dirHardLink

fn dirHardLink(
    userdata: ?*anyopaque,
    old_dir: Dir,
    old_sub_path: []const u8,
    new_dir: Dir,
    new_sub_path: []const u8,
    options: Dir.HardLinkOptions,
) Dir.HardLinkError!void {
    if (is_windows) return error.OperationUnsupported;
    const t: *Threaded = @ptrCast(@alignCast(userdata));
    _ = t;

    if (native_os == .wasi and !builtin.link_libc) {
        const flags: std.os.wasi.lookupflags_t = .{
            .SYMLINK_FOLLOW = options.follow_symlinks,
        };
        const syscall: Syscall = try .start();
        while (true) {
            switch (std.os.wasi.path_link(
                old_dir.handle,
                flags,
                old_sub_path.ptr,
                old_sub_path.len,
                new_dir.handle,
                new_sub_path.ptr,
                new_sub_path.len,
            )) {
                .SUCCESS => return syscall.finish(),
                .INTR => {
                    try syscall.checkCancel();
                    continue;
                },
                else => |e| {
                    syscall.finish();
                    switch (e) {
                        .ACCES => return error.AccessDenied,
                        .DQUOT => return error.DiskQuota,
                        .EXIST => return error.PathAlreadyExists,
                        .FAULT => |err| return errnoBug(err),
                        .IO => return error.HardwareFailure,
                        .LOOP => return error.SymLinkLoop,
                        .MLINK => return error.LinkQuotaExceeded,
                        .NAMETOOLONG => return error.NameTooLong,
                        .NOENT => return error.FileNotFound,
                        .NOMEM => return error.SystemResources,
                        .NOSPC => return error.NoSpaceLeft,
                        .NOTDIR => return error.NotDir,
                        .PERM => return error.PermissionDenied,
                        .ROFS => return error.ReadOnlyFileSystem,
                        .XDEV => return error.CrossDevice,
                        .INVAL => |err| return errnoBug(err),
                        .ILSEQ => return error.BadPathName,
                        else => |err| return posix.unexpectedErrno(err),
                    }
                },
            }
        }
    }

    var old_path_buffer: [posix.PATH_MAX]u8 = undefined;
    var new_path_buffer: [posix.PATH_MAX]u8 = undefined;

    const old_sub_path_posix = try pathToPosix(old_sub_path, &old_path_buffer);
    const new_sub_path_posix = try pathToPosix(new_sub_path, &new_path_buffer);

    const flags: u32 = if (options.follow_symlinks) posix.AT.SYMLINK_FOLLOW else 0;
    return linkat(old_dir.handle, old_sub_path_posix, new_dir.handle, new_sub_path_posix, flags);
}