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 95 /* BIONIC: avoid division and module for common cases */ 96 #define CASE_BASE(x) \ 97 case x: \ 98 if (neg) { \ 99 cutlim = INTMAX_MIN % x; \ 100 cutoff = INTMAX_MIN / x; \ 101 } else { \ 102 cutlim = INTMAX_MAX % x; \ 103 cutoff = INTMAX_MAX / x; \ 104 }; \ 105 break 106 107 switch (base) { 108 case 4: 109 if (neg) { 110 cutlim = (int)(INTMAX_MIN % 4); 111 cutoff = INTMAX_MIN / 4; 112 } else { 113 cutlim = (int)(INTMAX_MAX % 4); 114 cutoff = INTMAX_MAX / 4; 115 } 116 break; 117 118 CASE_BASE(8); 119 CASE_BASE(10); 120 CASE_BASE(16); 121 default: 122 cutoff = neg ? INTMAX_MIN : INTMAX_MAX; 123 cutlim = cutoff % base; 124 cutoff /= base; 125 } 126 #undef CASE_BASE 127 128 if (neg) { 129 if (cutlim > 0) { 130 cutlim -= base; 131 cutoff += 1; 132 } 133 cutlim = -cutlim; 134 } 135 for (acc = 0, any = 0;; c = (unsigned char) *s++) { 136 if (isdigit(c)) 137 c -= '0'; 138 else if (isalpha(c)) 139 c -= isupper(c) ? 'A' - 10 : 'a' - 10; 140 else 141 break; 142 if (c >= base) 143 break; 144 if (any < 0) 145 continue; 146 if (neg) { 147 if (acc < cutoff || (acc == cutoff && c > cutlim)) { 148 any = -1; 149 acc = INTMAX_MIN; 150 errno = ERANGE; 151 } else { 152 any = 1; 153 acc *= base; 154 acc -= c; 155 } 156 } else { 157 if (acc > cutoff || (acc == cutoff && c > cutlim)) { 158 any = -1; 159 acc = INTMAX_MAX; 160 errno = ERANGE; 161 } else { 162 any = 1; 163 acc *= base; 164 acc += c; 165 } 166 } 167 } 168 if (endptr != 0) 169 *endptr = (char *) (any ? s - 1 : nptr); 170 return (acc); 171 } 172
