duplicati/Duplicati/Library/Main/Operation/Restore/VolumeDecompressor.cs

using System;
using System.Linq;
using System.Threading.Tasks;
using CoCoL;
using Duplicati.Library.Main.Database;
using Duplicati.Library.Main.Volumes;

namespace Duplicati.Library.Main.Operation.Restore
{
    internal class VolumeDecompressor
    {
        public static Task Run(LocalRestoreDatabase db, Options options)
        {
            return AutomationExtensions.RunTask(
            new
            {
                Input = Channels.decryptedVolume.ForRead,
                Output = Channels.decompressedVolumes.ForWrite
            },
            async self =>
            {
                while (true)
                {
                    var (volume_id, volume) = await self.Input.ReadAsync();

                    var bids = db.Connection.CreateCommand().ExecuteReaderEnumerable(@$"SELECT ID, Hash, Size FROM Block WHERE VolumeID = ""{volume_id}""").Select(x => (x.GetInt64(0), x.GetString(1), x.GetInt64(2))).ToArray();

                    using (var blocks = new BlockVolumeReader(options.CompressionModule, volume, options))
                    {
                        var volume_blocks = blocks.Blocks.ToArray();
                        for (int i = 0; i < volume_blocks.Length; i++)
                        {
                            byte[] buffer = new byte[options.Blocksize];

                            System.Diagnostics.Debug.Assert(volume_blocks[i].Key == bids[i].Item2);
                            blocks.ReadBlock(volume_blocks[i].Key, buffer);

                            await self.Output.WriteAsync((bids[i].Item1, buffer[..(int)bids[i].Item3]));
                        }
                    }
                }
            });
        }
    }
}