Implement pid->workspace tracking

When you spawn a process with the exec command, sway now notes the
workspace you had focused and the pid of the child process, then assigns
that workspace to the child when its window appears.

Some of this is carried over from sway 0.15, but with some major
refactoring and centralization of state.

2 files changed, 146 insertions, 9 deletions

diff --git a/sway/tree/view.c b/sway/tree/view.c
index 06e9edc5..24fb6864 100644
--- a/sway/tree/view.c
+++ b/sway/tree/view.c
@@ -3,6 +3,7 @@
 #include <wayland-server.h>
 #include <wlr/render/wlr_renderer.h>
 #include <wlr/types/wlr_output_layout.h>
+#include <wlr/xwayland.h>
 #include "list.h"
 #include "log.h"
 #include "sway/criteria.h"
@@ -492,9 +493,21 @@ void view_map(struct sway_view *view, struct wlr_surface *wlr_surface) {
 		return;
 	}
 
+	pid_t pid;
+	if (view->type == SWAY_VIEW_XWAYLAND) {
+		struct wlr_xwayland_surface *surf =
+			wlr_xwayland_surface_from_wlr_surface(wlr_surface);
+		pid = surf->pid;
+	} else {
+		struct wl_client *client =
+			wl_resource_get_client(wlr_surface->resource);
+		wl_client_get_credentials(client, &pid, NULL, NULL);
+	}
+
 	struct sway_seat *seat = input_manager_current_seat(input_manager);
-	struct sway_container *focus =
+	struct sway_container *target_sibling =
 		seat_get_focus_inactive(seat, &root_container);
+	struct sway_container *prev_focus = target_sibling;
 	struct sway_container *cont = NULL;
 
 	// Check if there's any `assign` criteria for the view
@@ -508,18 +521,31 @@ void view_map(struct sway_view *view, struct wlr_surface *wlr_surface) {
 			if (!workspace) {
 				workspace = workspace_create(NULL, criteria->target);
 			}
-			focus = seat_get_focus_inactive(seat, workspace);
+			prev_focus = target_sibling;
+			target_sibling = seat_get_focus_inactive(seat, workspace);
 		} else {
 			// TODO: CT_ASSIGN_OUTPUT
 		}
 	}
+	list_free(criterias);
+
+	if (!workspace) {
+		workspace = workspace_for_pid(pid);
+		if (workspace) {
+			prev_focus = target_sibling;
+			target_sibling = seat_get_focus_inactive(seat, workspace);
+		}
+	}
 	// If we're about to launch the view into the floating container, then
 	// launch it as a tiled view in the root of the workspace instead.
-	if (container_is_floating(focus)) {
-		focus = focus->parent->parent;
+	if (container_is_floating(target_sibling)) {
+		if (prev_focus == target_sibling) {
+			prev_focus = target_sibling->parent->parent;
+		}
+		target_sibling = target_sibling->parent->parent;
 	}
-	free(criterias);
-	cont = container_view_create(focus, view);
+
+	cont = container_view_create(target_sibling, view);
 
 	view->surface = wlr_surface;
 	view->swayc = cont;
@@ -538,9 +564,8 @@ void view_map(struct sway_view *view, struct wlr_surface *wlr_surface) {
 		container_set_floating(view->swayc, true);
 	}
 
-	input_manager_set_focus(input_manager, cont);
-	if (workspace) {
-		workspace_switch(workspace);
+	if (prev_focus == target_sibling) {
+		input_manager_set_focus(input_manager, cont);
 	}
 
 	view_update_title(view, false);
diff --git a/sway/tree/workspace.c b/sway/tree/workspace.c
index 5eb4be0f..651cc011 100644
--- a/sway/tree/workspace.c
+++ b/sway/tree/workspace.c
@@ -9,6 +9,7 @@
 #include "sway/input/input-manager.h"
 #include "sway/input/seat.h"
 #include "sway/ipc-server.h"
+#include "sway/output.h"
 #include "sway/tree/arrange.h"
 #include "sway/tree/container.h"
 #include "sway/tree/workspace.h"
@@ -516,3 +517,114 @@ struct sway_container *workspace_output_get_highest_available(
 
