loadDsymFile

fn loadDsymFile(
    gpa: Allocator,
    io: Io,
    path: []const u8,
    arch: std.Target.Cpu.Arch,
    expected_uuid: Uuid,
) Error!DsymFile {
    const all_mapped_memory = try mapDebugInfoFile(io, path);
    errdefer posix.munmap(all_mapped_memory);
    const mapped_macho = try selectMachOSlice(all_mapped_memory, arch);

    var r: Io.Reader = .fixed(mapped_macho);
    const hdr = r.takeStruct(macho.mach_header_64, .little) catch |err| switch (err) {
        error.ReadFailed => unreachable,
        error.EndOfStream => return error.InvalidMachO,
    };
    if (hdr.magic != macho.MH_MAGIC_64) return error.InvalidMachO;
    if (hdr.filetype != macho.MH_DSYM) return error.MissingDebugInfo;

    var uuid: ?Uuid = null;
    var dwarf_sections: ?[]align(1) const macho.section_64 = null;

    var it: macho.LoadCommandIterator = try .init(&hdr, mapped_macho[@sizeOf(macho.mach_header_64)..]);
    while (try it.next()) |lc| switch (lc.hdr.cmd) {
        .SEGMENT_64 => if (lc.cast(macho.segment_command_64)) |seg_cmd| {
            if (!mem.eql(u8, "__DWARF", seg_cmd.segName())) continue;
            dwarf_sections = lc.getSections();
        },
        .UUID => if (lc.cast(macho.uuid_command)) |uuid_cmd| {
            uuid = uuid_cmd.uuid;
        },
        else => {},
    };

    const actual_uuid = uuid orelse return error.MissingDebugInfo;
    if (!mem.eql(u8, &actual_uuid, &expected_uuid)) return error.MissingDebugInfo;

    return .{
        .mapped_memory = all_mapped_memory,
        .dwarf = try loadDwarfFromSections(gpa, mapped_macho, dwarf_sections orelse return error.MissingDebugInfo),
    };
}