gnu/libexec/uucp/libuucp/strtol.c

/* Copyright (C) 1991 Free Software Foundation, Inc.
This file is part of the GNU C Library.

The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.

The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Library General Public License for more details.

You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB.  If
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
Cambridge, MA 02139, USA.

This file was modified slightly by Ian Lance Taylor, May 1992, for
Taylor UUCP.  */

#include "uucp.h"

#include <ctype.h>
#include <errno.h>

#if HAVE_LIMITS_H
#include <limits.h>
#else
#define ULONG_MAX 4294967295
#define LONG_MIN (- LONG_MAX - 1)
#define LONG_MAX 2147483647
#endif

#ifndef UNSIGNED
#define UNSIGNED        0
#endif

/* Convert NPTR to an `unsigned long int' or `long int' in base BASE.
   If BASE is 0 the base is determined by the presence of a leading
   zero, indicating octal or a leading "0x" or "0X", indicating hexadecimal.
   If BASE is < 2 or > 36, it is reset to 10.
   If ENDPTR is not NULL, a pointer to the character after the last
   one converted is stored in *ENDPTR.  */
#if     UNSIGNED
unsigned long int
#define strtol  strtoul
#else
long int
#endif
strtol (nptr, endptr, base)
     const char *nptr;
     char **endptr;
     int base;
{
  int negative;
  register unsigned long int cutoff;
  register unsigned int cutlim;
  register unsigned long int i;
  register const char *s;
  register unsigned int c;
  const char *save;
  int overflow;

  if (base < 0 || base == 1 || base > 36)
    base = 10;

  s = nptr;

  /* Skip white space.  */
  while (isspace(BUCHAR (*s)))
    ++s;
  if (*s == '\0')
    goto noconv;

  /* Check for a sign.  */
  if (*s == '-')
    {
      negative = 1;
      ++s;
    }
  else if (*s == '+')
    {
      negative = 0;
      ++s;
    }
  else
    negative = 0;

  if (base == 16
      && s[0] == '0'
      && (s[1] == 'x' || s[1] == 'X'))
    s += 2;

  /* If BASE is zero, figure it out ourselves.  */
  if (base == 0)
    if (*s == '0')
      {
        if (s[1] == 'x' || s[1] == 'X')
          {
            s += 2;
            base = 16;
          }
        else
          base = 8;
      }
    else
      base = 10;

  /* Save the pointer so we can check later if anything happened.  */
  save = s;

  cutoff = ULONG_MAX / (unsigned long int) base;
  cutlim = ULONG_MAX % (unsigned long int) base;

  overflow = 0;
  i = 0;
  for (c = BUCHAR (*s); c != '\0'; c = BUCHAR (*++s))
    {
      if (isdigit(c))
        c -= '0';
      else if (islower(c))
        c = c - 'a' + 10;
      else if (isupper(c))
        c = c - 'A' + 10;
      else
        break;
      if (c >= base)
        break;
      /* Check for overflow.  */
      if (i > cutoff || (i == cutoff && c > cutlim))
        overflow = 1;
      else
        {
          i *= (unsigned long int) base;
          i += c;
        }
    }

  /* Check if anything actually happened.  */
  if (s == save)
    goto noconv;

  /* Store in ENDPTR the address of one character
     past the last character we converted.  */
  if (endptr != NULL)
    *endptr = (char *) s;

#if     !UNSIGNED
  /* Check for a value that is within the range of
     `unsigned long int', but outside the range of `long int'.  */
  if (i > (negative ?
           - (unsigned long int) LONG_MIN : (unsigned long int) LONG_MAX))
    overflow = 1;
#endif

  if (overflow)
    {
      errno = ERANGE;
#if     UNSIGNED
      return ULONG_MAX;
#else
      return negative ? LONG_MIN : LONG_MAX;
#endif
    }

  /* Return the result of the appropriate sign.  */
  return (negative ? - i : i);

 noconv:
  /* There was no number to convert.  */
  if (endptr != NULL)
    *endptr = (char *) nptr;
  return 0L;
}