 	return NULL;
 }
+
+struct pid_workspace {
+	pid_t pid;
+	char *workspace;
+	struct timespec time_added;
+
+	struct sway_container *output;
+	struct wl_listener output_destroy;
+
+	struct wl_list link;
+};
+
+static struct wl_list pid_workspaces;
+
+struct sway_container *workspace_for_pid(pid_t pid) {
+	if (!pid_workspaces.prev && !pid_workspaces.next) {
+		wl_list_init(&pid_workspaces);
+		return NULL;
+	}
+
+	struct sway_container *ws = NULL;
+	struct pid_workspace *pw = NULL;
+
+	wlr_log(L_DEBUG, "Looking up workspace for pid %d", pid);
+
+	do {
+		struct pid_workspace *_pw = NULL;
+		wl_list_for_each(_pw, &pid_workspaces, link) {
+			if (pid == _pw->pid) {
+				pw = _pw;
+				wlr_log(L_DEBUG,
+						"found pid_workspace for pid %d, workspace %s",
+						pid, pw->workspace);
+				goto found;
+			}
+		}
+		pid = get_parent_pid(pid);
+	} while (pid > 1);
+found:
+
+	if (pw && pw->workspace) {
+		ws = workspace_by_name(pw->workspace);
+
+		if (!ws) {
+			wlr_log(L_DEBUG,
+					"Creating workspace %s for pid %d because it disappeared",
+					pw->workspace, pid);
+			ws = workspace_create(pw->output, pw->workspace);
+		}
+
+		wl_list_remove(&pw->output_destroy.link);
+		wl_list_remove(&pw->link);
+		free(pw->workspace);
+		free(pw);
+	}
+
+	return ws;
+}
+
+static void pw_handle_output_destroy(struct wl_listener *listener, void *data) {
+	struct pid_workspace *pw = wl_container_of(listener, pw, output_destroy);
+	pw->output = NULL;
+}
+
+void workspace_record_pid(pid_t pid) {
+	wlr_log(L_DEBUG, "Recording workspace for process %d", pid);
+	if (!pid_workspaces.prev && !pid_workspaces.next) {
+		wl_list_init(&pid_workspaces);
+	}
+
+	struct sway_seat *seat = input_manager_current_seat(input_manager);
+	struct sway_container *ws =
+		seat_get_focus_inactive(seat, &root_container);
+	if (ws && ws->type != C_WORKSPACE) {
+		ws = container_parent(ws, C_WORKSPACE);
+	}
+	if (!ws) {
+		wlr_log(L_DEBUG, "Bailing out, no workspace");
+		return;
+	}
+	struct sway_container *output = ws->parent;
+	if (!output) {
+		wlr_log(L_DEBUG, "Bailing out, no output");
+		return;
+	}
+
+	struct timespec now;
+	clock_gettime(CLOCK_MONOTONIC, &now);
+
+	// Remove expired entries
+	static const int timeout = 60;
+	struct pid_workspace *old, *_old;
+	wl_list_for_each_safe(old, _old, &pid_workspaces, link) {
+		if (now.tv_sec - old->time_added.tv_sec >= timeout) {
+			wl_list_remove(&old->output_destroy.link);
+			wl_list_remove(&old->link);
+			free(old->workspace);
+			free(old);
+		}
+	}
+
+	struct pid_workspace *pw = calloc(1, sizeof(struct pid_workspace));
+	pw->workspace = strdup(ws->name);
+	pw->output = output;
+	pw->pid = pid;
+	memcpy(&pw->time_added, &now, sizeof(struct timespec));
+	pw->output_destroy.notify = pw_handle_output_destroy;
+	wl_signal_add(&output->sway_output->wlr_output->events.destroy,
+			&pw->output_destroy);
+	wl_list_insert(&pid_workspaces, &pw->link);
+}