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  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 #if defined(LIBC_SCCS) && !defined(lint)
  35 static char sccsid[] = "@(#)strtol.c    8.1 (Berkeley) 6/4/93";
  36 #endif /* LIBC_SCCS and not lint */
  37 #include <sys/cdefs.h>
  38 __FBSDID("$FreeBSD: src/lib/libc/stdlib/strtol.c,v 1.17 2002/09/06 11:23:59 tjr Exp $");
  39
  40 #include <limits.h>
  41 #include <ctype.h>
  42 #include <errno.h>
  43 #include <stdlib.h>
  44
  45
  46 /*
  47  * Convert a string to a long integer.
  48  *
  49  * Assumes that the upper and lower case
  50  * alphabets and digits are each contiguous.
  51  */
  52 long
  53 strtol(const char * __restrict nptr, char ** __restrict endptr, int base)
  54 {
  55         const char *s;
  56         unsigned long acc;
  57         char c;
  58         unsigned long cutoff;
  59         int neg, any, cutlim;
  60
  61         /*
  62          * Skip white space and pick up leading +/- sign if any.
  63          * If base is 0, allow 0x for hex and 0 for octal, else
  64          * assume decimal; if base is already 16, allow 0x.
  65          */
  66         s = nptr;
  67         do {
  68                 c = *s++;
  69         } while (isspace((unsigned char)c));
  70         if (c == '-') {
  71                 neg = 1;
  72                 c = *s++;
  73         } else {
  74                 neg = 0;
  75                 if (c == '+')
  76                         c = *s++;
  77         }
  78         if ((base == 0 || base == 16) &&
  79             c == '0' && (*s == 'x' || *s == 'X')) {
  80                 c = s[1];
  81                 s += 2;
  82                 base = 16;
  83         }
  84         if (base == 0)
  85                 base = c == '0' ? 8 : 10;
  86         acc = any = 0;
  87         if (base < 2 || base > 36)
  88                 goto noconv;
  89
  90         /*
  91          * Compute the cutoff value between legal numbers and illegal
  92          * numbers.  That is the largest legal value, divided by the
  93          * base.  An input number that is greater than this value, if
  94          * followed by a legal input character, is too big.  One that
  95          * is equal to this value may be valid or not; the limit
  96          * between valid and invalid numbers is then based on the last
  97          * digit.  For instance, if the range for longs is
  98          * [-2147483648..2147483647] and the input base is 10,
  99          * cutoff will be set to 214748364 and cutlim to either
 100          * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated
 101          * a value > 214748364, or equal but the next digit is > 7 (or 8),
 102          * the number is too big, and we will return a range error.
 103          *
 104          * Set 'any' if any `digits' consumed; make it negative to indicate
 105          * overflow.
 106          */
 107         cutoff = neg ? (unsigned long)-(LONG_MIN + LONG_MAX) + LONG_MAX
 108             : LONG_MAX;
 109         cutlim = cutoff % base;
 110         cutoff /= base;
 111         for ( ; ; c = *s++) {
 112                 if (c >= '0' && c <= '9')
 113                         c -= '0';
 114                 else if (c >= 'A' && c <= 'Z')
 115                         c -= 'A' - 10;
 116                 else if (c >= 'a' && c <= 'z')
 117                         c -= 'a' - 10;
 118                 else
 119                         break;
 120                 if (c >= base)
 121                         break;
 122                 if (any < 0 || acc > cutoff || (acc == cutoff && c > cutlim))
 123                         any = -1;
 124                 else {
 125                         any = 1;
 126                         acc *= base;
 127                         acc += c;
 128                 }
 129         }
 130         if (any < 0) {
 131                 acc = neg ? LONG_MIN : LONG_MAX;
 132                 errno = ERANGE;
 133         } else if (!any) {
 134 noconv:
 135                 errno = EINVAL;
 136         } else if (neg)
 137                 acc = -acc;
 138         if (endptr != NULL)
 139                 *endptr = (char *)(any ? s - 1 : nptr);
 140         return (acc);
 141 }