1 /* $OpenBSD: strtol.c,v 1.2 2015/01/16 16:18:07 deraadt 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 #include "util.h" 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 _dl_strtol(const char *nptr, char **endptr, int base) 44 { 45 const char *s; 46 long acc, cutoff; 47 int c; 48 int neg, any, cutlim; 49 50 /* 51 * Skip white space and pick up leading +/- sign if any. 52 * If base is 0, allow 0x for hex and 0 for octal, else 53 * assume decimal; if base is already 16, allow 0x. 54 */ 55 s = nptr; 56 do { 57 c = (unsigned char) *s++; 58 } while (c <= ' ' || c >= 0x7f); 59 if (c == '-') { 60 neg = 1; 61 c = *s++; 62 } else { 63 neg = 0; 64 if (c == '+') 65 c = *s++; 66 } 67 if ((base == 0 || base == 16) && 68 c == '0' && (*s == 'x' || *s == 'X')) { 69 c = s[1]; 70 s += 2; 71 base = 16; 72 } 73 if (base == 0) 74 base = c == '0' ? 8 : 10; 75 76 /* 77 * Compute the cutoff value between legal numbers and illegal 78 * numbers. That is the largest legal value, divided by the 79 * base. An input number that is greater than this value, if 80 * followed by a legal input character, is too big. One that 81 * is equal to this value may be valid or not; the limit 82 * between valid and invalid numbers is then based on the last 83 * digit. For instance, if the range for longs is 84 * [-2147483648..2147483647] and the input base is 10, 85 * cutoff will be set to 214748364 and cutlim to either 86 * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated 87 * a value > 214748364, or equal but the next digit is > 7 (or 8), 88 * the number is too big, and we will return a range error. 89 * 90 * Set any if any `digits' consumed; make it negative to indicate 91 * overflow. 92 */ 93 cutoff = neg ? LONG_MIN : LONG_MAX; 94 cutlim = cutoff % base; 95 cutoff /= base; 96 if (neg) { 97 if (cutlim > 0) { 98 cutlim -= base; 99 cutoff += 1; 100 } 101 cutlim = -cutlim; 102 } 103 for (acc = 0, any = 0;; c = (unsigned char) *s++) { 104 if (c >= '0' && c <= '9') 105 c -= '0'; 106 else if (c >= 'A' && c <= 'Z') 107 c -= 'A' - 10; 108 else if (c >= 'a' && c <= 'z') 109 c -= 'a' - 10; 110 else 111 break; 112 if (c >= base) 113 break; 114 if (any < 0) 115 continue; 116 if (neg) { 117 if (acc < cutoff || (acc == cutoff && c > cutlim)) { 118 any = -1; 119 acc = LONG_MIN; 120 } else { 121 any = 1; 122 acc *= base; 123 acc -= c; 124 } 125 } else { 126 if (acc > cutoff || (acc == cutoff && c > cutlim)) { 127 any = -1; 128 acc = LONG_MAX; 129 } else { 130 any = 1; 131 acc *= base; 132 acc += c; 133 } 134 } 135 } 136 if (endptr != 0) 137 *endptr = (char *) (any ? s - 1 : nptr); 138 return (acc); 139 } 140