Subversion Repositories planix.SVN

#include <u.h>
#include <libc.h>


/*
 *  After a fork with fd's copied, both fd's are pointing to
 *  the same Chan structure.  Since the offset is kept in the Chan
 *  structure, the seek's and read's in the two processes can
 *  compete at moving the offset around.  Hence the unusual loop
 *  in the middle of this routine.
 */
static long
oldtime(long *tp)
{
        char b[20];
        static int f = -1;
        int i, retries;
        long t;

        memset(b, 0, sizeof(b));
        for(retries = 0; retries < 100; retries++){
                if(f < 0)
                        f = open("/dev/time", OREAD|OCEXEC);
                if(f < 0)
                        break;
                if(seek(f, 0, 0) < 0 || (i = read(f, b, sizeof(b))) < 0){
                        close(f);
                        f = -1;
                } else {
                        if(i != 0)
                                break;
                }
        }
        t = atol(b);
        if(tp)
                *tp = t;
        return t;
}

long
time(long *tp)
{
        vlong t;

        t = nsec()/((vlong)1000000000);
        if(t == 0)
                t = oldtime(0);
        if(tp != nil)
                *tp = t;
        return t;
}