Use noop output when there's no outputs connected

Instead of having NULL workspace->output pointers, use a noop output.
This should be safer.

8 files changed, 29 insertions, 28 deletions

diff --git a/include/sway/server.h b/include/sway/server.h
index 0f30653f..9242ceb7 100644
--- a/include/sway/server.h
+++ b/include/sway/server.h
@@ -24,6 +24,7 @@ struct sway_server {
         const char *socket;
 
         struct wlr_backend *backend;
+        struct wlr_backend *noop_backend;
 
         struct wlr_compositor *compositor;
         struct wlr_data_device_manager *data_device_manager;
diff --git a/include/sway/tree/root.h b/include/sway/tree/root.h
index ceccc920..8f4deaa7 100644
--- a/include/sway/tree/root.h
+++ b/include/sway/tree/root.h
@@ -31,7 +31,9 @@ struct sway_root {
 
         list_t *outputs; // struct sway_output
         list_t *scratchpad; // struct sway_container
-        list_t *saved_workspaces; // For when there's no connected outputs
+
+        // For when there's no connected outputs
+        struct sway_output *noop_output;
 
         struct {
                 struct wl_signal new_node;
diff --git a/sway/desktop/output.c b/sway/desktop/output.c
index edf77fbc..f18a118f 100644
--- a/sway/desktop/output.c
+++ b/sway/desktop/output.c
@@ -386,7 +386,7 @@ static void damage_handle_frame(struct wl_listener *listener, void *data) {
 void output_damage_whole(struct sway_output *output) {
         // The output can exist with no wlr_output if it's just been disconnected
         // and the transaction to evacuate it has't completed yet.
-        if (output && output->wlr_output) {
+        if (output && output->wlr_output && output->damage) {
                 wlr_output_damage_add_whole(output->damage);
         }
 }
diff --git a/sway/server.c b/sway/server.c
index 5ae9bb01..43dc3900 100644
--- a/sway/server.c
+++ b/sway/server.c
@@ -4,6 +4,7 @@
 #include <stdlib.h>
 #include <wayland-server.h>
 #include <wlr/backend.h>
+#include <wlr/backend/noop.h>
 #include <wlr/backend/session.h>
 #include <wlr/render/wlr_renderer.h>
 #include <wlr/types/wlr_compositor.h>
@@ -25,6 +26,7 @@
 #include "sway/config.h"
 #include "sway/desktop/idle_inhibit_v1.h"
 #include "sway/input/input-manager.h"
+#include "sway/output.h"
 #include "sway/server.h"
 #include "sway/tree/root.h"
 #if HAVE_XWAYLAND
@@ -36,6 +38,7 @@ bool server_privileged_prepare(struct sway_server *server) {
         server->wl_display = wl_display_create();
         server->wl_event_loop = wl_display_get_event_loop(server->wl_display);
         server->backend = wlr_backend_autocreate(server->wl_display, NULL);
+        server->noop_backend = wlr_noop_backend_create(server->wl_display);
 
         if (!server->backend) {
                 sway_log(SWAY_ERROR, "Unable to create backend");
@@ -116,6 +119,9 @@ bool server_init(struct sway_server *server) {
                 return false;
         }
 
+        struct wlr_output *wlr_output = wlr_noop_add_output(server->noop_backend);
+        root->noop_output = output_create(wlr_output);
+
         // This may have been set already via -Dtxn-timeout
         if (!server->txn_timeout_ms) {
                 server->txn_timeout_ms = 200;
diff --git a/sway/tree/output.c b/sway/tree/output.c
index 50a2c535..5a992f2d 100644
--- a/sway/tree/output.c
+++ b/sway/tree/output.c
@@ -57,12 +57,12 @@ static void restore_workspaces(struct sway_output *output) {
         }
 
         // Saved workspaces
-        for (int i = 0; i < root->saved_workspaces->length; ++i) {
-                struct sway_workspace *ws = root->saved_workspaces->items[i];
+        while (root->noop_output->workspaces->length) {
+                struct sway_workspace *ws = root->noop_output->workspaces->items[0];
+                workspace_detach(ws);
                 output_add_workspace(output, ws);
                 ipc_event_workspace(NULL, ws, "move");
         }
-        root->saved_workspaces->length = 0;
 
         output_sort_workspaces(output);
 }
@@ -177,6 +177,9 @@ static void output_evacuate(struct sway_output *output) {
                 if (!new_output) {
                         new_output = fallback_output;
                 }
+                if (!new_output) {
+                        new_output = root->noop_output;
+                }
 
                 if (workspace_is_empty(workspace)) {
                         // If floating is not empty, there are sticky containers to move
@@ -187,14 +190,10 @@ static void output_evacuate(struct sway_output *output) {
                         continue;
                 }
 
