minix/lib/ansi/strtol.c
2009-11-09 10:26:00 +00:00

101 lines
2.2 KiB
C

/*
* (c) copyright 1987 by the Vrije Universiteit, Amsterdam, The Netherlands.
* See the copyright notice in the ACK home directory, in the file "Copyright".
*/
/* $Header$ */
#include <ctype.h>
#include <errno.h>
#include <limits.h>
#include <stdlib.h>
static unsigned long
string2long(register const char *nptr, char **endptr,
int base, int is_signed);
long int
strtol(register const char *nptr, char **endptr, int base)
{
return (signed long)string2long(nptr, endptr, base, 1);
}
unsigned long int
strtoul(register const char *nptr, char **endptr, int base)
{
return (unsigned long)string2long(nptr, endptr, base, 0);
}
#define between(a, c, z) ((unsigned) ((c) - (a)) <= (unsigned) ((z) - (a)))
static unsigned long
string2long(register const char *nptr, char ** const endptr,
int base, int is_signed)
{
register unsigned int v;
register unsigned long val = 0;
register int c;
int ovfl = 0, sign = 1;
const char *startnptr = nptr, *nrstart;
if (endptr) *endptr = (char *)nptr;
while (isspace(*nptr)) nptr++;
c = *nptr;
if (c == '-' || c == '+') {
if (c == '-') sign = -1;
nptr++;
}
nrstart = nptr; /* start of the number */
/* When base is 0, the syntax determines the actual base */
if (base == 0)
if (*nptr == '0')
if (*++nptr == 'x' || *nptr == 'X') {
base = 16;
nptr++;
}
else base = 8;
else base = 10;
else if (base==16 && *nptr=='0' && (*++nptr =='x' || *nptr =='X'))
nptr++;
for (;;) {
c = *nptr;
if (between('0', c, '9')) {
v = c - '0';
} else
if (between('a', c, 'z')) {
v = c - 'a' + 0xa;
} else
if (between('A', c, 'Z')) {
v = c - 'A' + 0xA;
} else {
break;
}
if (v >= base) break;
if (val > (ULONG_MAX - v) / base) ovfl++;
val = (val * base) + v;
nptr++;
}
if (endptr) {
if (nrstart == nptr) *endptr = (char *)startnptr;
else *endptr = (char *)nptr;
}
if (!ovfl) {
/* Overflow is only possible when converting a signed long. */
if (is_signed
&& ( (sign < 0 && val > -(unsigned long)LONG_MIN)
|| (sign > 0 && val > LONG_MAX)))
ovfl++;
}
if (ovfl) {
errno = ERANGE;
if (is_signed)
if (sign < 0) return LONG_MIN;
else return LONG_MAX;
else return ULONG_MAX;
}
return (long) sign * val;
}