stdlib/FreeBSD/strtol.c

   1 /*-
   2  * Copyright (c) 1990, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 4. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  */
  29
  30 #if defined(LIBC_SCCS) && !defined(lint)
  31 static char sccsid[] = "@(#)strtol.c    8.1 (Berkeley) 6/4/93";
  32 #endif /* LIBC_SCCS and not lint */
  33 #include <sys/cdefs.h>
  34 __FBSDID("$FreeBSD: src/lib/libc/stdlib/strtol.c,v 1.20 2007/01/09 00:28:10 imp Exp $");
  35
  36 #include <limits.h>
  37 #include <ctype.h>
  38 #include <errno.h>
  39 #include <stdlib.h>
  40
  41
  42 /*
  43  * Convert a string to a long integer.
  44  *
  45  * Assumes that the upper and lower case
  46  * alphabets and digits are each contiguous.
  47  */
  48 long
  49 strtol(const char * __restrict nptr, char ** __restrict endptr, int base)
  50 {
  51         const char *s;
  52         unsigned long acc;
  53         char c;
  54         unsigned long cutoff;
  55         int neg, any, cutlim;
  56
  57         /*
  58          * Skip white space and pick up leading +/- sign if any.
  59          * If base is 0, allow 0x for hex and 0 for octal, else
  60          * assume decimal; if base is already 16, allow 0x.
  61          */
  62         s = nptr;
  63         do {
  64                 c = *s++;
  65         } while (isspace((unsigned char)c));
  66         if (c == '-') {
  67                 neg = 1;
  68                 c = *s++;
  69         } else {
  70                 neg = 0;
  71                 if (c == '+')
  72                         c = *s++;
  73         }
  74         if ((base == 0 || base == 16) &&
  75             c == '0' && (*s == 'x' || *s == 'X') &&
  76             ((s[1] >= '0' && s[1] <= '9') ||
  77             (s[1] >= 'A' && s[1] <= 'F') ||
  78             (s[1] >= 'a' && s[1] <= 'f'))) {
  79                 c = s[1];
  80                 s += 2;
  81                 base = 16;
  82         }
  83         if (base == 0)
  84                 base = c == '0' ? 8 : 10;
  85         acc = any = 0;
  86         if (base < 2 || base > 36)
  87                 goto noconv;
  88
  89         /*
  90          * Compute the cutoff value between legal numbers and illegal
  91          * numbers.  That is the largest legal value, divided by the
  92          * base.  An input number that is greater than this value, if
  93          * followed by a legal input character, is too big.  One that
  94          * is equal to this value may be valid or not; the limit
  95          * between valid and invalid numbers is then based on the last
  96          * digit.  For instance, if the range for longs is
  97          * [-2147483648..2147483647] and the input base is 10,
  98          * cutoff will be set to 214748364 and cutlim to either
  99          * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated
 100          * a value > 214748364, or equal but the next digit is > 7 (or 8),
 101          * the number is too big, and we will return a range error.
 102          *
 103          * Set 'any' if any `digits' consumed; make it negative to indicate
 104          * overflow.
 105          */
 106         cutoff = neg ? (unsigned long)-(LONG_MIN + LONG_MAX) + LONG_MAX
 107             : LONG_MAX;
 108         cutlim = cutoff % base;
 109         cutoff /= base;
 110         for ( ; ; c = *s++) {
 111                 if (c >= '0' && c <= '9')
 112                         c -= '0';
 113                 else if (c >= 'A' && c <= 'Z')
 114                         c -= 'A' - 10;
 115                 else if (c >= 'a' && c <= 'z')
 116                         c -= 'a' - 10;
 117                 else
 118                         break;
 119                 if (c >= base)
 120                         break;
 121                 if (any < 0 || acc > cutoff || (acc == cutoff && c > cutlim))
 122                         any = -1;
 123                 else {
 124                         any = 1;
 125                         acc *= base;
 126                         acc += c;
 127                 }
 128         }
 129         if (any < 0) {
 130                 acc = neg ? LONG_MIN : LONG_MAX;
 131                 errno = ERANGE;
 132         } else if (!any) {
 133 noconv:
 134                 errno = EINVAL;
 135         } else if (neg)
 136                 acc = -acc;
 137         if (endptr != NULL)
 138                 *endptr = (char *)(any ? s - 1 : nptr);
 139         return (acc);
 140 }