Add modem -r flag to set baud rate

Also fix it to continue reading output, rather than exiting as soon as
the child exits... Except on macOS this still doesn't seem to work
correctly for some reason.

2 files changed, 28 insertions, 15 deletions

diff --git a/bin/man1/modem.1 b/bin/man1/modem.1
index 522242b3..a4bbc3f1 100644
--- a/bin/man1/modem.1
+++ b/bin/man1/modem.1
@@ -1,4 +1,4 @@
-.Dd July 8, 2019
+.Dd December  8, 2020
 .Dt MODEM 1
 .Os
 .
@@ -8,6 +8,7 @@
 .
 .Sh SYNOPSIS
 .Nm
+.Op Fl r Ar rate
 .Ar command ...
 .
 .Sh DESCRIPTION
@@ -15,8 +16,15 @@
 runs the
 .Ar command
 in a new PTY
-with a fixed baud rate
-of 19.2 kbps.
+with a fixed baud rate.
+.
+.Pp
+The arguments are as follows:
+.Bl -tag -width Ds
+.It Fl r Ar rate
+Set the baud rate.
+The default is 19200.
+.El
 .
 .Sh BUGS
 Window size changes are not propagated
diff --git a/bin/modem.c b/bin/modem.c
index 5ee35822..4392e071 100644
--- a/bin/modem.c
+++ b/bin/modem.c
@@ -34,8 +34,6 @@
 typedef unsigned uint;
 typedef unsigned char byte;
 
-static const uint BaudRate = 19200;
-
 static struct termios saveTerm;
 static void restoreTerm(void) {
 	tcsetattr(STDIN_FILENO, TCSADRAIN, &saveTerm);
@@ -44,7 +42,14 @@ static void restoreTerm(void) {
 int main(int argc, char *argv[]) {
 	int error;
 
-	if (argc < 2) return EX_USAGE;
+	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");
@@ -64,8 +69,8 @@ int main(int argc, char *argv[]) {
 	if (pid < 0) err(EX_OSERR, "forkpty");
 
 	if (!pid) {
-		execvp(argv[1], &argv[1]);
-		err(EX_NOINPUT, "%s", argv[1]);
+		execvp(argv[optind], &argv[optind]);
+		err(EX_NOINPUT, "%s", argv[optind]);
 	}
 
 	byte c;
@@ -73,7 +78,7 @@ int main(int argc, char *argv[]) {
 		{ .events = POLLIN, .fd = STDIN_FILENO },
 		{ .events = POLLIN, .fd = pty },
 	};
-	while (usleep(8 * 1000000 / BaudRate), 0 < poll(fds, 2, -1)) {
+	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);
@@ -84,14 +89,14 @@ int main(int argc, char *argv[]) {
 		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, WNOHANG);
-		if (dead < 0) err(EX_OSERR, "waitpid");
-		if (dead) return WIFEXITED(status) ? WEXITSTATUS(status) : EX_SOFTWARE;
 	}
-	err(EX_IOERR, "poll");
+
+	int status;
+	pid_t dead = waitpid(pid, &status, 0);
+	if (dead < 0) err(EX_OSERR, "waitpid");
+	return WIFEXITED(status) ? WEXITSTATUS(status) : EX_SOFTWARE;
 }