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#define _XOPEN_SOURCE 600
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/select.h>
#include <sys/wait.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <unistd.h>
#include <termios.h>
#include <signal.h>
#include <errno.h>
#include <stdbool.h>
#include <stdarg.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
struct termios oldterm;
int master, slave;
int pipeout;
pid_t child;
bool encode_resize;
void
usage(void)
{
fprintf(stderr, "Usage: vtmitm [--encode-resize] -- CMD [ARG]..\n");
exit(1);
}
void
err(const char *fmtstr, ...)
{
va_list ap;
va_start(ap, fmtstr);
vfprintf(stderr, fmtstr, ap);
fprintf(stderr, ": %s\r\n", strerror(errno));
va_end(ap);
exit(1);
}
int
writeall(int fd, char *buffer, size_t size)
{
ssize_t nbytes;
while (size) {
nbytes = write(fd, buffer, size);
if (nbytes <= 0) return 1;
buffer += nbytes;
size -= nbytes;
}
return 0;
}
int
fwd(int in, int out, int out2)
{
static char buffer[8194];
ssize_t got, i, last;
do {
got = read(in, buffer, sizeof(buffer));
if (got < 0) return 1;
if (writeall(out, buffer, got))
return 1;
if (out2 >= 0) {
if (writeall(out2, buffer, got))
return 1;
}
} while (got == sizeof(buffer));
return 0;
}
void
mitm(int pts, int pipe)
{
fd_set fds;
while (1) {
FD_ZERO(&fds);
FD_SET(0, &fds);
FD_SET(pts, &fds);
if (select(pts + 1, &fds, 0, 0, 0) == -1) {
if (errno == EINTR) continue;
return;
}
if (FD_ISSET(0, &fds)) { /* stdin -> ptty */
if (fwd(0, pts, -1)) return;
}
if (FD_ISSET(pts, &fds)) { /* ptty -> stdout + pipe */
if (fwd(pts, 1, pipe)) return;
}
}
}
void
rawterm(struct termios *term)
{
term->c_iflag &= ~(IGNBRK | BRKINT | PARMRK | ISTRIP);
term->c_iflag &= ~(INLCR | IGNCR | ICRNL | IXON);
term->c_oflag &= ~OPOST;
term->c_lflag &= ~(ECHO | ECHONL | ICANON | ISIG | IEXTEN);
term->c_cflag &= ~(CSIZE | PARENB);
term->c_cflag |= CS8;
}
void
sigwinch(int sig)
{
char buf[64];
struct winsize wsize;
if (ioctl(0, TIOCGWINSZ, &wsize) != -1)
ioctl(slave, TIOCSWINSZ, &wsize);
kill(child, SIGWINCH);
signal(SIGWINCH, sigwinch);
/* transmit new size info in form of xterm resize escape sequence */
snprintf(buf, sizeof(buf), "\x1b[8;%u;%ut", wsize.ws_row, wsize.ws_col);
write(pipeout, buf, sizeof(buf));
}
void
sigchld(int sig)
{
int exitcode;
wait(&exitcode);
exit(exitcode);
}
void
cleanup(void)
{
tcsetattr(0, TCSANOW, &oldterm);
}
int
main(int argc, char *const *argv)
{
struct termios newterm;
struct winsize wsize;
char *const *arg, *const *cmd;
int exitcode;
cmd = NULL;
encode_resize = false;
for (arg = argv + 1; *arg; arg++) {
if (!strcmp(*arg, "--encode-resize")) {
encode_resize = true;
} else if (!strcmp(*arg, "--")) {
cmd = arg + 1;
break;
} else {
usage();
}
}
if (!cmd) usage();
pipeout = dup(1);
if (!freopen("/dev/tty", "w", stdout))
err("main: open /dev/tty");
dup2(fileno(stdout), 1);
master = posix_openpt(O_RDWR);
if (master == -1) err("main: posix_openpt");
if (grantpt(master)) err("main: grantpt");
if (unlockpt(master)) err("main: unlockpt");
slave = open(ptsname(master), O_RDWR);
if (slave == -1) err("main: open pts");
signal(SIGCHLD, sigchld);
child = fork();
if (child < 0) err("main: fork");
if (child == 0) {
close(master);
signal(SIGCHLD, SIG_DFL);
if (setsid() == -1)
err("slave: setsid");
if (ioctl(slave, TIOCSCTTY, 0) == -1)
err("slave: ioctl TIOCSCTTY");
if (dup2(slave, 0) == -1)
err("slave: dup2 stdin");
if (dup2(slave, 1) == -1)
err("slave: dup2 stdout");
if (dup2(slave, 2) == -1)
err("slave: dup2 stderr");
close(slave);
execvp(*cmd, cmd);
err("slave: execvp");
} else {
if (encode_resize) {
signal(SIGWINCH, sigwinch);
raise(SIGWINCH);
}
if (tcgetattr(0, &oldterm))
err("master: tcgetattr");
newterm = oldterm;
rawterm(&newterm);
if (tcsetattr(0, TCSANOW, &newterm))
err("master: tcsetattr");
atexit(cleanup);
mitm(master, pipeout);
waitpid(child, &exitcode, 0);
close(master);
}
return exitcode;
}
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