New getrusage

[Claudio Scordino <cloud.of.andor@gmail.com>]

Actually, I think that a better implementation of getrusage would be the 
following one, but it requires a (new) third parameter. That's why I didn't 
suggest it...

Many thanks,

            Claudio

Signed-off-by: Claudio Scordino <cloud.of.andor@gmail.com>

asmlinkage long sys_getrusage(int who, struct rusage __user *ru, pid_t pid)
{
 struct rusage r;
 struct task_struct* tsk = current;
 if ((pid < 0) || 
    ((who != RUSAGE_SELF) && (who != RUSAGE_CHILDREN))) 
  return -EINVAL;
 read_lock(&tasklist_lock);
 if (pid > 0) {
  tsk = find_task_by_pid(pid);
  if (tsk == NULL)
         goto bad; 
  if (((current->uid != tsk->euid) ||
     (current->uid != tsk->suid) ||
     (current->uid != tsk->uid) ||
     (current->gid != tsk->egid) ||
     (current->gid != tsk->sgid) ||
     (current->gid != tsk->gid)) && !capable(CAP_SYS_PTRACE))
   goto bad;
 }
 k_getrusage(tsk, who, &r);
 read_unlock(&tasklist_lock);
 return copy_to_user(ru, &r, sizeof(r)) ? -EFAULT : 0;

 bad:
 read_unlock(&tasklist_lock);
 return tsk ? -EPERM : -EINVAL;
}