sys/kern/subr_optstr.c

   1 /*      $NetBSD: subr_optstr.c,v 1.4 2007/02/22 06:34:44 thorpej Exp $  */
   2
   3 /*-
   4  * Copyright (c) 2006 The NetBSD Foundation, Inc.
   5  * All rights reserved.
   6  *
   7  * This code is derived from software contributed to The NetBSD Foundation
   8  * by Julio M. Merino Vidal.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
  20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
  23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  29  * POSSIBILITY OF SUCH DAMAGE.
  30  */
  31
  32 #include <sys/cdefs.h>
  33 __KERNEL_RCSID(0, "$NetBSD: subr_optstr.c,v 1.4 2007/02/22 06:34:44 thorpej Exp $");
  34
  35 #include <sys/param.h>
  36 #include <sys/optstr.h>
  37
  38 /* --------------------------------------------------------------------- */
  39
  40 /*
  41  * Given an options string of the form 'a=b c=d ... y=z' and a key,
  42  * looks for the given key's value in the string and returns it in buf
  43  * with a maximum of bufsize bytes.  If the key is found, returns true;
  44  * otherwise FALSE.
  45  */
  46 bool
  47 optstr_get(const char *optstr, const char *key, char *buf, size_t bufsize)
  48 {
  49         bool found;
  50
  51         found = false;
  52
  53         /* Skip any initial spaces until we find a word. */
  54         while (*optstr == ' ' && *optstr != '\0')
  55                 optstr++;
  56
  57         /* Search for the given key within the option string. */
  58         while (!found && *optstr != '\0') {
  59                 const char *keyp;
  60
  61                 /* Check if the next word matches the key. */
  62                 keyp = key;
  63                 while (*optstr == *keyp) {
  64                         optstr++;
  65                         keyp++;
  66                 }
  67
  68                 if (*optstr == '=' && *keyp == '\0')
  69                         found = true;
  70                 else {
  71                         /* Key not found; skip until next space. */
  72                         while (*optstr != ' ' && *optstr != '\0')
  73                                 optstr++;
  74
  75                         /* And now skip until next word. */
  76                         while (*optstr == ' ' && *optstr != '\0')
  77                                 optstr++;
  78                 }
  79         }
  80
  81         /* If the key was found; copy its value to the target buffer. */
  82         if (found) {
  83                 const char *lastbuf;
  84
  85                 lastbuf = buf + (bufsize - 1);
  86
  87                 optstr++; /* Skip '='. */
  88                 while (buf != lastbuf && *optstr != ' ' && *optstr != '\0')
  89                         *buf++ = *optstr++;
  90                 *buf = '\0';
  91         }
  92
  93         return found;
  94 }