1  /* Convert string to double, using the C locale.
       2  
       3     Copyright (C) 2003-2004, 2006, 2009-2023 Free Software Foundation, Inc.
       4  
       5     This program is free software: you can redistribute it and/or modify
       6     it under the terms of the GNU General Public License as published by
       7     the Free Software Foundation, either version 3 of the License, or
       8     (at your option) any later version.
       9  
      10     This program is distributed in the hope that it will be useful,
      11     but WITHOUT ANY WARRANTY; without even the implied warranty of
      12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      13     GNU General Public License for more details.
      14  
      15     You should have received a copy of the GNU General Public License
      16     along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
      17  
      18  /* Written by Paul Eggert.  */
      19  
      20  #include <config.h>
      21  
      22  #include "c-strtod.h"
      23  
      24  #include <errno.h>
      25  #include <locale.h>
      26  #include <stdlib.h>
      27  #include <string.h>
      28  
      29  #if LONG
      30  # define C_STRTOD c_strtold
      31  # define DOUBLE long double
      32  # define STRTOD_L strtold_l
      33  # define HAVE_GOOD_STRTOD_L (HAVE_STRTOLD_L && !GNULIB_defined_strtold_function)
      34  # define STRTOD strtold
      35  #else
      36  # define C_STRTOD c_strtod
      37  # define DOUBLE double
      38  # define STRTOD_L strtod_l
      39  # define HAVE_GOOD_STRTOD_L (HAVE_STRTOD_L && !GNULIB_defined_strtod_function)
      40  # define STRTOD strtod
      41  #endif
      42  
      43  #if defined LC_ALL_MASK \
      44      && ((LONG ? HAVE_GOOD_STRTOLD_L : HAVE_GOOD_STRTOD_L) \
      45          || HAVE_WORKING_USELOCALE)
      46  
      47  /* Cache for the C locale object.
      48     Marked volatile so that different threads see the same value
      49     (avoids locking).  */
      50  static volatile locale_t c_locale_cache;
      51  
      52  /* Return the C locale object, or (locale_t) 0 with errno set
      53     if it cannot be created.  */
      54  static locale_t
      55  c_locale (void)
      56  {
      57    if (!c_locale_cache)
      58      c_locale_cache = newlocale (LC_ALL_MASK, "C", (locale_t) 0);
      59    return c_locale_cache;
      60  }
      61  
      62  #endif
      63  
      64  DOUBLE
      65  C_STRTOD (char const *nptr, char **endptr)
      66  {
      67    DOUBLE r;
      68  
      69  #if defined LC_ALL_MASK \
      70      && ((LONG ? HAVE_GOOD_STRTOLD_L : HAVE_GOOD_STRTOD_L) \
      71          || HAVE_WORKING_USELOCALE)
      72  
      73    locale_t locale = c_locale ();
      74    if (!locale)
      75      {
      76        if (endptr)
      77          *endptr = (char *) nptr;
      78        return 0; /* errno is set here */
      79      }
      80  
      81  # if (LONG ? HAVE_GOOD_STRTOLD_L : HAVE_GOOD_STRTOD_L)
      82  
      83    r = STRTOD_L (nptr, endptr, locale);
      84  
      85  # else /* HAVE_WORKING_USELOCALE */
      86  
      87    locale_t old_locale = uselocale (locale);
      88    if (old_locale == (locale_t)0)
      89      {
      90        if (endptr)
      91          *endptr = (char *) nptr;
      92        return 0; /* errno is set here */
      93      }
      94  
      95    r = STRTOD (nptr, endptr);
      96  
      97    int saved_errno = errno;
      98    if (uselocale (old_locale) == (locale_t)0)
      99      /* We can't switch back to the old locale.  The thread is hosed.  */
     100      abort ();
     101    errno = saved_errno;
     102  
     103  # endif
     104  
     105  #else
     106  
     107    char *saved_locale = setlocale (LC_NUMERIC, NULL);
     108  
     109    if (saved_locale)
     110      {
     111        saved_locale = strdup (saved_locale);
     112        if (saved_locale == NULL)
     113          {
     114            if (endptr)
     115              *endptr = (char *) nptr;
     116            return 0; /* errno is set here */
     117          }
     118        setlocale (LC_NUMERIC, "C");
     119      }
     120  
     121    r = STRTOD (nptr, endptr);
     122  
     123    if (saved_locale)
     124      {
     125        int saved_errno = errno;
     126  
     127        setlocale (LC_NUMERIC, saved_locale);
     128        free (saved_locale);
     129        errno = saved_errno;
     130      }
     131  
     132  #endif
     133  
     134    return r;
     135  }