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Annotation of sys/lib/libsa/strtol.c, Revision 1.1.1.1

1.1       nbrk        1: /* $OpenBSD: strtol.c,v 1.6 2003/08/11 06:23:09 deraadt Exp $ */
                      2: /* Modified strtol() from stdlib */
                      3: /*-
                      4:  * Copyright (c) 1990 The Regents of the University of California.
                      5:  * All rights reserved.
                      6:  *
                      7:  * Redistribution and use in source and binary forms, with or without
                      8:  * modification, are permitted provided that the following conditions
                      9:  * are met:
                     10:  * 1. Redistributions of source code must retain the above copyright
                     11:  *    notice, this list of conditions and the following disclaimer.
                     12:  * 2. Redistributions in binary form must reproduce the above copyright
                     13:  *    notice, this list of conditions and the following disclaimer in the
                     14:  *    documentation and/or other materials provided with the distribution.
                     15:  * 3. Neither the name of the University nor the names of its contributors
                     16:  *    may be used to endorse or promote products derived from this software
                     17:  *    without specific prior written permission.
                     18:  *
                     19:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
                     20:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
                     21:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
                     22:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
                     23:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
                     24:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
                     25:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
                     26:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
                     27:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
                     28:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
                     29:  * SUCH DAMAGE.
                     30:  */
                     31:
                     32: #include <sys/param.h>
                     33: #include "stand.h"
                     34:
                     35: /*
                     36:  * Convert a string to a long integer.
                     37:  *
                     38:  * Ignores `locale' stuff.  Assumes that the upper and lower case
                     39:  * alphabets and digits are each contiguous.
                     40:  */
                     41: long
                     42: strtol(const char *nptr, char **endptr, int base)
                     43: {
                     44:        const char *s;
                     45:        long acc, cutoff;
                     46:        int c;
                     47:        int neg, any, cutlim;
                     48:
                     49:        /*
                     50:         * Skip white space and pick up leading +/- sign if any.
                     51:         * If base is 0, allow 0x for hex and 0 for octal, else
                     52:         * assume decimal; if base is already 16, allow 0x.
                     53:         */
                     54:        s = nptr;
                     55:        do {
                     56:                c = (unsigned char) *s++;
                     57:        } while (c <= ' ' || c >= 0x7f);
                     58:        if (c == '-') {
                     59:                neg = 1;
                     60:                c = *s++;
                     61:        } else {
                     62:                neg = 0;
                     63:                if (c == '+')
                     64:                        c = *s++;
                     65:        }
                     66:        if ((base == 0 || base == 16) &&
                     67:            c == '0' && (*s == 'x' || *s == 'X')) {
                     68:                c = s[1];
                     69:                s += 2;
                     70:                base = 16;
                     71:        }
                     72:        if (base == 0)
                     73:                base = c == '0' ? 8 : 10;
                     74:
                     75:        /*
                     76:         * Compute the cutoff value between legal numbers and illegal
                     77:         * numbers.  That is the largest legal value, divided by the
                     78:         * base.  An input number that is greater than this value, if
                     79:         * followed by a legal input character, is too big.  One that
                     80:         * is equal to this value may be valid or not; the limit
                     81:         * between valid and invalid numbers is then based on the last
                     82:         * digit.  For instance, if the range for longs is
                     83:         * [-2147483648..2147483647] and the input base is 10,
                     84:         * cutoff will be set to 214748364 and cutlim to either
                     85:         * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated
                     86:         * a value > 214748364, or equal but the next digit is > 7 (or 8),
                     87:         * the number is too big, and we will return a range error.
                     88:         *
                     89:         * Set any if any `digits' consumed; make it negative to indicate
                     90:         * overflow.
                     91:         */
                     92:        cutoff = neg ? LONG_MIN : LONG_MAX;
                     93:        cutlim = cutoff % base;
                     94:        cutoff /= base;
                     95:        if (neg) {
                     96:                if (cutlim > 0) {
                     97:                        cutlim -= base;
                     98:                        cutoff += 1;
                     99:                }
                    100:                cutlim = -cutlim;
                    101:        }
                    102:        for (acc = 0, any = 0;; c = (unsigned char) *s++) {
                    103:                if (c >= '0' && c <= '9')
                    104:                        c -= '0';
                    105:                else if (c >= 'A' && c <= 'Z')
                    106:                        c -= 'A' - 10;
                    107:                else if (c >= 'a' && c <= 'z')
                    108:                        c -= 'a' - 10;
                    109:                else
                    110:                        break;
                    111:                if (c >= base)
                    112:                        break;
                    113:                if (any < 0)
                    114:                        continue;
                    115:                if (neg) {
                    116:                        if (acc < cutoff || (acc == cutoff && c > cutlim)) {
                    117:                                any = -1;
                    118:                                acc = LONG_MIN;
                    119:                        } else {
                    120:                                any = 1;
                    121:                                acc *= base;
                    122:                                acc -= c;
                    123:                        }
                    124:                } else {
                    125:                        if (acc > cutoff || (acc == cutoff && c > cutlim)) {
                    126:                                any = -1;
                    127:                                acc = LONG_MAX;
                    128:                        } else {
                    129:                                any = 1;
                    130:                                acc *= base;
                    131:                                acc += c;
                    132:                        }
                    133:                }
                    134:        }
                    135:        if (endptr != 0)
                    136:                *endptr = (char *) (any ? s - 1 : nptr);
                    137:        return (acc);
                    138: }