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Code Issues 975 Packages Projects Releases 20 Wiki Activity

Fix ZStandardStream.IsZStandard to handle streams with insufficient bytes

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Co-authored-by: adamhathcock <527620+adamhathcock@users.noreply.github.com>
This commit is contained in:
copilot-swe-agent[bot]
2025-11-12 08:24:52 +00:00
parent 3ba27eba12
commit c586556614
2 changed files with 44 additions and 1 deletions
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7
src/SharpCompress/Compressors/ZStandard/ZStandardStream.cs
View File

@@ -35,7 +35,12 @@ internal class ZStandardStream : ZstdSharp.DecompressionStream, IStreamStack
internal static bool IsZStandard(Stream stream)
{
var br = new BinaryReader(stream);
var magic = br.ReadUInt32();
var bytes = br.ReadBytes(4);
if (bytes.Length < 4)
{
return false;
}
var magic = BitConverter.ToUInt32(bytes, 0);
if (ZstandardConstants.MAGIC != magic)
{
return false;

38
tests/SharpCompress.Test/Tar/TarArchiveTests.cs
View File

@@ -295,4 +295,42 @@ public class TarArchiveTests : ArchiveTests
Assert.False(isTar);
}
[Fact]
public void TarArchive_Open_SmallStream_DoesNotCrash()
{
// Create a small stream with less than 4 bytes (which would crash when checking ZStandard magic bytes)
var ms = new MemoryStream(new byte[] { 0x00, 0x01, 0x02 });
var options = new ReaderOptions();
options.ArchiveEncoding.Default = Encoding.Default;
// Open the archive (this won't fail immediately as TarArchive.Open doesn't validate)
var archive = TarArchive.Open(ms, options);
// Before the fix, accessing Entries.Count would crash with EndOfFileException when
// TarReader.Open tries to check ZStandard format with insufficient bytes
// After the fix, this should throw IncompleteArchiveException instead (graceful handling)
Assert.Throws<IncompleteArchiveException>(() =>
{
var count = archive.Entries.Count;
});
}
[Fact]
public void TarArchive_Open_EmptyStream_DoesNotCrash()
{
// Create an empty stream
var ms = new MemoryStream();
var options = new ReaderOptions();
options.ArchiveEncoding.Default = Encoding.Default;
// Open the archive (this won't fail immediately as TarArchive.Open doesn't validate)
var archive = TarArchive.Open(ms, options);
// Before the fix, accessing Entries would crash with EndOfFileException when
// TarReader.Open tries to check ZStandard format with insufficient bytes
// After the fix, this should handle the empty stream gracefully
var entries = archive.Entries;
Assert.Empty(entries);
}
}