const std = @import("std");
const Alloc = std.mem.Allocator;
+const Reader = std.io.AnyReader;
+const Writer = std.io.AnyWriter;
const Id = u160;
const Commit = struct {
- author: std.BoundedArray(u8, 64),
- message: std.BoundedArray(u8, 1024),
+ author: []u8,
+ message: []u8,
parent: Id,
tree: Id,
};
const Blob = struct {
- data: std.BoundedArray(u8, 1024),
+ data: []u8,
};
const Object = struct {
- alloc: Alloc,
+ kind: u3,
+ data: []u8,
+ pub fn init(kind: u3, data: []u8) Object {
+ return .{
+ .kind = kind,
+ .data = data,
+ };
+ }
// pub fn getCommit(self: *Object) Commit {}
// pub fn getBlob(self: *Object) Blob {}
};
+
const PackFile = struct {
alloc: Alloc,
+ idxFile: std.fs.File,
+ pckFile: std.fs.File,
+ objectOffsets: std.AutoArrayHashMap(Id, u32),
pub fn open(alloc: Alloc, dir: std.fs.Dir) !PackFile {
- var self = PackFile{ .alloc = alloc };
+ var self = PackFile{
+ .alloc = alloc,
+ .idxFile = undefined,
+ .pckFile = undefined,
+ .objectOffsets = std.AutoArrayHashMap(Id, u32).init(alloc),
+ };
var packDir = try dir.openDir("objects/pack", .{ .iterate = true });
defer packDir.close();
.{idxFilename[0 .. idxFilename.len - 4]},
);
- const idxFile = try packDir.openFile(idxFilename, .{});
- const pckFile = try packDir.openFile(pckFilename.constSlice(), .{});
- defer idxFile.close();
- defer pckFile.close();
+ self.idxFile = try packDir.openFile(idxFilename, .{});
+ self.pckFile = try packDir.openFile(pckFilename.constSlice(), .{});
- const idxReader = idxFile.reader().any();
- const pckReader = pckFile.reader().any();
-
- try self.parse(idxReader, pckReader);
+ try self.parseIndex();
}
}
return self;
}
- pub fn parse(self: *PackFile, idxReader: std.io.AnyReader, pckReader: std.io.AnyReader) !void {
- _ = self;
- var buffer: [16]u8 = undefined;
- _ = try idxReader.read(&buffer);
- std.debug.print("{s}\n", .{&buffer});
- _ = try pckReader.read(&buffer);
- std.debug.print("{s}\n", .{&buffer});
+
+ pub fn close(self: *PackFile) void {
+ self.objectOffsets.deinit();
+ self.idxFile.close();
+ self.pckFile.close();
+ }
+
+ pub fn parseIndex(self: *PackFile) !void {
+ const idxReader = self.idxFile.reader().any();
+
+ var fanoutTable: [256]u32 = undefined;
+
+ for (0..256) |i| {
+ try self.idxFile.seekTo(8 + i * 4);
+ fanoutTable[i] = try idxReader.readVarInt(u32, .big, 4);
+
+ const numObjects =
+ if (i > 0) fanoutTable[i] - fanoutTable[i - 1] else fanoutTable[i];
+
+ for (0..numObjects) |j| {
+ const idOffset =
+ 4 + 4 + 4 * 256 + (j + if (i > 0) fanoutTable[i - 1] else 0) * 20;
+ try self.idxFile.seekTo(idOffset);
+ const id = try idxReader.readVarInt(Id, .big, 20);
+
+ try self.objectOffsets.put(id, 0);
+ }
+ }
+
+ const numObjects = self.objectOffsets.keys().len;
+ for (0..numObjects) |i| {
+ const offsetOffset =
+ 4 + 4 + 4 * 256 + numObjects * (20 + 4) + i * 4;
+ try self.idxFile.seekTo(offsetOffset);
+ const offset = try idxReader.readVarInt(u32, .big, 4);
+
+ self.objectOffsets.values()[i] = offset;
+ }
+ }
+
+ fn getSize(reader: Reader, ignoreTypeBits: bool) !struct { size: u64, bytelen: u64 } {
+ var size: u64 = 0;
+ var counter: u6 = 0;
