Get a lua or sc shell on a norns.

1 files changed, 183 insertions, 0 deletions

diff --git a/norns_shell.c b/norns_shell.c
new file mode 100644
index 0000000..fbd556c
--- /dev/null
+++ b/norns_shell.c
@@ -0,0 +1,183 @@
+#include <time.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <signal.h>
+
+#include <nanomsg/nn.h>
+#include <nanomsg/bus.h>
+#include <nanomsg/ws.h>
+
+#define MAX_LINE 1024
+
+int killed = 0;
+void handle_signal(int sig_num)
+{
+	killed = 1;
+}
+
+
+int main (int argc, char **argv)
+{
+	char *endpoint = "ws://norns.local:5555";
+	int exit = 0;
+	int s = 0;
+
+	signal(SIGINT, handle_signal);
+	signal(SIGTERM, handle_signal);
+
+	/* Configure the websocket endpoint. */
+	if (argc > 2 ||
+	    (argc == 2 &&
+	     (!strcmp(argv[1], "--help")
+	      || !strcmp(argv[1], "-h")))) {
+		fprintf(stderr,
+			"Get a lua or supercollider shell on a norns.\n"
+			"Usage: %s [ws://norns.local:5555]\n",
+			argv[0]);
+		goto error;
+	}
+	if (argc == 2) endpoint = argv[1];
+
+	/* connect to the norns; use text, like it expects. */
+	if ((s = nn_socket(AF_SP, NN_BUS)) < 0) {
+		fprintf(stderr, "Can't create socket: %m\n");
+		goto error;
+	}
+	if (nn_connect(s, endpoint) < 0) {
+		fprintf(stderr, "Can't connect to %s: %m\n", endpoint);
+		goto error;
+	}
+	if (nn_setsockopt(s,
+			  NN_WS,
+			  NN_WS_MSG_TYPE,
+			  &(int) {NN_WS_MSG_TYPE_TEXT},
+			  sizeof(int)) < 0) {
+		fprintf(stderr, "Couldn't switch to text mode: %m\n");
+		goto error;
+	}
+
+	/* since nanomsg has its own poll framework, we'll read to this
+	   buffer in a nonblocking way until we get a newline. */
+	size_t line_n = 0;
+	char line[MAX_LINE + 1] = {0};
+	
+	int fl = 0;
+	if ((fl = fcntl(STDIN_FILENO, F_GETFL)) < 0) {
+		fprintf(stderr, "Couldn't read stdin fd flags: %m\n");
+		goto error;
+	}
+	if (fcntl(STDIN_FILENO, F_SETFL, fl | O_NONBLOCK)) {
+		fprintf(stderr, "Couldn't set stdin non-blocking: %m\n");
+		goto error;
+	}
+
+	/* NN_BUS doesn't guarantee delivery, unfortunately.
+	   in practice on a LAN this means that the first couple of
+	   messages are dropped while the connection is being set up.
+	   this seems strange to me (it seems like you'd have to go
+	   out of your way to drop messages in a websocket handler?)
+	   and I'm not sure this is the right fit for norns, but that's
+	   how it is.
+
+	   we partially solve this issue by sending an empty comment
+	   -- as a sentinel -- repeatedly until we get the corresponding
+	   <ok>.
+	*/
+	/* TODO: time out after three seconds or something. */
+	int received = 0;
+	struct timespec sent_sentinel = {0};
+
+	struct nn_pollfd poll_s = { .fd = s, .events = NN_POLLIN | NN_POLLOUT };
+	while (!killed) {
+		switch (nn_poll(&poll_s, 1, 1000)) {
+		case -1:
+			fprintf(stderr, "error polling: %m\n");
+			goto error;
+		case 0:
+			fprintf(stderr, "# timeout...\n");
+			break;
+		case 1:
+			/* If we can read, echo out the message (unless it's the
+			   response to the sentinel, which we handle differently). */
+			if (poll_s.revents & NN_POLLIN) {
+				char *buf = NULL;
+				size_t n = 0;
+				if ((n = nn_recv(s, &buf, NN_MSG, 0)) < 0) {
+					fprintf(stderr, "Couldn't receive: %m\n");
+					goto error;
+				}
+				/* swallow the first <ok> */
+				if (!received && !strncmp(buf, "<ok>\n\n", n)) {
+					fprintf(stderr, "# it lives!\n");
+				} else {
+					/* strip final newline, if there are two... */
+					if (n >= 2 && buf[n - 1] == '\n' && buf[n - 2] == '\n')
+						n -= 1;
+					if (write(STDOUT_FILENO, buf, n) < n) {
+						fprintf(stderr, "Couldn't write: %m\n");
+						goto error;
+					}
+				}
+				nn_freemsg(buf);
+				received = 1;
+			}
+			/* If we can write, see if there's a full line. */
+			if (poll_s.revents & NN_POLLOUT) {
+				if (!received) {
+					/* only do this five times a second... */
+					struct timespec now = {0};
+					if (clock_gettime(CLOCK_MONOTONIC, &now)) {
+						fprintf(stderr, "Can't use the clock? %m\n");
+						goto error;
+					}
+					/* first bit syncs with the clock... */
+					if ((now.tv_sec - sent_sentinel.tv_sec <= 1)
+					    && (now.tv_nsec - sent_sentinel.tv_nsec
+						<= (1000000000 / 5)))
+						break;
+					memcpy(&sent_sentinel, &now, sizeof(struct timespec));
+					
+					/* send the sentinel comment */
+					if (nn_send(s, "--\n", 3, 0) != 3) {
+						fprintf(stderr, "Couldn't send: %m\n");
+						goto error;
+					}
+				} else {
+					int n = 0;
+					if ((n = read(STDIN_FILENO,
+						      &line[line_n],
+						      MAX_LINE - line_n)) < 0) {
+						if (errno != EAGAIN) {
+							fprintf(stderr, "Can't read: %m\n");
+							goto error;
+						}
+						/* treat EAGAIN as "read 0" */
+						n = 0;
+					}
+					line_n += n;
+					if (line_n >= 1 && line[line_n - 1] == '\n') {
+						if ((nn_send(s, line, line_n, 0)) != line_n) {
+							fprintf(stderr, "Couldn't send: %m\n");
+							goto error;
+						}
+						line_n = 0;
+					}
+					if (line_n == MAX_LINE) {
+						fprintf(stderr, "Line too long :(.\n");
+						goto error;
+					}
+				}
+			}
+			break;
+		}
+	}
+	goto finish;
+error:
+	exit = 1;
+finish:
+	if (s > 0) nn_close(s);
+	return exit;
+}
+