ch                 92 kernel/pipe.c        char ch;
ch                 93 kernel/pipe.c        if(copyin(pr->pagetable, &ch, addr + i, 1) == -1)
ch                 95 kernel/pipe.c        pi->data[pi->nwrite++ % PIPESIZE] = ch;
ch                110 kernel/pipe.c    char ch;
ch                123 kernel/pipe.c      ch = pi->data[pi->nread++ % PIPESIZE];
ch                124 kernel/pipe.c      if(copyout(pr->pagetable, addr + i, &ch, 1) == -1)