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Annotation of prex-old/usr/lib/libc/stdlib/strtol.c, Revision 1.1

1.1     ! nbrk        1: /*-
        !             2:  * Copyright (c) 1990, 1993
        !             3:  *     The Regents of the University of California.  All rights reserved.
        !             4:  *
        !             5:  * Redistribution and use in source and binary forms, with or without
        !             6:  * modification, are permitted provided that the following conditions
        !             7:  * are met:
        !             8:  * 1. Redistributions of source code must retain the above copyright
        !             9:  *    notice, this list of conditions and the following disclaimer.
        !            10:  * 2. Redistributions in binary form must reproduce the above copyright
        !            11:  *    notice, this list of conditions and the following disclaimer in the
        !            12:  *    documentation and/or other materials provided with the distribution.
        !            13:  * 3. Neither the name of the University nor the names of its contributors
        !            14:  *    may be used to endorse or promote products derived from this software
        !            15:  *    without specific prior written permission.
        !            16:  *
        !            17:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
        !            18:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
        !            19:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
        !            20:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
        !            21:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
        !            22:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
        !            23:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
        !            24:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
        !            25:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
        !            26:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
        !            27:  * SUCH DAMAGE.
        !            28:  */
        !            29:
        !            30: #include <limits.h>
        !            31: #include <ctype.h>
        !            32: #include <errno.h>
        !            33: #include <stdlib.h>
        !            34:
        !            35:
        !            36: /*
        !            37:  * Convert a string to a long integer.
        !            38:  *
        !            39:  * Ignores `locale' stuff.  Assumes that the upper and lower case
        !            40:  * alphabets and digits are each contiguous.
        !            41:  */
        !            42: long
        !            43: strtol(nptr, endptr, base)
        !            44:        const char *nptr;
        !            45:        char **endptr;
        !            46:        int base;
        !            47: {
        !            48:        const char *s;
        !            49:        long acc, cutoff;
        !            50:        int c;
        !            51:        int neg, any, cutlim;
        !            52:
        !            53:        /*
        !            54:         * Skip white space and pick up leading +/- sign if any.
        !            55:         * If base is 0, allow 0x for hex and 0 for octal, else
        !            56:         * assume decimal; if base is already 16, allow 0x.
        !            57:         */
        !            58:        s = nptr;
        !            59:        do {
        !            60:                c = (unsigned char) *s++;
        !            61:        } while (isspace(c));
        !            62:        if (c == '-') {
        !            63:                neg = 1;
        !            64:                c = *s++;
        !            65:        } else {
        !            66:                neg = 0;
        !            67:                if (c == '+')
        !            68:                        c = *s++;
        !            69:        }
        !            70:        if ((base == 0 || base == 16) &&
        !            71:            c == '0' && (*s == 'x' || *s == 'X')) {
        !            72:                c = s[1];
        !            73:                s += 2;
        !            74:                base = 16;
        !            75:        }
        !            76:        if (base == 0)
        !            77:                base = c == '0' ? 8 : 10;
        !            78:
        !            79:        /*
        !            80:         * Compute the cutoff value between legal numbers and illegal
        !            81:         * numbers.  That is the largest legal value, divided by the
        !            82:         * base.  An input number that is greater than this value, if
        !            83:         * followed by a legal input character, is too big.  One that
        !            84:         * is equal to this value may be valid or not; the limit
        !            85:         * between valid and invalid numbers is then based on the last
        !            86:         * digit.  For instance, if the range for longs is
        !            87:         * [-2147483648..2147483647] and the input base is 10,
        !            88:         * cutoff will be set to 214748364 and cutlim to either
        !            89:         * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated
        !            90:         * a value > 214748364, or equal but the next digit is > 7 (or 8),
        !            91:         * the number is too big, and we will return a range error.
        !            92:         *
        !            93:         * Set any if any `digits' consumed; make it negative to indicate
        !            94:         * overflow.
        !            95:         */
        !            96:        cutoff = neg ? LONG_MIN : LONG_MAX;
        !            97:        cutlim = (int)(cutoff % base);
        !            98:        cutoff /= base;
        !            99:        if (neg) {
        !           100:                if (cutlim > 0) {
        !           101:                        cutlim -= base;
        !           102:                        cutoff += 1;
        !           103:                }
        !           104:                cutlim = -cutlim;
        !           105:        }
        !           106:        for (acc = 0, any = 0;; c = (unsigned char) *s++) {
        !           107:                if (isdigit(c))
        !           108:                        c -= '0';
        !           109:                else if (isalpha(c))
        !           110:                        c -= isupper(c) ? 'A' - 10 : 'a' - 10;
        !           111:                else
        !           112:                        break;
        !           113:                if (c >= base)
        !           114:                        break;
        !           115:                if (any < 0)
        !           116:                        continue;
        !           117:                if (neg) {
        !           118:                        if (acc < cutoff || (acc == cutoff && c > cutlim)) {
        !           119:                                any = -1;
        !           120:                                acc = LONG_MIN;
        !           121:                                errno = ERANGE;
        !           122:                        } else {
        !           123:                                any = 1;
        !           124:                                acc *= base;
        !           125:                                acc -= c;
        !           126:                        }
        !           127:                } else {
        !           128:                        if (acc > cutoff || (acc == cutoff && c > cutlim)) {
        !           129:                                any = -1;
        !           130:                                acc = LONG_MAX;
        !           131:                                errno = ERANGE;
        !           132:                        } else {
        !           133:                                any = 1;
        !           134:                                acc *= base;
        !           135:                                acc += c;
        !           136:                        }
        !           137:                }
        !           138:        }
        !           139:        if (endptr != 0)
        !           140:                /* LINTED interface specification */
        !           141:                *endptr = (char *)(any ? s - 1 : nptr);
        !           142:        return (acc);
        !           143: }