Commit 9a001e1f7c
Changed files (4)
src
src/git/testdata/testrepo.idx
Binary file
src/git/testdata/testrepo.pack
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src/git.zig
@@ -0,0 +1,1421 @@
+//! Git support for package fetching.
+//!
+//! This is not intended to support all features of Git: it is limited to the
+//! basic functionality needed to clone a repository for the purpose of fetching
+//! a package.
+
+const std = @import("std");
+const mem = std.mem;
+const testing = std.testing;
+const Allocator = mem.Allocator;
+const Sha1 = std.crypto.hash.Sha1;
+const assert = std.debug.assert;
+
+const ProgressReader = @import("Package.zig").ProgressReader;
+
+pub const oid_length = Sha1.digest_length;
+pub const fmt_oid_length = 2 * oid_length;
+/// The ID of a Git object (an SHA-1 hash).
+pub const Oid = [oid_length]u8;
+
+pub fn parseOid(s: []const u8) !Oid {
+ if (s.len != fmt_oid_length) return error.InvalidOid;
+ var oid: Oid = undefined;
+ for (&oid, 0..) |*b, i| {
+ b.* = std.fmt.parseUnsigned(u8, s[2 * i ..][0..2], 16) catch return error.InvalidOid;
+ }
+ return oid;
+}
+
+test parseOid {
+ try testing.expectEqualSlices(
+ u8,
+ &.{ 0xCE, 0x91, 0x9C, 0xCF, 0x45, 0x95, 0x18, 0x56, 0xA7, 0x62, 0xFF, 0xDB, 0x8E, 0xF8, 0x50, 0x30, 0x1C, 0xD8, 0xC5, 0x88 },
+ &try parseOid("ce919ccf45951856a762ffdb8ef850301cd8c588"),
+ );
+ try testing.expectError(error.InvalidOid, parseOid("ce919ccf"));
+ try testing.expectError(error.InvalidOid, parseOid("master"));
+ try testing.expectError(error.InvalidOid, parseOid("HEAD"));
+}
+
+pub const Repository = struct {
+ odb: Odb,
+
+ pub fn init(allocator: Allocator, pack_file: std.fs.File, index_file: std.fs.File) !Repository {
+ return .{ .odb = try Odb.init(allocator, pack_file, index_file) };
+ }
+
+ pub fn deinit(repository: *Repository) void {
+ repository.odb.deinit();
+ repository.* = undefined;
+ }
+
+ /// Checks out the repository at `commit_oid` to `worktree`.
+ pub fn checkout(
+ repository: *Repository,
+ worktree: std.fs.Dir,
+ commit_oid: Oid,
+ ) !void {
+ try repository.odb.seekOid(commit_oid);
+ const tree_oid = tree_oid: {
+ var commit_object = try repository.odb.readObject();
+ if (commit_object.type != .commit) return error.NotACommit;
+ break :tree_oid try getCommitTree(commit_object.data);
+ };
+ try repository.checkoutTree(worktree, tree_oid);
+ }
+
+ /// Checks out the tree at `tree_oid` to `worktree`.
+ fn checkoutTree(
+ repository: *Repository,
+ dir: std.fs.Dir,
+ tree_oid: Oid,
+ ) !void {
+ try repository.odb.seekOid(tree_oid);
+ const tree_object = try repository.odb.readObject();
+ if (tree_object.type != .tree) return error.NotATree;
+ // The tree object may be evicted from the object cache while we're
+ // iterating over it, so we can make a defensive copy here to make sure
+ // it remains valid until we're done with it
+ const tree_data = try repository.odb.allocator.dupe(u8, tree_object.data);
+ defer repository.odb.allocator.free(tree_data);
+
+ var tree_iter: TreeIterator = .{ .data = tree_data };
+ while (try tree_iter.next()) |entry| {
+ switch (entry.type) {
+ .directory => {
+ try dir.makeDir(entry.name);
+ var subdir = try dir.openDir(entry.name, .{});
+ defer subdir.close();
+ try repository.checkoutTree(subdir, entry.oid);
+ },
+ .file => {
+ var file = try dir.createFile(entry.name, .{});
+ defer file.close();
+ try repository.odb.seekOid(entry.oid);
+ var file_object = try repository.odb.readObject();
+ if (file_object.type != .blob) return error.InvalidFile;
+ try file.writeAll(file_object.data);
+ try file.sync();
+ },
+ .symlink => return error.SymlinkNotSupported,
+ .gitlink => {
+ // Consistent with git archive behavior, create the directory but
+ // do nothing else
+ try dir.makeDir(entry.name);
+ },
+ }
+ }
+ }
+
+ /// Returns the ID of the tree associated with the given commit (provided as
+ /// raw object data).
+ fn getCommitTree(commit_data: []const u8) !Oid {
+ if (!mem.startsWith(u8, commit_data, "tree ") or
+ commit_data.len < "tree ".len + fmt_oid_length + "\n".len or
+ commit_data["tree ".len + fmt_oid_length] != '\n')
+ {
+ return error.InvalidCommit;
+ }
+ return try parseOid(commit_data["tree ".len..][0..fmt_oid_length]);
+ }
+
+ const TreeIterator = struct {
+ data: []const u8,
+ pos: usize = 0,
+
+ const Entry = struct {
+ type: Type,
+ executable: bool,
+ name: [:0]const u8,
+ oid: Oid,
+
+ const Type = enum(u4) {
+ directory = 0o4,
+ file = 0o10,
+ symlink = 0o12,
+ gitlink = 0o16,
+ };
+ };
+
+ fn next(iterator: *TreeIterator) !?Entry {
+ if (iterator.pos == iterator.data.len) return null;
+
+ const mode_end = mem.indexOfScalarPos(u8, iterator.data, iterator.pos, ' ') orelse return error.InvalidTree;
+ const mode: packed struct {
+ permission: u9,
+ unused: u3,
+ type: u4,
+ } = @bitCast(std.fmt.parseUnsigned(u16, iterator.data[iterator.pos..mode_end], 8) catch return error.InvalidTree);
+ const @"type" = std.meta.intToEnum(Entry.Type, mode.type) catch return error.InvalidTree;
+ const executable = switch (mode.permission) {
+ 0 => if (@"type" == .file) return error.InvalidTree else false,
+ 0o644 => if (@"type" != .file) return error.InvalidTree else false,
+ 0o755 => if (@"type" != .file) return error.InvalidTree else true,
+ else => return error.InvalidTree,
+ };
+ iterator.pos = mode_end + 1;
+
+ const name_end = mem.indexOfScalarPos(u8, iterator.data, iterator.pos, 0) orelse return error.InvalidTree;
+ const name = iterator.data[iterator.pos..name_end :0];
+ iterator.pos = name_end + 1;
+
+ if (iterator.pos + oid_length > iterator.data.len) return error.InvalidTree;
+ const oid = iterator.data[iterator.pos..][0..oid_length].*;
+ iterator.pos += oid_length;
+
+ return .{ .type = @"type", .executable = executable, .name = name, .oid = oid };
+ }
+ };
+};
+
+/// A Git object database backed by a packfile. A packfile index is also used
+/// for efficient access to objects in the packfile.
+///
+/// The format of the packfile and its associated index are documented in
+/// [pack-format](https://git-scm.com/docs/pack-format).
+const Odb = struct {
+ pack_file: std.fs.File,
+ index_header: IndexHeader,
+ index_file: std.fs.File,
+ cache: ObjectCache = .{},
+ allocator: Allocator,
+
+ /// Initializes the database from open pack and index files.
+ fn init(allocator: Allocator, pack_file: std.fs.File, index_file: std.fs.File) !Odb {
+ try pack_file.seekTo(0);
+ try index_file.seekTo(0);
+ const index_header = try IndexHeader.read(index_file.reader());
+ return .{
+ .pack_file = pack_file,
+ .index_header = index_header,
+ .index_file = index_file,
+ .allocator = allocator,
+ };
+ }
+
+ fn deinit(odb: *Odb) void {
+ odb.cache.deinit(odb.allocator);
+ odb.* = undefined;
+ }
+
+ /// Reads the object at the current position in the database.
