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1 | /*- |
2 | * Copyright (c) 1990 The Regents of the University of California. | |
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3 | * All rights reserved. |
4 | * | |
40dadc22 | 5 | * %sccs.include.redist.c% |
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6 | */ |
7 | ||
8 | #if defined(LIBC_SCCS) && !defined(lint) | |
f0a345ab | 9 | static char sccsid[] = "@(#)strtol.c 5.4 (Berkeley) %G%"; |
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10 | #endif /* LIBC_SCCS and not lint */ |
11 | ||
40dadc22 | 12 | #include <limits.h> |
6c1d546f | 13 | #include <ctype.h> |
40dadc22 | 14 | #include <errno.h> |
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15 | #include <stdlib.h> |
16 | ||
6c1d546f | 17 | |
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18 | /* |
19 | * Convert a string to a long integer. | |
20 | * | |
21 | * Ignores `locale' stuff. Assumes that the upper and lower case | |
22 | * alphabets and digits are each contiguous. | |
23 | */ | |
6c1d546f | 24 | long |
40dadc22 | 25 | strtol(nptr, endptr, base) |
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26 | const char *nptr; |
27 | char **endptr; | |
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28 | register int base; |
29 | { | |
f0a345ab | 30 | register const char *s = nptr; |
40dadc22 | 31 | register unsigned long acc; |
6c1d546f | 32 | register int c; |
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33 | register unsigned long cutoff; |
34 | register int neg = 0, any, cutlim; | |
6c1d546f | 35 | |
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36 | /* |
37 | * Skip white space and pick up leading +/- sign if any. | |
38 | * If base is 0, allow 0x for hex and 0 for octal, else | |
39 | * assume decimal; if base is already 16, allow 0x. | |
40 | */ | |
41 | do { | |
42 | c = *s++; | |
43 | } while (isspace(c)); | |
44 | if (c == '-') { | |
45 | neg = 1; | |
46 | c = *s++; | |
47 | } else if (c == '+') | |
48 | c = *s++; | |
49 | if ((base == 0 || base == 16) && | |
50 | c == '0' && (*s == 'x' || *s == 'X')) { | |
51 | c = s[1]; | |
52 | s += 2; | |
53 | base = 16; | |
6c1d546f | 54 | } |
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55 | if (base == 0) |
56 | base = c == '0' ? 8 : 10; | |
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57 | |
58 | /* | |
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59 | * Compute the cutoff value between legal numbers and illegal |
60 | * numbers. That is the largest legal value, divided by the | |
61 | * base. An input number that is greater than this value, if | |
62 | * followed by a legal input character, is too big. One that | |
63 | * is equal to this value may be valid or not; the limit | |
64 | * between valid and invalid numbers is then based on the last | |
65 | * digit. For instance, if the range for longs is | |
66 | * [-2147483648..2147483647] and the input base is 10, | |
67 | * cutoff will be set to 214748364 and cutlim to either | |
68 | * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated | |
69 | * a value > 214748364, or equal but the next digit is > 7 (or 8), | |
70 | * the number is too big, and we will return a range error. | |
71 | * | |
72 | * Set any if any `digits' consumed; make it negative to indicate | |
73 | * overflow. | |
6c1d546f | 74 | */ |
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75 | cutoff = neg ? -(unsigned long)LONG_MIN : LONG_MAX; |
76 | cutlim = cutoff % (unsigned long)base; | |
77 | cutoff /= (unsigned long)base; | |
78 | for (acc = 0, any = 0;; c = *s++) { | |
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79 | if (isdigit(c)) |
80 | c -= '0'; | |
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81 | else if (isalpha(c)) |
82 | c -= isupper(c) ? 'A' - 10 : 'a' - 10; | |
83 | else | |
84 | break; | |
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85 | if (c >= base) |
86 | break; | |
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87 | if (any < 0 || acc > cutoff || acc == cutoff && c > cutlim) |
88 | any = -1; | |
89 | else { | |
90 | any = 1; | |
91 | acc *= base; | |
92 | acc += c; | |
93 | } | |
6c1d546f | 94 | } |
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95 | if (any < 0) { |
96 | acc = neg ? LONG_MIN : LONG_MAX; | |
97 | errno = ERANGE; | |
98 | } else if (neg) | |
99 | acc = -acc; | |
100 | if (endptr != 0) | |
f0a345ab | 101 | *endptr = any ? s - 1 : (char *)nptr; |
40dadc22 | 102 | return (acc); |
6c1d546f | 103 | } |