strtoul.c (3402B)
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 * Convert a string to an unsigned long integer. 41 * 42 * Assumes that the upper and lower case 43 * alphabets and digits are each contiguous. 44 */ 45 unsigned long 46 strtoul(const char * __restrict nptr, char ** __restrict endptr, int base) 47 { 48 const char *s; 49 unsigned long acc; 50 char c; 51 unsigned long cutoff; 52 int neg, any, cutlim; 53 54 /* 55 * See strtol for comments as to the logic used. 56 */ 57 s = nptr; 58 do { 59 c = *s++; 60 } while (isspace((unsigned char)c)); 61 if (c == '-') { 62 neg = 1; 63 c = *s++; 64 } else { 65 neg = 0; 66 if (c == '+') 67 c = *s++; 68 } 69 if ((base == 0 || base == 16) && 70 c == '0' && (*s == 'x' || *s == 'X') && 71 ((s[1] >= '0' && s[1] <= '9') || 72 (s[1] >= 'A' && s[1] <= 'F') || 73 (s[1] >= 'a' && s[1] <= 'f'))) { 74 c = s[1]; 75 s += 2; 76 base = 16; 77 } 78 if (base == 0) 79 base = c == '0' ? 8 : 10; 80 acc = any = 0; 81 if (base < 2 || base > 36) 82 goto noconv; 83 84 cutoff = ULONG_MAX / base; 85 cutlim = ULONG_MAX % base; 86 for ( ; ; c = *s++) { 87 if (c >= '0' && c <= '9') 88 c -= '0'; 89 else if (c >= 'A' && c <= 'Z') 90 c -= 'A' - 10; 91 else if (c >= 'a' && c <= 'z') 92 c -= 'a' - 10; 93 else 94 break; 95 if (c >= base) 96 break; 97 if (any < 0 || acc > cutoff || (acc == cutoff && c > cutlim)) 98 any = -1; 99 else { 100 any = 1; 101 acc *= base; 102 acc += c; 103 } 104 } 105 if (any < 0) { 106 acc = ULONG_MAX; 107 errno = ERANGE; 108 } else if (!any) { 109 noconv: 110 errno = EINVAL; 111 } else if (neg) 112 acc = -acc; 113 if (endptr != NULL) 114 *endptr = (char *)(any ? s - 1 : nptr); 115 return (acc); 116 }