+ fn readObject(odb: *Odb) !Object {
+ var base_offset = try odb.pack_file.getPos();
+ var base_header: EntryHeader = undefined;
+ var delta_offsets = std.ArrayListUnmanaged(u64){};
+ defer delta_offsets.deinit(odb.allocator);
+ const base_object = while (true) {
+ if (odb.cache.get(base_offset)) |base_object| break base_object;
+
+ base_header = try EntryHeader.read(odb.pack_file.reader());
+ switch (base_header) {
+ .ofs_delta => |ofs_delta| {
+ try delta_offsets.append(odb.allocator, base_offset);
+ base_offset = std.math.sub(u64, base_offset, ofs_delta.offset) catch return error.InvalidFormat;
+ try odb.pack_file.seekTo(base_offset);
+ },
+ .ref_delta => |ref_delta| {
+ try delta_offsets.append(odb.allocator, base_offset);
+ try odb.seekOid(ref_delta.base_object);
+ base_offset = try odb.pack_file.getPos();
+ },
+ else => {
+ const base_data = try readObjectRaw(odb.allocator, odb.pack_file.reader(), base_header.uncompressedLength());
+ errdefer odb.allocator.free(base_data);
+ const base_object: Object = .{ .type = base_header.objectType(), .data = base_data };
+ try odb.cache.put(odb.allocator, base_offset, base_object);
+ break base_object;
+ },
+ }
+ };
+
+ const base_data = try resolveDeltaChain(
+ odb.allocator,
+ odb.pack_file,
+ base_object,
+ delta_offsets.items,
+ &odb.cache,
+ );
+
+ return .{ .type = base_object.type, .data = base_data };
+ }
+
+ /// Seeks to the beginning of the object with the given ID.
+ fn seekOid(odb: *Odb, oid: Oid) !void {
+ const key = oid[0];
+ var start_index = if (key > 0) odb.index_header.fan_out_table[key - 1] else 0;
+ var end_index = odb.index_header.fan_out_table[key];
+ const found_index = while (start_index < end_index) {
+ const mid_index = start_index + (end_index - start_index) / 2;
+ try odb.index_file.seekTo(IndexHeader.size + mid_index * oid_length);
+ const mid_oid = try odb.index_file.reader().readBytesNoEof(oid_length);
+ switch (mem.order(u8, &mid_oid, &oid)) {
+ .lt => start_index = mid_index + 1,
+ .gt => end_index = mid_index,
+ .eq => break mid_index,
+ }
+ } else return error.ObjectNotFound;
+
+ const n_objects = odb.index_header.fan_out_table[255];
+ const offset_values_start = IndexHeader.size + n_objects * (oid_length + 4);
+ try odb.index_file.seekTo(offset_values_start + found_index * 4);
+ const l1_offset: packed struct { value: u31, big: bool } = @bitCast(try odb.index_file.reader().readIntBig(u32));
+ const pack_offset = pack_offset: {
+ if (l1_offset.big) {
+ const l2_offset_values_start = offset_values_start + n_objects * 4;
+ try odb.index_file.seekTo(l2_offset_values_start + l1_offset.value * 4);
+ break :pack_offset try odb.index_file.reader().readIntBig(u64);
+ } else {
+ break :pack_offset l1_offset.value;
+ }
+ };
+
+ try odb.pack_file.seekTo(pack_offset);
+ }
+};
+
+const Object = struct {
+ type: Type,
+ data: []const u8,
+
+ const Type = enum {
+ commit,
+ tree,
+ blob,
+ tag,
+ };
+};
+
+/// A cache for object data.
+///
+/// The purpose of this cache is to speed up resolution of deltas by caching the
+/// results of resolving delta objects, while maintaining a maximum cache size
+/// to avoid excessive memory usage. If the total size of the objects in the
+/// cache exceeds the maximum, the cache will begin evicting the least recently
+/// used objects: when resolving delta chains, the most recently used objects
+/// will likely be more helpful as they will be further along in the chain
+/// (skipping earlier reconstruction steps).
+///
+/// Object data stored in the cache is managed by the cache. It should not be
+/// freed by the caller at any point after inserting it into the cache. Any
+/// objects remaining in the cache will be freed when the cache itself is freed.
+const ObjectCache = struct {
+ objects: std.AutoHashMapUnmanaged(u64, CacheEntry) = .{},
+ lru_nodes: LruList = .{},
+ byte_size: usize = 0,
+
+ const max_byte_size = 128 * 1024 * 1024; // 128MiB
+ /// A list of offsets stored in the cache, with the most recently used
+ /// entries at the end.
+ const LruList = std.DoublyLinkedList(u64);
+ const CacheEntry = struct { object: Object, lru_node: *LruList.Node };
+
+ fn deinit(cache: *ObjectCache, allocator: Allocator) void {
+ var object_iterator = cache.objects.iterator();
+ while (object_iterator.next()) |object| {
+ allocator.free(object.value_ptr.object.data);
+ allocator.destroy(object.value_ptr.lru_node);
+ }
+ cache.objects.deinit(allocator);
+ cache.* = undefined;
+ }
+
+ /// Gets an object from the cache, moving it to the most recently used
+ /// position if it is present.
+ fn get(cache: *ObjectCache, offset: u64) ?Object {
+ if (cache.objects.get(offset)) |entry| {
+ cache.lru_nodes.remove(entry.lru_node);
+ cache.lru_nodes.append(entry.lru_node);
+ return entry.object;
+ } else {
+ return null;
+ }
+ }
+
+ /// Puts an object in the cache, possibly evicting older entries if the
+ /// cache exceeds its maximum size. Note that, although old objects may
+ /// be evicted, the object just added to the cache with this function
+ /// will not be evicted before the next call to `put` or `deinit` even if
+ /// it exceeds the maximum cache size.
+ fn put(cache: *ObjectCache, allocator: Allocator, offset: u64, object: Object) !void {
+ const lru_node = try allocator.create(LruList.Node);
+ errdefer allocator.destroy(lru_node);
+ lru_node.data = offset;
+
+ const gop = try cache.objects.getOrPut(allocator, offset);
+ if (gop.found_existing) {
+ cache.byte_size -= gop.value_ptr.object.data.len;
+ cache.lru_nodes.remove(gop.value_ptr.lru_node);
+ allocator.destroy(gop.value_ptr.lru_node);
+ allocator.free(gop.value_ptr.object.data);
+ }
+ gop.value_ptr.* = .{ .object = object, .lru_node = lru_node };
+ cache.byte_size += object.data.len;
+ cache.lru_nodes.append(lru_node);
+
+ while (cache.byte_size > max_byte_size and cache.lru_nodes.len > 1) {
+ // The > 1 check is to make sure that we don't evict the most
+ // recently added node, even if it by itself happens to exceed the
+ // maximum size of the cache.
+ const evict_node = cache.lru_nodes.popFirst().?;
+ const evict_offset = evict_node.data;
+ allocator.destroy(evict_node);
+ const evict_object = cache.objects.get(evict_offset).?.object;
+ cache.byte_size -= evict_object.data.len;
+ allocator.free(evict_object.data);
+ _ = cache.objects.remove(evict_offset);
+ }
+ }
+};
+
+/// A single pkt-line in the Git protocol.
+///
+/// The format of a pkt-line is documented in
+/// [protocol-common](https://git-scm.com/docs/protocol-common). The special
+/// meanings of the delimiter and response-end packets are documented in
+/// [protocol-v2](https://git-scm.com/docs/protocol-v2).
+const Packet = union(enum) {
+ flush,
+ delimiter,
+ response_end,
+ data: []const u8,
+
+ const max_data_length = 65516;
+
+ /// Reads a packet in pkt-line format.
+ fn read(reader: anytype, buf: *[max_data_length]u8) !Packet {
+ const length = std.fmt.parseUnsigned(u16, &try reader.readBytesNoEof(4), 16) catch return error.InvalidPacket;
+ switch (length) {
+ 0 => return .flush,
+ 1 => return .delimiter,
+ 2 => return .response_end,
+ 3 => return error.InvalidPacket,
+ else => if (length - 4 > max_data_length) return error.InvalidPacket,
+ }
+ const data = buf[0 .. length - 4];
+ try reader.readNoEof(data);
+ return .{ .data = data };
+ }
+
+ /// Writes a packet in pkt-line format.
+ fn write(packet: Packet, writer: anytype) !void {
+ switch (packet) {
+ .flush => try writer.writeAll("0000"),
+ .delimiter => try writer.writeAll("0001"),
+ .response_end => try writer.writeAll("0002"),
+ .data => |data| {
+ assert(data.len <= max_data_length);
+ try writer.print("{x:0>4}", .{data.len + 4});
+ try writer.writeAll(data);
+ },
+ }
+ }
+};
+
+/// A client session for the Git protocol, currently limited to an HTTP(S)
+/// transport. Only protocol version 2 is supported, as documented in
+/// [protocol-v2](https://git-scm.com/docs/protocol-v2).
