Add ptee

1 files changed, 98 insertions, 0 deletions

diff --git a/bin/ptee.c b/bin/ptee.c
new file mode 100644
index 00000000..ee035e8a
--- /dev/null
+++ b/bin/ptee.c
@@ -0,0 +1,98 @@
+/* Copyright (C) 2019  June McEnroe <june@causal.agency>
+ *
+ * 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 <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
+
+typedef unsigned char byte;
+
+static struct termios saveTerm;
+static void restoreTerm(void) {
+	tcsetattr(STDIN_FILENO, TCSADRAIN, &saveTerm);
+}
+
+int main(int argc, char *argv[]) {
+	if (argc < 2) return EX_USAGE;
+	if (isatty(STDOUT_FILENO)) errx(EX_USAGE, "stdout is not redirected");
+
+	int error = tcgetattr(STDIN_FILENO, &saveTerm);
+	if (error) err(EX_IOERR, "tcgetattr");
+	atexit(restoreTerm);
+
+	struct termios raw = saveTerm;
+	cfmakeraw(&raw);
+	error = tcsetattr(STDIN_FILENO, TCSADRAIN, &raw);
+	if (error) err(EX_IOERR, "tcsetattr");
+
+	struct winsize window;
+	error = ioctl(STDIN_FILENO, TIOCGWINSZ, &window);
+	if (error) err(EX_IOERR, "ioctl");
+
+	int pty;
+	pid_t pid = forkpty(&pty, NULL, NULL, &window);
+	if (pid < 0) err(EX_OSERR, "forkpty");
+
+	if (!pid) {
+		execvp(argv[1], &argv[1]);
+		err(EX_NOINPUT, "%s", argv[1]);
+	}
+
+	byte buf[4096];
+	struct pollfd fds[2] = {
+		{ .events = POLLIN, .fd = STDIN_FILENO },
+		{ .events = POLLIN, .fd = pty },
+	};
+	while (0 < poll(fds, 2, -1)) {
+		if (fds[0].revents & POLLIN) {
+			ssize_t rlen = read(STDIN_FILENO, buf, sizeof(buf));
+			if (rlen < 0) err(EX_IOERR, "read");
+			ssize_t wlen = write(pty, buf, rlen);
+			if (wlen < 0) err(EX_IOERR, "write");
+		}
+
+		if (fds[1].revents & POLLIN) {
+			ssize_t rlen = read(pty, buf, sizeof(buf));
+			if (rlen < 0) err(EX_IOERR, "read");
+
+			ssize_t wlen = write(STDIN_FILENO, buf, rlen);
+			if (wlen < 0) err(EX_IOERR, "write");
+
+			wlen = write(STDOUT_FILENO, buf, rlen);
+			if (wlen < 0) err(EX_IOERR, "write");
+		}
+
+		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");
+}