1 /*-
2 * Copyright (c) 1992, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * %sccs.include.redist.c%
6 */
7
8 #if defined(LIBC_SCCS) && !defined(lint)
9 static char sccsid[] = "@(#)strtoq.c 8.1 (Berkeley) 06/04/93";
10 #endif /* LIBC_SCCS and not lint */
11
12 #include <sys/types.h>
13
14 #include <limits.h>
15 #include <errno.h>
16 #include <ctype.h>
17 #include <stdlib.h>
18
19 /*
20 * Convert a string to a quad integer.
21 *
22 * Ignores `locale' stuff. Assumes that the upper and lower case
23 * alphabets and digits are each contiguous.
24 */
25 quad_t
strtoq(nptr,endptr,base)26 strtoq(nptr, endptr, base)
27 const char *nptr;
28 char **endptr;
29 register int base;
30 {
31 register const char *s;
32 register u_quad_t acc;
33 register int c;
34 register u_quad_t qbase, cutoff;
35 register int neg, any, cutlim;
36
37 /*
38 * Skip white space and pick up leading +/- sign if any.
39 * If base is 0, allow 0x for hex and 0 for octal, else
40 * assume decimal; if base is already 16, allow 0x.
41 */
42 s = nptr;
43 do {
44 c = *s++;
45 } while (isspace(c));
46 if (c == '-') {
47 neg = 1;
48 c = *s++;
49 } else {
50 neg = 0;
51 if (c == '+')
52 c = *s++;
53 }
54 if ((base == 0 || base == 16) &&
55 c == '0' && (*s == 'x' || *s == 'X')) {
56 c = s[1];
57 s += 2;
58 base = 16;
59 }
60 if (base == 0)
61 base = c == '0' ? 8 : 10;
62
63 /*
64 * Compute the cutoff value between legal numbers and illegal
65 * numbers. That is the largest legal value, divided by the
66 * base. An input number that is greater than this value, if
67 * followed by a legal input character, is too big. One that
68 * is equal to this value may be valid or not; the limit
69 * between valid and invalid numbers is then based on the last
70 * digit. For instance, if the range for quads is
71 * [-9223372036854775808..9223372036854775807] and the input base
72 * is 10, cutoff will be set to 922337203685477580 and cutlim to
73 * either 7 (neg==0) or 8 (neg==1), meaning that if we have
74 * accumulated a value > 922337203685477580, or equal but the
75 * next digit is > 7 (or 8), the number is too big, and we will
76 * return a range error.
77 *
78 * Set any if any `digits' consumed; make it negative to indicate
79 * overflow.
80 */
81 qbase = (unsigned)base;
82 cutoff = neg ? -(u_quad_t)QUAD_MIN : QUAD_MAX;
83 cutlim = cutoff % qbase;
84 cutoff /= qbase;
85 for (acc = 0, any = 0;; c = *s++) {
86 if (isdigit(c))
87 c -= '0';
88 else if (isalpha(c))
89 c -= isupper(c) ? 'A' - 10 : 'a' - 10;
90 else
91 break;
92 if (c >= base)
93 break;
94 if (any < 0 || acc > cutoff || acc == cutoff && c > cutlim)
95 any = -1;
96 else {
97 any = 1;
98 acc *= qbase;
99 acc += c;
100 }
101 }
102 if (any < 0) {
103 acc = neg ? QUAD_MIN : QUAD_MAX;
104 errno = ERANGE;
105 } else if (neg)
106 acc = -acc;
107 if (endptr != 0)
108 *endptr = (char *)(any ? s - 1 : nptr);
109 return (acc);
110 }
111