lib/c-strtod.c

   1 /* Convert string to double, using the C locale.
   2
   3    Copyright (C) 2003-2004, 2006, 2009-2018 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 #else
  34 # define C_STRTOD c_strtod
  35 # define DOUBLE double
  36 # define STRTOD_L strtod_l
  37 #endif
  38
  39 /* c_strtold falls back on strtod if strtold doesn't conform to C99.  */
  40 #if LONG && HAVE_C99_STRTOLD
  41 # define STRTOD strtold
  42 #else
  43 # define STRTOD strtod
  44 #endif
  45
  46 #if defined LC_ALL_MASK && (LONG ? HAVE_STRTOLD_L : HAVE_STRTOD_L)
  47
  48 /* Cache for the C locale object.
  49    Marked volatile so that different threads see the same value
  50    (avoids locking).  */
  51 static volatile locale_t c_locale_cache;
  52
  53 /* Return the C locale object, or (locale_t) 0 with errno set
  54    if it cannot be created.  */
  55 static locale_t
  56 c_locale (void)
  57 {
  58   if (!c_locale_cache)
  59     c_locale_cache = newlocale (LC_ALL_MASK, "C", (locale_t) 0);
  60   return c_locale_cache;
  61 }
  62
  63 #endif
  64
  65 DOUBLE
  66 C_STRTOD (char const *nptr, char **endptr)
  67 {
  68   DOUBLE r;
  69
  70 #if defined LC_ALL_MASK && (LONG ? HAVE_STRTOLD_L : HAVE_STRTOD_L)
  71
  72   locale_t locale = c_locale ();
  73   if (!locale)
  74     {
  75       if (endptr)
  76         *endptr = (char *) nptr;
  77       return 0; /* errno is set here */
  78     }
  79
  80   r = STRTOD_L (nptr, endptr, locale);
  81
  82 #else
  83
  84   char *saved_locale = setlocale (LC_NUMERIC, NULL);
  85
  86   if (saved_locale)
  87     {
  88       saved_locale = strdup (saved_locale);
  89       if (saved_locale == NULL)
  90         {
  91           if (endptr)
  92             *endptr = (char *) nptr;
  93           return 0; /* errno is set here */
  94         }
  95       setlocale (LC_NUMERIC, "C");
  96     }
  97
  98   r = STRTOD (nptr, endptr);
  99
 100   if (saved_locale)
 101     {
 102       int saved_errno = errno;
 103
 104       setlocale (LC_NUMERIC, saved_locale);
 105       free (saved_locale);
 106       errno = saved_errno;
 107     }
 108
 109 #endif
 110
 111   return r;
 112 }