+pub const Session = struct {
+ transport: *std.http.Client,
+ uri: std.Uri,
+ supports_agent: bool = false,
+ supports_shallow: bool = false,
+
+ const agent = "zig/" ++ @import("builtin").zig_version_string;
+ const agent_capability = std.fmt.comptimePrint("agent={s}\n", .{agent});
+
+ /// Discovers server capabilities. This should be called before using any
+ /// other client functionality, or the client will be forced to default to
+ /// the bare minimum server requirements, which may be considerably less
+ /// efficient (e.g. no shallow fetches).
+ ///
+ /// See the note on `getCapabilities` regarding `redirect_uri`.
+ pub fn discoverCapabilities(
+ session: *Session,
+ allocator: Allocator,
+ redirect_uri: *[]u8,
+ ) !void {
+ var capability_iterator = try session.getCapabilities(allocator, redirect_uri);
+ defer capability_iterator.deinit();
+ while (try capability_iterator.next()) |capability| {
+ if (mem.eql(u8, capability.key, "agent")) {
+ session.supports_agent = true;
+ } else if (mem.eql(u8, capability.key, "fetch")) {
+ var feature_iterator = mem.splitScalar(u8, capability.value orelse continue, ' ');
+ while (feature_iterator.next()) |feature| {
+ if (mem.eql(u8, feature, "shallow")) {
+ session.supports_shallow = true;
+ }
+ }
+ }
+ }
+ }
+
+ /// Returns an iterator over capabilities supported by the server.
+ ///
+ /// If the server redirects the request, `error.Redirected` is returned and
+ /// `redirect_uri` is populated with the URI resulting from the redirects.
+ /// When this occurs, the value of `redirect_uri` must be freed with
+ /// `allocator` when the caller is done with it.
+ fn getCapabilities(
+ session: Session,
+ allocator: Allocator,
+ redirect_uri: *[]u8,
+ ) !CapabilityIterator {
+ var info_refs_uri = session.uri;
+ info_refs_uri.path = try std.fs.path.resolvePosix(allocator, &.{ "/", session.uri.path, "info/refs" });
+ defer allocator.free(info_refs_uri.path);
+ info_refs_uri.query = "service=git-upload-pack";
+ info_refs_uri.fragment = null;
+
+ var headers = std.http.Headers.init(allocator);
+ defer headers.deinit();
+ try headers.append("Git-Protocol", "version=2");
+
+ var request = try session.transport.request(.GET, info_refs_uri, headers, .{
+ .max_redirects = 3,
+ });
+ errdefer request.deinit();
+ try request.start(.{});
+ try request.finish();
+
+ try request.wait();
+ if (request.response.status != .ok) return error.ProtocolError;
+ if (request.redirects_left < 3) {
+ if (!mem.endsWith(u8, request.uri.path, "/info/refs")) return error.UnparseableRedirect;
+ var new_uri = request.uri;
+ new_uri.path = new_uri.path[0 .. new_uri.path.len - "/info/refs".len];
+ new_uri.query = null;
+ redirect_uri.* = try std.fmt.allocPrint(allocator, "{+/}", .{new_uri});
+ return error.Redirected;
+ }
+
+ const reader = request.reader();
+ var buf: [Packet.max_data_length]u8 = undefined;
+ var state: enum { response_start, response_content } = .response_start;
+ while (true) {
+ // Some Git servers (at least GitHub) include an additional
+ // '# service=git-upload-pack' informative response before sending
+ // the expected 'version 2' packet and capability information.
+ // This is not universal: SourceHut, for example, does not do this.
+ // Thus, we need to skip any such useless additional responses
+ // before we get the one we're actually looking for. The responses
+ // will be delimited by flush packets.
+ const packet = Packet.read(reader, &buf) catch |e| switch (e) {
+ error.EndOfStream => return error.UnsupportedProtocol, // 'version 2' packet not found
+ else => |other| return other,
+ };
+ switch (packet) {
+ .flush => state = .response_start,
+ .data => |data| switch (state) {
+ .response_start => if (mem.eql(u8, data, "version 2\n")) {
+ return .{ .request = request };
+ } else {
+ state = .response_content;
+ },
+ else => {},
+ },
+ else => return error.UnexpectedPacket,
+ }
+ }
+ }
+
+ const CapabilityIterator = struct {
+ request: std.http.Client.Request,
+ buf: [Packet.max_data_length]u8 = undefined,
+
+ const Capability = struct {
+ key: []const u8,
+ value: ?[]const u8 = null,
+ };
+
+ fn deinit(iterator: *CapabilityIterator) void {
+ iterator.request.deinit();
+ iterator.* = undefined;
+ }
+
+ fn next(iterator: *CapabilityIterator) !?Capability {
+ switch (try Packet.read(iterator.request.reader(), &iterator.buf)) {
+ .flush => return null,
+ .data => |data| if (data.len > 0 and data[data.len - 1] == '\n') {
+ if (mem.indexOfScalar(u8, data, '=')) |separator_pos| {
+ return .{ .key = data[0..separator_pos], .value = data[separator_pos + 1 .. data.len - 1] };
+ } else {
+ return .{ .key = data[0 .. data.len - 1] };
+ }
+ } else return error.UnexpectedPacket,
+ else => return error.UnexpectedPacket,
+ }
+ }
+ };
+
+ const ListRefsOptions = struct {
+ /// The ref prefixes (if any) to use to filter the refs available on the
+ /// server. Note that the client must still check the returned refs
+ /// against its desired filters itself: the server is not required to
+ /// respect these prefix filters and may return other refs as well.
+ ref_prefixes: []const []const u8 = &.{},
+ /// Whether to include symref targets for returned symbolic refs.
+ include_symrefs: bool = false,
+ /// Whether to include the peeled object ID for returned tag refs.
+ include_peeled: bool = false,
+ };
+
+ /// Returns an iterator over refs known to the server.
+ pub fn listRefs(session: Session, allocator: Allocator, options: ListRefsOptions) !RefIterator {
+ var upload_pack_uri = session.uri;
+ upload_pack_uri.path = try std.fs.path.resolvePosix(allocator, &.{ "/", session.uri.path, "git-upload-pack" });
+ defer allocator.free(upload_pack_uri.path);
+ upload_pack_uri.query = null;
+ upload_pack_uri.fragment = null;
+
+ var headers = std.http.Headers.init(allocator);
+ defer headers.deinit();
+ try headers.append("Content-Type", "application/x-git-upload-pack-request");
+ try headers.append("Git-Protocol", "version=2");
+
+ var body = std.ArrayListUnmanaged(u8){};
+ defer body.deinit(allocator);
+ const body_writer = body.writer(allocator);
+ try Packet.write(.{ .data = "command=ls-refs\n" }, body_writer);
+ if (session.supports_agent) {
+ try Packet.write(.{ .data = agent_capability }, body_writer);
+ }
+ try Packet.write(.delimiter, body_writer);
+ for (options.ref_prefixes) |ref_prefix| {
+ const ref_prefix_packet = try std.fmt.allocPrint(allocator, "ref-prefix {s}\n", .{ref_prefix});
+ defer allocator.free(ref_prefix_packet);
+ try Packet.write(.{ .data = ref_prefix_packet }, body_writer);
+ }
+ if (options.include_symrefs) {
+ try Packet.write(.{ .data = "symrefs\n" }, body_writer);
+ }
+ if (options.include_peeled) {
+ try Packet.write(.{ .data = "peel\n" }, body_writer);
+ }
+ try Packet.write(.flush, body_writer);
+
+ var request = try session.transport.request(.POST, upload_pack_uri, headers, .{
+ .handle_redirects = false,
+ });
+ errdefer request.deinit();
+ request.transfer_encoding = .{ .content_length = body.items.len };
+ try request.start(.{});
+ try request.writeAll(body.items);
+ try request.finish();
+
+ try request.wait();
+ if (request.response.status != .ok) return error.ProtocolError;
+
+ return .{ .request = request };
+ }
+
+ pub const RefIterator = struct {
+ request: std.http.Client.Request,
+ buf: [Packet.max_data_length]u8 = undefined,
+
+ pub const Ref = struct {
+ oid: Oid,
+ name: []const u8,
+ symref_target: ?[]const u8,
+ peeled: ?Oid,
+ };
+
+ pub fn deinit(iterator: *RefIterator) void {
+ iterator.request.deinit();
+ iterator.* = undefined;
+ }
+
+ pub fn next(iterator: *RefIterator) !?Ref {
+ switch (try Packet.read(iterator.request.reader(), &iterator.buf)) {
+ .flush => return null,
+ .data => |data| {
+ const oid_sep_pos = mem.indexOfScalar(u8, data, ' ') orelse return error.InvalidRefPacket;
+ const oid = parseOid(data[0..oid_sep_pos]) catch return error.InvalidRefPacket;
+
+ const name_sep_pos = mem.indexOfAnyPos(u8, data, oid_sep_pos + 1, " \n") orelse return error.InvalidRefPacket;
+ const name = data[oid_sep_pos + 1 .. name_sep_pos];
+
+ var symref_target: ?[]const u8 = null;
+ var peeled: ?Oid = null;
+ var last_sep_pos = name_sep_pos;
+ while (data[last_sep_pos] == ' ') {
+ const next_sep_pos = mem.indexOfAnyPos(u8, data, last_sep_pos + 1, " \n") orelse return error.InvalidRefPacket;
+ const attribute = data[last_sep_pos + 1 .. next_sep_pos];
+ if (mem.startsWith(u8, attribute, "symref-target:")) {
+ symref_target = attribute["symref-target:".len..];
+ } else if (mem.startsWith(u8, attribute, "peeled:")) {
+ peeled = parseOid(attribute["peeled:".len..]) catch return error.InvalidRefPacket;
+ }
+ last_sep_pos = next_sep_pos;
+ }
+
+ return .{ .oid = oid, .name = name, .symref_target = symref_target, .peeled = peeled };
+ },
+ else => return error.UnexpectedPacket,
+ }
+ }
+ };
+
+ /// Fetches the given refs from the server. A shallow fetch (depth 1) is
+ /// performed if the server supports it.
