lib/getsubopt.c

   1 /* Parse comma separated list into words.
   2    Copyright (C) 1996-1997, 1999, 2004, 2007, 2009-2020 Free Software
   3    Foundation, Inc.
   4    This file is part of the GNU C Library.
   5    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.
   6
   7    This program is free software: you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  19
  20 #if !_LIBC
  21 # include <config.h>
  22 #endif
  23
  24 #include <stdlib.h>
  25 #include <string.h>
  26
  27 #if !_LIBC
  28 /* This code is written for inclusion in gnu-libc, and uses names in
  29    the namespace reserved for libc.  If we're compiling in gnulib,
  30    define those names to be the normal ones instead.  */
  31 # undef __strchrnul
  32 # define __strchrnul strchrnul
  33 #endif
  34
  35 /* Parse comma separated suboption from *OPTIONP and match against
  36    strings in TOKENS.  If found return index and set *VALUEP to
  37    optional value introduced by an equal sign.  If the suboption is
  38    not part of TOKENS return in *VALUEP beginning of unknown
  39    suboption.  On exit *OPTIONP is set to the beginning of the next
  40    token or at the terminating NUL character.  */
  41 int
  42 getsubopt (char **optionp, char *const *tokens, char **valuep)
  43 {
  44   char *endp, *vstart;
  45   int cnt;
  46
  47   if (**optionp == '\0')
  48     return -1;
  49
  50   /* Find end of next token.  */
  51   endp = __strchrnul (*optionp, ',');
  52
  53   /* Find start of value.  */
  54   vstart = memchr (*optionp, '=', endp - *optionp);
  55   if (vstart == NULL)
  56     vstart = endp;
  57
  58   /* Try to match the characters between *OPTIONP and VSTART against
  59      one of the TOKENS.  */
  60   for (cnt = 0; tokens[cnt] != NULL; ++cnt)
  61     if (strncmp (*optionp, tokens[cnt], vstart - *optionp) == 0
  62         && tokens[cnt][vstart - *optionp] == '\0')
  63       {
  64         /* We found the current option in TOKENS.  */
  65         *valuep = vstart != endp ? vstart + 1 : NULL;
  66
  67         if (*endp != '\0')
  68           *endp++ = '\0';
  69         *optionp = endp;
  70
  71         return cnt;
  72       }
  73
  74   /* The current suboption does not match any option.  */
  75   *valuep = *optionp;
  76
  77   if (*endp != '\0')
  78     *endp++ = '\0';
  79   *optionp = endp;
  80
  81   return -1;
  82 }