racket/collects/srfi/98.rkt
2013-01-09 01:17:26 -05:00

77 lines
3.3 KiB
Racket

;; Copyright (c) 2009-2013 Derick Eddington. All rights reserved.
;; Permission is hereby granted, free of charge, to any person obtaining a
;; copy of this software and associated documentation files (the "Software"),
;; to deal in the Software without restriction, including without limitation
;; the rights to use, copy, modify, merge, publish, distribute, sublicense,
;; and/or sell copies of the Software, and to permit persons to whom the
;; Software is furnished to do so, subject to the following conditions:
;; The above copyright notice and this permission notice shall be included in
;; all copies or substantial portions of the Software.
;; Except as contained in this notice, the name(s) of the above copyright
;; holders shall not be used in advertising or otherwise to promote the sale,
;; use or other dealings in this Software without prior written authorization.
;; THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
;; IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
;; FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
;; THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
;; LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
;; FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
;; DEALINGS IN THE SOFTWARE.
;; Inspired by Danny Yoo's get-environment PLaneT package.
#lang scheme/base
(require scheme/foreign)
(provide (rename-out (getenv get-environment-variable))
get-environment-variables)
(unsafe!)
(define (get-environment-variables)
(define (split-strings l)
(for/list ([next (in-list l)])
(let loop ((i 0) (len (string-length next)))
(if (< i len)
(if (char=? #\= (string-ref next i))
(cons (substring next 0 i)
(substring next (+ 1 i) len))
(loop (+ 1 i) len))
(cons next #f)))))
(case (system-type)
[(windows)
(let ([get (get-ffi-obj "GetEnvironmentStringsW" #f (_fun #:abi 'stdcall -> _bytes))]
[free (get-ffi-obj "FreeEnvironmentStringsW" #f (_fun #:abi 'stdcall _pointer -> _void))])
(let* ([strs (get)]
[len (let loop ([i 0])
(if (and (= 0 (ptr-ref strs _byte i))
(= 0 (ptr-ref strs _byte (+ i 1)))
(= 0 (ptr-ref strs _byte (+ i 2)))
(= 0 (ptr-ref strs _byte (+ i 3))))
(+ i 4)
(loop (+ i 2))))]
[strs (cast strs _pointer (_bytes o len))])
(begin0
(split-strings
(let loop ([pos 0])
(let ([m (regexp-match-positions #rx"(?:..)*?\0\0" strs pos)])
(if m
(if (= (cdar m) (+ pos 2))
null
(cons (cast (ptr-add strs pos) _pointer _string/utf-16)
(loop (cdar m))))
null))))
(free strs))))]
[else
(let ([environ (get-ffi-obj "environ" (ffi-lib #f) _pointer)])
(split-strings
(let loop ([i 0])
(let ((next (ptr-ref environ _string/locale i)))
(if next
(cons next (loop (+ 1 i)))
null)))))]))