+ pub fn fetch(session: Session, allocator: Allocator, wants: []const []const u8) !FetchStream {
+ var upload_pack_uri = session.uri;
+ upload_pack_uri.path = try std.fs.path.resolvePosix(allocator, &.{ "/", session.uri.path, "git-upload-pack" });
+ defer allocator.free(upload_pack_uri.path);
+ upload_pack_uri.query = null;
+ upload_pack_uri.fragment = null;
+
+ var headers = std.http.Headers.init(allocator);
+ defer headers.deinit();
+ try headers.append("Content-Type", "application/x-git-upload-pack-request");
+ try headers.append("Git-Protocol", "version=2");
+
+ var body = std.ArrayListUnmanaged(u8){};
+ defer body.deinit(allocator);
+ const body_writer = body.writer(allocator);
+ try Packet.write(.{ .data = "command=fetch\n" }, body_writer);
+ if (session.supports_agent) {
+ try Packet.write(.{ .data = agent_capability }, body_writer);
+ }
+ try Packet.write(.delimiter, body_writer);
+ // Our packfile parser supports the OFS_DELTA object type
+ try Packet.write(.{ .data = "ofs-delta\n" }, body_writer);
+ // We do not currently convey server progress information to the user
+ try Packet.write(.{ .data = "no-progress\n" }, body_writer);
+ if (session.supports_shallow) {
+ try Packet.write(.{ .data = "deepen 1\n" }, body_writer);
+ }
+ for (wants) |want| {
+ var buf: [Packet.max_data_length]u8 = undefined;
+ const arg = std.fmt.bufPrint(&buf, "want {s}\n", .{want}) catch unreachable;
+ try Packet.write(.{ .data = arg }, body_writer);
+ }
+ try Packet.write(.{ .data = "done\n" }, body_writer);
+ try Packet.write(.flush, body_writer);
+
+ var request = try session.transport.request(.POST, upload_pack_uri, headers, .{
+ .handle_redirects = false,
+ });
+ errdefer request.deinit();
+ request.transfer_encoding = .{ .content_length = body.items.len };
+ try request.start(.{});
+ try request.writeAll(body.items);
+ try request.finish();
+
+ try request.wait();
+ if (request.response.status != .ok) return error.ProtocolError;
+
+ const reader = request.reader();
+ // We are not interested in any of the sections of the returned fetch
+ // data other than the packfile section, since we aren't doing anything
+ // complex like ref negotiation (this is a fresh clone).
+ var state: enum { section_start, section_content } = .section_start;
+ while (true) {
+ var buf: [Packet.max_data_length]u8 = undefined;
+ const packet = try Packet.read(reader, &buf);
+ switch (state) {
+ .section_start => switch (packet) {
+ .data => |data| if (mem.eql(u8, data, "packfile\n")) {
+ return .{ .request = request };
+ } else {
+ state = .section_content;
+ },
+ else => return error.UnexpectedPacket,
+ },
+ .section_content => switch (packet) {
+ .delimiter => state = .section_start,
+ .data => {},
+ else => return error.UnexpectedPacket,
+ },
+ }
+ }
+ }
+
+ pub const FetchStream = struct {
+ request: std.http.Client.Request,
+ buf: [Packet.max_data_length]u8 = undefined,
+ pos: usize = 0,
+ len: usize = 0,
+
+ pub fn deinit(stream: *FetchStream) void {
+ stream.request.deinit();
+ }
+
+ pub const ReadError = std.http.Client.Request.ReadError || error{
+ InvalidPacket,
+ ProtocolError,
+ UnexpectedPacket,
+ };
+ pub const Reader = std.io.Reader(*FetchStream, ReadError, read);
+
+ const StreamCode = enum(u8) {
+ pack_data = 1,
+ progress = 2,
+ fatal_error = 3,
+ _,
+ };
+
+ pub fn reader(stream: *FetchStream) Reader {
+ return .{ .context = stream };
+ }
+
+ pub fn read(stream: *FetchStream, buf: []u8) !usize {
+ if (stream.pos == stream.len) {
+ while (true) {
+ switch (try Packet.read(stream.request.reader(), &stream.buf)) {
+ .flush => return 0,
+ .data => |data| if (data.len > 1) switch (@as(StreamCode, @enumFromInt(data[0]))) {
+ .pack_data => {
+ stream.pos = 1;
+ stream.len = data.len;
+ break;
+ },
+ .fatal_error => return error.ProtocolError,
+ else => {},
+ },
+ else => return error.UnexpectedPacket,
+ }
+ }
+ }
+
+ const size = @min(buf.len, stream.len - stream.pos);
+ @memcpy(buf[0..size], stream.buf[stream.pos .. stream.pos + size]);
+ stream.pos += size;
+ return size;
+ }
+ };
+};
+
+const PackHeader = struct {
+ total_objects: u32,
+
+ const signature = "PACK";
+ const supported_version = 2;
+
+ fn read(reader: anytype) !PackHeader {
+ const actual_signature = reader.readBytesNoEof(4) catch |e| switch (e) {
+ error.EndOfStream => return error.InvalidHeader,
+ else => |other| return other,
+ };
+ if (!mem.eql(u8, &actual_signature, signature)) return error.InvalidHeader;
+ const version = reader.readIntBig(u32) catch |e| switch (e) {
+ error.EndOfStream => return error.InvalidHeader,
+ else => |other| return other,
+ };
+ if (version != supported_version) return error.UnsupportedVersion;
+ const total_objects = reader.readIntBig(u32) catch |e| switch (e) {
+ error.EndOfStream => return error.InvalidHeader,
+ else => |other| return other,
+ };
+ return .{ .total_objects = total_objects };
+ }
+};
+
+const EntryHeader = union(Type) {
+ commit: Undeltified,
+ tree: Undeltified,
+ blob: Undeltified,
+ tag: Undeltified,
+ ofs_delta: OfsDelta,
+ ref_delta: RefDelta,
+
+ const Type = enum(u3) {
+ commit = 1,
+ tree = 2,
+ blob = 3,
+ tag = 4,
+ ofs_delta = 6,
+ ref_delta = 7,
+ };
+
+ const Undeltified = struct {
+ uncompressed_length: u64,
+ };
+
+ const OfsDelta = struct {
+ offset: u64,
+ uncompressed_length: u64,
+ };
+
+ const RefDelta = struct {
+ base_object: Oid,
+ uncompressed_length: u64,
+ };
+
+ fn objectType(header: EntryHeader) Object.Type {
+ return switch (header) {
+ inline .commit, .tree, .blob, .tag => |_, tag| @field(Object.Type, @tagName(tag)),
+ else => unreachable,
+ };
+ }
+
+ fn uncompressedLength(header: EntryHeader) u64 {
+ return switch (header) {
+ inline else => |entry| entry.uncompressed_length,
+ };
+ }
+
+ fn read(reader: anytype) !EntryHeader {
+ const InitialByte = packed struct { len: u4, type: u3, has_next: bool };
+ const initial: InitialByte = @bitCast(reader.readByte() catch |e| switch (e) {
