Merge pull request #891 from Morilli/fix-zip-datadescriptor-header

Fix zip entry handling for entries with data descriptors

Author: adamhathcock

src/SharpCompress/Common/Zip/SeekableZipFilePart.cs

@@ -1,25 +1,19 @@
 using System.IO;
 using SharpCompress.Common.Zip.Headers;
-using SharpCompress.IO;
 
 namespace SharpCompress.Common.Zip;
 
 internal class SeekableZipFilePart : ZipFilePart
 {
     private bool _isLocalHeaderLoaded;
     private readonly SeekableZipHeaderFactory _headerFactory;
-    private readonly DirectoryEntryHeader _directoryEntryHeader;
 
     internal SeekableZipFilePart(
         SeekableZipHeaderFactory headerFactory,
         DirectoryEntryHeader header,
         Stream stream
     )
-        : base(header, stream)
-    {
-        _headerFactory = headerFactory;
-        _directoryEntryHeader = header;
-    }
+        : base(header, stream) => _headerFactory = headerFactory;
 
     internal override Stream GetCompressedStream()
     {
@@ -44,16 +38,6 @@ protected override Stream CreateBaseStream()
     {
         BaseStream.Position = Header.DataStartPosition.NotNull();
 
-        if (
-            (Header.CompressedSize == 0)
-            && FlagUtility.HasFlag(Header.Flags, HeaderFlags.UsePostDataDescriptor)
-            && _directoryEntryHeader.HasData
-            && (_directoryEntryHeader.CompressedSize != 0)
-        )
-        {
-            return new ReadOnlySubStream(BaseStream, _directoryEntryHeader.CompressedSize);
-        }
-
         return BaseStream;
     }
 }

src/SharpCompress/Common/Zip/SeekableZipHeaderFactory.cs

@@ -149,6 +149,12 @@ DirectoryEntryHeader directoryEntryHeader
         {
             throw new InvalidOperationException();
         }
+        if (FlagUtility.HasFlag(localEntryHeader.Flags, HeaderFlags.UsePostDataDescriptor))
+        {
+            localEntryHeader.Crc = directoryEntryHeader.Crc;
+            localEntryHeader.CompressedSize = directoryEntryHeader.CompressedSize;
+            localEntryHeader.UncompressedSize = directoryEntryHeader.UncompressedSize;
+        }
         return localEntryHeader;
     }
 }

tests/SharpCompress.Test/Zip/ZipArchiveTests.cs

@@ -808,4 +808,16 @@ public void Zip_Forced_Ignores_UnicodePathExtra()
             Assert.Equal("きょきゅんきゃんきゅ_wav.frq", reader.Entry.Key);
         }
     }
+
+    [Fact]
+    public void TestDataDescriptorRead()
+    {
+        using var archive = ArchiveFactory.Open(
+            Path.Combine(TEST_ARCHIVES_PATH, "Zip.none.datadescriptors.zip")
+        );
+        var firstEntry = archive.Entries.First();
+        Assert.Equal(199, firstEntry.Size);
+        using var _ = firstEntry.OpenEntryStream();
+        Assert.Equal(199, firstEntry.Size);
+    }
 }