Make all messages sent between the client and server fixed size.

This is the first of two changes to make the protocol more resilient and less
sensitive to other changes in the code, particularly with commands. The client
now packs argv into a buffer and sends it to the server for parsing, rather
than doing it itself and sending the parsed command data.

As a side-effect this also removes a lot of now-unused command marshalling
code.

Mixing a server without this change and a client with or vice versa will cause
tmux to hang or crash, please ensure that tmux is entirely killed before
upgrading.

82 files changed, 253 insertions, 780 deletions

diff --git a/client-fn.c b/client-fn.c
index 3f42a105..b7a9b1f0 100644
--- a/client-fn.c
+++ b/client-fn.c
@@ -74,19 +74,3 @@ client_write_server(
 	if (buf != NULL && len > 0)
 		buffer_write(cctx->srv_out, buf, len);
 }
-
-void
-client_write_server2(struct client_ctx *cctx,
-    enum hdrtype type, void *buf1, size_t len1, void *buf2, size_t len2)
-{
-	struct hdr	hdr;
-
-	hdr.type = type;
-	hdr.size = len1 + len2;
-	buffer_write(cctx->srv_out, &hdr, sizeof hdr);
-
-	if (buf1 != NULL && len1 > 0)
-		buffer_write(cctx->srv_out, buf1, len1);
-	if (buf2 != NULL && len2 > 0)
-		buffer_write(cctx->srv_out, buf2, len2);
-}
diff --git a/client-msg.c b/client-msg.c
index 5a95ff62..845f10b0 100644
--- a/client-msg.c
+++ b/client-msg.c
@@ -70,16 +70,15 @@ client_msg_dispatch(struct client_ctx *cctx)
 int
 client_msg_fn_error(struct hdr *hdr, struct client_ctx *cctx)
 {
-	char	*errstr;
+	struct msg_print_data	data;
 
-	if (hdr->size == SIZE_MAX)
-		fatalx("bad MSG_ERROR size");
+	if (hdr->size < sizeof data)
+		fatalx("bad MSG_PRINT size");
+	buffer_read(cctx->srv_in, &data, sizeof data);
 
-	errstr = xmalloc(hdr->size + 1);
-	buffer_read(cctx->srv_in, errstr, hdr->size);
-	errstr[hdr->size] = '\0';
+	data.msg[(sizeof data.msg) - 1] = '\0';
+	cctx->errstr = xstrdup(data.msg);
 
-	cctx->errstr = errstr;
 	return (-1);
 }
 
diff --git a/client.c b/client.c
index 57fe1d1d..f29c2569 100644
--- a/client.c
+++ b/client.c
@@ -44,8 +44,7 @@ client_init(char *path, struct client_ctx *cctx, int cmdflags, int flags)
 	struct winsize			ws;
 	size_t				size;
 	int				mode;
-	struct buffer		       *b;
-	char			       *name;
+	char			       *name, *term;
 	char		 		rpathbuf[MAXPATHLEN];
 
 	if (realpath(path, rpathbuf) == NULL)
@@ -103,20 +102,24 @@ server_started:
 		data.flags = flags;
 		data.sx = ws.ws_col;
 		data.sy = ws.ws_row;
-		*data.tty = '\0';
+
 		if (getcwd(data.cwd, sizeof data.cwd) == NULL)
 			*data.cwd = '\0';
 
+		*data.term = '\0';
+		if ((term = getenv("TERM")) != NULL) {
+			if (strlcpy(data.term,
+			    term, sizeof data.term) >= sizeof data.term)
+				*data.term = '\0';
+		}
+
+		*data.tty = '\0';
 		if ((name = ttyname(STDIN_FILENO)) == NULL)
 			fatal("ttyname failed");
 		if (strlcpy(data.tty, name, sizeof data.tty) >= sizeof data.tty)
 			fatalx("ttyname failed");
 
-		b = buffer_create(BUFSIZ);
-		cmd_send_string(b, getenv("TERM"));
-		client_write_server2(cctx, MSG_IDENTIFY,
-		    &data, sizeof data, BUFFER_OUT(b), BUFFER_USED(b));
-		buffer_destroy(b);
+		client_write_server(cctx, MSG_IDENTIFY, &data, sizeof data);
 	}
 
 	return (0);
diff --git a/cmd-attach-session.c b/cmd-attach-session.c
index 2d930560..3278ea7f 100644
--- a/cmd-attach-session.c
+++ b/cmd-attach-session.c
@@ -33,8 +33,6 @@ const struct cmd_entry cmd_attach_session_entry = {
 	cmd_target_init,
 	cmd_target_parse,
 	cmd_attach_session_exec,
-	cmd_target_send,
-	cmd_target_recv,
 	cmd_target_free,
 	cmd_target_print
 };
diff --git a/cmd-bind-key.c b/cmd-bind-key.c
index 82ab14b0..41d8eeb8 100644
--- a/cmd-bind-key.c
+++ b/cmd-bind-key.c
@@ -26,8 +26,6 @@
 
