stdlib/getsubopt.c

   1 /* Parse comma separate list into words.
   2    Copyright (C) 1996-2020 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    <https://www.gnu.org/licenses/>.  */
  19
  20 #include <stdlib.h>
  21 #include <string.h>
  22
  23 #if !_LIBC
  24 /* This code is written for inclusion in gnu-libc, and uses names in
  25    the namespace reserved for libc.  If we're compiling in gnulib,
  26    define those names to be the normal ones instead.  */
  27 # include "strchrnul.h"
  28 # undef __strchrnul
  29 # define __strchrnul strchrnul
  30 #endif
  31
  32 /* Parse comma separated suboption from *OPTIONP and match against
  33    strings in TOKENS.  If found return index and set *VALUEP to
  34    optional value introduced by an equal sign.  If the suboption is
  35    not part of TOKENS return in *VALUEP beginning of unknown
  36    suboption.  On exit *OPTIONP is set to the beginning of the next
  37    token or at the terminating NUL character.  */
  38 int
  39 getsubopt (char **optionp, char *const *tokens, char **valuep)
  40 {
  41   char *endp, *vstart;
  42   int cnt;
  43
  44   if (**optionp == '\0')
  45     return -1;
  46
  47   /* Find end of next token.  */
  48   endp = __strchrnul (*optionp, ',');
  49
  50   /* Find start of value.  */
  51   vstart = memchr (*optionp, '=', endp - *optionp);
  52   if (vstart == NULL)
  53     vstart = endp;
  54
  55   /* Try to match the characters between *OPTIONP and VSTART against
  56      one of the TOKENS.  */
  57   for (cnt = 0; tokens[cnt] != NULL; ++cnt)
  58     if (strncmp (*optionp, tokens[cnt], vstart - *optionp) == 0
  59         && tokens[cnt][vstart - *optionp] == '\0')
  60       {
  61         /* We found the current option in TOKENS.  */
  62         *valuep = vstart != endp ? vstart + 1 : NULL;
  63
  64         if (*endp != '\0')
  65           *endp++ = '\0';
  66         *optionp = endp;
  67
  68         return cnt;
  69       }
  70
  71   /* The current suboption does not match any option.  */
  72   *valuep = *optionp;
  73
  74   if (*endp != '\0')
  75     *endp++ = '\0';
  76   *optionp = endp;
  77
  78   return -1;
  79 }