strtoll.c

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/*-
 * Copyright (c) 1992, 1993
 *  The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <limits.h>
#include <errno.h>
#include <ctype.h>
#include <stdlib.h>

#ifndef LLONG_MAX
#define LLONG_MAX     0x7FFFFFFFFFFFFFFFLL
#define LLONG_MIN     (-0x7FFFFFFFFFFFFFFFLL - 1)
#endif

/*
 * Convert a string to a long long integer.
 *
 * Assumes that the upper and lower case
 * alphabets and digits are each contiguous.
 */
long long
strtoll(const char * __restrict nptr, char ** __restrict endptr, int base)
{
    const char *s;
    unsigned long long acc;
    char c;
    unsigned long long cutoff;
    int neg, any, cutlim;

    /*
     * Skip white space and pick up leading +/- sign if any.
     * If base is 0, allow 0x for hex and 0 for octal, else
     * assume decimal; if base is already 16, allow 0x.
     */
    s = nptr;
    do {
        c = *s++;
    } while (isspace((unsigned char)c));
    if (c == '-') {
        neg = 1;
        c = *s++;
    } else {
        neg = 0;
        if (c == '+')
            c = *s++;
    }
    if ((base == 0 || base == 16) &&
        c == '0' && (*s == 'x' || *s == 'X') &&
        ((s[1] >= '0' && s[1] <= '9') ||
        (s[1] >= 'A' && s[1] <= 'F') ||
        (s[1] >= 'a' && s[1] <= 'f'))) {
        c = s[1];
        s += 2;
        base = 16;
    }
    if (base == 0)
        base = c == '0' ? 8 : 10;
    acc = any = 0;
    if (base < 2 || base > 36)
        goto noconv;

    /*
     * Compute the cutoff value between legal numbers and illegal
     * numbers.  That is the largest legal value, divided by the
     * base.  An input number that is greater than this value, if
     * followed by a legal input character, is too big.  One that
     * is equal to this value may be valid or not; the limit
     * between valid and invalid numbers is then based on the last
     * digit.  For instance, if the range for quads is
     * [-9223372036854775808..9223372036854775807] and the input base
     * is 10, cutoff will be set to 922337203685477580 and cutlim to
     * either 7 (neg==0) or 8 (neg==1), meaning that if we have
     * accumulated a value > 922337203685477580, or equal but the
     * next digit is > 7 (or 8), the number is too big, and we will
     * return a range error.
     *
     * Set 'any' if any `digits' consumed; make it negative to indicate
     * overflow.
     */
    cutoff = neg ? (unsigned long long)-(LLONG_MIN + LLONG_MAX) + LLONG_MAX
        : LLONG_MAX;
    cutlim = cutoff % base;
    cutoff /= base;
    for ( ; ; c = *s++) {
        if (c >= '0' && c <= '9')
            c -= '0';
        else if (c >= 'A' && c <= 'Z')
            c -= 'A' - 10;
        else if (c >= 'a' && c <= 'z')
            c -= 'a' - 10;
        else
            break;
        if (c >= base)
            break;
        if (any < 0 || acc > cutoff || (acc == cutoff && c > cutlim))
            any = -1;
        else {
            any = 1;
            acc *= base;
            acc += c;
        }
    }
    if (any < 0) {
        acc = neg ? LLONG_MIN : LLONG_MAX;
        errno = ERANGE;
    } else if (!any) {
noconv:
        errno = EINVAL;
    } else if (neg)
        acc = -acc;
    if (endptr != NULL)
        *endptr = (char *)(any ? s - 1 : nptr);
    return (acc);
}