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301 lines
7.0 KiB
301 lines
7.0 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* Copyright (C) 2000 - 2007 Jeff Dike (jdike@{linux.intel,addtoit}.com) |
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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 (n == 0) |
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return -EIO; |
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else if (errno == EAGAIN) |
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return 0; |
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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_port *port, 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_port *port) |
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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, port)) { |
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register_winch_irq(-1, fd, -1, port, 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, port, &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, port, 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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