+ error.EndOfStream => return error.InvalidFormat,
+ else => |other| return other,
+ });
+ const rest_len = if (initial.has_next) try readSizeVarInt(reader) else 0;
+ var uncompressed_length: u64 = initial.len;
+ uncompressed_length |= std.math.shlExact(u64, rest_len, 4) catch return error.InvalidFormat;
+ const @"type" = std.meta.intToEnum(EntryHeader.Type, initial.type) catch return error.InvalidFormat;
+ return switch (@"type") {
+ inline .commit, .tree, .blob, .tag => |tag| @unionInit(EntryHeader, @tagName(tag), .{
+ .uncompressed_length = uncompressed_length,
+ }),
+ .ofs_delta => .{ .ofs_delta = .{
+ .offset = try readOffsetVarInt(reader),
+ .uncompressed_length = uncompressed_length,
+ } },
+ .ref_delta => .{ .ref_delta = .{
+ .base_object = reader.readBytesNoEof(oid_length) catch |e| switch (e) {
+ error.EndOfStream => return error.InvalidFormat,
+ else => |other| return other,
+ },
+ .uncompressed_length = uncompressed_length,
+ } },
+ };
+ }
+};
+
+fn readSizeVarInt(r: anytype) !u64 {
+ const Byte = packed struct { value: u7, has_next: bool };
+ var b: Byte = @bitCast(try r.readByte());
+ var value: u64 = b.value;
+ var shift: u6 = 0;
+ while (b.has_next) {
+ b = @bitCast(try r.readByte());
+ shift = std.math.add(u6, shift, 7) catch return error.InvalidFormat;
+ value |= @as(u64, b.value) << shift;
+ }
+ return value;
+}
+
+fn readOffsetVarInt(r: anytype) !u64 {
+ const Byte = packed struct { value: u7, has_next: bool };
+ var b: Byte = @bitCast(try r.readByte());
+ var value: u64 = b.value;
+ while (b.has_next) {
+ b = @bitCast(try r.readByte());
+ value = std.math.shlExact(u64, value + 1, 7) catch return error.InvalidFormat;
+ value |= b.value;
+ }
+ return value;
+}
+
+const IndexHeader = struct {
+ fan_out_table: [256]u32,
+
+ const signature = "\xFFtOc";
+ const supported_version = 2;
+ const size = 4 + 4 + @sizeOf([256]u32);
+
+ fn read(reader: anytype) !IndexHeader {
+ var header_bytes = try reader.readBytesNoEof(size);
+ if (!mem.eql(u8, header_bytes[0..4], signature)) return error.InvalidHeader;
+ const version = mem.readIntBig(u32, header_bytes[4..8]);
+ if (version != supported_version) return error.UnsupportedVersion;
+
+ var fan_out_table: [256]u32 = undefined;
+ var fan_out_table_stream = std.io.fixedBufferStream(header_bytes[8..]);
+ const fan_out_table_reader = fan_out_table_stream.reader();
+ for (&fan_out_table) |*entry| {
+ entry.* = fan_out_table_reader.readIntBig(u32) catch unreachable;
+ }
+ return .{ .fan_out_table = fan_out_table };
+ }
+};
+
+const IndexEntry = struct {
+ offset: u64,
+ crc32: u32,
+};
+
+/// Writes out a version 2 index for the given packfile, as documented in
+/// [pack-format](https://git-scm.com/docs/pack-format).
+pub fn indexPack(allocator: Allocator, pack: std.fs.File, index_writer: anytype) !void {
+ try pack.seekTo(0);
+
+ var index_entries = std.AutoHashMapUnmanaged(Oid, IndexEntry){};
+ defer index_entries.deinit(allocator);
+ var pending_deltas = std.ArrayListUnmanaged(IndexEntry){};
+ defer pending_deltas.deinit(allocator);
+
+ const pack_checksum = try indexPackFirstPass(allocator, pack, &index_entries, &pending_deltas);
+
+ var cache: ObjectCache = .{};
+ defer cache.deinit(allocator);
+ var remaining_deltas = pending_deltas.items.len;
+ while (remaining_deltas > 0) {
+ var i: usize = remaining_deltas;
+ while (i > 0) {
+ i -= 1;
+ const delta = pending_deltas.items[i];
+ if (try indexPackHashDelta(allocator, pack, delta, index_entries, &cache)) |oid| {
+ try index_entries.put(allocator, oid, delta);
+ _ = pending_deltas.swapRemove(i);
+ }
+ }
+ if (pending_deltas.items.len == remaining_deltas) return error.IncompletePack;
+ remaining_deltas = pending_deltas.items.len;
+ }
+
+ var oids = std.ArrayListUnmanaged(Oid){};
+ defer oids.deinit(allocator);
+ try oids.ensureTotalCapacityPrecise(allocator, index_entries.count());
+ var index_entries_iter = index_entries.iterator();
+ while (index_entries_iter.next()) |entry| {
+ oids.appendAssumeCapacity(entry.key_ptr.*);
+ }
+ mem.sortUnstable(Oid, oids.items, {}, struct {
+ fn lessThan(_: void, o1: Oid, o2: Oid) bool {
+ return mem.lessThan(u8, &o1, &o2);
+ }
+ }.lessThan);
+
+ var fan_out_table: [256]u32 = undefined;
+ var count: u32 = 0;
+ var fan_out_index: u8 = 0;
+ for (oids.items) |oid| {
+ if (oid[0] > fan_out_index) {
+ @memset(fan_out_table[fan_out_index..oid[0]], count);
+ fan_out_index = oid[0];
+ }
+ count += 1;
+ }
+ @memset(fan_out_table[fan_out_index..], count);
+
+ var index_hashed_writer = hashedWriter(index_writer, Sha1.init(.{}));
+ const writer = index_hashed_writer.writer();
+ try writer.writeAll(IndexHeader.signature);
+ try writer.writeIntBig(u32, IndexHeader.supported_version);
+ for (fan_out_table) |fan_out_entry| {
+ try writer.writeIntBig(u32, fan_out_entry);
+ }
+
+ for (oids.items) |oid| {
+ try writer.writeAll(&oid);
+ }
+
+ for (oids.items) |oid| {
+ try writer.writeIntBig(u32, index_entries.get(oid).?.crc32);
+ }
+
+ var big_offsets = std.ArrayListUnmanaged(u64){};
+ defer big_offsets.deinit(allocator);
+ for (oids.items) |oid| {
+ const offset = index_entries.get(oid).?.offset;
+ if (offset <= std.math.maxInt(u31)) {
+ try writer.writeIntBig(u32, @intCast(offset));
+ } else {
+ const index = big_offsets.items.len;
+ try big_offsets.append(allocator, offset);
+ try writer.writeIntBig(u32, @as(u32, @intCast(index)) | (1 << 31));
+ }
+ }
+ for (big_offsets.items) |offset| {
+ try writer.writeIntBig(u64, offset);
+ }
+
+ try writer.writeAll(&pack_checksum);
+ const index_checksum = index_hashed_writer.hasher.finalResult();
+ try index_writer.writeAll(&index_checksum);
+}
+
+/// Performs the first pass over the packfile data for index construction.
+/// This will index all non-delta objects, queue delta objects for further
+/// processing, and return the pack checksum (which is part of the index
+/// format).