-                if (new_output) {
-                        workspace_output_add_priority(workspace, new_output);
-                        output_add_workspace(new_output, workspace);
-                        output_sort_workspaces(new_output);
-                        ipc_event_workspace(NULL, workspace, "move");
-                } else {
-                        list_add(root->saved_workspaces, workspace);
-                }
+                workspace_output_add_priority(workspace, new_output);
+                output_add_workspace(new_output, workspace);
+                output_sort_workspaces(new_output);
+                ipc_event_workspace(NULL, workspace, "move");
         }
 }
 
diff --git a/sway/tree/root.c b/sway/tree/root.c
index d4b97be3..ec6bccf6 100644
--- a/sway/tree/root.c
+++ b/sway/tree/root.c
@@ -39,7 +39,6 @@ struct sway_root *root_create(void) {
         wl_signal_init(&root->events.new_node);
         root->outputs = create_list();
         root->scratchpad = create_list();
-        root->saved_workspaces = create_list();
 
         root->output_layout_change.notify = output_layout_handle_change;
         wl_signal_add(&root->output_layout->events.change,
@@ -50,7 +49,6 @@ struct sway_root *root_create(void) {
 void root_destroy(struct sway_root *root) {
         wl_list_remove(&root->output_layout_change.link);
         list_free(root->scratchpad);
-        list_free(root->saved_workspaces);
         list_free(root->outputs);
         wlr_output_layout_destroy(root->output_layout);
         free(root);
@@ -327,8 +325,8 @@ void root_for_each_container(void (*f)(struct sway_container *con, void *data),
         }
 
         // Saved workspaces
-        for (int i = 0; i < root->saved_workspaces->length; ++i) {
-                struct sway_workspace *ws = root->saved_workspaces->items[i];
+        for (int i = 0; i < root->noop_output->workspaces->length; ++i) {
+                struct sway_workspace *ws = root->noop_output->workspaces->items[i];
                 workspace_for_each_container(ws, f, data);
         }
 }
@@ -380,8 +378,8 @@ struct sway_container *root_find_container(
         }
 
         // Saved workspaces
-        for (int i = 0; i < root->saved_workspaces->length; ++i) {
-                struct sway_workspace *ws = root->saved_workspaces->items[i];
+        for (int i = 0; i < root->noop_output->workspaces->length; ++i) {
+                struct sway_workspace *ws = root->noop_output->workspaces->items[i];
                 if ((result = workspace_find_container(ws, test, data))) {
                         return result;
                 }
diff --git a/sway/tree/view.c b/sway/tree/view.c
index bc252521..edbfca97 100644
--- a/sway/tree/view.c
+++ b/sway/tree/view.c
@@ -518,9 +518,10 @@ static struct sway_workspace *select_workspace(struct sway_view *view) {
                 return node->sway_container->workspace;
         }
 
-        // If there's no focus_inactive workspace then we must be running without
-        // any outputs connected
-        return root->saved_workspaces->items[0];
+        // When there's no outputs connected, the above should match a workspace on
+        // the noop output.
+        sway_assert(false, "Expected to find a workspace");
+        return NULL;
 }
 
 static bool should_focus(struct sway_view *view) {
diff --git a/sway/tree/workspace.c b/sway/tree/workspace.c
index e89c0849..8b3eb2ad 100644
--- a/sway/tree/workspace.c
+++ b/sway/tree/workspace.c
@@ -158,13 +158,7 @@ void workspace_begin_destroy(struct sway_workspace *workspace) {
 
         if (workspace->output) {
                 workspace_detach(workspace);
-        } else {
-                int index = list_find(root->saved_workspaces, workspace);
-                if (index != -1) {
-                        list_del(root->saved_workspaces, index);
-                }
         }
-
         workspace->node.destroying = true;
         node_set_dirty(&workspace->node);
 }