302 lines
6.9 KiB
C
302 lines
6.9 KiB
C
/*
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* Copyright (C) 2000 - 2007 Jeff Dike (jdike@{linux.intel,addtoit}.com)
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* Licensed under the GPL
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*/
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#include <stdlib.h>
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#include <unistd.h>
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#include <errno.h>
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#include <sched.h>
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#include <signal.h>
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#include <termios.h>
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#include <sys/ioctl.h>
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#include "chan_user.h"
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#include "os.h"
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#include "um_malloc.h"
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void generic_close(int fd, void *unused)
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{
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close(fd);
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}
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int generic_read(int fd, char *c_out, void *unused)
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{
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int n;
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n = read(fd, c_out, sizeof(*c_out));
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if (n > 0)
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return n;
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else if (errno == EAGAIN)
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return 0;
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else if (n == 0)
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return -EIO;
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return -errno;
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}
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/* XXX Trivial wrapper around write */
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int generic_write(int fd, const char *buf, int n, void *unused)
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{
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int err;
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err = write(fd, buf, n);
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if (err > 0)
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return err;
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else if (errno == EAGAIN)
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return 0;
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else if (err == 0)
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return -EIO;
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return -errno;
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}
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int generic_window_size(int fd, void *unused, unsigned short *rows_out,
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unsigned short *cols_out)
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{
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struct winsize size;
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int ret;
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if (ioctl(fd, TIOCGWINSZ, &size) < 0)
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return -errno;
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ret = ((*rows_out != size.ws_row) || (*cols_out != size.ws_col));
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*rows_out = size.ws_row;
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*cols_out = size.ws_col;
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return ret;
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}
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void generic_free(void *data)
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{
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kfree(data);
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}
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int generic_console_write(int fd, const char *buf, int n)
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{
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sigset_t old, no_sigio;
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struct termios save, new;
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int err;
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if (isatty(fd)) {
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sigemptyset(&no_sigio);
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sigaddset(&no_sigio, SIGIO);
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if (sigprocmask(SIG_BLOCK, &no_sigio, &old))
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goto error;
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CATCH_EINTR(err = tcgetattr(fd, &save));
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if (err)
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goto error;
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new = save;
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/*
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* The terminal becomes a bit less raw, to handle \n also as
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* "Carriage Return", not only as "New Line". Otherwise, the new
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* line won't start at the first column.
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*/
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new.c_oflag |= OPOST;
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CATCH_EINTR(err = tcsetattr(fd, TCSAFLUSH, &new));
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if (err)
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goto error;
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}
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err = generic_write(fd, buf, n, NULL);
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/*
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* Restore raw mode, in any case; we *must* ignore any error apart
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* EINTR, except for debug.
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*/
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if (isatty(fd)) {
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CATCH_EINTR(tcsetattr(fd, TCSAFLUSH, &save));
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sigprocmask(SIG_SETMASK, &old, NULL);
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}
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return err;
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error:
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return -errno;
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}
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/*
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* UML SIGWINCH handling
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*
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* The point of this is to handle SIGWINCH on consoles which have host
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* ttys and relay them inside UML to whatever might be running on the
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* console and cares about the window size (since SIGWINCH notifies
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* about terminal size changes).
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*
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* So, we have a separate thread for each host tty attached to a UML
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* device (side-issue - I'm annoyed that one thread can't have
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* multiple controlling ttys for the purpose of handling SIGWINCH, but
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* I imagine there are other reasons that doesn't make any sense).
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*
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* SIGWINCH can't be received synchronously, so you have to set up to
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* receive it as a signal. That being the case, if you are going to
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* wait for it, it is convenient to sit in sigsuspend() and wait for
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* the signal to bounce you out of it (see below for how we make sure
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* to exit only on SIGWINCH).
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*/
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static void winch_handler(int sig)
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{
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}
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struct winch_data {
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int pty_fd;
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int pipe_fd;
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};
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static int winch_thread(void *arg)
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{
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struct winch_data *data = arg;
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sigset_t sigs;
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int pty_fd, pipe_fd;
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int count;
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char c = 1;
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pty_fd = data->pty_fd;
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pipe_fd = data->pipe_fd;
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count = write(pipe_fd, &c, sizeof(c));
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if (count != sizeof(c))
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printk(UM_KERN_ERR "winch_thread : failed to write "
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"synchronization byte, err = %d\n", -count);
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/*
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* We are not using SIG_IGN on purpose, so don't fix it as I thought to
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* do! If using SIG_IGN, the sigsuspend() call below would not stop on
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* SIGWINCH.
