1 files changed, 102 insertions, 0 deletions
diff --git a/bin/modem.c b/bin/modem.c
new file mode 100644
index 00000000..2133ae08
--- /dev/null
+++ b/bin/modem.c
@@ -0,0 +1,102 @@
+/* Copyright (C) 2018  C. 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 <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 uint;
+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;
+
+	uint baudRate = 19200;
+	for (int opt; 0 < (opt = getopt(argc, argv, "r:"));) {
+		switch (opt) {
+			break; case 'r': baudRate = strtoul(optarg, NULL, 10);
+			break; default:  return EX_USAGE;
+		}
+	}
+	if (argc - optind < 1) return EX_USAGE;
+
+	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, "TIOCGWINSZ");
+
+	int pty;
+	pid_t pid = forkpty(&pty, NULL, NULL, &window);
+	if (pid < 0) err(EX_OSERR, "forkpty");
+
+	if (!pid) {
+		execvp(argv[optind], &argv[optind]);
+		err(EX_NOINPUT, "%s", argv[optind]);
+	}
+
+	byte c;
+	struct pollfd fds[2] = {
+		{ .events = POLLIN, .fd = STDIN_FILENO },
+		{ .events = POLLIN, .fd = pty },
+	};
+	while (usleep(8 * 1000000 / baudRate), 0 < poll(fds, 2, -1)) {
+		if (fds[0].revents) {
+			ssize_t size = read(STDIN_FILENO, &c, 1);
+			if (size < 0) err(EX_IOERR, "read(%d)", STDIN_FILENO);
+			size = write(pty, &c, 1);
+			if (size < 0) err(EX_IOERR, "write(%d)", pty);
+		}
+
+		if (fds[1].revents) {
+			ssize_t size = read(pty, &c, 1);
+			if (size < 0) err(EX_IOERR, "read(%d)", pty);
+			if (!size) break;
+			size = write(STDOUT_FILENO, &c, 1);
+			if (size < 0) err(EX_IOERR, "write(%d)", STDOUT_FILENO);
+		}
+	}
+
+	int status;
+	pid_t dead = waitpid(pid, &status, 0);
+	if (dead < 0) err(EX_OSERR, "waitpid");
+	return WIFEXITED(status) ? WEXITSTATUS(status) : EX_SOFTWARE;
+}