stdlib/getsubopt.c

   1 /* getsubopt -- parse comma separate list into words
   2 Copyright (C) 1996 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 Library General Public License as
   8 published by the Free Software Foundation; either version 2 of the
   9 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 Library General Public License for more details.
  15
  16 You should have received a copy of the GNU Library General Public
  17 License along with the GNU C Library; see the file COPYING.LIB.  If
  18 not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19 Boston, MA 02111-1307, USA.  */
  20
  21 #include <stdlib.h>
  22 #include <string.h>
  23
  24
  25 /* Parse comma separated suboption from *OPTIONP and match against
  26    strings in TOKENS.  If found return index and set *VALUEP to
  27    optional value introduced by an equal sign.  If the suboption is
  28    not part of TOKENS return in *VALUEP beginning of unknown
  29    suboption.  On exit *OPTIONP is set to the beginning of the next
  30    otken or at the terminating NUL character.  */
  31 int
  32 getsubopt (optionp, tokens, valuep)
  33      char **optionp;
  34      const char *const *tokens;
  35      char **valuep;
  36 {
  37   char *endp, *vstart;
  38   int cnt;
  39
  40   if (**optionp == '\0')
  41     return -1;
  42
  43   /* Find end of next token.  */
  44   endp = strchr (*optionp, ',');
  45   if (endp == NULL)
  46     endp = strchr (*optionp, '\0');
  47
  48   /* Find start of value.  */
  49   vstart = memchr (*optionp, '=', endp - *optionp);
  50   if (vstart == NULL)
  51     vstart = endp;
  52
  53   /* Try to match the characters between *OPTIONP and VSTART against
  54      one of the TOKENS.  */
  55   for (cnt = 0; tokens[cnt] != NULL; ++cnt)
  56     if (memcmp (*optionp, tokens[cnt], vstart - *optionp) == 0
  57         && tokens[cnt][vstart - *optionp] == '\0')
  58       {
  59         /* We found the current option in TOKENS.  */
  60         *valuep = vstart != endp ? vstart : NULL;
  61
  62         if (*endp != '\0')
  63           *endp++ = '\0';
  64         *optionp = endp;
  65
  66         return cnt;
  67       }
  68
  69   /* The current suboption does not match any option.  */
  70   *valuep = *optionp;
  71
  72   if (*endp != '\0')
  73     *endp++ = '\0';
  74   *optionp = endp;
  75
  76   return -1;
  77 }