ref: 0c569f7d3bfa46dab9b35fc4298fe8509f1181a1
dir: /sys/src/libc/9sys/getppid.c/
#include	<u.h>
#include	<libc.h>
int
getppid(void)
{
	char b[20];
	int f;
	memset(b, 0, sizeof(b));
	f = open("/dev/ppid", 0);
	if(f >= 0) {
		read(f, b, sizeof(b));
		close(f);
	}
	return atol(b);
}