Annotation of prex/usr/lib/libc/stdlib/strtol.c, Revision 1.1.1.1
1.1 nbrk 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:
30: #include <limits.h>
31: #include <ctype.h>
32: #include <errno.h>
33: #include <stdlib.h>
34:
35:
36: /*
37: * Convert a string to a long integer.
38: *
39: * Ignores `locale' stuff. Assumes that the upper and lower case
40: * alphabets and digits are each contiguous.
41: */
42: long
43: strtol(nptr, endptr, base)
44: const char *nptr;
45: char **endptr;
46: int base;
47: {
48: const char *s;
49: long acc, cutoff;
50: int c;
51: int neg, any, cutlim;
52:
53: /*
54: * Skip white space and pick up leading +/- sign if any.
55: * If base is 0, allow 0x for hex and 0 for octal, else
56: * assume decimal; if base is already 16, allow 0x.
57: */
58: s = nptr;
59: do {
60: c = (unsigned char) *s++;
61: } while (isspace(c));
62: if (c == '-') {
63: neg = 1;
64: c = *s++;
65: } else {
66: neg = 0;
67: if (c == '+')
68: c = *s++;
69: }
70: if ((base == 0 || base == 16) &&
71: c == '0' && (*s == 'x' || *s == 'X')) {
72: c = s[1];
73: s += 2;
74: base = 16;
75: }
76: if (base == 0)
77: base = c == '0' ? 8 : 10;
78:
79: /*
80: * Compute the cutoff value between legal numbers and illegal
81: * numbers. That is the largest legal value, divided by the
82: * base. An input number that is greater than this value, if
83: * followed by a legal input character, is too big. One that
84: * is equal to this value may be valid or not; the limit
85: * between valid and invalid numbers is then based on the last
86: * digit. For instance, if the range for longs is
87: * [-2147483648..2147483647] and the input base is 10,
88: * cutoff will be set to 214748364 and cutlim to either
89: * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated
90: * a value > 214748364, or equal but the next digit is > 7 (or 8),
91: * the number is too big, and we will return a range error.
92: *
93: * Set any if any `digits' consumed; make it negative to indicate
94: * overflow.
95: */
96: cutoff = neg ? LONG_MIN : LONG_MAX;
97: cutlim = (int)(cutoff % base);
98: cutoff /= base;
99: if (neg) {
100: if (cutlim > 0) {
101: cutlim -= base;
102: cutoff += 1;
103: }
104: cutlim = -cutlim;
105: }
106: for (acc = 0, any = 0;; c = (unsigned char) *s++) {
107: if (isdigit(c))
108: c -= '0';
109: else if (isalpha(c))
110: c -= isupper(c) ? 'A' - 10 : 'a' - 10;
111: else
112: break;
113: if (c >= base)
114: break;
115: if (any < 0)
116: continue;
117: if (neg) {
118: if (acc < cutoff || (acc == cutoff && c > cutlim)) {
119: any = -1;
120: acc = LONG_MIN;
121: errno = ERANGE;
122: } else {
123: any = 1;
124: acc *= base;
125: acc -= c;
126: }
127: } else {
128: if (acc > cutoff || (acc == cutoff && c > cutlim)) {
129: any = -1;
130: acc = LONG_MAX;
131: errno = ERANGE;
132: } else {
133: any = 1;
134: acc *= base;
135: acc += c;
136: }
137: }
138: }
139: if (endptr != 0)
140: /* LINTED interface specification */
141: *endptr = (char *)(any ? s - 1 : nptr);
142: return (acc);
143: }
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