1 // SPDX-License-Identifier: GPL-2.0
3 * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{linux.intel,addtoit}.com)
12 #include <sys/ioctl.h>
13 #include "chan_user.h"
15 #include <um_malloc.h>
17 void generic_close(int fd, void *unused)
22 int generic_read(int fd, char *c_out, void *unused)
26 n = read(fd, c_out, sizeof(*c_out));
31 else if (errno == EAGAIN)
36 /* XXX Trivial wrapper around write */
38 int generic_write(int fd, const char *buf, int n, void *unused)
42 err = write(fd, buf, n);
45 else if (errno == EAGAIN)
52 int generic_window_size(int fd, void *unused, unsigned short *rows_out,
53 unsigned short *cols_out)
58 if (ioctl(fd, TIOCGWINSZ, &size) < 0)
61 ret = ((*rows_out != size.ws_row) || (*cols_out != size.ws_col));
63 *rows_out = size.ws_row;
64 *cols_out = size.ws_col;
69 void generic_free(void *data)
74 int generic_console_write(int fd, const char *buf, int n)
76 sigset_t old, no_sigio;
77 struct termios save, new;
81 sigemptyset(&no_sigio);
82 sigaddset(&no_sigio, SIGIO);
83 if (sigprocmask(SIG_BLOCK, &no_sigio, &old))
86 CATCH_EINTR(err = tcgetattr(fd, &save));
91 * The terminal becomes a bit less raw, to handle \n also as
92 * "Carriage Return", not only as "New Line". Otherwise, the new
93 * line won't start at the first column.
96 CATCH_EINTR(err = tcsetattr(fd, TCSAFLUSH, &new));
100 err = generic_write(fd, buf, n, NULL);
102 * Restore raw mode, in any case; we *must* ignore any error apart
103 * EINTR, except for debug.
106 CATCH_EINTR(tcsetattr(fd, TCSAFLUSH, &save));
107 sigprocmask(SIG_SETMASK, &old, NULL);
116 * UML SIGWINCH handling
118 * The point of this is to handle SIGWINCH on consoles which have host
119 * ttys and relay them inside UML to whatever might be running on the
120 * console and cares about the window size (since SIGWINCH notifies
121 * about terminal size changes).
123 * So, we have a separate thread for each host tty attached to a UML
124 * device (side-issue - I'm annoyed that one thread can't have
125 * multiple controlling ttys for the purpose of handling SIGWINCH, but
126 * I imagine there are other reasons that doesn't make any sense).
128 * SIGWINCH can't be received synchronously, so you have to set up to
129 * receive it as a signal. That being the case, if you are going to
130 * wait for it, it is convenient to sit in sigsuspend() and wait for
131 * the signal to bounce you out of it (see below for how we make sure
132 * to exit only on SIGWINCH).
135 static void winch_handler(int sig)
144 static int winch_thread(void *arg)
146 struct winch_data *data = arg;
152 pty_fd = data->pty_fd;
153 pipe_fd = data->pipe_fd;
154 count = write(pipe_fd, &c, sizeof(c));
155 if (count != sizeof(c))
156 printk(UM_KERN_ERR "winch_thread : failed to write "
157 "synchronization byte, err = %d\n", -count);
160 * We are not using SIG_IGN on purpose, so don't fix it as I thought to
161 * do! If using SIG_IGN, the sigsuspend() call below would not stop on
165 signal(SIGWINCH, winch_handler);
167 /* Block all signals possible. */
168 if (sigprocmask(SIG_SETMASK, &sigs, NULL) < 0) {
169 printk(UM_KERN_ERR "winch_thread : sigprocmask failed, "
170 "errno = %d\n", errno);
173 /* In sigsuspend(), block anything else than SIGWINCH. */
174 sigdelset(&sigs, SIGWINCH);
177 printk(UM_KERN_ERR "winch_thread : setsid failed, errno = %d\n",
182 if (ioctl(pty_fd, TIOCSCTTY, 0) < 0) {
183 printk(UM_KERN_ERR "winch_thread : TIOCSCTTY failed on "
184 "fd %d err = %d\n", pty_fd, errno);
188 if (tcsetpgrp(pty_fd, os_getpid()) < 0) {
189 printk(UM_KERN_ERR "winch_thread : tcsetpgrp failed on "
190 "fd %d err = %d\n", pty_fd, errno);
195 * These are synchronization calls between various UML threads on the
196 * host - since they are not different kernel threads, we cannot use
197 * kernel semaphores. We don't use SysV semaphores because they are
200 count = read(pipe_fd, &c, sizeof(c));
201 if (count != sizeof(c))
202 printk(UM_KERN_ERR "winch_thread : failed to read "
203 "synchronization byte, err = %d\n", errno);
207 * This will be interrupted by SIGWINCH only, since
208 * other signals are blocked.
212 count = write(pipe_fd, &c, sizeof(c));
213 if (count != sizeof(c))
214 printk(UM_KERN_ERR "winch_thread : write failed, "
215 "err = %d\n", errno);
219 static int winch_tramp(int fd, struct tty_port *port, int *fd_out,
220 unsigned long *stack_out)
222 struct winch_data data;
226 err = os_pipe(fds, 1, 1);
228 printk(UM_KERN_ERR "winch_tramp : os_pipe failed, err = %d\n",
233 data = ((struct winch_data) { .pty_fd = fd,
234 .pipe_fd = fds[1] } );
236 * CLONE_FILES so this thread doesn't hold open files which are open
237 * now, but later closed in a different thread. This is a
238 * problem with /dev/net/tun, which if held open by this
239 * thread, prevents the TUN/TAP device from being reused.
241 err = run_helper_thread(winch_thread, &data, CLONE_FILES, stack_out);
243 printk(UM_KERN_ERR "fork of winch_thread failed - errno = %d\n",
249 n = read(fds[0], &c, sizeof(c));
250 if (n != sizeof(c)) {
251 printk(UM_KERN_ERR "winch_tramp : failed to read "
252 "synchronization byte\n");
253 printk(UM_KERN_ERR "read failed, err = %d\n", errno);
254 printk(UM_KERN_ERR "fd %d will not support SIGWINCH\n", fd);
259 err = os_set_fd_block(*fd_out, 0);
261 printk(UM_KERN_ERR "winch_tramp: failed to set thread_fd "
275 void register_winch(int fd, struct tty_port *port)
278 int pid, thread, count, thread_fd = -1;
285 if (is_skas_winch(pid, fd, port)) {
286 register_winch_irq(-1, fd, -1, port, 0);
291 thread = winch_tramp(fd, port, &thread_fd, &stack);
295 register_winch_irq(thread_fd, fd, thread, port, stack);
297 count = write(thread_fd, &c, sizeof(c));
298 if (count != sizeof(c))
299 printk(UM_KERN_ERR "register_winch : failed to write "
300 "synchronization byte, err = %d\n", errno);