source: umon/main/glib/strtoul.c @ a7b6f00

/*
 * Copyright (c) 1990, 1993
 *  The Regents of the University of California.  All rights reserved.
 *
 * Copyright (c) 2011 The FreeBSD Foundation
 * All rights reserved.
 * Portions of this software were developed by David Chisnall
 * under sponsorship from the FreeBSD Foundation.
 *
 * 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.
 * 3. 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.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)strtoul.c   8.1 (Berkeley) 6/4/93";
#endif /* LIBC_SCCS and not lint */
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

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

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

    /*
     * See strtol for comments as to the logic used.
     */
    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;
    }

    cutoff = ULONG_MAX / base;
    cutlim = ULONG_MAX % 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 = ULONG_MAX;
    } else if(!any) {
    } else if(neg) {
        acc = -acc;
    }
noconv:
    if(endptr != NULL) {
        *endptr = (char *)(any ? s - 1 : nptr);
    }
    return (acc);
}