| // SPDX-License-Identifier: GPL-2.0 |
| /* |
| * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{linux.intel,addtoit}.com) |
| */ |
| |
| #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> |
| |
| 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 (n == 0) |
| return -EIO; |
| else if (errno == EAGAIN) |
| return 0; |
| 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 \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. |
| */ |
| 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\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 |
| * 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\n", 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\n", |
| errno); |
| exit(1); |
| } |
| |
| if (ioctl(pty_fd, TIOCSCTTY, 0) < 0) { |
| printk(UM_KERN_ERR "winch_thread : TIOCSCTTY failed on " |
| "fd %d err = %d\n", 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\n", 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\n", 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\n", errno); |
| } |
| } |
| |
| static int winch_tramp(int fd, struct tty_port *port, 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\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 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\n", |
| -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\n"); |
| printk(UM_KERN_ERR "read failed, err = %d\n", errno); |
| printk(UM_KERN_ERR "fd %d will not support SIGWINCH\n", 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.\n"); |
| goto out_close; |
| } |
| |
| return err; |
| |
| out_close: |
| close(fds[1]); |
| close(fds[0]); |
| out: |
| return err; |
| } |
| |
| void register_winch(int fd, struct tty_port *port) |
| { |
| 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, port)) { |
| register_winch_irq(-1, fd, -1, port, 0); |
| return; |
| } |
| |
| if (pid == -1) { |
| thread = winch_tramp(fd, port, &thread_fd, &stack); |
| if (thread < 0) |
| return; |
| |
| register_winch_irq(thread_fd, fd, thread, port, 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\n", errno); |
| } |
| } |