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/* Copyright (c) 2018, Curtis McEnroe <programble@gmail.com>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <err.h>
#include <poll.h>
#include <pwd.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/ioctl.h>
#include <sys/wait.h>
#include <sysexits.h>
#include <termios.h>
#include <unistd.h>
#if defined __FreeBSD__
#include <libutil.h>
#elif defined __linux__
#include <pty.h>
#else
#include <util.h>
#endif
static struct termios saveTerm;
static void restoreTerm(void) {
tcsetattr(STDERR_FILENO, TCSADRAIN, &saveTerm);
}
int main(int argc, char *argv[]) {
int error;
if (argc > 1) {
argv++;
} else {
uid_t uid = getuid();
struct passwd *user = getpwuid(uid);
if (!user) err(EX_OSFILE, "/etc/passwd");
argv[0] = user->pw_shell;
}
int input = STDIN_FILENO;
int local = STDERR_FILENO;
int remote = STDOUT_FILENO;
if (isatty(remote)) {
errx(EX_USAGE, "stdout is not redirected");
}
error = tcgetattr(local, &saveTerm);
if (error) err(EX_IOERR, "tcgetattr");
atexit(restoreTerm);
struct termios raw;
cfmakeraw(&raw);
error = tcsetattr(local, TCSADRAIN, &raw);
if (error) err(EX_IOERR, "tcsetattr");
struct winsize window;
error = ioctl(local, TIOCGWINSZ, &window);
if (error) err(EX_IOERR, "ioctl(%d, TIOCGWINSZ, ...)", local);
ssize_t size = write(remote, &window, sizeof(window));
if (size < 0) err(EX_IOERR, "write(%d)", remote);
if ((size_t)size < sizeof(window)) errx(EX_IOERR, "short write(%d)", remote);
int pty;
pid_t pid = forkpty(&pty, NULL, NULL, &window);
if (pid < 0) err(EX_OSERR, "forkpty");
if (!pid) {
execvp(*argv, argv);
err(EX_USAGE, "%s", *argv);
}
char buf[4096];
ssize_t totalSize = 0;
struct pollfd fds[2] = {
{ .fd = input, .events = POLLIN },
{ .fd = pty, .events = POLLIN },
};
while (0 < poll(fds, 2, -1)) {
if (fds[0].revents) {
ssize_t readSize = read(input, buf, sizeof(buf));
if (readSize < 0) err(EX_IOERR, "read(%d)", input);
ssize_t writeSize = write(pty, buf, readSize);
if (writeSize < 0) err(EX_IOERR, "write(%d)", pty);
if (writeSize < readSize) errx(EX_IOERR, "short write(%d)", pty);
}
if (fds[1].revents) {
ssize_t readSize = read(pty, buf, sizeof(buf));
if (readSize < 0) err(EX_IOERR, "read(%d)", pty);
ssize_t writeSize = write(local, buf, readSize);
if (writeSize < 0) err(EX_IOERR, "write(%d)", local);
if (writeSize < readSize) errx(EX_IOERR, "short write(%d)", local);
writeSize = write(remote, buf, readSize);
if (writeSize < 0) err(EX_IOERR, "write(%d)", remote);
if (writeSize < readSize) errx(EX_IOERR, "short write(%d)", remote);
totalSize += readSize;
if (totalSize > 1024 * 1024) {
buf[0] = CTRL('L');
writeSize = write(pty, buf, 1);
if (writeSize < 0) err(EX_IOERR, "write(%d)", pty);
totalSize = 0;
}
}
int status;
pid_t dead = waitpid(pid, &status, WNOHANG);
if (dead < 0) err(EX_OSERR, "waitpid");
if (dead) return WIFEXITED(status) ? WEXITSTATUS(status) : EX_SOFTWARE;
}
err(EX_IOERR, "poll");
}
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