1 /*- 2 * Copyright (c) 1990 The Regents of the University of California. 3 * 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 30 #if defined(LIBC_SCCS) && !defined(lint) 31 static char *rcsid = "$OpenBSD: strtol.c,v 1.5 2003/06/02 20:18:38 millert Exp $"; 32 #endif /* LIBC_SCCS and not lint */ 33 34 #include <ctype.h> 35 #include <errno.h> 36 #include <limits.h> 37 #include <stdlib.h> 38 39 40 /* 41 * Convert a string to a long integer. 42 * 43 * Ignores `locale' stuff. Assumes that the upper and lower case 44 * alphabets and digits are each contiguous. 45 */ 46 long 47 strtol(nptr, endptr, base) 48 const char *nptr; 49 char **endptr; 50 register int base; 51 { 52 register const char *s; 53 register long acc, cutoff; 54 register int c; 55 register int neg, any, cutlim; 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 = (unsigned char) *s++; 65 } while (isspace(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 c = s[1]; 77 s += 2; 78 base = 16; 79 } 80 if (base == 0) 81 base = c == '0' ? 8 : 10; 82 83 /* 84 * Compute the cutoff value between legal numbers and illegal 85 * numbers. That is the largest legal value, divided by the 86 * base. An input number that is greater than this value, if 87 * followed by a legal input character, is too big. One that 88 * is equal to this value may be valid or not; the limit 89 * between valid and invalid numbers is then based on the last 90 * digit. For instance, if the range for longs is 91 * [-2147483648..2147483647] and the input base is 10, 92 * cutoff will be set to 214748364 and cutlim to either 93 * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated 94 * a value > 214748364, or equal but the next digit is > 7 (or 8), 95 * the number is too big, and we will return a range error. 96 * 97 * Set any if any `digits' consumed; make it negative to indicate 98 * overflow. 99 */ 100 cutoff = neg ? LONG_MIN : LONG_MAX; 101 cutlim = cutoff % base; 102 cutoff /= base; 103 if (neg) { 104 if (cutlim > 0) { 105 cutlim -= base; 106 cutoff += 1; 107 } 108 cutlim = -cutlim; 109 } 110 for (acc = 0, any = 0;; c = (unsigned char) *s++) { 111 if (isdigit(c)) 112 c -= '0'; 113 else if (isalpha(c)) 114 c -= isupper(c) ? 'A' - 10 : 'a' - 10; 115 else 116 break; 117 if (c >= base) 118 break; 119 if (any < 0) 120 continue; 121 if (neg) { 122 if (acc < cutoff || acc == cutoff && c > cutlim) { 123 any = -1; 124 acc = LONG_MIN; 125 errno = ERANGE; 126 } else { 127 any = 1; 128 acc *= base; 129 acc -= c; 130 } 131 } else { 132 if (acc > cutoff || acc == cutoff && c > cutlim) { 133 any = -1; 134 acc = LONG_MAX; 135 errno = ERANGE; 136 } else { 137 any = 1; 138 acc *= base; 139 acc += c; 140 } 141 } 142 } 143 if (endptr != 0) 144 *endptr = (char *) (any ? s - 1 : nptr); 145 return (acc); 146 } 147