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*/
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signal(SIGWINCH, winch_handler);
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sigfillset(&sigs);
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/* Block all signals possible. */
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if (sigprocmask(SIG_SETMASK, &sigs, NULL) < 0) {
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printk(UM_KERN_ERR "winch_thread : sigprocmask failed, "
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"errno = %d\n", errno);
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exit(1);
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}
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/* In sigsuspend(), block anything else than SIGWINCH. */
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sigdelset(&sigs, SIGWINCH);
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if (setsid() < 0) {
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printk(UM_KERN_ERR "winch_thread : setsid failed, errno = %d\n",
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errno);
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exit(1);
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}
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if (ioctl(pty_fd, TIOCSCTTY, 0) < 0) {
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printk(UM_KERN_ERR "winch_thread : TIOCSCTTY failed on "
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"fd %d err = %d\n", pty_fd, errno);
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exit(1);
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}
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if (tcsetpgrp(pty_fd, os_getpid()) < 0) {
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printk(UM_KERN_ERR "winch_thread : tcsetpgrp failed on "
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"fd %d err = %d\n", pty_fd, errno);
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exit(1);
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}
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/*
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* These are synchronization calls between various UML threads on the
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* host - since they are not different kernel threads, we cannot use
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* kernel semaphores. We don't use SysV semaphores because they are
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* persistent.
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*/
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count = read(pipe_fd, &c, sizeof(c));
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if (count != sizeof(c))
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printk(UM_KERN_ERR "winch_thread : failed to read "
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"synchronization byte, err = %d\n", errno);
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while(1) {
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/*
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* This will be interrupted by SIGWINCH only, since
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* other signals are blocked.
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*/
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sigsuspend(&sigs);
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count = write(pipe_fd, &c, sizeof(c));
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if (count != sizeof(c))
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printk(UM_KERN_ERR "winch_thread : write failed, "
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"err = %d\n", errno);
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}
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}
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static int winch_tramp(int fd, struct tty_struct *tty, int *fd_out,
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unsigned long *stack_out)
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{
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struct winch_data data;
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int fds[2], n, err;
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char c;
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err = os_pipe(fds, 1, 1);
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if (err < 0) {
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printk(UM_KERN_ERR "winch_tramp : os_pipe failed, err = %d\n",
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-err);
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goto out;
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}
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data = ((struct winch_data) { .pty_fd = fd,
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.pipe_fd = fds[1] } );
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/*
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* CLONE_FILES so this thread doesn't hold open files which are open
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* now, but later closed in a different thread. This is a
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* problem with /dev/net/tun, which if held open by this
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* thread, prevents the TUN/TAP device from being reused.
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*/
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err = run_helper_thread(winch_thread, &data, CLONE_FILES, stack_out);
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if (err < 0) {
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printk(UM_KERN_ERR "fork of winch_thread failed - errno = %d\n",
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-err);
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goto out_close;
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}
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*fd_out = fds[0];
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n = read(fds[0], &c, sizeof(c));
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if (n != sizeof(c)) {
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printk(UM_KERN_ERR "winch_tramp : failed to read "
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"synchronization byte\n");
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printk(UM_KERN_ERR "read failed, err = %d\n", errno);
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printk(UM_KERN_ERR "fd %d will not support SIGWINCH\n", fd);
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err = -EINVAL;
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goto out_close;
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}
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if (os_set_fd_block(*fd_out, 0)) {
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printk(UM_KERN_ERR "winch_tramp: failed to set thread_fd "
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"non-blocking.\n");
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goto out_close;
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}
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return err;
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out_close:
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close(fds[1]);
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close(fds[0]);
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out:
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return err;
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}
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void register_winch(int fd, struct tty_struct *tty)
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{
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unsigned long stack;
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int pid, thread, count, thread_fd = -1;
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char c = 1;
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if (!isatty(fd))
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return;
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pid = tcgetpgrp(fd);
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if (is_skas_winch(pid, fd, tty)) {
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register_winch_irq(-1, fd, -1, tty, 0);
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return;
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}
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if (pid == -1) {
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thread = winch_tramp(fd, tty, &thread_fd, &stack);
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if (thread < 0)
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return;
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register_winch_irq(thread_fd, fd, thread, tty, stack);
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count = write(thread_fd, &c, sizeof(c));
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if (count != sizeof(c))
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printk(UM_KERN_ERR "register_winch : failed to write "
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"synchronization byte, err = %d\n", errno);
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}
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}
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