1 /*- 2 * Copyright (c) 1990, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 * @(#)strtol.c 8.1 (Berkeley) 6/4/93 30 */ 31 32 #include "stand.h" 33 #include <limits.h> 34 35 /* 36 * Convert a string to a long integer. 37 * 38 * Ignores `locale' stuff. Assumes that the upper and lower case 39 * alphabets and digits are each contiguous. 40 */ 41 long 42 strtol(const char *nptr, char **endptr, int base) 43 { 44 const char *s; 45 unsigned long acc; 46 unsigned char c; 47 unsigned long cutoff; 48 int neg = 0, any, cutlim; 49 50 /* Be sensible about NULL strings */ 51 if (nptr == NULL) 52 nptr = ""; 53 s = nptr; 54 55 /* 56 * Skip white space and pick up leading +/- sign if any. 57 * If base is 0, allow 0x for hex and 0 for octal, else 58 * assume decimal; if base is already 16, allow 0x. 59 */ 60 do { 61 c = *s++; 62 } while (isspace(c)); 63 if (c == '-') { 64 neg = 1; 65 c = *s++; 66 } else if (c == '+') 67 c = *s++; 68 if ((base == 0 || base == 16) && 69 c == '0' && (*s == 'x' || *s == 'X')) { 70 c = s[1]; 71 s += 2; 72 base = 16; 73 } 74 if (base == 0) 75 base = c == '0' ? 8 : 10; 76 77 /* 78 * Compute the cutoff value between legal numbers and illegal 79 * numbers. That is the largest legal value, divided by the 80 * base. An input number that is greater than this value, if 81 * followed by a legal input character, is too big. One that 82 * is equal to this value may be valid or not; the limit 83 * between valid and invalid numbers is then based on the last 84 * digit. For instance, if the range for longs is 85 * [-2147483648..2147483647] and the input base is 10, 86 * cutoff will be set to 214748364 and cutlim to either 87 * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated 88 * a value > 214748364, or equal but the next digit is > 7 (or 8), 89 * the number is too big, and we will return a range error. 90 * 91 * Set any if any `digits' consumed; make it negative to indicate 92 * overflow. 93 */ 94 cutoff = neg ? -(unsigned long)LONG_MIN : LONG_MAX; 95 cutlim = cutoff % (unsigned long)base; 96 cutoff /= (unsigned long)base; 97 for (acc = 0, any = 0;; c = *s++) { 98 if (!isascii(c)) 99 break; 100 if (isdigit(c)) 101 c -= '0'; 102 else if (isalpha(c)) 103 c -= isupper(c) ? 'A' - 10 : 'a' - 10; 104 else 105 break; 106 if (c >= base) 107 break; 108 if (any < 0 || acc > cutoff || (acc == cutoff && c > cutlim)) 109 any = -1; 110 else { 111 any = 1; 112 acc *= base; 113 acc += c; 114 } 115 } 116 if (any < 0) { 117 acc = neg ? LONG_MIN : LONG_MAX; 118 errno = ERANGE; 119 } else if (neg) 120 acc = -acc; 121 if (endptr != NULL) 122 *endptr = (char *)(any ? s - 1 : nptr); 123 return (acc); 124 } 125