1/* $OpenBSD: strtoimax.c,v 1.2 2014/09/13 20:10:12 schwarze Exp $ */ 2/* 3 * Copyright (c) 1992 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 <inttypes.h> 34 35/* 36 * Convert a string to an intmax_t 37 * 38 * Ignores `locale' stuff. Assumes that the upper and lower case 39 * alphabets and digits are each contiguous. 40 */ 41intmax_t 42strtoimax(const char *nptr, char **endptr, int base) 43{ 44 const char *s; 45 intmax_t acc, cutoff; 46 int c; 47 int neg, any, cutlim; 48 49 /* 50 * Ensure that base is between 2 and 36 inclusive, or the special 51 * value of 0. 52 */ 53 if (base < 0 || base == 1 || base > 36) { 54 if (endptr != 0) 55 *endptr = (char *)nptr; 56 errno = EINVAL; 57 return 0; 58 } 59 60 /* 61 * Skip white space and pick up leading +/- sign if any. 62 * If base is 0, allow 0x for hex and 0 for octal, else 63 * assume decimal; if base is already 16, allow 0x. 64 */ 65 s = nptr; 66 do { 67 c = (unsigned char) *s++; 68 } while (isspace(c)); 69 if (c == '-') { 70 neg = 1; 71 c = *s++; 72 } else { 73 neg = 0; 74 if (c == '+') 75 c = *s++; 76 } 77 if ((base == 0 || base == 16) && 78 c == '0' && (*s == 'x' || *s == 'X')) { 79 c = s[1]; 80 s += 2; 81 base = 16; 82 } 83 if (base == 0) 84 base = c == '0' ? 8 : 10; 85 86 /* 87 * Compute the cutoff value between legal numbers and illegal 88 * numbers. That is the largest legal value, divided by the 89 * base. An input number that is greater than this value, if 90 * followed by a legal input character, is too big. One that 91 * is equal to this value may be valid or not; the limit 92 * between valid and invalid numbers is then based on the last 93 * digit. For instance, if the range for intmax_t is 94 * [-9223372036854775808..9223372036854775807] and the input base 95 * is 10, cutoff will be set to 922337203685477580 and cutlim to 96 * either 7 (neg==0) or 8 (neg==1), meaning that if we have 97 * accumulated a value > 922337203685477580, or equal but the 98 * next digit is > 7 (or 8), the number is too big, and we will 99 * return a range error. 100 * 101 * Set any if any `digits' consumed; make it negative to indicate 102 * overflow. 103 */ 104 cutoff = neg ? INTMAX_MIN : INTMAX_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 = INTMAX_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 = INTMAX_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