 int	cmd_bind_key_parse(struct cmd *, int, char **, char **);
 int	cmd_bind_key_exec(struct cmd *, struct cmd_ctx *);
-void	cmd_bind_key_send(struct cmd *, struct buffer *);
-void	cmd_bind_key_recv(struct cmd *, struct buffer *);
 void	cmd_bind_key_free(struct cmd *);
 size_t	cmd_bind_key_print(struct cmd *, char *, size_t);
 
@@ -44,8 +42,6 @@ const struct cmd_entry cmd_bind_key_entry = {
 	NULL,
 	cmd_bind_key_parse,
 	cmd_bind_key_exec,
-	cmd_bind_key_send,
-	cmd_bind_key_recv,
 	cmd_bind_key_free,
 	cmd_bind_key_print
 };
@@ -114,25 +110,6 @@ cmd_bind_key_exec(struct cmd *self, unused struct cmd_ctx *ctx)
 }
 
 void
-cmd_bind_key_send(struct cmd *self, struct buffer *b)
-{
-	struct cmd_bind_key_data	*data = self->data;
-
-	buffer_write(b, data, sizeof *data);
-	cmd_list_send(data->cmdlist, b);
-}
-
-void
-cmd_bind_key_recv(struct cmd *self, struct buffer *b)
-{
-	struct cmd_bind_key_data	*data;
-
-	self->data = data = xmalloc(sizeof *data);
-	buffer_read(b, data, sizeof *data);
-	data->cmdlist = cmd_list_recv(b);
-}
-
-void
 cmd_bind_key_free(struct cmd *self)
 {
 	struct cmd_bind_key_data	*data = self->data;
diff --git a/cmd-break-pane.c b/cmd-break-pane.c
index 8eeb7f42..6a237c6d 100644
--- a/cmd-break-pane.c
+++ b/cmd-break-pane.c
@@ -35,8 +35,6 @@ const struct cmd_entry cmd_break_pane_entry = {
 	cmd_pane_init,
 	cmd_pane_parse,
 	cmd_break_pane_exec,
-       	cmd_pane_send,
-	cmd_pane_recv,
 	cmd_pane_free,
 	cmd_pane_print
 };
diff --git a/cmd-choose-session.c b/cmd-choose-session.c
index 09c8216d..cf5e3c82 100644
--- a/cmd-choose-session.c
+++ b/cmd-choose-session.c
@@ -35,8 +35,6 @@ const struct cmd_entry cmd_choose_session_entry = {
 	cmd_target_init,
 	cmd_target_parse,
 	cmd_choose_session_exec,
-	cmd_target_send,
-	cmd_target_recv,
 	cmd_target_free,
 	cmd_target_print
 };
diff --git a/cmd-choose-window.c b/cmd-choose-window.c
index 80a2518e..9386c5fa 100644
--- a/cmd-choose-window.c
+++ b/cmd-choose-window.c
@@ -35,8 +35,6 @@ const struct cmd_entry cmd_choose_window_entry = {
 	cmd_target_init,
 	cmd_target_parse,
 	cmd_choose_window_exec,
-	cmd_target_send,
-	cmd_target_recv,
 	cmd_target_free,
 	cmd_target_print
 };
diff --git a/cmd-clear-history.c b/cmd-clear-history.c
index de24ac57..2e4c118d 100644
--- a/cmd-clear-history.c
+++ b/cmd-clear-history.c
@@ -33,8 +33,6 @@ const struct cmd_entry cmd_clear_history_entry = {
 	cmd_pane_init,
 	cmd_pane_parse,
 	cmd_clear_history_exec,
-	cmd_pane_send,
-	cmd_pane_recv,
 	cmd_pane_free,
 	cmd_pane_print
 };
diff --git a/cmd-clock-mode.c b/cmd-clock-mode.c
index 4399b7ba..0fc43a54 100644
--- a/cmd-clock-mode.c
+++ b/cmd-clock-mode.c
@@ -33,8 +33,6 @@ const struct cmd_entry cmd_clock_mode_entry = {
 	cmd_target_init,
 	cmd_target_parse,
 	cmd_clock_mode_exec,
-       	cmd_target_send,
-	cmd_target_recv,
 	cmd_target_free,
 	cmd_target_print
 };
diff --git a/cmd-command-prompt.c b/cmd-command-prompt.c
index 872fa326..f729a66e 100644
--- a/cmd-command-prompt.c
+++ b/cmd-command-prompt.c
@@ -40,8 +40,6 @@ const struct cmd_entry cmd_command_prompt_entry = {
 	cmd_command_prompt_init,
 	cmd_target_parse,
 	cmd_command_prompt_exec,
-	cmd_target_send,
-	cmd_target_recv,
 	cmd_target_free,
 	cmd_target_print
 };
diff --git a/cmd-confirm-before.c b/cmd-confirm-before.c
index f1f5bfe1..db799a4b 100644
--- a/cmd-confirm-before.c
+++ b/cmd-confirm-before.c
@@ -38,8 +38,6 @@ const struct cmd_entry cmd_confirm_before_entry = {
 	cmd_confirm_before_init,
 	cmd_target_parse,
 	cmd_confirm_before_exec,
-	cmd_target_send,
-	cmd_target_recv,
 	cmd_target_free,
 	cmd_target_print
 };
diff --git a/cmd-copy-buffer.c b/cmd-copy-buffer.c
index 544cf1c6..7cef21ef 100644
--- a/cmd-copy-buffer.c
+++ b/cmd-copy-buffer.c
@@ -26,8 +26,6 @@
 
