ref: d05dbeb9a44c298a01e741c1bffb68591b87b5f5
dir: /sys/src/ape/lib/ap/plan9/getpgrp.c/
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <stdio.h>
#include "sys9.h"
#include "lib.h"
pid_t
getpgrp(void)
{
int n, f, pid;
char pgrpbuf[15], fname[30];
pid = getpid();
sprintf(fname, "/proc/%d/noteid", pid);
f = open(fname, 0);
n = read(f, pgrpbuf, sizeof pgrpbuf);
if(n < 0)
_syserrno();
else
n = atoi(pgrpbuf);
close(f);
return n;
}