1 /* $OpenBSD: strtoimax.c,v 1.1 2006/01/13 17:58:09 millert Exp $ */ 2 3 /*- 4 * Copyright (c) 1992 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 <ctype.h> 33 #include <errno.h> 34 #include <inttypes.h> 35 36 /* 37 * Convert a string to an intmax_t 38 * 39 * Ignores `locale' stuff. Assumes that the upper and lower case 40 * alphabets and digits are each contiguous. 41 */ 42 intmax_t 43 strtoimax(const char *nptr, char **endptr, int base) 44 { 45 const char *s; 46 intmax_t 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 (isspace(c)); 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 intmax_t is 84 * [-9223372036854775808..9223372036854775807] and the input base 85 * is 10, cutoff will be set to 922337203685477580 and cutlim to 86 * either 7 (neg==0) or 8 (neg==1), meaning that if we have 87 * accumulated a value > 922337203685477580, or equal but the 88 * next digit is > 7 (or 8), the number is too big, and we will 89 * return a range error. 90 * 91 * Set any if any `digits' consumed; make it negative to indicate 92 * overflow. 93 */ 94 cutoff = neg ? INTMAX_MIN : INTMAX_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 (isdigit(c)) 106 c -= '0'; 107 else if (isalpha(c)) 108 c -= isupper(c) ? 'A' - 10 : '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 = INTMAX_MIN; 119 errno = ERANGE; 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 = INTMAX_MAX; 129 errno = ERANGE; 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