lib/strtol.c

   1 /* Copyright (C) 1989, 1990, 1991 Free Software Foundation, Inc.
   2      Written by James Clark (jjc@jclark.uucp)
   3
   4 This file is part of groff.
   5
   6 groff is free software; you can redistribute it and/or modify it under
   7 the terms of the GNU General Public License as published by the Free
   8 Software Foundation; either version 1, or (at your option) any later
   9 version.
  10
  11 groff is distributed in the hope that it will be useful, but WITHOUT ANY
  12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14 for more details.
  15
  16 You should have received a copy of the GNU General Public License along
  17 with groff; see the file LICENSE.  If not, write to the Free Software
  18 Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
  19
  20 #include <string.h>
  21 #include <ctype.h>
  22 #include <errno.h>
  23
  24 /* Not everybody has limits.h. Sigh. */
  25
  26 #include "lib.h"
  27 #ifndef LONG_MAX
  28 #define LONG_MAX INT_MAX
  29 #endif
  30 #ifndef LONG_MIN
  31 #define LONG_MIN INT_MIN
  32 #endif
  33
  34 long strtol(str, ptr, base)
  35      char *str, **ptr;
  36      int base;
  37 {
  38   char *start = str;
  39   int neg = 0;
  40   long val;
  41   char *p;
  42   static char digits[] = "0123456789abcdefghijklmnopqrstuvwxyz";
  43
  44   while (isascii(*str) && isspace(*str))
  45     str++;
  46
  47   if (*str == '-') {
  48     neg = 1;
  49     str++;
  50   }
  51   if (base == 0) {
  52     if (*str == '0') {
  53       if (str[1] == 'x' || str[1] == 'X') {
  54         str += 2;
  55         base = 16;
  56       }
  57       else
  58         base = 8;
  59     }
  60     else
  61       base = 10;
  62   }
  63   if (base < 2 || base > 36)
  64     base = 10;
  65   else if (base == 16 && *str == '0' && (str[1] == 'x' || str[1] == 'X'))
  66     str += 2;
  67
  68   p = strchr(digits, isascii(*str) && isupper(*str) ? tolower(*str) : *str);
  69   if (p == 0 || (val = (p - digits)) >= base) {
  70     if (base == 16 && str > start && (str[-1] == 'x' || str[-1] == 'X')) {
  71       if (ptr)
  72         *ptr = str - 1;
  73     }
  74     else {
  75       if (ptr)
  76         *ptr = start;
  77       errno = ERANGE;
  78     }
  79     return 0;
  80   }
  81   if (neg)
  82     val = -val;
  83
  84   while (*++str != '\0') {
  85     int n;
  86
  87     p = strchr(digits, isascii(*str) && isupper(*str) ? tolower(*str) : *str);
  88     if (p == 0)
  89       break;
  90     n = p - digits;
  91     if (n >= base)
  92       break;
  93     if (neg) {
  94       if (-(unsigned long)val > (-(unsigned long)LONG_MIN - n)/base) {
  95         val = LONG_MIN;
  96         errno = ERANGE;
  97       }
  98       else
  99         val = val*base - n;
 100     }
 101     else {
 102       if (val > (LONG_MAX - n)/base) {
 103         val = LONG_MAX;
 104         errno = ERANGE;
 105       }
 106       else
 107         val = val*base + n;
 108     }
 109   }
 110
 111   if (ptr)
 112     *ptr = str;
 113
 114   return val;
 115 }