1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1990, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Copyright (c) 2011 The FreeBSD Foundation 8 * All rights reserved. 9 * Portions of this software were developed by David Chisnall 10 * under sponsorship from the FreeBSD Foundation. 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 3. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 */ 36 37 #include <errno.h> 38 #include <limits.h> 39 #include <stddef.h> 40 #include <stdlib.h> 41 42 /* 43 * Convert a string to a long integer. 44 * 45 * Assumes that the upper and lower case 46 * alphabets and digits are each contiguous. 47 */ 48 long strtol(const char *nptr, char **endptr, int base) 49 { 50 const char *s; 51 unsigned long acc; 52 char c; 53 unsigned long cutoff; 54 int neg, any, cutlim; 55 56 /* 57 * Skip white space and pick up leading +/- sign if any. 58 * If base is 0, allow 0x for hex and 0 for octal, else 59 * assume decimal; if base is already 16, allow 0x. 60 */ 61 s = nptr; 62 do { 63 c = *s++; 64 } while (isspace((unsigned char)c)); 65 if (c == '-') { 66 neg = 1; 67 c = *s++; 68 } else { 69 neg = 0; 70 if (c == '+') 71 c = *s++; 72 } 73 if ((base == 0 || base == 16) && 74 c == '0' && (*s == 'x' || *s == 'X') && 75 ((s[1] >= '0' && s[1] <= '9') || 76 (s[1] >= 'A' && s[1] <= 'F') || 77 (s[1] >= 'a' && s[1] <= 'f'))) { 78 c = s[1]; 79 s += 2; 80 base = 16; 81 } 82 if (base == 0) 83 base = c == '0' ? 8 : 10; 84 acc = any = 0; 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 longs is 94 * [-2147483648..2147483647] and the input base is 10, 95 * cutoff will be set to 214748364 and cutlim to either 96 * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated 97 * a value > 214748364, or equal but the next digit is > 7 (or 8), 98 * the number is too big, and we will return a range error. 99 * 100 * Set 'any' if any `digits' consumed; make it negative to indicate 101 * overflow. 102 */ 103 cutoff = neg ? (unsigned long)-(LONG_MIN + LONG_MAX) + LONG_MAX 104 : LONG_MAX; 105 cutlim = cutoff % base; 106 cutoff /= base; 107 for ( ; ; c = *s++) { 108 if (c >= '0' && c <= '9') 109 c -= '0'; 110 else if (c >= 'A' && c <= 'Z') 111 c -= 'A' - 10; 112 else if (c >= 'a' && c <= 'z') 113 c -= 'a' - 10; 114 else 115 break; 116 if (c >= base) 117 break; 118 if (any < 0 || acc > cutoff || (acc == cutoff && c > cutlim)) 119 any = -1; 120 else { 121 any = 1; 122 acc *= base; 123 acc += c; 124 } 125 } 126 if (any < 0) { 127 acc = neg ? LONG_MIN : LONG_MAX; 128 } else if (neg) 129 acc = -acc; 130 if (endptr != NULL) 131 *endptr = (char *)(any ? s - 1 : nptr); 132 return (acc); 133 } 134