1  /* error-checking interface to strtod-like functions
       2  
       3     Copyright (C) 1996, 1999-2000, 2003-2006, 2009-2023 Free Software
       4     Foundation, Inc.
       5  
       6     This program is free software: you can redistribute it and/or modify
       7     it under the terms of the GNU General Public License as published by
       8     the Free Software Foundation, either version 3 of the License, or
       9     (at your option) any later version.
      10  
      11     This program 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
      14     GNU General Public License for more details.
      15  
      16     You should have received a copy of the GNU General Public License
      17     along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
      18  
      19  /* Written by Jim Meyering.  */
      20  
      21  #include <config.h>
      22  
      23  #include "xstrtod.h"
      24  
      25  #include <errno.h>
      26  #include <limits.h>
      27  #include <stdio.h>
      28  
      29  #if LONG
      30  # define XSTRTOD xstrtold
      31  # define DOUBLE long double
      32  #else
      33  # define XSTRTOD xstrtod
      34  # define DOUBLE double
      35  #endif
      36  
      37  /* An interface to a string-to-floating-point conversion function that
      38     encapsulates all the error checking one should usually perform.
      39     Like strtod/strtold, but stores the conversion in *RESULT,
      40     and returns true upon successful conversion.
      41     CONVERT specifies the conversion function, e.g., strtod itself.  */
      42  
      43  bool
      44  XSTRTOD (char const *str, char const **ptr, DOUBLE *result,
      45           DOUBLE (*convert) (char const *, char **))
      46  {
      47    DOUBLE val;
      48    char *terminator;
      49    bool ok = true;
      50  
      51    errno = 0;
      52    val = convert (str, &terminator);
      53  
      54    /* Having a non-zero terminator is an error only when PTR is NULL. */
      55    if (terminator == str || (ptr == NULL && *terminator != '\0'))
      56      ok = false;
      57    else
      58      {
      59        /* Allow underflow (in which case CONVERT returns zero),
      60           but flag overflow as an error.  The user can decide
      61           to use the limits in RESULT upon ERANGE.  */
      62        if (val != 0 && errno == ERANGE)
      63          ok = false;
      64      }
      65  
      66    if (ptr != NULL)
      67      *ptr = terminator;
      68  
      69    *result = val;
      70    return ok;
      71  }