root/kernel/chr_drv/pty.c

/* */

DEFINITIONS

1. pty_close
2. pty_copy
3. pty_write
4. pty_open

   1 /*
   2  *  linux/kernel/chr_drv/pty.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6 
   7 /*
   8  *      pty.c
   9  *
  10  * This module exports the following pty function:
  11  * 
  12  *      int  pty_open(struct tty_struct * tty, struct file * filp);
  13  */
  14 
  15 #include <linux/errno.h>
  16 #include <linux/sched.h>
  17 #include <linux/tty.h>
  18 #include <linux/fcntl.h>
  19 #include <linux/interrupt.h>
  20 
  21 #include <asm/system.h>
  22 #include <asm/bitops.h>
  23 
  24 static void pty_close(struct tty_struct * tty, struct file * filp)
     /*  */
  25 {
  26         if (!tty || (tty->count > 1))
  27                 return;
  28         wake_up_interruptible(&tty->read_q.proc_list);
  29         if (!tty->link)
  30                 return;
  31         wake_up_interruptible(&tty->link->write_q.proc_list);
  32         if (IS_A_PTY_MASTER(tty->line))
  33                 tty_hangup(tty->link);
  34 }
  35 
  36 static inline void pty_copy(struct tty_struct * from, struct tty_struct * to)
     /*  */
  37 {
  38         int c;
  39 
  40         while (!from->stopped && !EMPTY(&from->write_q)) {
  41                 if (FULL(&to->read_q)) {
  42                         if (FULL(&to->secondary))
  43                                 break;
  44                         TTY_READ_FLUSH(to);
  45                         continue;
  46                 }
  47                 c = get_tty_queue(&from->write_q);
  48                 put_tty_queue(c, &to->read_q);
  49                 if (current->signal & ~current->blocked)
  50                         break;
  51         }
  52         TTY_READ_FLUSH(to);
  53         wake_up_interruptible(&from->write_q.proc_list);
  54         if (from->write_data_cnt) {
  55                 set_bit(from->line, &tty_check_write);
  56                 mark_bh(TTY_BH);
  57         }
  58 }
  59 
  60 /*
  61  * This routine gets called when tty_write has put something into
  62  * the write_queue. It copies the input to the output-queue of it's
  63  * slave.
  64  */
  65 static void pty_write(struct tty_struct * tty)
     /*  */
  66 {
  67         if (tty->link)
  68                 pty_copy(tty,tty->link);
  69 }
  70 
  71 int pty_open(struct tty_struct *tty, struct file * filp)
     /*  */
  72 {
  73         if (!tty || !tty->link)
  74                 return -ENODEV;
  75         tty->write = tty->link->write = pty_write;
  76         tty->close = tty->link->close = pty_close;
  77         wake_up_interruptible(&tty->read_q.proc_list);
  78         if (filp->f_flags & O_NDELAY)
  79                 return 0;
  80         while (!tty->link->count && !(current->signal & ~current->blocked))
  81                 interruptible_sleep_on(&tty->link->read_q.proc_list);
  82         if (!tty->link->count)
  83                 return -ERESTARTSYS;
  84         return 0;
  85 }

/* */