1 /* $OpenBSD: strtol.c,v 1.3 2017/08/16 18:52:01 millert 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) && c == '0' && 68 (*s == 'x' || *s == 'X') && ((s[1] >= '0' && s[1] <= '9') || 69 (s[1] >= 'A' && s[1] <= 'F') || (s[1] >= 'a' && s[1] <= 'f'))) { 70 c = s[1]; 71 s += 2; 72 base = 16; 73 } 74 if (base == 0) 75 base = c == '0' ? 8 : 10; 76 77 /* 78 * Compute the cutoff value between legal numbers and illegal 79 * numbers. That is the largest legal value, divided by the 80 * base. An input number that is greater than this value, if 81 * followed by a legal input character, is too big. One that 82 * is equal to this value may be valid or not; the limit 83 * between valid and invalid numbers is then based on the last 84 * digit. For instance, if the range for longs is 85 * [-2147483648..2147483647] and the input base is 10, 86 * cutoff will be set to 214748364 and cutlim to either 87 * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated 88 * a value > 214748364, or equal but the next digit is > 7 (or 8), 89 * the number is too big, and we will return a range error. 90 * 91 * Set any if any `digits' consumed; make it negative to indicate 92 * overflow. 93 */ 94 cutoff = neg ? LONG_MIN : LONG_MAX; 95 cutlim = cutoff % base; 96 cutoff /= base; 97 if (neg) { 98 if (cutlim > 0) { 99 cutlim -= base; 100 cutoff += 1; 101 } 102 cutlim = -cutlim; 103 } 104 for (acc = 0, any = 0;; c = (unsigned char) *s++) { 105 if (c >= '0' && c <= '9') 106 c -= '0'; 107 else if (c >= 'A' && c <= 'Z') 108 c -= 'A' - 10; 109 else if (c >= 'a' && c <= 'z') 110 c -= '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 } else { 122 any = 1; 123 acc *= base; 124 acc -= c; 125 } 126 } else { 127 if (acc > cutoff || (acc == cutoff && c > cutlim)) { 128 any = -1; 129 acc = LONG_MAX; 130 } else { 131 any = 1; 132 acc *= base; 133 acc += c; 134 } 135 } 136 } 137 if (endptr != 0) 138 *endptr = (char *) (any ? s - 1 : nptr); 139 return (acc); 140 } 141