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Skip ZIP64 extensible data without size-driven allocations

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This commit is contained in:
Adam Hathcock
2026-10-16 15:33:10 +01:00
parent bc1ade2bbc
commit 9b0be6f984
4 changed files with 111 additions and 15 deletions
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19
src/SharpCompress/Common/Zip/Headers/Zip64DirectoryEndHeader.Async.cs
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@@ -1,3 +1,4 @@
using System;
using System.IO;
using System.Threading.Tasks;
using SharpCompress.IO;
@@ -8,7 +9,9 @@ internal partial class Zip64DirectoryEndHeader
{
internal override async ValueTask Read(AsyncBinaryReader reader)
{
SizeOfDirectoryEndRecord = (long)await reader.ReadUInt64Async().ConfigureAwait(false);
SizeOfDirectoryEndRecord = ValidateRecordSize(
await reader.ReadUInt64Async().ConfigureAwait(false)
);
VersionMadeBy = await reader.ReadUInt16Async().ConfigureAwait(false);
VersionNeededToExtract = await reader.ReadUInt16Async().ConfigureAwait(false);
VolumeNumber = await reader.ReadUInt32Async().ConfigureAwait(false);
@@ -18,10 +21,14 @@ internal partial class Zip64DirectoryEndHeader
DirectorySize = (long)await reader.ReadUInt64Async().ConfigureAwait(false);
DirectoryStartOffsetRelativeToDisk = (long)
await reader.ReadUInt64Async().ConfigureAwait(false);
var size = (int)(
SizeOfDirectoryEndRecord - SIZE_OF_FIXED_HEADER_DATA_EXCEPT_SIGNATURE_AND_SIZE_FIELDS
);
DataSector = new byte[size];
await reader.ReadBytesAsync(DataSector, 0, size).ConfigureAwait(false);
var remaining =
SizeOfDirectoryEndRecord - SIZE_OF_FIXED_HEADER_DATA_EXCEPT_SIGNATURE_AND_SIZE_FIELDS;
var buffer = new byte[4096];
while (remaining > 0)
{
var size = (int)Math.Min(buffer.Length, remaining);
await reader.ReadBytesAsync(buffer, 0, size).ConfigureAwait(false);
remaining -= size;
}
}
}

36
src/SharpCompress/Common/Zip/Headers/Zip64DirectoryEndHeader.cs
View File

@@ -1,3 +1,4 @@
using System;
using System.IO;
namespace SharpCompress.Common.Zip.Headers;
@@ -9,7 +10,7 @@ internal partial class Zip64DirectoryEndHeader : ZipHeader
internal override void Read(BinaryReader reader)
{
SizeOfDirectoryEndRecord = (long)reader.ReadUInt64();
SizeOfDirectoryEndRecord = ValidateRecordSize(reader.ReadUInt64());
VersionMadeBy = reader.ReadUInt16();
VersionNeededToExtract = reader.ReadUInt16();
VolumeNumber = reader.ReadUInt32();
@@ -18,12 +19,31 @@ internal partial class Zip64DirectoryEndHeader : ZipHeader
TotalNumberOfEntries = (long)reader.ReadUInt64();
DirectorySize = (long)reader.ReadUInt64();
DirectoryStartOffsetRelativeToDisk = (long)reader.ReadUInt64();
DataSector = reader.ReadBytes(
(int)(
SizeOfDirectoryEndRecord
- SIZE_OF_FIXED_HEADER_DATA_EXCEPT_SIGNATURE_AND_SIZE_FIELDS
)
);
// Extensible data is not interpreted. Consume it without allocating from its declared size.
var remaining =
SizeOfDirectoryEndRecord - SIZE_OF_FIXED_HEADER_DATA_EXCEPT_SIGNATURE_AND_SIZE_FIELDS;
var buffer = new byte[4096];
while (remaining > 0)
{
var read = reader.Read(buffer, 0, (int)Math.Min(buffer.Length, remaining));
if (read == 0)
{
throw new IncompleteArchiveException("Truncated ZIP64 extensible data.");
}
remaining -= read;
}
}
private static long ValidateRecordSize(ulong size)
{
if (
size < SIZE_OF_FIXED_HEADER_DATA_EXCEPT_SIGNATURE_AND_SIZE_FIELDS
|| size > long.MaxValue
)
{
throw new InvalidFormatException("Invalid ZIP64 end record size.");
}
return (long)size;
}
private const int SIZE_OF_FIXED_HEADER_DATA_EXCEPT_SIGNATURE_AND_SIZE_FIELDS = 44;
@@ -45,6 +65,4 @@ internal partial class Zip64DirectoryEndHeader : ZipHeader
public long DirectorySize { get; private set; }
public long DirectoryStartOffsetRelativeToDisk { get; private set; }
public byte[]? DataSector { get; private set; }
}