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) 1996-2023 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     <https://www.gnu.org/licenses/>.  */
      19  
      20  #include <langinfo.h>
      21  #include <stdlib.h>
      22  #include <regex.h>
      23  
      24  
      25  /* Match against one of the response patterns, compiling the pattern
      26     first if necessary.  */
      27  static int
      28  try (const char *response,
      29       const int tag, const int match, const int nomatch,
      30       const char **lastp, regex_t *re)
      31  {
      32    const char *pattern = nl_langinfo (tag);
      33    if (pattern != *lastp)
      34      {
      35        /* The pattern has changed.  */
      36        if (*lastp != NULL)
      37          {
      38            /* Free the old compiled pattern.  */
      39            __regfree (re);
      40            *lastp = NULL;
      41          }
      42        /* Compile the pattern and cache it for future runs.  */
      43        if (__regcomp (re, pattern, REG_EXTENDED) != 0)
      44          return -1;
      45        *lastp = pattern;
      46      }
      47  
      48    /* Try the pattern.  */
      49    return __regexec (re, response, 0, NULL, 0) == 0 ? match : nomatch;
      50  }
      51  
      52  int
      53  rpmatch (const char *response)
      54  {
      55    /* We cache the response patterns and compiled regexps here.  */
      56    static const char *yesexpr, *noexpr;
      57    static regex_t yesre, nore;
      58  
      59    return (try (response, YESEXPR, 1, 0, &yesexpr, &yesre) ?:
      60  	  try (response, NOEXPR, 0, -1, &noexpr, &nore));
      61  }