readopen           17 pipe.c           int readopen;   // read fd is still open
readopen           32 pipe.c           p->readopen = 1;
readopen           66 pipe.c             p->readopen = 0;
readopen           69 pipe.c           if(p->readopen == 0 && p->writeopen == 0){
readopen           85 pipe.c               if(p->readopen == 0 || proc->killed){