strtol.c (4415B)
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. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34 #include <limits.h> 35 #include <ctype.h> 36 #include <errno.h> 37 #include <stdlib.h> 38 39 40 /* 41 * Convert a string to a long integer. 42 * 43 * Assumes that the upper and lower case 44 * alphabets and digits are each contiguous. 45 */ 46 long 47 strtol(const char * __restrict nptr, char ** __restrict endptr, int base) 48 { 49 const char *s; 50 unsigned long acc; 51 char c; 52 unsigned long cutoff; 53 int neg, any, cutlim; 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 s = nptr; 61 do { 62 c = *s++; 63 } while (isspace((unsigned char)c)); 64 if (c == '-') { 65 neg = 1; 66 c = *s++; 67 } else { 68 neg = 0; 69 if (c == '+') 70 c = *s++; 71 } 72 if ((base == 0 || base == 16) && 73 c == '0' && (*s == 'x' || *s == 'X') && 74 ((s[1] >= '0' && s[1] <= '9') || 75 (s[1] >= 'A' && s[1] <= 'F') || 76 (s[1] >= 'a' && s[1] <= 'f'))) { 77 c = s[1]; 78 s += 2; 79 base = 16; 80 } 81 if (base == 0) 82 base = c == '0' ? 8 : 10; 83 acc = any = 0; 84 if (base < 2 || base > 36) 85 goto noconv; 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 if (any < 0) { 128 acc = neg ? LONG_MIN : LONG_MAX; 129 errno = ERANGE; 130 } else if (!any) { 131 noconv: 132 errno = EINVAL; 133 } else if (neg) 134 acc = -acc; 135 if (endptr != NULL) 136 *endptr = (char *)(any ? s - 1 : nptr); 137 return (acc); 138 }