }
 

src/SharpCompress/Common/Rar/RarVolume.cs

@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
+using System.Text;
 using SharpCompress.Common.Rar.Headers;
 using SharpCompress.IO;
 using SharpCompress.Readers;
@@ -70,11 +71,7 @@ internal IEnumerable<RarFilePart> GetVolumeFileParts()
                             var part = CreateFilePart(lastMarkHeader!, fh);
                             var buffer = new byte[fh.CompressedSize];
                             part.GetCompressedStream().Read(buffer, 0, buffer.Length);
-                            Comment = System
-                                .Text
-                                .Encoding
-                                .UTF8
-                                .GetString(buffer, 0, buffer.Length - 1);
+                            Comment = Encoding.UTF8.GetString(buffer, 0, buffer.Length - 1);
                         }
                     }
                     break;

tests/SharpCompress.Test/Rar/RarReaderTests.cs

@@ -284,6 +284,12 @@ public void Rar_Jpg_Reader()
     [Fact]
     public void Rar_Solid_Reader() => Read("Rar.solid.rar", CompressionType.Rar);
 
+    [Fact]
+    public void Rar_Comment_Reader() => Read("Rar.comment.rar", CompressionType.Rar);
+
+    [Fact]
+    public void Rar5_Comment_Reader() => Read("Rar5.comment.rar", CompressionType.Rar);
+
     [Fact]
     public void Rar5_Solid_Reader() => Read("Rar5.solid.rar", CompressionType.Rar);