async ValueTask ReadChunks(long chunkTableOffset, int chunkCount)
{
if (ChunkReader is null)
{
throw new InvalidOperationException();
}
var chunkTable = new byte[(chunkCount + 1) * (4 + sizeof(long))];
if (await ChunkReader.ReadAtAsync(chunkTableOffset, chunkTable).ConfigureAwait(false) != chunkTable.Length)
{
return;
}
_chunks = Enumerable.Range(0, chunkCount + 1).Select(i => new Chunk
{
Name = (i < chunkCount) ? Encoding.ASCII.GetString(chunkTable, 12 * i, 4) : null,
Position = NetBitConverter.ToInt64(chunkTable, 12 * i + 4)
}).ToArray();
for (int i = 0; i < chunkCount; i++)
{
_chunks[i].Length = _chunks[i + 1].Position - _chunks[i].Position;
}
FanOut = await ReadFanOutAsync().ConfigureAwait(false);
}
protected override async ValueTask <(GitIdType IdType, int ChunkCount, long ChunkTableOffset)> ReadHeaderAsync()
{
if (ChunkReader is null)
{
throw new InvalidOperationException();
}
var headerBuffer = new byte[8];
if (await ChunkReader.ReadAtAsync(0, headerBuffer).ConfigureAwait(false) != headerBuffer.Length)
{
return(GitIdType.None, 0, -1);
}
if (!"CGPH\x01".Select(x => (byte)x).SequenceEqual(headerBuffer.Take(5)))
{
return(GitIdType.None, 0, -1);
}
var idType = (GitIdType)headerBuffer[5];
int chunkCount = headerBuffer[6];
int baseCommitGraphs = headerBuffer[7];
if (baseCommitGraphs <= 0)
{
_baseCommitGraphs = -1;
}
else
{
_baseCommitGraphs = baseCommitGraphs;
}
return(idType, chunkCount, headerBuffer.Length);
}
protected ValueTask <int> ReadFromChunkAsync(string chunkType, long position, byte[] buffer, int length)
{
if (_chunks == null || ChunkReader == null)
{
return(new ValueTask <int>(0));
}
else if (length <= 0)
{
throw new ArgumentOutOfRangeException(nameof(length));
}
Chunk?ch = null;
foreach (var c in _chunks)
{
if (c.Name == chunkType)
{
ch = c;
break;
}
}
if (ch == null)
{
return(new ValueTask <int>(0));
}
int requested = (int)Math.Min(length, ch.Value.Length - position);
if (requested <= 0)
{
return(new ValueTask <int>(0));
}
return(ChunkReader.ReadAtAsync(ch.Value.Position + position, buffer, requested));
}
async ValueTask <bool> GetHasBitmap()
{
if (ChunkReader is null)
{
return(false);
}
byte[] multiPackId = new byte[Repository.InternalConfig.IdType.HashLength()];
if (multiPackId.Length != (await ChunkReader.ReadAtAsync(AfterChunkPosition, multiPackId).ConfigureAwait(false)))
{
return(false);
}
GitId id = new GitId(Repository.InternalConfig.IdType, multiPackId);
_multiPackBitmapPath = Path.Combine(_dir, $"multi-pack-index-{id}.bitmap");
return(File.Exists(_multiPackBitmapPath));
}