scc

 1#include <ctype.h>
 2#include <errno.h>
 3#include <limits.h>
 4#include <stdlib.h>
 5#include <string.h>
 6
 7#include "../libc.h"
 8
 9#undef strtol
10
11long
12strtol(const char * restrict ptr, char ** restrict end, int base)
13{
14	int d, sign = -1;
15	long n;
16	char *t, *s = (char *) ptr;
17
18	if (end)
19		*end = s;
20
21	while (isspace(*s))
22		++s;
23
24	switch (*s) {
25	case '-':
26		sign = 1;
27	case '+':
28		++s;
29	}
30
31	if (base == 0) {
32		if (*s == '0')
33			base = toupper(s[1]) == 'X' ? 16 : 8;
34		else
35			base = 10;
36	}
37	if (base == 16 && *s == '0' && toupper(s[1]) == 'X')
38		s += 2;
39
40	n = 0;
41	/* Compute n as a negative number to avoid overflow on LONG_MIN */
42	for (t = s; (d = _dtoi(*t)) < base; ++t) {
43		if (n < LONG_MIN/base)
44			goto overflow;
45		n *= base;
46		if (-d < LONG_MIN - n)
47			goto overflow;
48		n -= d;
49		if (n == LONG_MIN && sign < 0)
50			goto overflow;
51	}
52
53	if (end && t != s)
54		*end = t;
55
56	return n*sign;
57
58overflow:
59	if (end)
60		*end = t;
61	errno = ERANGE;
62
63	return sign < 0 ? LONG_MAX : LONG_MIN;
64}