 int	cmd_copy_buffer_parse(struct cmd *, int, char **, char **);
 int	cmd_copy_buffer_exec(struct cmd *, struct cmd_ctx *);
-void	cmd_copy_buffer_send(struct cmd *, struct buffer *);
-void	cmd_copy_buffer_recv(struct cmd *, struct buffer *);
 void	cmd_copy_buffer_free(struct cmd *);
 void	cmd_copy_buffer_init(struct cmd *, int);
 size_t	cmd_copy_buffer_print(struct cmd *, char *, size_t);
@@ -46,8 +44,6 @@ const struct cmd_entry cmd_copy_buffer_entry = {
 	cmd_copy_buffer_init,
 	cmd_copy_buffer_parse,
 	cmd_copy_buffer_exec,
-	cmd_copy_buffer_send,
-	cmd_copy_buffer_recv,
 	cmd_copy_buffer_free,
 	cmd_copy_buffer_print
 };
@@ -161,27 +157,6 @@ cmd_copy_buffer_exec(struct cmd *self, struct cmd_ctx *ctx)
 }
 
 void
-cmd_copy_buffer_send(struct cmd *self, struct buffer *b)
-{
-	struct cmd_copy_buffer_data	*data = self->data;
-
-	buffer_write(b, data, sizeof *data);
-	cmd_send_string(b, data->dst_session);
-	cmd_send_string(b, data->src_session);
-}
-
-void
-cmd_copy_buffer_recv(struct cmd *self, struct buffer *b)
-{
-	struct cmd_copy_buffer_data	*data;
-
-	self->data = data = xmalloc(sizeof *data);
-	buffer_read(b, data, sizeof *data);
-	data->dst_session = cmd_recv_string(b);
-	data->src_session = cmd_recv_string(b);
-}
-
-void
 cmd_copy_buffer_free(struct cmd *self)
 {
 	struct cmd_copy_buffer_data	*data = self->data;
diff --git a/cmd-copy-mode.c b/cmd-copy-mode.c
index e9891179..3e6b2228 100644
--- a/cmd-copy-mode.c
+++ b/cmd-copy-mode.c
@@ -33,8 +33,6 @@ const struct cmd_entry cmd_copy_mode_entry = {
 	cmd_target_init,
 	cmd_target_parse,
 	cmd_copy_mode_exec,
-	cmd_target_send,
-	cmd_target_recv,
 	cmd_target_free,
 	NULL
 };
diff --git a/cmd-delete-buffer.c b/cmd-delete-buffer.c
index 81b69417..b193438c 100644
--- a/cmd-delete-buffer.c
+++ b/cmd-delete-buffer.c
@@ -35,8 +35,6 @@ const struct cmd_entry cmd_delete_buffer_entry = {
 	cmd_buffer_init,
 	cmd_buffer_parse,
 	cmd_delete_buffer_exec,
-	cmd_buffer_send,
-	cmd_buffer_recv,
 	cmd_buffer_free,
 	cmd_buffer_print
 };
diff --git a/cmd-detach-client.c b/cmd-detach-client.c
index 0a28cdc7..dd480226 100644
--- a/cmd-detach-client.c
+++ b/cmd-detach-client.c
@@ -33,8 +33,6 @@ const struct cmd_entry cmd_detach_client_entry = {
 	cmd_target_init,
 	cmd_target_parse,
 	cmd_detach_client_exec,
-	cmd_target_send,
-	cmd_target_recv,
 	cmd_target_free,
 	cmd_target_print
 };
diff --git a/cmd-display-message.c b/cmd-display-message.c
index 332b6e28..20758daa 100644
--- a/cmd-display-message.c
+++ b/cmd-display-message.c
@@ -35,8 +35,6 @@ const struct cmd_entry cmd_display_message_entry = {
 	cmd_target_init,
 	cmd_target_parse,
 	cmd_display_message_exec,
-	cmd_target_send,
-	cmd_target_recv,
 	cmd_target_free,
 	cmd_target_print
 };
diff --git a/cmd-down-pane.c b/cmd-down-pane.c
index c3c12dba..242c6ac3 100644
--- a/cmd-down-pane.c
+++ b/cmd-down-pane.c
@@ -33,8 +33,6 @@ const struct cmd_entry cmd_down_pane_entry = {
 	cmd_target_init,
 	cmd_target_parse,
 	cmd_down_pane_exec,
-	cmd_target_send,
-	cmd_target_recv,
 	cmd_target_free,
 	cmd_target_print
 };
diff --git a/cmd-find-window.c b/cmd-find-window.c
index 34ea75ec..0a1c38da 100644
--- a/cmd-find-window.c
+++ b/cmd-find-window.c
@@ -38,8 +38,6 @@ const struct cmd_entry cmd_find_window_entry = {
 	cmd_target_init,
 	cmd_target_parse,
 	cmd_find_window_exec,
-	cmd_target_send,
-	cmd_target_recv,
 	cmd_target_free,
 	cmd_target_print
 };
diff --git a/cmd-generic.c b/cmd-generic.c
index ea0d4d16..39c18d51 100644
--- a/cmd-generic.c
+++ b/cmd-generic.c
@@ -177,27 +177,6 @@ usage:
 }
 
