stdlib/rpmatch.c

   1 /* Determine whether string value is affirmation or negative response
   2    according to current locale's data.
   3    This file is part of the GNU C Library.
   4    Copyright (C) 1996, 1997, 2000, 2003 Free Software Foundation, Inc.
   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, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21 #include <langinfo.h>
  22 #include <stdlib.h>
  23 #include <regex.h>
  24
  25
  26 int
  27 rpmatch (response)
  28      const char *response;
  29 {
  30   /* Match against one of the response patterns, compiling the pattern
  31      first if necessary.  */
  32   auto int try (const int tag, const int match, const int nomatch,
  33                 const char **lastp, regex_t *re);
  34
  35   int try (const int tag, const int match, const int nomatch,
  36            const char **lastp, regex_t *re)
  37     {
  38       const char *pattern = nl_langinfo (tag);
  39       if (pattern != *lastp)
  40         {
  41           /* The pattern has changed.  */
  42           if (*lastp)
  43             {
  44               /* Free the old compiled pattern.  */
  45               __regfree (re);
  46               *lastp = NULL;
  47             }
  48           /* Compile the pattern and cache it for future runs.  */
  49           if (__regcomp (re, pattern, REG_EXTENDED) != 0)
  50             return -1;
  51           *lastp = pattern;
  52         }
  53
  54       /* Try the pattern.  */
  55       return __regexec (re, response, 0, NULL, 0) == 0 ? match : nomatch;
  56     }
  57
  58   /* We cache the response patterns and compiled regexps here.  */
  59   static const char *yesexpr, *noexpr;
  60   static regex_t yesre, nore;
  61
  62   return (try (YESEXPR, 1, 0, &yesexpr, &yesre) ?:
  63           try (NOEXPR, 0, -1, &noexpr, &nore));
  64 }