+fn indexPackFirstPass(
+ allocator: Allocator,
+ pack: std.fs.File,
+ index_entries: *std.AutoHashMapUnmanaged(Oid, IndexEntry),
+ pending_deltas: *std.ArrayListUnmanaged(IndexEntry),
+) ![Sha1.digest_length]u8 {
+ var pack_buffered_reader = std.io.bufferedReader(pack.reader());
+ var pack_counting_reader = std.io.countingReader(pack_buffered_reader.reader());
+ var pack_hashed_reader = std.compress.hashedReader(pack_counting_reader.reader(), Sha1.init(.{}));
+ const pack_reader = pack_hashed_reader.reader();
+
+ const pack_header = try PackHeader.read(pack_reader);
+
+ var current_entry: u32 = 0;
+ while (current_entry < pack_header.total_objects) : (current_entry += 1) {
+ const entry_offset = pack_counting_reader.bytes_read;
+ var entry_crc32_reader = std.compress.hashedReader(pack_reader, std.hash.Crc32.init());
+ const entry_header = try EntryHeader.read(entry_crc32_reader.reader());
+ switch (entry_header) {
+ inline .commit, .tree, .blob, .tag => |object, tag| {
+ var entry_decompress_stream = try std.compress.zlib.decompressStream(allocator, entry_crc32_reader.reader());
+ defer entry_decompress_stream.deinit();
+ var entry_counting_reader = std.io.countingReader(entry_decompress_stream.reader());
+ var entry_hashed_writer = hashedWriter(std.io.null_writer, Sha1.init(.{}));
+ const entry_writer = entry_hashed_writer.writer();
+ // The object header is not included in the pack data but is
+ // part of the object's ID
+ try entry_writer.print("{s} {}\x00", .{ @tagName(tag), object.uncompressed_length });
+ var fifo = std.fifo.LinearFifo(u8, .{ .Static = 4096 }).init();
+ try fifo.pump(entry_counting_reader.reader(), entry_writer);
+ if (entry_counting_reader.bytes_read != object.uncompressed_length) {
+ return error.InvalidObject;
+ }
+ const oid = entry_hashed_writer.hasher.finalResult();
+ try index_entries.put(allocator, oid, .{
+ .offset = entry_offset,
+ .crc32 = entry_crc32_reader.hasher.final(),
+ });
+ },
+ inline .ofs_delta, .ref_delta => |delta| {
+ var entry_decompress_stream = try std.compress.zlib.decompressStream(allocator, entry_crc32_reader.reader());
+ defer entry_decompress_stream.deinit();
+ var entry_counting_reader = std.io.countingReader(entry_decompress_stream.reader());
+ var fifo = std.fifo.LinearFifo(u8, .{ .Static = 4096 }).init();
+ try fifo.pump(entry_counting_reader.reader(), std.io.null_writer);
+ if (entry_counting_reader.bytes_read != delta.uncompressed_length) {
+ return error.InvalidObject;
+ }
+ try pending_deltas.append(allocator, .{
+ .offset = entry_offset,
+ .crc32 = entry_crc32_reader.hasher.final(),
+ });
+ },
+ }
+ }
+
+ const pack_checksum = pack_hashed_reader.hasher.finalResult();
+ const recorded_checksum = try pack_buffered_reader.reader().readBytesNoEof(Sha1.digest_length);
+ if (!mem.eql(u8, &pack_checksum, &recorded_checksum)) {
+ return error.CorruptedPack;
+ }
+ _ = pack_buffered_reader.reader().readByte() catch |e| switch (e) {
+ error.EndOfStream => return pack_checksum,
+ else => |other| return other,
+ };
+ return error.InvalidFormat;
+}
+
+/// Attempts to determine the final object ID of the given deltified object.
+/// May return null if this is not yet possible (if the delta is a ref-based
+/// delta and we do not yet know the offset of the base object).
+fn indexPackHashDelta(
+ allocator: Allocator,
+ pack: std.fs.File,
+ delta: IndexEntry,
+ index_entries: std.AutoHashMapUnmanaged(Oid, IndexEntry),
+ cache: *ObjectCache,
+) !?Oid {
+ // Figure out the chain of deltas to resolve
+ var base_offset = delta.offset;
+ var base_header: EntryHeader = undefined;
+ var delta_offsets = std.ArrayListUnmanaged(u64){};
+ defer delta_offsets.deinit(allocator);
+ const base_object = while (true) {
+ if (cache.get(base_offset)) |base_object| break base_object;
+
+ try pack.seekTo(base_offset);
+ base_header = try EntryHeader.read(pack.reader());
+ switch (base_header) {
+ .ofs_delta => |ofs_delta| {
+ try delta_offsets.append(allocator, base_offset);
+ base_offset = std.math.sub(u64, base_offset, ofs_delta.offset) catch return error.InvalidObject;
+ },
+ .ref_delta => |ref_delta| {
+ try delta_offsets.append(allocator, base_offset);
+ base_offset = (index_entries.get(ref_delta.base_object) orelse return null).offset;
+ },
+ else => {
+ const base_data = try readObjectRaw(allocator, pack.reader(), base_header.uncompressedLength());
+ errdefer allocator.free(base_data);
+ const base_object: Object = .{ .type = base_header.objectType(), .data = base_data };
+ try cache.put(allocator, base_offset, base_object);
+ break base_object;
+ },
+ }
+ };
+
+ const base_data = try resolveDeltaChain(allocator, pack, base_object, delta_offsets.items, cache);
+
+ var entry_hasher = Sha1.init(.{});
+ var entry_hashed_writer = hashedWriter(std.io.null_writer, &entry_hasher);
+ try entry_hashed_writer.writer().print("{s} {}\x00", .{ @tagName(base_object.type), base_data.len });
+ entry_hasher.update(base_data);
+ return entry_hasher.finalResult();
+}
+
+/// Resolves a chain of deltas, returning the final base object data. `pack` is
+/// assumed to be looking at the start of the object data for the base object of
+/// the chain, and will then apply the deltas in `delta_offsets` in reverse order
+/// to obtain the final object.
+fn resolveDeltaChain(
+ allocator: Allocator,
+ pack: std.fs.File,
+ base_object: Object,
+ delta_offsets: []const u64,
+ cache: *ObjectCache,
+) ![]const u8 {
+ var base_data = base_object.data;
+ var i: usize = delta_offsets.len;
+ while (i > 0) {
+ i -= 1;
+
+ const delta_offset = delta_offsets[i];
+ try pack.seekTo(delta_offset);
+ const delta_header = try EntryHeader.read(pack.reader());
+ var delta_data = try readObjectRaw(allocator, pack.reader(), delta_header.uncompressedLength());
+ defer allocator.free(delta_data);
+ var delta_stream = std.io.fixedBufferStream(delta_data);
+ const delta_reader = delta_stream.reader();
+ _ = try readSizeVarInt(delta_reader); // base object size
+ const expanded_size = try readSizeVarInt(delta_reader);
+
+ const expanded_alloc_size = std.math.cast(usize, expanded_size) orelse return error.ObjectTooLarge;
+ var expanded_data = try allocator.alloc(u8, expanded_alloc_size);
+ errdefer allocator.free(expanded_data);
+ var expanded_delta_stream = std.io.fixedBufferStream(expanded_data);
+ var base_stream = std.io.fixedBufferStream(base_data);
+ try expandDelta(&base_stream, delta_reader, expanded_delta_stream.writer());
+ if (expanded_delta_stream.pos != expanded_size) return error.InvalidObject;
+
+ try cache.put(allocator, delta_offset, .{ .type = base_object.type, .data = expanded_data });
+ base_data = expanded_data;
+ }
+ return base_data;
+}
+
+/// Reads the complete contents of an object from `reader`. This function may
+/// read more bytes than required from `reader`, so the reader position after
+/// returning is not reliable.
+fn readObjectRaw(allocator: Allocator, reader: anytype, size: u64) ![]u8 {
+ const alloc_size = std.math.cast(usize, size) orelse return error.ObjectTooLarge;
+ var buffered_reader = std.io.bufferedReader(reader);
+ var decompress_stream = try std.compress.zlib.decompressStream(allocator, buffered_reader.reader());
+ defer decompress_stream.deinit();
+ var data = try allocator.alloc(u8, alloc_size);
+ errdefer allocator.free(data);
+ try decompress_stream.reader().readNoEof(data);
+ _ = decompress_stream.reader().readByte() catch |e| switch (e) {
+ error.EndOfStream => return data,
+ else => |other| return other,
+ };
+ return error.InvalidFormat;
+}
+
+/// Expands delta data from `delta_reader` to `writer`. `base_object` must
+/// support `reader` and `seekTo` (such as a `std.io.FixedBufferStream`).
+///
+/// The format of the delta data is documented in
+/// [pack-format](https://git-scm.com/docs/pack-format).
