1/* $OpenBSD: strtol.c,v 1.4 2022/01/08 06:49:41 guenther Exp $ */ 2 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/types.h> 33#include <limits.h> 34 35#include "util.h" 36 37/* 38 * Convert a string to a long integer. 39 * 40 * Ignores `locale' stuff. Assumes that the upper and lower case 41 * alphabets and digits are each contiguous. 42 */ 43long 44_dl_strtol(const char *nptr, char **endptr, int base) 45{ 46 const char *s; 47 long acc, cutoff; 48 int c; 49 int neg, any, cutlim; 50 51 /* 52 * Skip white space and pick up leading +/- sign if any. 53 * If base is 0, allow 0x for hex and 0 for octal, else 54 * assume decimal; if base is already 16, allow 0x. 55 */ 56 s = nptr; 57 do { 58 c = (unsigned char) *s++; 59 } while (c <= ' ' || c >= 0x7f); 60 if (c == '-') { 61 neg = 1; 62 c = *s++; 63 } else { 64 neg = 0; 65 if (c == '+') 66 c = *s++; 67 } 68 if ((base == 0 || base == 16) && c == '0' && 69 (*s == 'x' || *s == 'X') && ((s[1] >= '0' && s[1] <= '9') || 70 (s[1] >= 'A' && s[1] <= 'F') || (s[1] >= 'a' && s[1] <= 'f'))) { 71 c = s[1]; 72 s += 2; 73 base = 16; 74 } 75 if (base == 0) 76 base = c == '0' ? 8 : 10; 77 78 /* 79 * Compute the cutoff value between legal numbers and illegal 80 * numbers. That is the largest legal value, divided by the 81 * base. An input number that is greater than this value, if 82 * followed by a legal input character, is too big. One that 83 * is equal to this value may be valid or not; the limit 84 * between valid and invalid numbers is then based on the last 85 * digit. For instance, if the range for longs is 86 * [-2147483648..2147483647] and the input base is 10, 87 * cutoff will be set to 214748364 and cutlim to either 88 * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated 89 * a value > 214748364, or equal but the next digit is > 7 (or 8), 90 * the number is too big, and we will return a range error. 91 * 92 * Set any if any `digits' consumed; make it negative to indicate 93 * overflow. 94 */ 95 cutoff = neg ? LONG_MIN : LONG_MAX; 96 cutlim = cutoff % base; 97 cutoff /= base; 98 if (neg) { 99 if (cutlim > 0) { 100 cutlim -= base; 101 cutoff += 1; 102 } 103 cutlim = -cutlim; 104 } 105 for (acc = 0, any = 0;; c = (unsigned char) *s++) { 106 if (c >= '0' && c <= '9') 107 c -= '0'; 108 else if (c >= 'A' && c <= 'Z') 109 c -= 'A' - 10; 110 else if (c >= 'a' && c <= 'z') 111 c -= 'a' - 10; 112 else 113 break; 114 if (c >= base) 115 break; 116 if (any < 0) 117 continue; 118 if (neg) { 119 if (acc < cutoff || (acc == cutoff && c > cutlim)) { 120 any = -1; 121 acc = LONG_MIN; 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 } else { 132 any = 1; 133 acc *= base; 134 acc += c; 135 } 136 } 137 } 138 if (endptr != 0) 139 *endptr = (char *) (any ? s - 1 : nptr); 140 return (acc); 141} 142