glibc/stdlib/rpmatch.c

/* Determine whether string value is affirmation or negative response
   according to current locale's data.
   This file is part of the GNU C Library.
   Copyright (C) 1996-2013 Free Software Foundation, Inc.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 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
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <http://www.gnu.org/licenses/>.  */

#include <langinfo.h>
#include <stdlib.h>
#include <regex.h>


int
rpmatch (response)
     const char *response;
{
  /* Match against one of the response patterns, compiling the pattern
     first if necessary.  */
  auto int try (const int tag, const int match, const int nomatch,
		const char **lastp, regex_t *re);

  int try (const int tag, const int match, const int nomatch,
	   const char **lastp, regex_t *re)
    {
      const char *pattern = nl_langinfo (tag);
      if (pattern != *lastp)
	{
	  /* The pattern has changed.  */
	  if (*lastp)
	    {
	      /* Free the old compiled pattern.  */
	      __regfree (re);
	      *lastp = NULL;
	    }
	  /* Compile the pattern and cache it for future runs.  */
	  if (__regcomp (re, pattern, REG_EXTENDED) != 0)
	    return -1;
	  *lastp = pattern;
	}

      /* Try the pattern.  */
      return __regexec (re, response, 0, NULL, 0) == 0 ? match : nomatch;
    }

  /* We cache the response patterns and compiled regexps here.  */
  static const char *yesexpr, *noexpr;
  static regex_t yesre, nore;

  return (try (YESEXPR, 1, 0, &yesexpr, &yesre) ?:
	  try (NOEXPR, 0, -1, &noexpr, &nore));
}