blob: 2f880cb167a582f5f10be75d4647facd1f82e274 [file] [log] [blame]
* Copyright (C) 2000 - 2003 Jeff Dike (
* Licensed under the GPL
#include <unistd.h>
#include <stdlib.h>
#include <errno.h>
#include <termios.h>
#include <string.h>
#include <signal.h>
#include <sched.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include "kern_util.h"
#include "user_util.h"
#include "chan_user.h"
#include "user.h"
#include "os.h"
#include "choose-mode.h"
#include "mode.h"
int generic_console_write(int fd, const char *buf, int n)
struct termios save, new;
int err;
CATCH_EINTR(err = tcgetattr(fd, &save));
if (err)
goto error;
new = save;
/* The terminal becomes a bit less raw, to handle \n 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.*/
CATCH_EINTR(tcsetattr(fd, TCSAFLUSH, &save));
* 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 purposed 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, err;
char c = 1;
pty_fd = data->pty_fd;
pipe_fd = data->pipe_fd;
count = os_write_file(pipe_fd, &c, sizeof(c));
if(count != sizeof(c))
printk("winch_thread : failed to write synchronization "
"byte, err = %d\n", -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
signal(SIGWINCH, winch_handler);
/* Block all signals possible. */
if(sigprocmask(SIG_SETMASK, &sigs, NULL) < 0){
printk("winch_thread : sigprocmask failed, errno = %d\n",
/* In sigsuspend(), block anything else than SIGWINCH. */
sigdelset(&sigs, SIGWINCH);
if(setsid() < 0){
printk("winch_thread : setsid failed, errno = %d\n", errno);
err = os_new_tty_pgrp(pty_fd, os_getpid());
if(err < 0){
printk("winch_thread : new_tty_pgrp failed, err = %d\n", -err);
/* 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
* persistant. */
count = os_read_file(pipe_fd, &c, sizeof(c));
if(count != sizeof(c))
printk("winch_thread : failed to read synchronization byte, "
"err = %d\n", -count);
/* This will be interrupted by SIGWINCH only, since other signals
* are blocked.*/
count = os_write_file(pipe_fd, &c, sizeof(c));
if(count != sizeof(c))
printk("winch_thread : write failed, err = %d\n",
static int winch_tramp(int fd, struct tty_struct *tty, int *fd_out)
struct winch_data data;
unsigned long stack;
int fds[2], n, err;
char c;
err = os_pipe(fds, 1, 1);
if(err < 0){
printk("winch_tramp : os_pipe failed, err = %d\n", -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. This is a problem with /dev/net/tun.
err = run_helper_thread(winch_thread, &data, CLONE_FILES, &stack, 0);
if(err < 0){
printk("fork of winch_thread failed - errno = %d\n", errno);
goto out_close;
*fd_out = fds[0];
n = os_read_file(fds[0], &c, sizeof(c));
if(n != sizeof(c)){
printk("winch_tramp : failed to read synchronization byte\n");
printk("read failed, err = %d\n", -n);
printk("fd %d will not support SIGWINCH\n", fd);
err = -EINVAL;
goto out_close;
return err ;
return err;
void register_winch(int fd, struct tty_struct *tty)
int pid, thread, thread_fd = -1;
int count;
char c = 1;
pid = tcgetpgrp(fd);
if(!CHOOSE_MODE_PROC(is_tracer_winch, is_skas_winch, pid, fd,
tty) && (pid == -1)){
thread = winch_tramp(fd, tty, &thread_fd);
if(thread > 0){
register_winch_irq(thread_fd, fd, thread, tty);
count = os_write_file(thread_fd, &c, sizeof(c));
if(count != sizeof(c))
printk("register_winch : failed to write "
"synchronization byte, err = %d\n",
* Overrides for Emacs so that we follow Linus's tabbing style.
* Emacs will notice this stuff at the end of the file and automatically
* adjust the settings for this buffer only. This must remain at the end
* of the file.
* ---------------------------------------------------------------------------
* Local variables:
* c-file-style: "linux"
* End: