const std = @import("std"); const ptr_size = @import("cgroup.zig").ptr_size; const mem = std.mem; const meta = std.meta; const Allocator = mem.Allocator; const Group = @This(); gid: u32, name: []const u8, members: []align(1) const []const u8, // storage of name, members and members strings. for no particular reason. // Everything (name, members, member strings) could be allocated separately // (one extreme) and only once (another extreme). For some reason I chose the // right extreme, but it doesn't have to be this way. _buf: []const u8, pub fn init( allocator: Allocator, gid: u32, name: []const u8, members: []align(1) const []const u8, ) error{OutOfMemory}!Group { const buf_len = @sizeOf([]const u8) * members.len + name.len + blk: { var sum: usize = 0; for (members) |member| sum += member.len; break :blk @intCast(u32, sum); }; var buf = try allocator.alloc(u8, buf_len); errdefer allocator.free(buf); var ptr_end = @sizeOf([]const u8) * members.len; var members_ptr = mem.bytesAsSlice([]const u8, buf[0..ptr_end]); var offset: usize = ptr_end; for (members) |member, i| { mem.copy(u8, buf[offset..], member); members_ptr[i] = buf[offset .. offset + member.len]; offset += member.len; } mem.copy(u8, buf[offset..], name); return Group{ .gid = gid, .name = buf[offset .. offset + name.len], .members = members_ptr, ._buf = buf, }; } // This could be made more efficient, but clone() is never in the hot path. pub fn clone(self: *const Group, allocator: Allocator) error{OutOfMemory}!Group { return init(allocator, self.gid, self.name, self.members); } pub fn deinit(self: *Group, allocator: Allocator) void { allocator.free(self._buf); self.* = undefined; } // buffer size in bytes if all strings were zero-terminated. pub fn strlenZ(self: *const Group) usize { var count: usize = 0; for (self.members) |member| count += member.len + 1; count += ptr_size * (self.members.len + 1); count += self.name.len + 1; return count; } const testing = std.testing; test "Group.clone" { // TODO: how to do this on stack? var member1 = mem.sliceTo(try testing.allocator.dupeZ(u8, "member1"), 0); defer testing.allocator.free(member1); var group = try init(testing.allocator, 1, "foo", &[_][]const u8{ member1, "member2" }); defer group.deinit(testing.allocator); var cloned = try group.clone(testing.allocator); defer cloned.deinit(testing.allocator); group.gid = 2; group.name = "bar"; member1[0] = 'x'; try testing.expectEqual(cloned.gid, 1); try testing.expectEqualSlices(u8, cloned.name, "foo"); try testing.expectEqualSlices(u8, cloned.members[0], "member1"); }