1/* error-checking interface to strtod-like functions
2
3   Copyright (C) 1996, 1999, 2000, 2003, 2004 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 2, or (at your option)
8   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, write to the Free Software Foundation,
17   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
18
19/* Written by Jim Meyering.  */
20
21#ifdef HAVE_CONFIG_H
22# include <config.h>
23#endif
24
25#include "xstrtod.h"
26
27#include <errno.h>
28#include <limits.h>
29#include <stdio.h>
30
31/* Tell the compiler that non-default rounding modes are used.  */
32#if 199901 <= __STDC_VERSION__
33 #pragma STDC FENV_ACCESS ON
34#endif
35
36/* An interface to strtod that encapsulates all the error checking
37   one should usually perform.  Like strtod, but upon successful
38   conversion put the result in *RESULT and return true.  Return
39   false and don't modify *RESULT upon any failure.  CONVERT
40   specifies the conversion function, e.g., strtod itself.  */
41
42bool
43xstrtod (char const *str, char const **ptr, double *result,
44	 double (*convert) (char const *, char **))
45{
46  double val;
47  char *terminator;
48  bool ok = true;
49
50  errno = 0;
51  val = convert (str, &terminator);
52
53  /* Having a non-zero terminator is an error only when PTR is NULL. */
54  if (terminator == str || (ptr == NULL && *terminator != '\0'))
55    ok = false;
56  else
57    {
58      /* Allow underflow (in which case strtod returns zero),
59	 but flag overflow as an error. */
60      if (val != 0.0 && errno == ERANGE)
61	ok = false;
62    }
63
64  if (ptr != NULL)
65    *ptr = terminator;
66
67  *result = val;
68  return ok;
69}
70