pty11.c

linux字符驱动源码

/*
 *  linux/kernel/chr_drv/pty.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 */
 
/*
 *      pty.c
 *
 * This module implements the pty functions
 *      void mpty_write(struct tty_struct * queue);
 *      void spty_write(struct tty_struct * queue);
 */
 
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/tty.h>
#include <linux/fcntl.h>

#include <asm/system.h>
#include <asm/io.h>

int pty_open(unsigned int dev, struct file * filp)
{
        struct tty_struct * tty;

        tty = tty_table + dev;
        if (!tty->link)
              return -ENODEV;
        wake_up(&tty->read_q->proc_list);
        if (filp->f_flags & O_NDELAY)
                 return 0;
        while (!tty->link->count && !(current->signal & ~current->blocked))
                  interruptible_sleep_on(&tty->link->read_q->proc_list);
          if (!tty->link->count)
                return -ERESTARTSYS;
        return 0;
}
 
void pty_close(unsigned int dev, struct file * filp)
  {
        struct tty_struct * tty;

        tty = tty_table + dev;
         wake_up(&tty->read_q->proc_list);
       wake_up(&tty->link->write_q->proc_list);
        if (IS_A_PTY_MASTER(dev)) {
                 if (tty->link->pgrp > 0)
                        kill_pg(tty->link->pgrp,SIGHUP,1);
         }
 }
  
static inline void pty_copy(struct tty_struct * from, struct tty_struct * to)
{
         int c;
 
        while (!from->stopped && !EMPTY(from->write_q)) {
               if (FULL(to->read_q)) {
                        if (FULL(to->secondary))
                                 break;
                        TTY_READ_FLUSH(to);
                        continue;
                 }
                c = get_tty_queue(from->write_q);
               put_tty_queue(c,to->read_q);
                 if (current->signal & ~current->blocked)
                          break;
          }
        TTY_READ_FLUSH(to);
          wake_up(&from->write_q->proc_list);
 }
 
/*
 * This routine gets called when tty_write has put something into
 * the write_queue. It copies the input to the output-queue of it's
 * slave.
 */
void mpty_write(struct tty_struct * tty)
 {
          if (tty->link)
                 pty_copy(tty,tty->link);
 }
 
void spty_write(struct tty_struct * tty)
 {
          if (tty->link)
                  pty_copy(tty,tty->link);
  }