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. 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 #if defined(LIBC_SCCS) && !defined(lint)
35 static char sccsid[] = "@(#)strtol.c 5.4 (Berkeley) 2/23/91";
36 #endif /* LIBC_SCCS and not lint */
37
38 #include <limits.h>
39 #include <ctype.h>
40 #include <errno.h>
41 #include <stdlib.h>
42
43
44 /*
45 * Convert a string to a long integer.
46 *
47 * Ignores `locale' stuff. Assumes that the upper and lower case
48 * alphabets and digits are each contiguous.
49 */
50 long
strtol(nptr,endptr,base)51 strtol(nptr, endptr, base)
52 const char *nptr;
53 char **endptr;
54 register int base;
55 {
56 register const char *s = nptr;
57 register unsigned long acc;
58 register int c;
59 register unsigned long cutoff;
60 register int neg = 0, any, cutlim;
61
62 /*
63 * Skip white space and pick up leading +/- sign if any.
64 * If base is 0, allow 0x for hex and 0 for octal, else
65 * assume decimal; if base is already 16, allow 0x.
66 */
67 do {
68 c = *s++;
69 } while (isspace(c));
70 if (c == '-') {
71 neg = 1;
72 c = *s++;
73 } else if (c == '+')
74 c = *s++;
75 if ((base == 0 || base == 16) &&
76 c == '0' && (*s == 'x' || *s == 'X')) {
77 c = s[1];
78 s += 2;
79 base = 16;
80 }
81 if (base == 0)
82 base = c == '0' ? 8 : 10;
83
84 /*
85 * Compute the cutoff value between legal numbers and illegal
86 * numbers. That is the largest legal value, divided by the
87 * base. An input number that is greater than this value, if
88 * followed by a legal input character, is too big. One that
89 * is equal to this value may be valid or not; the limit
90 * between valid and invalid numbers is then based on the last
91 * digit. For instance, if the range for longs is
92 * [-2147483648..2147483647] and the input base is 10,
93 * cutoff will be set to 214748364 and cutlim to either
94 * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated
95 * a value > 214748364, or equal but the next digit is > 7 (or 8),
96 * the number is too big, and we will return a range error.
97 *
98 * Set any if any `digits' consumed; make it negative to indicate
99 * overflow.
100 */
101 cutoff = neg ? -(unsigned long)LONG_MIN : LONG_MAX;
102 cutlim = cutoff % (unsigned long)base;
103 cutoff /= (unsigned long)base;
104 for (acc = 0, any = 0;; c = *s++) {
105 if (isdigit(c))
106 c -= '0';
107 else if (isalpha(c))
108 c -= isupper(c) ? 'A' - 10 : 'a' - 10;
109 else
110 break;
111 if (c >= base)
112 break;
113 if (any < 0 || acc > cutoff || acc == cutoff && c > cutlim)
114 any = -1;
115 else {
116 any = 1;
117 acc *= base;
118 acc += c;
119 }
120 }
121 if (any < 0) {
122 acc = neg ? LONG_MIN : LONG_MAX;
123 errno = ERANGE;
124 } else if (neg)
125 acc = -acc;
126 if (endptr != 0)
127 *endptr = any ? s - 1 : (char *)nptr;
128 return (acc);
129 }
130