libc/unistd/getsubopt.c

   1 /* Parse comma separate list into words.
   2    Copyright (C) 1996, 1997, 1999, 2004 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #include <stdlib.h>
  21 #include <string.h>
  22
  23
  24 /* Parse comma separated suboption from *OPTIONP and match against
  25    strings in TOKENS.  If found return index and set *VALUEP to
  26    optional value introduced by an equal sign.  If the suboption is
  27    not part of TOKENS return in *VALUEP beginning of unknown
  28    suboption.  On exit *OPTIONP is set to the beginning of the next
  29    token or at the terminating NUL character.  */
  30 int
  31 getsubopt (char **optionp, char *const *tokens, char **valuep)
  32 {
  33   char *endp, *vstart;
  34   int cnt;
  35
  36   if (**optionp == '\0')
  37     return -1;
  38
  39   /* Find end of next token.  */
  40   endp = strchrnul (*optionp, ',');
  41
  42   /* Find start of value.  */
  43   vstart = memchr (*optionp, '=', endp - *optionp);
  44   if (vstart == NULL)
  45     vstart = endp;
  46
  47   /* Try to match the characters between *OPTIONP and VSTART against
  48      one of the TOKENS.  */
  49   for (cnt = 0; tokens[cnt] != NULL; ++cnt)
  50     if (strncmp (*optionp, tokens[cnt], vstart - *optionp) == 0
  51         && tokens[cnt][vstart - *optionp] == '\0')
  52       {
  53         /* We found the current option in TOKENS.  */
  54         *valuep = vstart != endp ? vstart + 1 : NULL;
  55
  56         if (*endp != '\0')
  57           *endp++ = '\0';
  58         *optionp = endp;
  59
  60         return cnt;
  61       }
  62
  63   /* The current suboption does not match any option.  */
  64   *valuep = *optionp;
  65
  66   if (*endp != '\0')
  67     *endp++ = '\0';
  68   *optionp = endp;
  69
  70   return -1;
  71 }