gettimeofday.lisp - clic - Clic is an command line interactive client for gopher written in Common LISP (HTM) git clone git://bitreich.org/clic/ git://enlrupgkhuxnvlhsf6lc3fziv5h2hhfrinws65d7roiv6bfj7d652fid.onion/clic/ (DIR) Log (DIR) Files (DIR) Refs (DIR) Tags (DIR) README (DIR) LICENSE --- gettimeofday.lisp (3778B) --- 1 ;;;; -*- Mode: lisp; indent-tabs-mode: nil -*- 2 ;;; 3 ;;; gettimeofday.lisp --- Example CFFI binding to gettimeofday(2) 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: gettimeofday binding 29 ;;; 30 ;;; This example illustrates the use of foreign structures, typedefs, 31 ;;; and using type translators to do checking of input and output 32 ;;; arguments to a foreign function. 33 34 (defpackage #:cffi-example-gettimeofday 35 (:use #:common-lisp #:cffi) 36 (:export #:gettimeofday)) 37 38 (in-package #:cffi-example-gettimeofday) 39 40 ;;; Define the TIMEVAL structure used by 'gettimeofday'. This assumes 41 ;;; that 'time_t' is a 'long' --- it would be nice if CFFI could 42 ;;; provide a proper :TIME-T type to help make this portable. 43 (defcstruct timeval 44 (tv-sec :long) 45 (tv-usec :long)) 46 47 ;;; A NULL-POINTER is a foreign :POINTER that must always be NULL. 48 ;;; Both a NULL pointer and NIL are legal values---any others will 49 ;;; result in a runtime error. 50 (define-foreign-type null-pointer-type () 51 () 52 (:actual-type :pointer) 53 (:simple-parser null-pointer)) 54 55 ;;; This type translator is used to ensure that a NULL-POINTER has a 56 ;;; null value. It also converts NIL to a null pointer. 57 (defmethod translate-to-foreign (value (type null-pointer-type)) 58 (cond 59 ((null value) (null-pointer)) 60 ((null-pointer-p value) value) 61 (t (error "~A is not a null pointer." value)))) 62 63 ;;; The SYSCALL-RESULT type is an integer type used for the return 64 ;;; value of C functions that return -1 and set errno on errors. 65 ;;; Someday when CFFI has a portable interface for dealing with 66 ;;; 'errno', this error reporting can be more useful. 67 (define-foreign-type syscall-result-type () 68 () 69 (:actual-type :int) 70 (:simple-parser syscall-result)) 71 72 ;;; Type translator to check a SYSCALL-RESULT and signal a Lisp error 73 ;;; if the value is negative. 74 (defmethod translate-from-foreign (value (type syscall-result-type)) 75 (if (minusp value) 76 (error "System call failed with return value ~D." value) 77 value)) 78 79 ;;; Define the Lisp function %GETTIMEOFDAY to call the C function 80 ;;; 'gettimeofday', passing a pointer to the TIMEVAL structure to fill 81 ;;; in. The TZP parameter is deprecated and should be NULL --- we can 82 ;;; enforce this by using our NULL-POINTER type defined above. 83 (defcfun ("gettimeofday" %gettimeofday) syscall-result 84 (tp :pointer) 85 (tzp null-pointer)) 86 87 ;;; Define a Lispy interface to 'gettimeofday' that returns the 88 ;;; seconds and microseconds as multiple values. 89 (defun gettimeofday () 90 (with-foreign-object (tv 'timeval) 91 (%gettimeofday tv nil) 92 (with-foreign-slots ((tv-sec tv-usec) tv timeval) 93 (values tv-sec tv-usec))))