Make workspace back_and_forth seat-specific

* When using multiple seats, each seat has its own prev_workspace_name
for the purpose of workspace back_and_forth.
* Removes prev_workspace_name global variable.
* Removes unused next_name_map function in tree/workspace.c.
* Fixes memory leak in seat_destroy (seat was not freed).

include/sway/input/seat.h

@@ -51,6 +51,7 @@ struct sway_seat {
 	bool has_focus;
 	struct wl_list focus_stack; // list of containers in focus order
 	struct sway_workspace *workspace;
+	char *prev_workspace_name; // for workspace back_and_forth
 
 	// If the focused layer is set, views cannot receive keyboard focus
 	struct wlr_layer_surface_v1 *focused_layer;

include/sway/tree/workspace.h

@@ -45,8 +45,6 @@ struct sway_workspace {
 	struct sway_workspace_state current;
 };
 
-extern char *prev_workspace_name;
-
 struct workspace_config *workspace_find_config(const char *ws_name);
 
 struct sway_output *workspace_get_initial_output(const char *name);

sway/commands/move.c

@@ -429,8 +429,8 @@ static struct cmd_results *cmd_move_container(int argc, char **argv) {
 			ws = workspace_by_name(argv[2]);
 		} else if (strcasecmp(argv[2], "back_and_forth") == 0) {
 			if (!(ws = workspace_by_name(argv[2]))) {
-				if (prev_workspace_name) {
-					ws_name = strdup(prev_workspace_name);
+				if (seat->prev_workspace_name) {
+					ws_name = strdup(seat->prev_workspace_name);
 				} else {
 					return cmd_results_new(CMD_FAILURE, "move",
 							"No workspace was previously active.");
@@ -455,13 +455,13 @@ static struct cmd_results *cmd_move_container(int argc, char **argv) {
 			}
 
 			if (!no_auto_back_and_forth && config->auto_back_and_forth &&
-					prev_workspace_name) {
+					seat->prev_workspace_name) {
 				// auto back and forth move
 				if (old_ws && old_ws->name &&
 						strcmp(old_ws->name, ws_name) == 0) {
 					// if target workspace is the current one
 					free(ws_name);
-					ws_name = strdup(prev_workspace_name);
+					ws_name = strdup(seat->prev_workspace_name);
 					ws = workspace_by_name(ws_name);
 				}
 			}

sway/commands/swap.c

@@ -116,8 +116,8 @@ static void container_swap(struct sway_container *con1,
 		output_get_active_workspace(con2->workspace->output);
 
 	char *stored_prev_name = NULL;
-	if (prev_workspace_name) {
-		stored_prev_name = strdup(prev_workspace_name);
+	if (seat->prev_workspace_name) {
+		stored_prev_name = strdup(seat->prev_workspace_name);
 	}
 
 	swap_places(con1, con2);
@@ -132,8 +132,8 @@ static void container_swap(struct sway_container *con1,
 	swap_focus(con1, con2, seat, focus);
 
 	if (stored_prev_name) {
-		free(prev_workspace_name);
-		prev_workspace_name = stored_prev_name;
+		free(seat->prev_workspace_name);
+		seat->prev_workspace_name = stored_prev_name;
 	}
 
 	if (fs1) {

sway/commands/workspace.c

@@ -142,12 +142,13 @@ struct cmd_results *cmd_workspace(int argc, char **argv) {
 				strcasecmp(argv[0], "current") == 0) {
 			ws = workspace_by_name(argv[0]);
 		} else if (strcasecmp(argv[0], "back_and_forth") == 0) {
-			if (!prev_workspace_name) {
+			struct sway_seat *seat = config->handler_context.seat;
+			if (!seat->prev_workspace_name) {
 				return cmd_results_new(CMD_INVALID, "workspace",
 						"There is no previous workspace");
 			}
 			if (!(ws = workspace_by_name(argv[0]))) {
-				ws = workspace_create(NULL, prev_workspace_name);
+				ws = workspace_create(NULL, seat->prev_workspace_name);
 			}
 		} else {
 			char *name = join_args(argv, argc);