+ while (true) {
+ const byte = try reader.readByte();
+
+ if (counter == 0) {
+ if (ignoreTypeBits) {
+ const bits: u4 = @truncate(byte);
+ size = bits;
+ } else {
+ const bits: u7 = @truncate(byte);
+ size = bits;
+ }
+ } else {
+ if (ignoreTypeBits) {
+ const bits: u7 = @truncate(byte);
+ size += @as(u64, bits) << (7 * (counter - 1) + 4);
+ } else {
+ const bits: u7 = @truncate(byte);
+ size += @as(u64, bits) << (7 * (counter));
+ }
+ }
+
+ if (byte & 0b10000000 == 0) {
+ break;
+ }
+
+ counter += 1;
+ }
+
+ const nBytes = counter + 1;
+
+ return .{
+ .size = size,
+ .bytelen = nBytes,
+ };
+ }
+
+ fn getOffset(reader: Reader) !struct { offset: u64, bytelen: u64 } {
+ var offset: u64 = 0;
+ var counter: u4 = 0;
+ while (true) {
+ const byte = try reader.readByte();
+
+ const bits: u7 = @truncate(byte);
+ offset <<= 7;
+ offset += @as(u64, bits);
+
+ if (byte & 0b10000000 == 0) {
+ break;
+ }
+
+ counter += 1;
+ }
+
+ const nBytes = counter + 1;
+
+ if (nBytes >= 2) {
+ for (1..nBytes) |i| {
+ offset += std.math.pow(u64, 2, 7 * i);
+ }
+ }
+ return .{
+ .offset = offset,
+ .bytelen = nBytes,
+ };
+ }
+
+ fn decompress(alloc: Alloc, reader: Reader, size: usize) ![]u8 {
+ const outBuffer = try alloc.alloc(u8, size);
+ errdefer alloc.free(outBuffer);
+
+ var outFbs = std.io.fixedBufferStream(outBuffer);
+ const writer = outFbs.writer();
+
+ try std.compress.zlib.decompress(reader, writer);
+
+ return outBuffer;
}
- // pub fn init(alloc: Alloc, path: []const u8) PackFile {}
- // pub fn deinit(self: *PackFile) void {}
- // pub fn getObject(self: *PackFile, id: Id) Object {}
+ fn applyDelta(alloc: Alloc, baseData: []const u8, deltData: []const u8) ![]u8 {
+ var fbs = std.io.fixedBufferStream(deltData);
+ const deltDataReader = fbs.reader().any();
+ const baseObjectSize = try getSize(deltDataReader, false);
+ const resultObjectSize = try getSize(deltDataReader, false);
+ const deltaDataOffset = baseObjectSize.bytelen + resultObjectSize.bytelen;
+
+ const result = try alloc.alloc(u8, resultObjectSize.size);
+ var resultCounter: u64 = 0;
+
+ var counter: u64 = 0;
+ while (true) {
+ const b = deltData[deltaDataOffset + counter];
+
+ if (b & 0b10000000 != 0) {
+ var dataOffset: u64 = 0;
+ var dataSize: u64 = 0;
+ var bitsSet: u8 = 0;
+ for (0..4) |i| { // offset bits
+ if (b & (@as(u64, 1) << @min(3, i)) != 0) {
+ dataOffset += @as(u64, deltData[deltaDataOffset + counter + 1 + bitsSet]) << @min(3 * 8, i * 8);
+ bitsSet += 1;
+ }
+ }
+ for (4..7) |i| { // size bits
+ if (b & (@as(u64, 1) << @min(6, i)) != 0) {
+ dataSize += @as(u64, deltData[deltaDataOffset + counter + 1 + bitsSet]) << @min(6 * 8, (i - 4) * 8);
+ bitsSet += 1;
+ }
+ }
+ counter += bitsSet;
+
+ std.mem.copyForwards(
+ u8,
+ result[resultCounter..result.len],
+ baseData[dataOffset .. dataOffset + dataSize],
+ );
+
+ resultCounter += dataSize;
+ } else {
+ const dataSize: u7 = @truncate(b);
+
+ std.mem.copyForwards(
+ u8,
+ result[resultCounter..result.len],
+ deltData[deltaDataOffset + counter + 1 .. deltaDataOffset + counter + 1 + dataSize],
+ );
+ resultCounter += dataSize;
