/*

   * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{linux.intel,addtoit}.com)

   * Licensed under the GPL
   */

  #include <stdlib.h>

  #include <unistd.h>

  #include <errno.h>

  #include <sched.h>

  #include <signal.h>
  #include <termios.h>

  #include <sys/ioctl.h>

  #include "chan_user.h"

  #include "os.h"

  #include "um_malloc.h"

  #include "user.h"

  
  void generic_close(int fd, void *unused)
  {

  	close(fd);

  }
  
  int generic_read(int fd, char *c_out, void *unused)
  {
  	int n;

  	n = read(fd, c_out, sizeof(*c_out));
  	if (n > 0)
  		return n;
  	else if (errno == EAGAIN)

  		return 0;

  	else if (n == 0)

  		return -EIO;

  	return -errno;

  }

  /* XXX Trivial wrapper around write */

  
  int generic_write(int fd, const char *buf, int n, void *unused)
  {

  	int err;
  
  	err = write(fd, buf, n);
  	if (err > 0)
  		return err;
  	else if (errno == EAGAIN)
  		return 0;
  	else if (err == 0)
  		return -EIO;
  	return -errno;

  }
  
  int generic_window_size(int fd, void *unused, unsigned short *rows_out,
  			unsigned short *cols_out)
  {

  	struct winsize size;

  	int ret;

  	if (ioctl(fd, TIOCGWINSZ, &size) < 0)

  		return -errno;

  	ret = ((*rows_out != size.ws_row) || (*cols_out != size.ws_col));

  	*rows_out = size.ws_row;
  	*cols_out = size.ws_col;

  
  	return ret;
  }
  
  void generic_free(void *data)
  {
  	kfree(data);
  }

  int generic_console_write(int fd, const char *buf, int n)

  {

  	sigset_t old, no_sigio;

  	struct termios save, new;
  	int err;

  	if (isatty(fd)) {

  		sigemptyset(&no_sigio);
  		sigaddset(&no_sigio, SIGIO);
  		if (sigprocmask(SIG_BLOCK, &no_sigio, &old))
  			goto error;

  		CATCH_EINTR(err = tcgetattr(fd, &save));
  		if (err)
  			goto error;
  		new = save;

  		/*
  		 * The terminal becomes a bit less raw, to handle 
   also as

  		 * "Carriage Return", not only as "New Line". Otherwise, the new

  		 * line won't start at the first column.
  		 */

  		new.c_oflag |= OPOST;
  		CATCH_EINTR(err = tcsetattr(fd, TCSAFLUSH, &new));
  		if (err)
  			goto error;
  	}
  	err = generic_write(fd, buf, n, NULL);

  	/*
  	 * Restore raw mode, in any case; we *must* ignore any error apart
  	 * EINTR, except for debug.
  	 */

  	if (isatty(fd)) {

  		CATCH_EINTR(tcsetattr(fd, TCSAFLUSH, &save));

  		sigprocmask(SIG_SETMASK, &old, NULL);
  	}

  	return err;

  error:

  	return -errno;

  }
  
  /*
   * UML SIGWINCH handling
   *

   * The point of this is to handle SIGWINCH on consoles which have host
   * ttys and relay them inside UML to whatever might be running on the
   * console and cares about the window size (since SIGWINCH notifies
   * about terminal size changes).

   *

   * So, we have a separate thread for each host tty attached to a UML
   * device (side-issue - I'm annoyed that one thread can't have
   * multiple controlling ttys for the purpose of handling SIGWINCH, but
   * I imagine there are other reasons that doesn't make any sense).

   *

   * SIGWINCH can't be received synchronously, so you have to set up to
   * receive it as a signal.  That being the case, if you are going to
   * wait for it, it is convenient to sit in sigsuspend() and wait for
   * the signal to bounce you out of it (see below for how we make sure
   * to exit only on SIGWINCH).

   */
  
  static void winch_handler(int sig)
  {
  }
  
  struct winch_data {
  	int pty_fd;
  	int pipe_fd;

  };
  
  static int winch_thread(void *arg)
  {
  	struct winch_data *data = arg;
  	sigset_t sigs;
  	int pty_fd, pipe_fd;

  	int count;

  	char c = 1;

  	pty_fd = data->pty_fd;
  	pipe_fd = data->pipe_fd;

  	count = write(pipe_fd, &c, sizeof(c));

  	if (count != sizeof(c))
  		printk(UM_KERN_ERR "winch_thread : failed to write "
  		       "synchronization byte, err = %d
  ", -count);

  	/*
  	 * We are not using SIG_IGN on purpose, so don't fix it as I thought to

  	 * do! If using SIG_IGN, the sigsuspend() call below would not stop on

  	 * SIGWINCH.
  	 */

  
  	signal(SIGWINCH, winch_handler);
  	sigfillset(&sigs);