sway/input/seat.c

@@ -51,6 +51,8 @@ void seat_destroy(struct sway_seat *seat) {
 	wl_list_remove(&seat->new_drag_icon.link);
 	wl_list_remove(&seat->link);
 	wlr_seat_destroy(seat->wlr_seat);
+	free(seat->prev_workspace_name);
+	free(seat);
 }
 
 static struct sway_seat_node *seat_node_from_node(

sway/tree/view.c

@@ -465,8 +465,8 @@ static struct sway_workspace *select_workspace(struct sway_view *view) {
 
 			if (!ws) {
 				if (strcasecmp(criteria->target, "back_and_forth") == 0) {
-					if (prev_workspace_name) {
-						ws = workspace_create(NULL, prev_workspace_name);
+					if (seat->prev_workspace_name) {
+						ws = workspace_create(NULL, seat->prev_workspace_name);
 					}
 				} else {
 					ws = workspace_create(NULL, criteria->target);

sway/tree/workspace.c

@@ -140,13 +140,6 @@ void workspace_consider_destroy(struct sway_workspace *ws) {
 	workspace_begin_destroy(ws);
 }
 
-char *prev_workspace_name = NULL;
-
-void next_name_map(struct sway_container *ws, void *data) {
-	int *count = data;
-	++count;
-}
-
 static bool workspace_valid_on_output(const char *output_name,
 		const char *ws_name) {
 	struct workspace_config *wsc = workspace_find_config(ws_name);
@@ -309,9 +302,12 @@ struct sway_workspace *workspace_by_name(const char *name) {
 	} else if (strcmp(name, "current") == 0) {
 		return current;
 	} else if (strcasecmp(name, "back_and_forth") == 0) {
-		return prev_workspace_name ?
-			root_find_workspace(_workspace_by_name, (void*)prev_workspace_name)
-			: NULL;
+		struct sway_seat *seat = input_manager_current_seat();
+		if (!seat->prev_workspace_name) {
+			return NULL;
+		}
+		return root_find_workspace(_workspace_by_name,
+				(void*)seat->prev_workspace_name);
 	} else {
 		return root_find_workspace(_workspace_by_name, (void*)name);
 	}
@@ -380,23 +376,24 @@ bool workspace_switch(struct sway_workspace *workspace,
 	struct sway_workspace *active_ws = seat_get_focused_workspace(seat);
 
 	if (!no_auto_back_and_forth && config->auto_back_and_forth
-			&& active_ws == workspace
-			&& prev_workspace_name) {
-		struct sway_workspace *new_ws = workspace_by_name(prev_workspace_name);
+			&& active_ws == workspace && seat->prev_workspace_name) {
+		struct sway_workspace *new_ws =
+			workspace_by_name(seat->prev_workspace_name);
 		workspace = new_ws ?
 			new_ws :
-			workspace_create(NULL, prev_workspace_name);
+			workspace_create(NULL, seat->prev_workspace_name);
 	}
 
-	if (!prev_workspace_name || (strcmp(prev_workspace_name, active_ws->name)
+	if (!seat->prev_workspace_name ||
+			(strcmp(seat->prev_workspace_name, active_ws->name)
 				&& active_ws != workspace)) {
-		free(prev_workspace_name);
-		prev_workspace_name = malloc(strlen(active_ws->name) + 1);
-		if (!prev_workspace_name) {
+		free(seat->prev_workspace_name);
+		seat->prev_workspace_name = malloc(strlen(active_ws->name) + 1);
+		if (!seat->prev_workspace_name) {
 			wlr_log(WLR_ERROR, "Unable to allocate previous workspace name");
 			return false;
 		}
-		strcpy(prev_workspace_name, active_ws->name);
+		strcpy(seat->prev_workspace_name, active_ws->name);
 	}
 
 	wlr_log(WLR_DEBUG, "Switching to workspace %p:%s",