From 121c3cf37a8edff8e23e3fcf946c677970140e5a Mon Sep 17 00:00:00 2001 From: Meghan Denny Date: Sun, 12 Apr 2026 14:17:45 -0700 Subject: [PATCH] implement ref_delta packed object type --- git.zig | 80 ++++++++++++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 73 insertions(+), 7 deletions(-) diff --git a/git.zig b/git.zig index 64693a1c682db7104f4ec92190788e6eb1c734e0..a307093565929bd0d27eb31adde7e5951753c2b2 100644 --- a/git.zig +++ b/git.zig @@ -950,7 +950,7 @@ pub const Repository = struct { r.tags.deinit(r.gpa); } - pub fn getObject(r: *Repository, arena: std.mem.Allocator, oid: Id) !?GitObject { + pub fn getObject(r: *Repository, arena: std.mem.Allocator, oid: Id) anyerror!?GitObject { const t = tracer.trace(@src(), " {s}", .{oid}); defer t.end(); @@ -1042,10 +1042,10 @@ pub const Repository = struct { // parse .pack // std.log.debug("pack_index={d} pack_offset={d}", .{ pack_index, pack_offset }); - return try r.getPackedObject(oid, pack_index, pack_offset); + return try r.getPackedObject(arena, oid, pack_index, pack_offset); } - fn getPackedObject(r: *Repository, maybe_oid: ?Id, pack_index: usize, pack_offset: usize) !GitObject { + fn getPackedObject(r: *Repository, arena: std.mem.Allocator, maybe_oid: ?Id, pack_index: usize, pack_offset: usize) !GitObject { const t = tracer.trace(@src(), " {?s} {d} {d}", .{ maybe_oid, pack_index, pack_offset }); defer t.end(); @@ -1096,7 +1096,7 @@ pub const Repository = struct { offset += 1; } const base_pack_offset = pack_offset - offset; - const base_obj = try r.getPackedObject(null, pack_index, base_pack_offset); + const base_obj = try r.getPackedObject(arena, null, pack_index, base_pack_offset); // std.log.debug("base: type={s} content=[{d}]", .{ @tagName(base_obj.type), base_obj.content.len }); const compressed_content = packedobj_fbs.rest()[0..size]; @@ -1106,7 +1106,6 @@ pub const Repository = struct { defer list.deinit(r.gpa); try list.ensureUnusedCapacity(r.gpa, size); try std.compress.flate.inflate.decompress(.zlib, bufr.anyReadable(), list.writer(r.gpa)); - // std.log.debug("transformation data={d}", .{list.items}); var unpackedobj_fbs = nio.FixedBufferStream([]const u8).init(list.items); @@ -1167,8 +1166,75 @@ pub const Repository = struct { return obj; }, .ref_delta => { - std.log.debug("type={s} size={d}", .{ @tagName(ty), size }); - unreachable; + // std.log.debug("type={s} size={d}", .{ @tagName(ty), size }); + const base_oid = extras.to_hex(packedobj_fbs.takeSlice(20)[0..20].*); + const base_obj = (try r.getObject(arena, &base_oid)).?; + + const compressed_content = packedobj_fbs.rest()[0..size]; + var bufr = nio.FixedBufferStream([]const u8).init(compressed_content); + + var list: std.ArrayListUnmanaged(u8) = .empty; + defer list.deinit(r.gpa); + try list.ensureUnusedCapacity(r.gpa, size); + try std.compress.flate.inflate.decompress(.zlib, bufr.anyReadable(), list.writer(r.gpa)); + // std.log.debug("transformation data={d}", .{list.items}); + + var unpackedobj_fbs = nio.FixedBufferStream([]const u8).init(list.items); + + var list2: std.ArrayListUnmanaged(u8) = .empty; + errdefer list2.deinit(r.gpa); + + var base_size: usize = 0; + while (true) { + const c2: usize = unpackedobj_fbs.takeByte(); + base_size = (base_size << 7) | (c2 & 0x7f); + if (c2 & 0x80 == 0) break; + base_size += 1; + } + // std.log.debug("base_size={d}", .{base_size}); + + var obj_size: usize = 0; + while (true) { + const c2: usize = unpackedobj_fbs.takeByte(); + obj_size = (obj_size << 7) | (c2 & 0x7f); + if (c2 & 0x80 == 0) break; + obj_size += 1; + } + // std.log.debug("obj_size={d}", .{obj_size}); + + while (unpackedobj_fbs.pos < unpackedobj_fbs.buffer.len) { + const c2 = unpackedobj_fbs.takeByte(); + if (c2 & 0x80 > 0) { + // copy range from base + var b: extras.RingBuffer(u8, 7) = .{}; + for (0..7) |i| { + const mask = @as(u8, 1) << @intCast(i); + b.append(if (c2 & mask > 0) unpackedobj_fbs.takeByte() else 0); + } + const start: u32 = @bitCast(b.items[0..4].*); + const nbytes: u24 = @bitCast(b.items[4..7].*); + // std.log.debug("- copy from base: start={d} nbytes={d}", .{ start, nbytes }); + const bytes = base_obj.content[start..][0..nbytes]; + // std.log.debug("{s}\n", .{bytes}); + try list2.appendSlice(r.gpa, bytes); + } else { + // append new data + const nbytes = c2 & 0x7f; + // std.log.debug("- append new bytes={d}", .{nbytes}); + if (nbytes == 0) continue; + const bytes = unpackedobj_fbs.takeSlice(nbytes); + // std.log.debug("{s}\n", .{bytes}); + try list2.appendSlice(r.gpa, bytes); + } + } + + // std.log.debug("- done", .{}); + // std.log.debug("{s}\n", .{list2.items}); + const _type = base_obj.type; + const content = try list2.toOwnedSlice(r.gpa); + const obj: GitObject = .{ .type = _type, .content = content }; + if (maybe_oid) |oid| try r.unpacked_objects.put(r.gpa, oid, obj); + return obj; }, } comptime unreachable; -- 2.54.0