ZipGenericExtraField.cs

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using System.Collections.Generic;
 
namespace System.IO.Compression;
 
internal struct ZipGenericExtraField
{
    private ushort _tag;
 
    private ushort _size;
 
    private byte[] _data;
 
    public ushort Tag => _tag;
 
    public ushort Size => _size;
 
    public byte[] Data => _data;
 
    public void WriteBlock(Stream stream)
    {
        BinaryWriter binaryWriter = new BinaryWriter(stream);
        binaryWriter.Write(Tag);
        binaryWriter.Write(Size);
        binaryWriter.Write(Data);
    }
 
    public static bool TryReadBlock(BinaryReader reader, long endExtraField, out ZipGenericExtraField field)
    {
        field = default(ZipGenericExtraField);
        if (endExtraField - reader.BaseStream.Position < 4)
        {
            return false;
        }
        field._tag = reader.ReadUInt16();
        field._size = reader.ReadUInt16();
        if (endExtraField - reader.BaseStream.Position < field._size)
        {
            return false;
        }
        field._data = reader.ReadBytes(field._size);
        return true;
    }
 
    public static List<ZipGenericExtraField> ParseExtraField(Stream extraFieldData)
    {
        List<ZipGenericExtraField> list = new List<ZipGenericExtraField>();
        using BinaryReader reader = new BinaryReader(extraFieldData);
        ZipGenericExtraField field;
        while (TryReadBlock(reader, extraFieldData.Length, out field))
        {
            list.Add(field);
        }
        return list;
    }
 
    public static int TotalSize(List<ZipGenericExtraField> fields)
    {
        int num = 0;
        foreach (ZipGenericExtraField field in fields)
        {
            num += field.Size + 4;
        }
        return num;
    }
 
    public static void WriteAllBlocks(List<ZipGenericExtraField> fields, Stream stream)
    {
        foreach (ZipGenericExtraField field in fields)
        {
            field.WriteBlock(stream);
        }
    }
}