Similarly for MSG_COMMAND - allow full imsg limit not arbitrary 2048.

client.c

@@ -54,7 +54,8 @@ int		client_get_lock(char *);
 int		client_connect(char *, int);
 void		client_send_identify(int);
 void		client_send_environ(void);
-void		client_write_server(enum msgtype, void *, size_t);
+int		client_write_one(enum msgtype, int, const void *, size_t);
+int		client_write_server(enum msgtype, const void *, size_t);
 void		client_update_event(void);
 void		client_signal(int, short, void *);
 void		client_stdin_callback(int, short, void *);
@@ -165,12 +166,13 @@ client_main(int argc, char **argv, int flags)
 {
 	struct cmd		*cmd;
 	struct cmd_list		*cmdlist;
-	struct msg_command_data	 cmddata;
-	int			 cmdflags, fd;
+	struct msg_command_data	*data;
+	int			 cmdflags, fd, i;
 	pid_t			 ppid;
 	enum msgtype		 msg;
 	char			*cause;
 	struct termios		 tio, saved_tio;
+	size_t			 size;
 
 	/* Set up the initial command. */
 	cmdflags = 0;
@@ -265,19 +267,32 @@ client_main(int argc, char **argv, int flags)
 
 	/* Send first command. */
 	if (msg == MSG_COMMAND) {
+		/* How big is the command? */
+		size = 0;
+		for (i = 0; i < argc; i++)
+			size += strlen(argv[i]) + 1;
+		data = xmalloc((sizeof *data) + size);
+
 		/* Fill in command line arguments. */
-		cmddata.pid = environ_pid;
-		cmddata.session_id = environ_session_id;
+		data->pid = environ_pid;
+		data->session_id = environ_session_id;
 
 		/* Prepare command for server. */
-		cmddata.argc = argc;
-		if (cmd_pack_argv(
-		    argc, argv, cmddata.argv, sizeof cmddata.argv) != 0) {
+		data->argc = argc;
+		if (cmd_pack_argv(argc, argv, (char*)(data + 1), size) != 0) {
 			fprintf(stderr, "command too long\n");
+			free(data);
 			return (1);
 		}
+		size += sizeof *data;
 
-		client_write_server(msg, &cmddata, sizeof cmddata);
+		/* Send the command. */
+		if (client_write_server(msg, data, size) != 0) {
+			fprintf(stderr, "failed to send command\n");
+			free(data);
+			return (1);
+		}
+		free(data);
 	} else if (msg == MSG_SHELL)
 		client_write_server(msg, NULL, 0);
 
@@ -349,12 +364,29 @@ client_send_environ(void)
 	}
 }
 
-/* Write a message to the server without a file descriptor. */
-void
-client_write_server(enum msgtype type, void *buf, size_t len)
+/* Helper to send one message. */
+int
+client_write_one(enum msgtype type, int fd, const void *buf, size_t len)
 {
-	imsg_compose(&client_ibuf, type, PROTOCOL_VERSION, -1, -1, buf, len);
-	client_update_event();
+	int	retval;
+
+	retval = imsg_compose(&client_ibuf, type, PROTOCOL_VERSION, -1, fd,
+	    (void*)buf, len);
+	if (retval != 1)
+		return (-1);
+	return (0);
+}
+
+/* Write a message to the server without a file descriptor. */
+int
+client_write_server(enum msgtype type, const void *buf, size_t len)
+{
+	int	retval;
+
+	retval = client_write_one(type, -1, buf, len);
+	if (retval == 0)
+		client_update_event();
+	return (retval);
 }
 
 /* Update client event based on whether it needs to read or read and write. */
@@ -537,14 +569,16 @@ client_dispatch_wait(void *data0)
 				fatalx("bad MSG_STDOUT size");
 			memcpy(&stdoutdata, data, sizeof stdoutdata);
 
-			client_write(STDOUT_FILENO, stdoutdata.data, stdoutdata.size);
+			client_write(STDOUT_FILENO, stdoutdata.data,
+			    stdoutdata.size);
 			break;
 		case MSG_STDERR:
 			if (datalen != sizeof stderrdata)
 				fatalx("bad MSG_STDERR size");
 			memcpy(&stderrdata, data, sizeof stderrdata);
 
-			client_write(STDERR_FILENO, stderrdata.data, stderrdata.size);
+			client_write(STDERR_FILENO, stderrdata.data,
+			    stderrdata.size);
 			break;
 		case MSG_VERSION:
 			if (datalen != 0)

server-client.c

@@ -40,7 +40,7 @@ void	server_client_reset_state(struct client *);
 int	server_client_assume_paste(struct session *);
 
 int	server_client_msg_dispatch(struct client *);
-void	server_client_msg_command(struct client *, struct msg_command_data *);
+void	server_client_msg_command(struct client *, struct imsg *);
 void	server_client_msg_identify(
 	    struct client *, struct msg_identify_data *, int);
 void	server_client_msg_shell(struct client *);
@@ -786,10 +786,10 @@ int
 server_client_msg_dispatch(struct client *c)
 {
 	struct imsg		 imsg;
-	struct msg_command_data	 commanddata;
 	struct msg_identify_data identifydata;
 	struct msg_environ_data	 environdata;
 	struct msg_stdin_data	 stdindata;
+	const char		*data;
 	ssize_t			 n, datalen;
 
 	if ((n = imsg_read(&c->ibuf)) == -1 || n == 0)
@@ -800,6 +800,8 @@ server_client_msg_dispatch(struct client *c)
 			return (-1);
 		if (n == 0)
 			return (0);
+
+		data = imsg.data;
 		datalen = imsg.hdr.len - IMSG_HEADER_SIZE;
 