+fn expandDelta(base_object: anytype, delta_reader: anytype, writer: anytype) !void {
+ while (true) {
+ const inst: packed struct { value: u7, copy: bool } = @bitCast(delta_reader.readByte() catch |e| switch (e) {
+ error.EndOfStream => return,
+ else => |other| return other,
+ });
+ if (inst.copy) {
+ const available: packed struct {
+ offset1: bool,
+ offset2: bool,
+ offset3: bool,
+ offset4: bool,
+ size1: bool,
+ size2: bool,
+ size3: bool,
+ } = @bitCast(inst.value);
+ var offset_parts: packed struct { offset1: u8, offset2: u8, offset3: u8, offset4: u8 } = .{
+ .offset1 = if (available.offset1) try delta_reader.readByte() else 0,
+ .offset2 = if (available.offset2) try delta_reader.readByte() else 0,
+ .offset3 = if (available.offset3) try delta_reader.readByte() else 0,
+ .offset4 = if (available.offset4) try delta_reader.readByte() else 0,
+ };
+ const offset: u32 = @bitCast(offset_parts);
+ var size_parts: packed struct { size1: u8, size2: u8, size3: u8 } = .{
+ .size1 = if (available.size1) try delta_reader.readByte() else 0,
+ .size2 = if (available.size2) try delta_reader.readByte() else 0,
+ .size3 = if (available.size3) try delta_reader.readByte() else 0,
+ };
+ var size: u24 = @bitCast(size_parts);
+ if (size == 0) size = 0x10000;
+ try base_object.seekTo(offset);
+ var copy_reader = std.io.limitedReader(base_object.reader(), size);
+ var fifo = std.fifo.LinearFifo(u8, .{ .Static = 4096 }).init();
+ try fifo.pump(copy_reader.reader(), writer);
+ } else if (inst.value != 0) {
+ var data_reader = std.io.limitedReader(delta_reader, inst.value);
+ var fifo = std.fifo.LinearFifo(u8, .{ .Static = 4096 }).init();
+ try fifo.pump(data_reader.reader(), writer);
+ } else {
+ return error.InvalidDeltaInstruction;
+ }
+ }
+}
+
+fn HashedWriter(
+ comptime WriterType: anytype,
+ comptime HasherType: anytype,
+) type {
+ return struct {
+ child_writer: WriterType,
+ hasher: HasherType,
+
+ const Error = WriterType.Error;
+ const Writer = std.io.Writer(*@This(), Error, write);
+
+ fn write(hashed_writer: *@This(), buf: []const u8) Error!usize {
+ const amt = try hashed_writer.child_writer.write(buf);
+ hashed_writer.hasher.update(buf);
+ return amt;
+ }
+
+ fn writer(hashed_writer: *@This()) Writer {
+ return .{ .context = hashed_writer };
+ }
+ };
+}
+
+fn hashedWriter(
+ writer: anytype,
+ hasher: anytype,
+) HashedWriter(@TypeOf(writer), @TypeOf(hasher)) {
+ return .{ .child_writer = writer, .hasher = hasher };
+}
+
+test "packfile indexing and checkout" {
+ // To verify the contents of this packfile without using the code in this
+ // file:
+ //
+ // 1. Create a new empty Git repository (`git init`)
+ // 2. `git unpack-objects <path/to/testdata.pack`
+ // 3. `git fsck` -> note the "dangling commit" ID (which matches the commit
+ // checked out below)
+ // 4. `git checkout dd582c0720819ab7130b103635bd7271b9fd4feb`
+ const testrepo_pack = @embedFile("git/testdata/testrepo.pack");
+
+ var git_dir = testing.tmpDir(.{});
+ defer git_dir.cleanup();
+ var pack_file = try git_dir.dir.createFile("testrepo.pack", .{ .read = true });
+ defer pack_file.close();
+ try pack_file.writeAll(testrepo_pack);
+
+ var index_file = try git_dir.dir.createFile("testrepo.idx", .{ .read = true });
+ defer index_file.close();
+ try indexPack(testing.allocator, pack_file, index_file.writer());
+
+ // Arbitrary size limit on files read while checking the repository contents
+ // (all files in the test repo are known to be much smaller than this)
+ const max_file_size = 4096;
+
+ const index_file_data = try git_dir.dir.readFileAlloc(testing.allocator, "testrepo.idx", max_file_size);
+ defer testing.allocator.free(index_file_data);
+ // testrepo.idx is generated by Git. The index created by this file should
+ // match it exactly. Running `git verify-pack -v testrepo.pack` can verify
+ // this.
+ const testrepo_idx = @embedFile("git/testdata/testrepo.idx");
+ try testing.expectEqualSlices(u8, testrepo_idx, index_file_data);
+
+ var repository = try Repository.init(testing.allocator, pack_file, index_file);
+ defer repository.deinit();
+
+ var worktree = testing.tmpIterableDir(.{});
+ defer worktree.cleanup();
+
+ const commit_id = try parseOid("dd582c0720819ab7130b103635bd7271b9fd4feb");
+ try repository.checkout(worktree.iterable_dir.dir, commit_id);
+
+ const expected_files: []const []const u8 = &.{
+ "dir/file",
+ "dir/subdir/file",
+ "dir/subdir/file2",
+ "dir2/file",
+ "dir3/file",
+ "dir3/file2",
+ "file",
+ "file2",
+ "file3",
+ "file4",
+ "file5",
+ "file6",
+ "file7",
+ "file8",
+ "file9",
+ };
+ var actual_files: std.ArrayListUnmanaged([]u8) = .{};
+ defer actual_files.deinit(testing.allocator);
+ defer for (actual_files.items) |file| testing.allocator.free(file);
+ var walker = try worktree.iterable_dir.walk(testing.allocator);
+ defer walker.deinit();
+ while (try walker.next()) |entry| {
+ if (entry.kind != .file) continue;
+ var path = try testing.allocator.dupe(u8, entry.path);
+ errdefer testing.allocator.free(path);
+ mem.replaceScalar(u8, path, std.fs.path.sep, '/');
+ try actual_files.append(testing.allocator, path);
+ }
+ mem.sortUnstable([]u8, actual_files.items, {}, struct {
+ fn lessThan(_: void, a: []u8, b: []u8) bool {
+ return mem.lessThan(u8, a, b);
+ }
+ }.lessThan);
+ try testing.expectEqualDeep(expected_files, actual_files.items);
+
+ const expected_file_contents =
+ \\revision 1
+ \\revision 2
+ \\revision 4
+ \\revision 5
+ \\revision 7
+ \\revision 8
+ \\revision 9
+ \\revision 10
+ \\revision 12
+ \\revision 13
+ \\revision 14
+ \\revision 18
+ \\revision 19
+ \\
+ ;
+ const actual_file_contents = try worktree.iterable_dir.dir.readFileAlloc(testing.allocator, "file", max_file_size);
+ defer testing.allocator.free(actual_file_contents);
+ try testing.expectEqualStrings(expected_file_contents, actual_file_contents);
+}
+
+/// Checks out a commit of a packfile. Intended for experimenting with and
+/// benchmarking possible optimizations to the indexing and checkout behavior.
