strtol.c

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/*
 * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 *
 * The contents of this file constitute Original Code as defined in and
 * are subject to the Apple Public Source License Version 1.1 (the
 * "License").  You may not use this file except in compliance with the
 * License.  Please obtain a copy of the License at
 * http://www.apple.com/publicsource and read it before using this file.
 *
 * This Original Code and all software distributed under the License are
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 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
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/*      Copyright (c) 1995 NeXT Computer, Inc.  All rights reserved.
 *
 * strol.c - The functions strtol() & strtoul() are exported as public API
 *           via the header file ~driverkit/generalFuncs.h
 *
 * HISTORY
 * 25-Oct-1995    Dean Reece at NeXT
 *      Created based on BSD4.4's strtol.c & strtoul.c.
 *      Removed dependency on _ctype_ by static versions of isupper()...
 *      Added support for "0b101..." binary constants.
 *      Commented out references to errno.
 */

/*-
 * Copyright (c) 1990, 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.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *  This product includes software developed by the University of
 *  California, Berkeley and its contributors.
 * 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 <ctype.h>
#include <limits.h>
#include <stdlib.h>

/*
 * Convert a string to a long integer.
 *
 * Ignores `locale' stuff.  Assumes that the upper and lower case
 * alphabets and digits are each contiguous.
 */
long strtol(nptr, endptr, base) const char* nptr;
char** endptr;
register int base;
{
    register const char* s = nptr;
    register unsigned long acc;
    register int c;
    register unsigned long cutoff;
    register int neg = 0, any, cutlim;

    // check base
    if(base < 0 || base > 36)
    {
        // errno = EINVAL

        if(endptr)
        {
            *endptr = (char*)(uintptr_t)nptr;
        }

        return 0;
    }

    /*
     * 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.
     */
    do
    {
        c = *s++;
    } while(isspace(c));
    if(c == '-')
    {
        neg = 1;
        c = *s++;
    }
    else if(c == '+')
    {
        {
            c = *s++;
        }
    }
    if((base == 0 || base == 16) && c == '0' && (*s == 'x' || *s == 'X'))
    {
        c = s[1];
        s += 2;
        base = 16;
    }
    else if((base == 0 || base == 2) && c == '0' && (*s == 'b' || *s == 'B'))
    {
        c = s[1];
        s += 2;
        base = 2;
    }
    if(base == 0)
    {
        {
            base = c == '0' ? 8 : 10;
        }
    }

    /*
     * 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 longs is
     * [-2147483648..2147483647] and the input base is 10,
     * cutoff will be set to 214748364 and cutlim to either
     * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated
     * a value > 214748364, 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_MIN : LONG_MAX;
    cutlim = (int)(cutoff % (unsigned long)base);
    cutoff /= (unsigned long)base;
    for(acc = 0, any = 0;; c = *s++)
    {
        if(isdigit(c))
        {
            c -= '0';
        }
        else if(isalpha(c))
        {
            c -= isupper(c) ? 'A' - 10 : 'a' - 10;
        }
        else
        {
            break;
        }
        if(c >= base)
        {
            break;
        }
        if(any < 0 || acc > cutoff || (acc == cutoff && c > cutlim))
        {
            any = -1;
        }
        else
        {
            any = 1;
            acc *= (unsigned long)base;
            acc += (unsigned long)c;
        }
    }
    if(any < 0)
    {
        acc = neg ? (unsigned long)LONG_MIN : (unsigned long)LONG_MAX;
        //      errno = ERANGE;
    }
    else if(neg)
    {
        acc = -acc;
    }
    if(endptr != 0)
    {
        *endptr = (char*)(uintptr_t)(any ? s - 1 : nptr);
    }
    return (long)(acc);
}