 		if (imsg.hdr.peerid != PROTOCOL_VERSION) {
@@ -811,13 +813,6 @@ server_client_msg_dispatch(struct client *c)
 
 		log_debug("got %d from client %d", imsg.hdr.type, c->ibuf.fd);
 		switch (imsg.hdr.type) {
-		case MSG_COMMAND:
-			if (datalen != sizeof commanddata)
-				fatalx("bad MSG_COMMAND size");
-			memcpy(&commanddata, imsg.data, sizeof commanddata);
-
-			server_client_msg_command(c, &commanddata);
-			break;
 		case MSG_IDENTIFY:
 			if (datalen != sizeof identifydata)
 				fatalx("bad MSG_IDENTIFY size");
@@ -827,10 +822,13 @@ server_client_msg_dispatch(struct client *c)
 #endif
 			server_client_msg_identify(c, &identifydata, imsg.fd);
 			break;
+		case MSG_COMMAND:
+			server_client_msg_command(c, &imsg);
+			break;
 		case MSG_STDIN:
 			if (datalen != sizeof stdindata)
 				fatalx("bad MSG_STDIN size");
-			memcpy(&stdindata, imsg.data, sizeof stdindata);
+			memcpy(&stdindata, data, sizeof stdindata);
 
 			if (c->stdin_callback == NULL)
 				break;
@@ -905,15 +903,26 @@ server_client_msg_dispatch(struct client *c)
 
 /* Handle command message. */
 void
-server_client_msg_command(struct client *c, struct msg_command_data *data)
+server_client_msg_command(struct client *c, struct imsg *imsg)
 {
-	struct cmd_list	*cmdlist = NULL;
-	int		 argc;
-	char	       **argv, *cause;
+	struct msg_command_data	  data;
+	char			 *buf;
+	size_t			  len;
+	struct cmd_list		 *cmdlist = NULL;
+	int			  argc;
+	char			**argv, *cause;
 
-	argc = data->argc;
-	data->argv[(sizeof data->argv) - 1] = '\0';
-	if (cmd_unpack_argv(data->argv, sizeof data->argv, argc, &argv) != 0) {
+	if (imsg->hdr.len - IMSG_HEADER_SIZE < sizeof data)
+		fatalx("bad MSG_COMMAND size");
+	memcpy(&data, imsg->data, sizeof data);
+
+	buf = (char*)imsg->data + sizeof data;
+	len = imsg->hdr.len  - IMSG_HEADER_SIZE - sizeof data;
+	if (len > 0 && buf[len - 1] != '\0')
+		fatalx("bad MSG_COMMAND string");
+
+	argc = data.argc;
+	if (cmd_unpack_argv(buf, len, argc, &argv) != 0) {
 		cmdq_error(c->cmdq, "command too long");
 		goto error;
 	}

server-fn.c

@@ -236,7 +236,6 @@ void
 server_lock_client(struct client *c)
 {
 	const char	*cmd;
-	size_t		 cmdlen;
 
 	if (c->flags & CLIENT_CONTROL)
 		return;

tmux.h

@@ -55,7 +55,6 @@ extern char   **environ;
  * Maximum sizes of strings in message data. Don't forget to bump
  * PROTOCOL_VERSION if any of these change!
  */
-#define COMMAND_LENGTH 2048	/* packed argv size */
 #define TERMINAL_LENGTH 128	/* length of TERM environment variable */
 #define ENVIRON_LENGTH 1024	/* environment variable length */
 
@@ -468,16 +467,14 @@ enum msgtype {
  * Don't forget to bump PROTOCOL_VERSION if any of these change!
  */
 struct msg_command_data {
-	pid_t		pid;		/* from $TMUX or -1 */
-	int		session_id;	/* from $TMUX or -1 */
+	pid_t	pid;		/* from $TMUX or -1 */
+	int	session_id;	/* from $TMUX or -1 */
 
-	int		argc;
-	char		argv[COMMAND_LENGTH];
-};
+	int	argc;
+}; /* followed by packed argv */
 
 struct msg_identify_data {
 	char		cwd[MAXPATHLEN];
-
 	char		term[TERMINAL_LENGTH];
 
 #ifdef __CYGWIN__
@@ -1316,7 +1313,7 @@ struct client {
 #define CLIENT_EXIT 0x4
 #define CLIENT_REDRAW 0x8
 #define CLIENT_STATUS 0x10
-#define CLIENT_REPEAT 0x20 /* allow command to repeat within repeat time */
+#define CLIENT_REPEAT 0x20
 #define CLIENT_SUSPENDED 0x40
 #define CLIENT_BAD 0x80
 #define CLIENT_IDENTIFY 0x100
@@ -1919,10 +1916,10 @@ void	 server_window_loop(void);
 /* server-fn.c */
 void	 server_fill_environ(struct session *, struct environ *);
 void	 server_write_ready(struct client *);
-int	 server_write_client(
-	     struct client *, enum msgtype, const void *, size_t);
-void	 server_write_session(
-	     struct session *, enum msgtype, const void *, size_t);
+int	 server_write_client(struct client *, enum msgtype, const void *,
+	     size_t);
+void	 server_write_session(struct session *, enum msgtype, const void *,
+	     size_t);
 void	 server_redraw_client(struct client *);
 void	 server_status_client(struct client *);
 void	 server_redraw_session(struct session *);