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Code Issues 975 Packages Projects Releases 20 Wiki Activity

more subtle check of magic bytes for ARJ archives

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This commit is contained in:
Twan van Dongen
2026-01-03 17:59:17 +01:00
parent e1c8aa226d
commit 909d36c237
2 changed files with 19 additions and 9 deletions
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21
src/SharpCompress/Common/Arj/Headers/ArjHeader.cs
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@@ -34,14 +34,13 @@ namespace SharpCompress.Common.Arj.Headers
public byte[] ReadHeader(Stream stream)
{
// check for magic bytes
Span<byte> magic = stackalloc byte[2];
var magic = new byte[2];
if (stream.Read(magic) != 2)
{
return Array.Empty<byte>();
}
var magicValue = (ushort)(magic[0] | magic[1] << 8);
if (magicValue != ARJ_MAGIC)
if (!CheckMagicBytes(magic))
{
throw new InvalidDataException("Not an ARJ file (wrong magic bytes)");
}
@@ -138,5 +137,21 @@ namespace SharpCompress.Common.Arj.Headers
? (FileType)value
: Headers.FileType.Unknown;
}
public static bool IsArchive(Stream stream)
{
var bytes = new byte[2];
if (stream.Read(bytes, 0, 2) != 2)
{
return false;
}
return CheckMagicBytes(bytes);
}
protected static bool CheckMagicBytes(byte[] headerBytes)
{
var magicValue = (ushort)(headerBytes[0] | headerBytes[1] << 8);
return magicValue == ARJ_MAGIC;
}
}
}

7
src/SharpCompress/Factories/ArjFactory.cs
View File

@@ -28,12 +28,7 @@ namespace SharpCompress.Factories
int bufferSize = ReaderOptions.DefaultBufferSize
)
{
var arjHeader = new ArjMainHeader(new ArchiveEncoding());
if (arjHeader.Read(stream) == null)
{
return false;
}
return true;
return ArjHeader.IsArchive(stream);
}
public IReader OpenReader(Stream stream, ReaderOptions? options) =>