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 long result; 56 57 /* 58 * Skip white space and pick up leading +/- sign if any. 59 * If base is 0, allow 0x for hex and 0 for octal, else 60 * assume decimal; if base is already 16, allow 0x. 61 */ 62 s = nptr; 63 do { 64 c = *s++; 65 } while (isspace((unsigned char)c)); 66 if (c == '-') { 67 neg = 1; 68 c = *s++; 69 } else { 70 neg = 0; 71 if (c == '+') 72 c = *s++; 73 } 74 if ((base == 0 || base == 16) && 75 c == '0' && (*s == 'x' || *s == 'X') && 76 ((s[1] >= '0' && s[1] <= '9') || 77 (s[1] >= 'A' && s[1] <= 'F') || 78 (s[1] >= 'a' && s[1] <= 'f'))) { 79 c = s[1]; 80 s += 2; 81 base = 16; 82 } 83 if (base == 0) 84 base = c == '0' ? 8 : 10; 85 acc = any = 0; 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 ? (unsigned long)-(LONG_MIN + LONG_MAX) + LONG_MAX 105 : LONG_MAX; 106 cutlim = cutoff % base; 107 cutoff /= base; 108 for ( ; ; c = *s++) { 109 if (c >= '0' && c <= '9') 110 c -= '0'; 111 else if (c >= 'A' && c <= 'Z') 112 c -= 'A' - 10; 113 else if (c >= 'a' && c <= 'z') 114 c -= 'a' - 10; 115 else 116 break; 117 if (c >= base) 118 break; 119 if (any < 0 || acc > cutoff || (acc == cutoff && c > cutlim)) 120 any = -1; 121 else { 122 any = 1; 123 acc *= base; 124 acc += c; 125 } 126 } 127 128 if (any < 0) { 129 result = neg ? LONG_MIN : LONG_MAX; 130 } else { 131 result = neg ? -(long)acc : (long)acc; 132 } 133 134 if (endptr != NULL) 135 *endptr = (char *)(any ? s - 1 : nptr); 136 137 return result; 138 } 139