 void
-cmd_target_send(struct cmd *self, struct buffer *b)
-{
-	struct cmd_target_data	*data = self->data;
-
-	buffer_write(b, data, sizeof *data);
-	cmd_send_string(b, data->target);
-	cmd_send_string(b, data->arg);
-}
-
-void
-cmd_target_recv(struct cmd *self, struct buffer *b)
-{
-	struct cmd_target_data	*data;
-
-	self->data = data = xmalloc(sizeof *data);
-	buffer_read(b, data, sizeof *data);
-	data->target = cmd_recv_string(b);
-	data->arg = cmd_recv_string(b);
-}
-
-void
 cmd_target_free(struct cmd *self)
 {
 	struct cmd_target_data	*data = self->data;
@@ -279,29 +258,6 @@ usage:
 }
 
 void
-cmd_srcdst_send(struct cmd *self, struct buffer *b)
-{
-	struct cmd_srcdst_data	*data = self->data;
-
-	buffer_write(b, data, sizeof *data);
-	cmd_send_string(b, data->src);
-	cmd_send_string(b, data->dst);
-	cmd_send_string(b, data->arg);
-}
-
-void
-cmd_srcdst_recv(struct cmd *self, struct buffer *b)
-{
-	struct cmd_srcdst_data	*data;
-
-	self->data = data = xmalloc(sizeof *data);
-	buffer_read(b, data, sizeof *data);
-	data->src = cmd_recv_string(b);
-	data->dst = cmd_recv_string(b);
-	data->arg = cmd_recv_string(b);
-}
-
-void
 cmd_srcdst_free(struct cmd *self)
 {
 	struct cmd_srcdst_data	*data = self->data;
@@ -395,27 +351,6 @@ error:
 }
 
 void
-cmd_buffer_send(struct cmd *self, struct buffer *b)
-{
-	struct cmd_buffer_data	*data = self->data;
-
-	buffer_write(b, data, sizeof *data);
-	cmd_send_string(b, data->target);
-	cmd_send_string(b, data->arg);
-}
-
-void
-cmd_buffer_recv(struct cmd *self, struct buffer *b)
-{
-	struct cmd_buffer_data	*data;
-
-	self->data = data = xmalloc(sizeof *data);
-	buffer_read(b, data, sizeof *data);
-	data->target = cmd_recv_string(b);
-	data->arg = cmd_recv_string(b);
-}
-
-void
 cmd_buffer_free(struct cmd *self)
 {
 	struct cmd_buffer_data	*data = self->data;
@@ -501,29 +436,6 @@ usage:
 }
 
 void
-cmd_option_send(struct cmd *self, struct buffer *b)
-{
-	struct cmd_option_data	*data = self->data;
-
-	buffer_write(b, data, sizeof *data);
-	cmd_send_string(b, data->target);
-	cmd_send_string(b, da