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root/usr/lib/libc/stdlib/strtol.c

DEFINITIONS

1. strtol

   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. 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  */
  30 #include <limits.h>
  31 #include <ctype.h>
  32 #include <errno.h>
  33 #include <stdlib.h>
  36 /*
  37  * Convert a string to a long integer.
  38  *
  39  * Ignores `locale' stuff.  Assumes that the upper and lower case
  40  * alphabets and digits are each contiguous.
  41  */
  42 long
strtol(nptr, endptr, base)
  44         const char *nptr;
  45         char **endptr;
  46         int base;
  47 {
  48         const char *s;
  49         long acc, cutoff;
  50         int c;
  51         int neg, any, cutlim;
  53         /*
  54          * Skip white space and pick up leading +/- sign if any.
  55          * If base is 0, allow 0x for hex and 0 for octal, else
  56          * assume decimal; if base is already 16, allow 0x.
  57          */
s = nptr;
  59         do {
c = (unsigned char) *s++;
  61         } while (isspace(c));
  62         if (c == '-') {
neg = 1;
c = *s++;
  65         } else {
neg = 0;
  67                 if (c == '+')
c = *s++;
  69         }
  70         if ((base == 0 || base == 16) &&
c == '0' && (*s == 'x' || *s == 'X')) {
c = s[1];
s += 2;
base = 16;
  75         }
  76         if (base == 0)
base = c == '0' ? 8 : 10;
  79         /*
  80          * Compute the cutoff value between legal numbers and illegal
  81          * numbers.  That is the largest legal value, divided by the
  82          * base.  An input number that is greater than this value, if
  83          * followed by a legal input character, is too big.  One that
  84          * is equal to this value may be valid or not; the limit
  85          * between valid and invalid numbers is then based on the last
  86          * digit.  For instance, if the range for longs is
  87          * [-2147483648..2147483647] and the input base is 10,
  88          * cutoff will be set to 214748364 and cutlim to either
  89          * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated
  90          * a value > 214748364, or equal but the next digit is > 7 (or 8),
  91          * the number is too big, and we will return a range error.
  92          *
  93          * Set any if any `digits' consumed; make it negative to indicate
  94          * overflow.
  95          */
cutoff = neg ? LONG_MIN : LONG_MAX;
cutlim = (int)(cutoff % base);
cutoff /= base;
  99         if (neg) {
 100                 if (cutlim > 0) {
cutlim -= base;
cutoff += 1;
 103                 }
cutlim = -cutlim;
 105         }
 106         for (acc = 0, any = 0;; c = (unsigned char) *s++) {
 107                 if (isdigit(c))
c -= '0';
 109                 else if (isalpha(c))
c -= isupper(c) ? 'A' - 10 : 'a' - 10;
 111                 else
 112                         break;
 113                 if (c >= base)
 114                         break;
 115                 if (any < 0)
 116                         continue;
 117                 if (neg) {
 118                         if (acc < cutoff || (acc == cutoff && c > cutlim)) {
any = -1;
acc = LONG_MIN;
errno = ERANGE;
 122                         } else {
any = 1;
acc *= base;
acc -= c;
 126                         }
 127                 } else {
 128                         if (acc > cutoff || (acc == cutoff && c > cutlim)) {
any = -1;
acc = LONG_MAX;
errno = ERANGE;
 132                         } else {
any = 1;
acc *= base;
acc += c;
 136                         }
 137                 }
 138         }
 139         if (endptr != 0)
 140                 /* LINTED interface specification */
 141                 *endptr = (char *)(any ? s - 1 : nptr);
 142         return (acc);
 143 }