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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:49:45 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:49:45 +0000 |
commit | 2c3c1048746a4622d8c89a29670120dc8fab93c4 (patch) | |
tree | 848558de17fb3008cdf4d861b01ac7781903ce39 /arch/um/drivers/chan_user.c | |
parent | Initial commit. (diff) | |
download | linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.tar.xz linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.zip |
Adding upstream version 6.1.76.upstream/6.1.76
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'arch/um/drivers/chan_user.c')
-rw-r--r-- | arch/um/drivers/chan_user.c | 303 |
1 files changed, 303 insertions, 0 deletions
diff --git a/arch/um/drivers/chan_user.c b/arch/um/drivers/chan_user.c new file mode 100644 index 000000000..25727ed64 --- /dev/null +++ b/arch/um/drivers/chan_user.c @@ -0,0 +1,303 @@ +// 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, pid; + 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. + */ + pid = run_helper_thread(winch_thread, &data, CLONE_FILES, stack_out); + if (pid < 0) { + err = pid; + 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; + } + + err = os_set_fd_block(*fd_out, 0); + if (err) { + printk(UM_KERN_ERR "winch_tramp: failed to set thread_fd " + "non-blocking.\n"); + goto out_close; + } + + return pid; + + 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); + } +} |