external/cffi.darcs/_darcs/pristine/examples/gethostname.lisp

   1 ;;;; -*- Mode: lisp; indent-tabs-mode: nil -*-
   2 ;;;
   3 ;;; gethostname.lisp --- A simple CFFI example.
   4 ;;;
   5 ;;; Copyright (C) 2005-2006, James Bielman  <jamesjb@jamesjb.com>
   6 ;;;
   7 ;;; Permission is hereby granted, free of charge, to any person
   8 ;;; obtaining a copy of this software and associated documentation
   9 ;;; files (the "Software"), to deal in the Software without
  10 ;;; restriction, including without limitation the rights to use, copy,
  11 ;;; modify, merge, publish, distribute, sublicense, and/or sell copies
  12 ;;; of the Software, and to permit persons to whom the Software is
  13 ;;; furnished to do so, subject to the following conditions:
  14 ;;;
  15 ;;; The above copyright notice and this permission notice shall be
  16 ;;; included in all copies or substantial portions of the Software.
  17 ;;;
  18 ;;; THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  19 ;;; EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  20 ;;; MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  21 ;;; NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
  22 ;;; HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
  23 ;;; WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  24 ;;; OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  25 ;;; DEALINGS IN THE SOFTWARE.
  26 ;;;
  27
  28 ;;;# CFFI Example: gethostname binding
  29 ;;;
  30 ;;; This is a very simple CFFI example that illustrates calling a C
  31 ;;; function that fills in a user-supplied string buffer.
  32
  33 (defpackage #:cffi-example-gethostname
  34   (:use #:common-lisp #:cffi)
  35   (:export #:gethostname))
  36
  37 (in-package #:cffi-example-gethostname)
  38
  39 ;;; Define the Lisp function %GETHOSTNAME to call the C 'gethostname'
  40 ;;; function, which will fill BUF with up to BUFSIZE characters of the
  41 ;;; system's hostname.
  42 (defcfun ("gethostname" %gethostname) :int
  43   (buf :pointer)
  44   (bufsize :int))
  45
  46 ;;; Define a Lispy interface to 'gethostname'.  The utility macro
  47 ;;; WITH-FOREIGN-POINTER-AS-STRING is used to allocate a temporary
  48 ;;; buffer and return it as a Lisp string.
  49 (defun gethostname ()
  50   (with-foreign-pointer-as-string (buf 255 bufsize)
  51     (%gethostname buf bufsize)))