1 /* $OpenBSD: strtol.c,v 1.12 2017/07/06 16:23:11 millert Exp $ */ 2 /* 3 * Copyright (c) 1990 The Regents of the University of California. 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. Neither the name of the University nor the names of its contributors 15 * may be used to endorse or promote products derived from this software 16 * without specific prior written permission. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28 * SUCH DAMAGE. 29 */ 30 31 #include <ctype.h> 32 #include <errno.h> 33 #include <limits.h> 34 #include <stdlib.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 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 * Ensure that base is between 2 and 36 inclusive, or the special 52 * value of 0. 53 */ 54 if (base < 0 || base == 1 || base > 36) { 55 if (endptr != 0) 56 *endptr = (char *)nptr; 57 errno = EINVAL; 58 return 0; 59 } 60 61 /* 62 * Skip white space and pick up leading +/- sign if any. 63 * If base is 0, allow 0x for hex and 0 for octal, else 64 * assume decimal; if base is already 16, allow 0x. 65 */ 66 s = nptr; 67 do { 68 c = (unsigned char) *s++; 69 } while (isspace(c)); 70 if (c == '-') { 71 neg = 1; 72 c = *s++; 73 } else { 74 neg = 0; 75 if (c == '+') 76 c = *s++; 77 } 78 if ((base == 0 || base == 16) && c == '0' && 79 (*s == 'x' || *s == 'X') && isxdigit((unsigned char)s[1])) { 80 c = s[1]; 81 s += 2; 82 base = 16; 83 } 84 if (base == 0) 85 base = c == '0' ? 8 : 10; 86 87 /* 88 * Compute the cutoff value between legal numbers and illegal 89 * numbers. That is the largest legal value, divided by the 90 * base. An input number that is greater than this value, if 91 * followed by a legal input character, is too big. One that 92 * is equal to this value may be valid or not; the limit 93 * between valid and invalid numbers is then based on the last 94 * digit. For instance, if the range for longs is 95 * [-2147483648..2147483647] and the input base is 10, 96 * cutoff will be set to 214748364 and cutlim to either 97 * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated 98 * a value > 214748364, or equal but the next digit is > 7 (or 8), 99 * the number is too big, and we will return a range error. 100 * 101 * Set any if any `digits' consumed; make it negative to indicate 102 * overflow. 103 */ 104 cutoff = neg ? LONG_MIN : LONG_MAX; 105 cutlim = cutoff % base; 106 cutoff /= base; 107 if (neg) { 108 if (cutlim > 0) { 109 cutlim -= base; 110 cutoff += 1; 111 } 112 cutlim = -cutlim; 113 } 114 for (acc = 0, any = 0;; c = (unsigned char) *s++) { 115 if (isdigit(c)) 116 c -= '0'; 117 else if (isalpha(c)) 118 c -= isupper(c) ? 'A' - 10 : 'a' - 10; 119 else 120 break; 121 if (c >= base) 122 break; 123 if (any < 0) 124 continue; 125 if (neg) { 126 if (acc < cutoff || (acc == cutoff && c > cutlim)) { 127 any = -1; 128 acc = LONG_MIN; 129 errno = ERANGE; 130 } else { 131 any = 1; 132 acc *= base; 133 acc -= c; 134 } 135 } else { 136 if (acc > cutoff || (acc == cutoff && c > cutlim)) { 137 any = -1; 138 acc = LONG_MAX; 139 errno = ERANGE; 140 } else { 141 any = 1; 142 acc *= base; 143 acc += c; 144 } 145 } 146 } 147 if (endptr != 0) 148 *endptr = (char *) (any ? s - 1 : nptr); 149 return (acc); 150 } 151 DEF_STRONG(strtol); 152