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using LibGit.Extensions;
namespace LibGit;
public class GitPack
{
public string PackId { get; set; }
public GitRepo Repo { get; set; }
public int Version { get; set; }
public int ObjectCount { get; set; }
public List<GitPackObject> Objects { get; set; } = new List<GitPackObject>();
public GitPack Read(Stream stream)
{
stream.Peek(12).HexDump(16);
Console.Write(" Header: "); stream.Peek(04).ToArray()[0..].HexDump(4);
Console.Write("Version: "); stream.Peek(08).ToArray()[4..].HexDump(4);
Console.Write(" ObjCnt: "); stream.Peek(12).ToArray()[8..].HexDump(4);
if(!stream.StartsWith("PACK"))
throw new Exception("Invalid pack file header");
stream.Skip(4);
Version = stream.ReadInt32BE();
ObjectCount = stream.ReadInt32BE();
Console.WriteLine($"Got git v{Version} pack with {ObjectCount} objects");
for (int i = 0; i < ObjectCount; i++)
{
Objects.Add(new GitPackObject().Read(stream));
}
return this;
}
public GitPack(string packId, GitRepo repo)
{
PackId = packId;
Repo = repo;
}
}
public class GitPackIndex
{
public int Version { get; set; }
public int[] fanOutTable = new int[256];
public GitPackIndex Read(Stream stream)
{
if(!stream.StartsWith(new byte[]{0xff,0x74,0x4f,0x63}))
throw new Exception("Invalid pack index file header or pack is v1");
stream.Skip(4);
Version = stream.ReadInt32BE();
Console.WriteLine($"Got git v{Version} pack index");
//fan-out table
for (int i = 0; i < 256; i++)
{
fanOutTable[i] = stream.ReadInt32BE();
}
return this;
}
}
public class GitPackObject
{
private const bool _debug = true;
public GitPackObject Read(Stream stream)
{
stream.Peek(64).HexDump(32);
var header = stream.ReadBytes(4).ToArray();
ObjType = (GitObjectType)((header[0] & 0b0111_0000) >> 4);
if(ObjType == 0 || (int)ObjType == 5 || (int)ObjType > 7)
throw new Exception($"Invalid object type: {(int)ObjType}");
Size = header[0] & 0b0000_1111;
Offset = 0;
for (int i = 1; i < 4; i++)
{
Offset <<= 8;
Offset |= header[i];
}
if ((Size & 0b0000_1000) != 0)
{
Size <<= 4;
Size |= stream.ReadVLQ();
}
// ObjType = Type switch
// {
// 1 => GitObjectType.Commit,
// 2 => GitObjectType.Tree,
// 3 => GitObjectType.Blob,
// 4 => GitObjectType.Tag,
// 5 => GitObjectType.Invalid,
// 6 => GitObjectType.OffsDelta,
// 7 => GitObjectType.RefDelta,
// _ => throw new Exception($"Invalid object type {Type}")
// };
if(_debug) Console.WriteLine($"pack obj type: {ObjType} ({(int)ObjType}), size: {Size}, offset: {Offset}, sizeBytes: {SizeBytes}");
Console.WriteLine("Data: ");
stream.Peek(Size).Take(16).ToArray().HexDump(16);
stream.ReadBytes(Size).ZlibDecompress().Take(16).HexDump(16);
return this;
}
public GitObjectType ObjType { get; set; }
public int SizeBytes { get; set; }
public int Size { get; set; }
public int Offset { get; set; }
}
public enum GitObjectType
{
Commit = 1,
Tree,
Blob,
Tag,
Invalid, // Reserved for future expansion, see https://git-scm.com/docs/pack-format#_object_types
OffsDelta,
RefDelta
}
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