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/* Copyright (c) 2017, 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 <stdbool.h>
#include <stdlib.h>
#include <string.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
typedef unsigned char byte;
static struct termios saveTerm;
static void restoreTerm(void) {
tcsetattr(STDIN_FILENO, TCSADRAIN, &saveTerm);
}
int main(int argc, char *argv[]) {
int error;
if (argc < 4) return EX_USAGE;
byte table[256] = {0};
if (strlen(argv[1]) != strlen(argv[2])) return EX_USAGE;
for (const char *from = argv[1], *to = argv[2]; *from; ++from, ++to) {
table[(byte)*from] = *to;
}
error = tcgetattr(STDERR_FILENO, &saveTerm);
if (error) err(EX_IOERR, "tcgetattr");
atexit(restoreTerm);
struct termios raw = saveTerm;
cfmakeraw(&raw);
error = tcsetattr(STDERR_FILENO, TCSADRAIN, &raw);
if (error) err(EX_IOERR, "tcsetattr");
struct winsize window;
error = ioctl(STDERR_FILENO, TIOCGWINSZ, &window);
if (error) err(EX_IOERR, "TIOCGWINSZ");
int pty;
pid_t pid = forkpty(&pty, NULL, NULL, &window);
if (pid < 0) err(EX_OSERR, "forkpty");
if (!pid) {
execvp(argv[3], &argv[3]);
err(EX_NOINPUT, "%s", argv[3]);
}
bool enable = true;
byte buf[4096];
struct pollfd fds[2] = {
{ .fd = STDIN_FILENO, .events = POLLIN },
{ .fd = pty, .events = POLLIN },
};
while (0 < poll(fds, 2, -1)) {
if (fds[0].revents & POLLIN) {
ssize_t readSize = read(STDIN_FILENO, buf, sizeof(buf));
if (readSize < 0) err(EX_IOERR, "read(%d)", STDIN_FILENO);
if (readSize == 1) {
if (buf[0] == CTRL('S')) {
enable ^= true;
continue;
}
byte c = buf[0];
if (enable && table[c]) buf[0] = table[c];
}
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 & POLLIN) {
ssize_t readSize = read(pty, buf, sizeof(buf));
if (readSize < 0) err(EX_IOERR, "read(%d)", pty);
ssize_t writeSize = write(STDOUT_FILENO, buf, readSize);
if (writeSize < 0) err(EX_IOERR, "write(%d)", STDOUT_FILENO);
if (writeSize < readSize) {
errx(EX_IOERR, "short write(%d)", STDOUT_FILENO);
}
}
int status;
pid_t dead = waitpid(pid, &status, WNOHANG);
if (dead < 0) err(EX_OSERR, "waitpid(%d)", pid);
if (dead) return WIFEXITED(status) ? WEXITSTATUS(status) : EX_SOFTWARE;
}
err(EX_IOERR, "poll");
}
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