141 lines
4.1 KiB
C
141 lines
4.1 KiB
C
/* $OpenBSD: strtol.c,v 1.7 2005/08/08 08:05:37 espie Exp $ */
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/*-
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* Copyright (c) 1990 The Regents of the University of California.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <ctype.h>
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#include <errno.h>
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#include <limits.h>
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#include <stdlib.h>
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/*
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* Convert a string to a long integer.
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*
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* Ignores `locale' stuff. Assumes that the upper and lower case
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* alphabets and digits are each contiguous.
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*/
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long
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strtol(const char *nptr, char **endptr, int base)
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{
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const char *s;
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long acc, cutoff;
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int c;
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int neg, any, cutlim;
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/*
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* Skip white space and pick up leading +/- sign if any.
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* If base is 0, allow 0x for hex and 0 for octal, else
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* assume decimal; if base is already 16, allow 0x.
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*/
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s = nptr;
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do {
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c = (unsigned char) *s++;
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} while (isspace(c));
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if (c == '-') {
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neg = 1;
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c = *s++;
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} else {
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neg = 0;
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if (c == '+')
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c = *s++;
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}
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if ((base == 0 || base == 16) &&
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c == '0' && (*s == 'x' || *s == 'X')) {
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c = s[1];
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s += 2;
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base = 16;
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}
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if (base == 0)
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base = c == '0' ? 8 : 10;
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/*
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* Compute the cutoff value between legal numbers and illegal
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* numbers. That is the largest legal value, divided by the
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* base. An input number that is greater than this value, if
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* followed by a legal input character, is too big. One that
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* is equal to this value may be valid or not; the limit
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* between valid and invalid numbers is then based on the last
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* digit. For instance, if the range for longs is
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* [-2147483648..2147483647] and the input base is 10,
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* cutoff will be set to 214748364 and cutlim to either
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* 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated
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* a value > 214748364, or equal but the next digit is > 7 (or 8),
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* the number is too big, and we will return a range error.
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*
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* Set any if any `digits' consumed; make it negative to indicate
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* overflow.
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*/
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cutoff = neg ? LONG_MIN : LONG_MAX;
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cutlim = cutoff % base;
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cutoff /= base;
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if (neg) {
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if (cutlim > 0) {
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cutlim -= base;
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cutoff += 1;
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}
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cutlim = -cutlim;
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}
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for (acc = 0, any = 0;; c = (unsigned char) *s++) {
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if (isdigit(c))
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c -= '0';
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else if (isalpha(c))
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c -= isupper(c) ? 'A' - 10 : 'a' - 10;
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else
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break;
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if (c >= base)
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break;
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if (any < 0)
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continue;
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if (neg) {
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if (acc < cutoff || (acc == cutoff && c > cutlim)) {
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any = -1;
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acc = LONG_MIN;
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errno = ERANGE;
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} else {
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any = 1;
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acc *= base;
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acc -= c;
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}
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} else {
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if (acc > cutoff || (acc == cutoff && c > cutlim)) {
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any = -1;
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acc = LONG_MAX;
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errno = ERANGE;
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} else {
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any = 1;
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acc *= base;
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acc += c;
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}
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}
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}
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if (endptr != 0)
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*endptr = (char *) (any ? s - 1 : nptr);
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return (acc);
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}
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