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Annotation of 43BSDReno/lib/libc/stdlib/strtol.c, revision 1.1

1.1     ! root        1: /*-
        !             2:  * Copyright (c) 1990 The Regents of the University of California.
        !             3:  * All rights reserved.
        !             4:  *
        !             5:  * Redistribution and use in source and binary forms are permitted
        !             6:  * provided that: (1) source distributions retain this entire copyright
        !             7:  * notice and comment, and (2) distributions including binaries display
        !             8:  * the following acknowledgement:  ``This product includes software
        !             9:  * developed by the University of California, Berkeley and its contributors''
        !            10:  * in the documentation or other materials provided with the distribution
        !            11:  * and in all advertising materials mentioning features or use of this
        !            12:  * software. Neither the name of the University nor the names of its
        !            13:  * contributors may be used to endorse or promote products derived
        !            14:  * from this software without specific prior written permission.
        !            15:  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
        !            16:  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
        !            17:  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
        !            18:  */
        !            19: 
        !            20: #if defined(LIBC_SCCS) && !defined(lint)
        !            21: static char sccsid[] = "@(#)strtol.c   5.3 (Berkeley) 5/17/90";
        !            22: #endif /* LIBC_SCCS and not lint */
        !            23: 
        !            24: #include <limits.h>
        !            25: #include <ctype.h>
        !            26: #include <errno.h>
        !            27: #include <stdlib.h>
        !            28: 
        !            29: 
        !            30: /*
        !            31:  * Convert a string to a long integer.
        !            32:  *
        !            33:  * Ignores `locale' stuff.  Assumes that the upper and lower case
        !            34:  * alphabets and digits are each contiguous.
        !            35:  */
        !            36: long
        !            37: strtol(nptr, endptr, base)
        !            38:        char *nptr, **endptr;
        !            39:        register int base;
        !            40: {
        !            41:        register char *s = nptr;
        !            42:        register unsigned long acc;
        !            43:        register int c;
        !            44:        register unsigned long cutoff;
        !            45:        register int neg = 0, any, cutlim;
        !            46: 
        !            47:        /*
        !            48:         * Skip white space and pick up leading +/- sign if any.
        !            49:         * If base is 0, allow 0x for hex and 0 for octal, else
        !            50:         * assume decimal; if base is already 16, allow 0x.
        !            51:         */
        !            52:        do {
        !            53:                c = *s++;
        !            54:        } while (isspace(c));
        !            55:        if (c == '-') {
        !            56:                neg = 1;
        !            57:                c = *s++;
        !            58:        } else if (c == '+')
        !            59:                c = *s++;
        !            60:        if ((base == 0 || base == 16) &&
        !            61:            c == '0' && (*s == 'x' || *s == 'X')) {
        !            62:                c = s[1];
        !            63:                s += 2;
        !            64:                base = 16;
        !            65:        }
        !            66:        if (base == 0)
        !            67:                base = c == '0' ? 8 : 10;
        !            68: 
        !            69:        /*
        !            70:         * Compute the cutoff value between legal numbers and illegal
        !            71:         * numbers.  That is the largest legal value, divided by the
        !            72:         * base.  An input number that is greater than this value, if
        !            73:         * followed by a legal input character, is too big.  One that
        !            74:         * is equal to this value may be valid or not; the limit
        !            75:         * between valid and invalid numbers is then based on the last
        !            76:         * digit.  For instance, if the range for longs is
        !            77:         * [-2147483648..2147483647] and the input base is 10,
        !            78:         * cutoff will be set to 214748364 and cutlim to either
        !            79:         * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated
        !            80:         * a value > 214748364, or equal but the next digit is > 7 (or 8),
        !            81:         * the number is too big, and we will return a range error.
        !            82:         *
        !            83:         * Set any if any `digits' consumed; make it negative to indicate
        !            84:         * overflow.
        !            85:         */
        !            86:        cutoff = neg ? -(unsigned long)LONG_MIN : LONG_MAX;
        !            87:        cutlim = cutoff % (unsigned long)base;
        !            88:        cutoff /= (unsigned long)base;
        !            89:        for (acc = 0, any = 0;; c = *s++) {
        !            90:                if (isdigit(c))
        !            91:                        c -= '0';
        !            92:                else if (isalpha(c))
        !            93:                        c -= isupper(c) ? 'A' - 10 : 'a' - 10;
        !            94:                else
        !            95:                        break;
        !            96:                if (c >= base)
        !            97:                        break;
        !            98:                if (any < 0 || acc > cutoff || acc == cutoff && c > cutlim)
        !            99:                        any = -1;
        !           100:                else {
        !           101:                        any = 1;
        !           102:                        acc *= base;
        !           103:                        acc += c;
        !           104:                }
        !           105:        }
        !           106:        if (any < 0) {
        !           107:                acc = neg ? LONG_MIN : LONG_MAX;
        !           108:                errno = ERANGE;
        !           109:        } else if (neg)
        !           110:                acc = -acc;
        !           111:        if (endptr != 0)
        !           112:                *endptr = any ? s - 1 : nptr;
        !           113:        return (acc);
        !           114: }

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