+pub fn main() !void {
+ const allocator = std.heap.c_allocator;
+
+ const args = try std.process.argsAlloc(allocator);
+ defer std.process.argsFree(allocator, args);
+ if (args.len != 4) {
+ return error.InvalidArguments; // Arguments: packfile commit worktree
+ }
+
+ var pack_file = try std.fs.cwd().openFile(args[1], .{});
+ defer pack_file.close();
+ const commit = try parseOid(args[2]);
+ var worktree = try std.fs.cwd().makeOpenPath(args[3], .{});
+ defer worktree.close();
+
+ var git_dir = try worktree.makeOpenPath(".git", .{});
+ defer git_dir.close();
+
+ std.debug.print("Starting index...\n", .{});
+ var index_file = try git_dir.createFile("idx", .{ .read = true });
+ defer index_file.close();
+ var index_buffered_writer = std.io.bufferedWriter(index_file.writer());
+ try indexPack(allocator, pack_file, index_buffered_writer.writer());
+ try index_buffered_writer.flush();
+ try index_file.sync();
+
+ std.debug.print("Starting checkout...\n", .{});
+ var repository = try Repository.init(allocator, pack_file, index_file);
+ defer repository.deinit();
+ try repository.checkout(worktree, commit);
+}
src/Package.zig
@@ -17,6 +17,7 @@ const Module = @import("Module.zig");
const Cache = std.Build.Cache;
const build_options = @import("build_options");
const Manifest = @import("Manifest.zig");
+const git = @import("git.zig");
pub const Table = std.StringHashMapUnmanaged(*Package);
@@ -514,6 +515,7 @@ const FetchLocation = union(enum) {
file: []const u8,
directory: []const u8,
http_request: std.Uri,
+ git_request: std.Uri,
pub fn init(gpa: Allocator, dep: Manifest.Dependency, root_dir: Compilation.Directory, report: Report) !FetchLocation {
switch (dep.location) {
@@ -524,8 +526,13 @@ const FetchLocation = union(enum) {
};
if (ascii.eqlIgnoreCase(uri.scheme, "file")) {
return report.fail(dep.location_tok, "'file' scheme is not allowed for URLs. Use '.path' instead", .{});
+ } else if (ascii.eqlIgnoreCase(uri.scheme, "http") or ascii.eqlIgnoreCase(uri.scheme, "https")) {
+ return .{ .http_request = uri };
+ } else if (ascii.eqlIgnoreCase(uri.scheme, "git+http") or ascii.eqlIgnoreCase(uri.scheme, "git+https")) {
+ return .{ .git_request = uri };
+ } else {
+ return report.fail(dep.location_tok, "Unsupported URL scheme: {s}", .{uri.scheme});
}
- return .{ .http_request = uri };
},
.path => |path| {
if (fs.path.isAbsolute(path)) {
@@ -548,7 +555,7 @@ const FetchLocation = union(enum) {
pub fn deinit(f: *FetchLocation, gpa: Allocator) void {
switch (f.*) {
inline .file, .directory => |path| gpa.free(path),
- .http_request => {},
+ .http_request, .git_request => {},
}
f.* = undefined;
}
@@ -592,6 +599,71 @@ const FetchLocation = union(enum) {
.resource = .{ .http_request = req },
};
},
+ .git_request => |uri| {
+ var transport_uri = uri;
+ transport_uri.scheme = uri.scheme["git+".len..];
+ var redirect_uri: []u8 = undefined;
+ var session: git.Session = .{ .transport = http_client, .uri = transport_uri };
+ session.discoverCapabilities(gpa, &redirect_uri) catch |e| switch (e) {
+ error.Redirected => {
+ defer gpa.free(redirect_uri);
+ return report.fail(dep.location_tok, "Repository moved to {s}", .{redirect_uri});
+ },
+ else => |other| return other,
+ };
+
+ const want_oid = want_oid: {
+ const want_ref = uri.fragment orelse "HEAD";
+ if (git.parseOid(want_ref)) |oid| break :want_oid oid else |_| {}
+
+ const want_ref_head = try std.fmt.allocPrint(gpa, "refs/heads/{s}", .{want_ref});
+ defer gpa.free(want_ref_head);
+ const want_ref_tag = try std.fmt.allocPrint(gpa, "refs/tags/{s}", .{want_ref});
+ defer gpa.free(want_ref_tag);
+
+ var ref_iterator = try session.listRefs(gpa, .{
+ .ref_prefixes = &.{ want_ref, want_ref_head, want_ref_tag },
+ .include_peeled = true,
+ });
+ defer ref_iterator.deinit();
+ while (try ref_iterator.next()) |ref| {
+ if (mem.eql(u8, ref.name, want_ref) or
+ mem.eql(u8, ref.name, want_ref_head) or
+ mem.eql(u8, ref.name, want_ref_tag))
+ {
+ break :want_oid ref.peeled orelse ref.oid;
+ }
+ }
+ return report.fail(dep.location_tok, "Ref not found: {s}", .{want_ref});
+ };
+ if (uri.fragment == null) {
+ const file_path = try report.directory.join(gpa, &.{Manifest.basename});
+ defer gpa.free(file_path);
+
+ const eb = report.error_bundle;
+ const notes_len = 1;
+ try Report.addErrorMessage(report.ast.*, file_path, eb, notes_len, .{
+ .tok = dep.location_tok,
+ .off = 0,
+ .msg = "url field is missing an explicit ref",
+ });
+ const notes_start = try eb.reserveNotes(notes_len);
+ eb.extra.items[notes_start] = @intFromEnum(try eb.addErrorMessage(.{
+ .msg = try eb.printString("try .url = \"{+/}#{}\",", .{ uri, std.fmt.fmtSliceHexLower(&want_oid) }),
+ }));
+ return error.PackageFetchFailed;
+ }
+
+ var want_oid_buf: [git.fmt_oid_length]u8 = undefined;
+ _ = std.fmt.bufPrint(&want_oid_buf, "{}", .{std.fmt.fmtSliceHexLower(&want_oid)}) catch unreachable;
+ var fetch_stream = try session.fetch(gpa, &.{&want_oid_buf});
+ errdefer fetch_stream.deinit();
+
+ return .{
+ .path = try gpa.dupe(u8, &want_oid_buf),
+ .resource = .{ .git_fetch_stream = fetch_stream },
+ };
+ },
.directory => unreachable, // Directories do not require fetching
}
}
@@ -602,6 +674,7 @@ const ReadableResource = struct {
resource: union(enum) {
file: fs.File,
http_request: std.http.Client.Request,
+ git_fetch_stream: git.Session.FetchStream,
},
/// Unpack the package into the global cache directory.
@@ -617,7 +690,7 @@ const ReadableResource = struct {
pkg_prog_node: *std.Progress.Node,
) !PackageLocation {
switch (rr.resource) {
- inline .file, .http_request => |*r| {
+ inline .file, .http_request, .git_fetch_stream => |*r| {
const s = fs.path.sep_str;
const rand_int = std.crypto.random.int(u64);
const tmp_dir_sub_path = "tmp" ++ s ++ Manifest.hex64(rand_int);
@@ -663,6 +736,7 @@ const ReadableResource = struct {
// I have not checked what buffer sizes the xz decompression implementation uses
// by default, so the same logic applies for buffering the reader as for gzip.
.@"tar.xz" => try unpackTarball(allocator, prog_reader, tmp_directory.handle, std.compress.xz),
+ .git_pack => try unpackGitPack(allocator, &prog_reader, git.parseOid(rr.path) catch unreachable, tmp_directory.handle),
}
// Unpack completed - stop showing amount as progress
@@ -697,13 +771,15 @@ const ReadableResource = struct {
const FileType = enum {
@"tar.gz",
@"tar.xz",
+ git_pack,
};
pub fn getSize(rr: ReadableResource) !?u64 {
switch (rr.resource) {
+ .file => |f| return (try f.metadata()).size(),
// TODO: Handle case of chunked content-length
.http_request => |req| return req.response.content_length,
- .file => |f| return (try f.metadata()).size(),
+ .git_fetch_stream => |stream| return stream.request.response.content_length,
}
}
@@ -734,6 +810,7 @@ const ReadableResource = struct {
return report.fail(dep.location_tok, "Unsupported 'Content-Disposition' header value: '{s}' for Content-Type=application/octet-stream", .{content_disposition});
} else return report.fail(dep.location_tok, "Unrecognized value for 'Content-Type' header: {s}", .{content_type});
},
+ .git_fetch_stream => return .git_pack,
}
}
@@ -769,6 +846,7 @@ const ReadableResource = struct {
switch (rr.resource) {
.file => |file| file.close(),
.http_request => |*req| req.deinit(),
+ .git_fetch_stream => |*stream| stream.deinit(),
}
rr.* = undefined;
}
@@ -947,7 +1025,7 @@ fn fetchAndUnpack(
/// is only intended to be human-readable for progress reporting.
name_for_prog: []const u8,
) !DependencyModule {
- assert(fetch_location == .file or fetch_location == .http_request);
+ assert(fetch_location != .directory);
const gpa = http_client.allocator;
@@ -1024,6 +1102,51 @@ fn unpackTarball(
});
}
+fn unpackGitPack(
+ gpa: Allocator,
+ reader: anytype,
+ want_oid: git.Oid,
+ out_dir: fs.Dir,
+) !void {
+ // The .git directory is used to store the packfile and associated index, but
+ // we do not attempt to replicate the exact structure of a real .git
+ // directory, since that isn't relevant for fetching a package.
+ {
+ var pack_dir = try out_dir.makeOpenPath(".git", .{});
+ defer pack_dir.close();
+ var pack_file = try pack_dir.createFile("pkg.pack", .{ .read = true });
+ defer pack_file.close();
+ var fifo = std.fifo.LinearFifo(u8, .{ .Static = 4096 }).init();
+ try fifo.pump(reader.reader(), pack_file.writer());
+ try pack_file.sync();
+
+ var index_file = try pack_dir.createFile("pkg.idx", .{ .read = true });
+ defer index_file.close();
+ {
+ var index_prog_node = reader.prog_node.start("Index pack", 0);
+ defer index_prog_node.end();
+ index_prog_node.activate();
+ index_prog_node.context.refresh();
+ var index_buffered_writer = std.io.bufferedWriter(index_file.writer());
+ try git.indexPack(gpa, pack_file, index_buffered_writer.writer());
+ try index_buffered_writer.flush();
+ try index_file.sync();
+ }
+
+ {
+ var checkout_prog_node = reader.prog_node.start("Checkout", 0);
+ defer checkout_prog_node.end();
+ checkout_prog_node.activate();
+ checkout_prog_node.context.refresh();
+ var repository = try git.Repository.init(gpa, pack_file, index_file);
+ defer repository.deinit();
+ try repository.checkout(out_dir, want_oid);
+ }
+ }
+
+ try out_dir.deleteTree(".git");
+}
+
const HashedFile = struct {
fs_path: []const u8,
normalized_path: []const u8,