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) 1996-2014 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, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #include <langinfo.h>
  21 #include <stdlib.h>
  22 #include <regex.h>
  23
  24
  25 int
  26 rpmatch (response)
  27      const char *response;
  28 {
  29   /* Match against one of the response patterns, compiling the pattern
  30      first if necessary.  */
  31   auto int try (const int tag, const int match, const int nomatch,
  32                 const char **lastp, regex_t *re);
  33
  34   int try (const int tag, const int match, const int nomatch,
  35            const char **lastp, regex_t *re)
  36     {
  37       const char *pattern = nl_langinfo (tag);
  38       if (pattern != *lastp)
  39         {
  40           /* The pattern has changed.  */
  41           if (*lastp)
  42             {
  43               /* Free the old compiled pattern.  */
  44               __regfree (re);
  45               *lastp = NULL;
  46             }
  47           /* Compile the pattern and cache it for future runs.  */
  48           if (__regcomp (re, pattern, REG_EXTENDED) != 0)
  49             return -1;
  50           *lastp = pattern;
  51         }
  52
  53       /* Try the pattern.  */
  54       return __regexec (re, response, 0, NULL, 0) == 0 ? match : nomatch;
  55     }
  56
  57   /* We cache the response patterns and compiled regexps here.  */
  58   static const char *yesexpr, *noexpr;
  59   static regex_t yesre, nore;
  60
  61   return (try (YESEXPR, 1, 0, &yesexpr, &yesre) ?:
  62           try (NOEXPR, 0, -1, &noexpr, &nore));
  63 }