  	/* Block all signals possible. */

  	if (sigprocmask(SIG_SETMASK, &sigs, NULL) < 0) {
  		printk(UM_KERN_ERR "winch_thread : sigprocmask failed, "
  		       "errno = %d
  ", errno);

  		exit(1);
  	}

  	/* In sigsuspend(), block anything else than SIGWINCH. */
  	sigdelset(&sigs, SIGWINCH);

  	if (setsid() < 0) {
  		printk(UM_KERN_ERR "winch_thread : setsid failed, errno = %d
  ",
  		       errno);

  		exit(1);
  	}

  	if (ioctl(pty_fd, TIOCSCTTY, 0) < 0) {

  		printk(UM_KERN_ERR "winch_thread : TIOCSCTTY failed on "
  		       "fd %d err = %d
  ", pty_fd, errno);
  		exit(1);
  	}

  	if (tcsetpgrp(pty_fd, os_getpid()) < 0) {

  		printk(UM_KERN_ERR "winch_thread : tcsetpgrp failed on "
  		       "fd %d err = %d
  ", pty_fd, errno);

  		exit(1);
  	}

  	/*
  	 * These are synchronization calls between various UML threads on the

  	 * host - since they are not different kernel threads, we cannot use
  	 * kernel semaphores. We don't use SysV semaphores because they are

  	 * persistent.
  	 */

  	count = read(pipe_fd, &c, sizeof(c));

  	if (count != sizeof(c))
  		printk(UM_KERN_ERR "winch_thread : failed to read "

  		       "synchronization byte, err = %d
  ", errno);

  	while(1) {
  		/*
  		 * This will be interrupted by SIGWINCH only, since

  		 * other signals are blocked.
  		 */

  		sigsuspend(&sigs);

  		count = write(pipe_fd, &c, sizeof(c));

  		if (count != sizeof(c))
  			printk(UM_KERN_ERR "winch_thread : write failed, "

  			       "err = %d
  ", errno);

  	}
  }

  static int winch_tramp(int fd, struct tty_struct *tty, int *fd_out,
  		       unsigned long *stack_out)

  {
  	struct winch_data data;

  	int fds[2], n, err;

  	char c;
  
  	err = os_pipe(fds, 1, 1);

  	if (err < 0) {
  		printk(UM_KERN_ERR "winch_tramp : os_pipe failed, err = %d
  ",
  		       -err);

  		goto out;

  	}
  
  	data = ((struct winch_data) { .pty_fd 		= fd,

  				      .pipe_fd 		= fds[1] } );

  	/*
  	 * CLONE_FILES so this thread doesn't hold open files which are open

  	 * now, but later closed in a different thread.  This is a
  	 * problem with /dev/net/tun, which if held open by this
  	 * thread, prevents the TUN/TAP device from being reused.

  	 */

  	err = run_helper_thread(winch_thread, &data, CLONE_FILES, stack_out);

  	if (err < 0) {
  		printk(UM_KERN_ERR "fork of winch_thread failed - errno = %d
  ",
  		       -err);

  		goto out_close;

  	}

  	*fd_out = fds[0];

  	n = read(fds[0], &c, sizeof(c));

  	if (n != sizeof(c)) {
  		printk(UM_KERN_ERR "winch_tramp : failed to read "
  		       "synchronization byte
  ");

  		printk(UM_KERN_ERR "read failed, err = %d
  ", errno);

  		printk(UM_KERN_ERR "fd %d will not support SIGWINCH
  ", fd);
  		err = -EINVAL;

  		goto out_close;

  	}

  
  	if (os_set_fd_block(*fd_out, 0)) {

  		printk(UM_KERN_ERR "winch_tramp: failed to set thread_fd "
  		       "non-blocking.
  ");

  		goto out_close;
  	}
  
  	return err;

  
   out_close:

  	close(fds[1]);
  	close(fds[0]);

   out:
  	return err;

  }
  
  void register_winch(int fd, struct tty_struct *tty)
  {

  	unsigned long stack;
  	int pid, thread, count, thread_fd = -1;

  	char c = 1;

  	if (!isatty(fd))

  		return;
  
  	pid = tcgetpgrp(fd);

  	if (!is_skas_winch(pid, fd, tty) && (pid == -1)) {

  		thread = winch_tramp(fd, tty, &thread_fd, &stack);
  		if (thread < 0)
  			return;
  
  		register_winch_irq(thread_fd, fd, thread, tty, stack);

  		count = write(thread_fd, &c, sizeof(c));

  		if (count != sizeof(c))
  			printk(UM_KERN_ERR "register_winch : failed to write "

  			       "synchronization byte, err = %d
  ", errno);

  	}
  }