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freebsd/contrib/ntp/libntp/atouint.c
1999-12-09 13:01:21 +00:00

36 lines
575 B
C

/*
* atouint - convert an ascii string to an unsigned long, with error checking
*/
#include <sys/types.h>
#include <ctype.h>
#include "ntp_types.h"
#include "ntp_stdlib.h"
int
atouint(
const char *str,
u_long *uval
)
{
register u_long u;
register const char *cp;
cp = str;
if (*cp == '\0')
return 0;
u = 0;
while (*cp != '\0') {
if (!isdigit((int)*cp))
return 0;
if (u > 429496729 || (u == 429496729 && *cp >= '6'))
return 0; /* overflow */
u = (u << 3) + (u << 1);
u += *cp++ - '0'; /* ascii dependent */
}
*uval = u;
return 1;
}