+ counter += dataSize;
+ }
+
+ counter += 1;
+ if (deltaDataOffset + counter >= deltData.len)
+ break;
+ }
+
+ return result;
+ }
+
+ fn ofsDelta(self: *PackFile, offset: i64, size: usize) anyerror!Object {
+ const pckReader = self.pckFile.reader().any();
+
+ const pos = try self.pckFile.getPos();
+
+ try self.pckFile.seekBy(-offset);
+ const baseObject = try self.readObject(pckReader);
+ defer self.alloc.free(baseObject.data);
+
+ try self.pckFile.seekTo(pos);
+ const deltaData = try decompress(self.alloc, pckReader, size);
+ defer self.alloc.free(deltaData);
+
+ const objectData = try applyDelta(self.alloc, baseObject.data, deltaData);
+ return Object.init(baseObject.kind, objectData);
+ }
+
+ fn readObject(self: *PackFile, reader: Reader) anyerror!Object {
+ const firstByte = try reader.readByte();
+ const objectKind: u3 = @truncate(firstByte >> 4);
+ try self.pckFile.seekBy(-1);
+ const objectSize = try getSize(reader, true);
+
+ if (objectKind == 6) {
+ const offset = try getOffset(reader);
+ return try self.ofsDelta(
+ @intCast(offset.offset + objectSize.bytelen + offset.bytelen),
+ objectSize.size,
+ );
+ } else {
+ const objectData = try decompress(self.alloc, reader, objectSize.size);
+ return Object.init(objectKind, objectData);
+ }
+ }
+
+ pub fn getObject(self: *PackFile, id: Id) !?Object {
+ if (self.objectOffsets.get(id)) |offset| {
+ const pckReader = self.pckFile.reader().any();
+ try self.pckFile.seekTo(offset);
+
+ return try self.readObject(pckReader);
+ }
+ return null;
+ }
};
+
const Repo = struct {
alloc: Alloc,
dir: std.fs.Dir,
.packfile = packfile,
};
}
+
pub fn close(self: *Repo) void {
self.dir.close();
+ self.packfile.close();
}
+
pub fn getHead(self: *Repo) !Id {
// read file HEAD
const head = try self.dir.readFileAlloc(self.alloc, "HEAD", 1024);
// parse id from file
return try std.fmt.parseUnsigned(u160, idStr, 16);
}
- // pub fn getObject(self: *Repo, id: Id) Object {}
+
+ pub fn getObject(self: *Repo, id: Id) !?Object {
+ return self.packfile.getObject(id);
+ }
};
test "print HEAD" {
std.debug.print("HEAD: {}\n", .{head});
}
+test "parse idx" {
+ var repo = try Repo.open(std.testing.allocator, "../microwindows/.git");
+ defer repo.close();
+
+ std.debug.print("{}\n", .{repo.packfile.objectOffsets.keys().len});
+ std.debug.print("{}\n", .{repo.packfile.objectOffsets.values().len});
+}
+
+test "get object" {
+ var repo = try Repo.open(std.testing.allocator, "../microwindows/.git");
+ defer repo.close();
+
+ const head = try repo.getHead();
+
+ if (try repo.getObject(head)) |o| {
+ defer std.testing.allocator.free(o.data);
+
+ std.debug.print("object: {s}\n", .{o.data});
+ }
+}
+
+test "get tree" {
+ var repo = try Repo.open(std.testing.allocator, "../microwindows/.git");
+ defer repo.close();
+
+ if (try repo.getObject(0xe59b68a950b643f9ea50997b3cf359a5956e852c)) |o| {
+ defer std.testing.allocator.free(o.data);
+
+ std.debug.print("tree: {s}\n", .{o.data});
+ }
+}
// test "list commits" {
// var repo = Repo.open(std.testing.allocator, "../microwindows/.git");
// defer repo.close();
projects / ziggit / commitdiff