1 /* $OpenBSD: strtol.c,v 1.1 2003/07/06 20:03:58 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/param.h> 33 #include "util.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 _dl_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 } 139