glibc/stdlib/getsubopt.c

/* Parse comma separate list into words.
   Copyright (C) 1996, 1997 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public License as
   published by the Free Software Foundation; either version 2 of the
   License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with the GNU C Library; see the file COPYING.LIB.  If not,
   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#include <stdlib.h>
#include <string.h>


/* Parse comma separated suboption from *OPTIONP and match against
   strings in TOKENS.  If found return index and set *VALUEP to
   optional value introduced by an equal sign.  If the suboption is
   not part of TOKENS return in *VALUEP beginning of unknown
   suboption.  On exit *OPTIONP is set to the beginning of the next
   token or at the terminating NUL character.  */
int
getsubopt (optionp, tokens, valuep)
     char **optionp;
     const char *const *tokens;
     char **valuep;
{
  char *endp, *vstart;
  int cnt;

  if (**optionp == '\0')
    return -1;

  /* Find end of next token.  */
  endp = strchr (*optionp, ',');
  if (endp == NULL)
    endp = strchr (*optionp, '\0');

  /* Find start of value.  */
  vstart = memchr (*optionp, '=', endp - *optionp);
  if (vstart == NULL)
    vstart = endp;

  /* Try to match the characters between *OPTIONP and VSTART against
     one of the TOKENS.  */
  for (cnt = 0; tokens[cnt] != NULL; ++cnt)
    if (memcmp (*optionp, tokens[cnt], vstart - *optionp) == 0
	&& tokens[cnt][vstart - *optionp] == '\0')
      {
	/* We found the current option in TOKENS.  */
	*valuep = vstart != endp ? vstart + 1 : NULL;

	if (*endp != '\0')
	  *endp++ = '\0';
	*optionp = endp;

	return cnt;
      }

  /* The current suboption does not match any option.  */
  *valuep = *optionp;

  if (*endp != '\0')
    *endp++ = '\0';
  *optionp = endp;

  return -1;
}