XBPS includes the following software from third parties for
internal use in the code:

- queue.h from NetBSD: include/queue.h.

- package pattern matching code from NetBSD:
  lib/external/dewey.c and lib/external/match.c

- strlcat and strlcpy functions from OpenBSD:
  lib/compat/strlc{at,cpy}.c

- humanize_number(3) from NetBSD: lib/external/humanize_number.c

- mkpath from NetBSD's mkdir(1): lib/external/mkpath.c

- fexec from NetBSD's pkg_install: lib/external/fexec.c

- libfetch-2.31 from NetBSD: lib/fetch

- portableproplib-0.4.1 (lib/portableproplib) from
  http://code.google.com/p/portableproplib