mirror of
https://github.com/topjohnwu/Magisk.git
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294 lines
6.1 KiB
C++
294 lines
6.1 KiB
C++
/*
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* Copyright 2013, Tan Chee Eng (@tan-ce)
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*/
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/*
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* pts.c
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*
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* Manages the pseudo-terminal driver on Linux/Android and provides some
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* helper functions to handle raw input mode and terminal window resizing
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*/
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#include <stdlib.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include <signal.h>
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#include <termios.h>
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#include <errno.h>
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#include <pthread.h>
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#include <magisk.h>
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#include "pts.h"
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/**
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* Helper functions
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*/
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// Ensures all the data is written out
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static int write_blocking(int fd, char *buf, ssize_t bufsz) {
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ssize_t ret, written;
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written = 0;
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do {
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ret = write(fd, buf + written, bufsz - written);
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if (ret == -1) return -1;
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written += ret;
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} while (written < bufsz);
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return 0;
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}
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/**
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* Pump data from input FD to output FD. If close_output is
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* true, then close the output FD when we're done.
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*/
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static void pump(int input, int output, bool close_output = true) {
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char buf[4096];
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int len;
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while ((len = read(input, buf, 4096)) > 0) {
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if (write_blocking(output, buf, len) == -1) break;
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}
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close(input);
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if (close_output) close(output);
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}
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static void* pump_thread(void* data) {
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int *fds = (int*) data;
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pump(fds[0], fds[1]);
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delete[] fds;
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return nullptr;
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}
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static void pump_async(int input, int output) {
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pthread_t writer;
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int *fds = new int[2];
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fds[0] = input;
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fds[1] = output;
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pthread_create(&writer, nullptr, pump_thread, fds);
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}
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/**
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* pts_open
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*
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* Opens a pts device and returns the name of the slave tty device.
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*
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* Arguments
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* slave_name the name of the slave device
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* slave_name_size the size of the buffer passed via slave_name
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*
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* Return Values
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* on failure either -2 or -1 (errno set) is returned.
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* on success, the file descriptor of the master device is returned.
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*/
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int pts_open(char *slave_name, size_t slave_name_size) {
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int fdm;
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char sn_tmp[256];
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// Open master ptmx device
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fdm = open("/dev/ptmx", O_RDWR);
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if (fdm == -1)
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goto error;
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// Get the slave name
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if (ptsname_r(fdm, slave_name, slave_name_size-1))
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goto error;
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slave_name[slave_name_size - 1] = '\0';
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// Grant, then unlock
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if (grantpt(fdm) == -1)
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goto error;
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if (unlockpt(fdm) == -1)
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goto error;
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return fdm;
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error:
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close(fdm);
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PLOGE("pts_open");
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return -1;
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}
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// Stores the previous termios of stdin
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static struct termios old_stdin;
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static int stdin_is_raw = 0;
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/**
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* set_stdin_raw
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*
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* Changes stdin to raw unbuffered mode, disables echo,
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* auto carriage return, etc.
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*
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* Return Value
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* on failure -1, and errno is set
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* on success 0
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*/
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int set_stdin_raw(void) {
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struct termios new_termios;
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// Save the current stdin termios
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if (tcgetattr(STDIN_FILENO, &old_stdin) < 0) {
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return -1;
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}
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// Start from the current settings
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new_termios = old_stdin;
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// Make the terminal like an SSH or telnet client
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new_termios.c_iflag |= IGNPAR;
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new_termios.c_iflag &= ~(ISTRIP | INLCR | IGNCR | ICRNL | IXON | IXANY | IXOFF);
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new_termios.c_lflag &= ~(ISIG | ICANON | ECHO | ECHOE | ECHOK | ECHONL);
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new_termios.c_oflag &= ~OPOST;
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new_termios.c_cc[VMIN] = 1;
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new_termios.c_cc[VTIME] = 0;
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if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &new_termios) < 0) {
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return -1;
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}
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stdin_is_raw = 1;
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return 0;
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}
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/**
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* restore_stdin
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*
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* Restore termios on stdin to the state it was before
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* set_stdin_raw() was called. If set_stdin_raw() was
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* never called, does nothing and doesn't return an error.
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*
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* This function is async-safe.
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*
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* Return Value
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* on failure, -1 and errno is set
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* on success, 0
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*/
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int restore_stdin(void) {
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if (!stdin_is_raw) return 0;
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if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &old_stdin) < 0) {
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return -1;
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}
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stdin_is_raw = 0;
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return 0;
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}
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// Flag indicating whether the sigwinch watcher should terminate.
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static volatile bool close_sigwinch_watcher = false;
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/**
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* Thread process. Wait for a SIGWINCH to be received, then update
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* the terminal size.
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*/
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static void *watch_sigwinch(void *data) {
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sigset_t winch;
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int *fds = (int *)data;
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int sig;
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sigemptyset(&winch);
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sigaddset(&winch, SIGWINCH);
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pthread_sigmask(SIG_UNBLOCK, &winch, nullptr);
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do {
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if (close_sigwinch_watcher)
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break;
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// Get the new terminal size
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struct winsize w;
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if (ioctl(fds[0], TIOCGWINSZ, &w) == -1)
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continue;
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// Set the new terminal size
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ioctl(fds[1], TIOCSWINSZ, &w);
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} while (sigwait(&winch, &sig) == 0);
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delete[] fds;
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return nullptr;
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}
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/**
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* watch_sigwinch_async
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*
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* After calling this function, if the application receives
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* SIGWINCH, the terminal window size will be read from
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* "input" and set on "output".
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*
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* NOTE: This function blocks SIGWINCH and spawns a thread.
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* NOTE 2: This function must be called before any of the
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* pump functions.
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*
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* Arguments
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* master A file descriptor of the TTY window size to follow
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* slave A file descriptor of the TTY window size which is
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* to be set on SIGWINCH
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*
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* Return Value
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* on failure, -1 and errno will be set. In this case, no
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* thread has been spawned and SIGWINCH will not be
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* blocked.
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* on success, 0
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*/
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int watch_sigwinch_async(int master, int slave) {
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pthread_t watcher;
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int *fds = new int[2];
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// Block SIGWINCH so sigwait can later receive it
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sigset_t winch;
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sigemptyset(&winch);
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sigaddset(&winch, SIGWINCH);
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if (pthread_sigmask(SIG_BLOCK, &winch, nullptr) == -1) {
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delete[] fds;
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return -1;
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}
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// Initialize some variables, then start the thread
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close_sigwinch_watcher = 0;
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fds[0] = master;
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fds[1] = slave;
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int ret = pthread_create(&watcher, nullptr, &watch_sigwinch, fds);
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if (ret != 0) {
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delete[] fds;
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errno = ret;
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return -1;
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}
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return 0;
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}
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/**
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* pump_stdin_async
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*
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* Forward data from STDIN to the given FD
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* in a seperate thread
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*/
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void pump_stdin_async(int outfd) {
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// Put stdin into raw mode
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set_stdin_raw();
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// Pump data from stdin to the PTY
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pump_async(STDIN_FILENO, outfd);
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}
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/**
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* pump_stdout_blocking
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*
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* Forward data from the FD to STDOUT.
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* Returns when the remote end of the FD closes.
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*
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* Before returning, restores stdin settings.
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*/
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void pump_stdout_blocking(int infd) {
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// Pump data from stdout to PTY
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pump(infd, STDOUT_FILENO, false /* Don't close output when done */);
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// Cleanup
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restore_stdin();
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close_sigwinch_watcher = true;
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raise(SIGWINCH);
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}
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