root: move the workspace matching code to its own file

This removes the pid_workspace bits from tree/root before it gets
too interesting.

No functional change.

include/sway/desktop/launcher.h

@@ -0,0 +1,14 @@
+#ifndef _SWAY_LAUNCHER_H
+#define _SWAY_LAUNCHER_H
+
+#include <stdlib.h>
+
+struct sway_workspace *root_workspace_for_pid(pid_t pid);
+
+void root_record_workspace_pid(pid_t pid);
+
+void root_remove_workspace_pid(pid_t pid);
+
+void root_rename_pid_workspaces(const char *old_name, const char *new_name);
+
+#endif

include/sway/tree/root.h

@@ -69,12 +69,6 @@ void root_scratchpad_show(struct sway_container *con);
  */
 void root_scratchpad_hide(struct sway_container *con);
 
-struct sway_workspace *root_workspace_for_pid(pid_t pid);
-
-void root_record_workspace_pid(pid_t pid);
-
-void root_remove_workspace_pid(pid_t pid);
-
 void root_for_each_workspace(void (*f)(struct sway_workspace *ws, void *data),
 		void *data);
 
@@ -92,6 +86,4 @@ struct sway_container *root_find_container(
 
 void root_get_box(struct sway_root *root, struct wlr_box *box);
 
-void root_rename_pid_workspaces(const char *old_name, const char *new_name);
-
 #endif

sway/commands/exec_always.c

@@ -8,6 +8,7 @@
 #include "sway/commands.h"
 #include "sway/config.h"
 #include "sway/server.h"
+#include "sway/desktop/launcher.h"
 #include "sway/tree/container.h"
 #include "sway/tree/root.h"
 #include "sway/tree/workspace.h"

sway/commands/rename.c

@@ -7,6 +7,7 @@
 #include "sway/config.h"
 #include "sway/ipc-server.h"
 #include "sway/output.h"
+#include "sway/desktop/launcher.h"
 #include "sway/tree/container.h"
 #include "sway/tree/workspace.h"
 #include "sway/tree/root.h"

sway/desktop/launcher.c

@@ -0,0 +1,189 @@
+#define _POSIX_C_SOURCE 200809L
+#include <stdlib.h>
+#include <string.h>
+#include "sway/input/seat.h"
+#include "sway/output.h"
+#include "sway/desktop/launcher.h"
+#include "sway/tree/container.h"
+#include "sway/tree/workspace.h"
+#include "log.h"
+
+static struct wl_list pid_workspaces;
+
+struct pid_workspace {
+	pid_t pid;
+	char *workspace;
+	struct timespec time_added;
+
+	struct sway_output *output;
+	struct wl_listener output_destroy;
+
+	struct wl_list link;
+};
+
+/**
+ * Get the pid of a parent process given the pid of a child process.
+ *
+ * Returns the parent pid or NULL if the parent pid cannot be determined.
+ */
+static pid_t get_parent_pid(pid_t child) {
+	pid_t parent = -1;
+	char file_name[100];
+	char *buffer = NULL;
+	const char *sep = " ";
+	FILE *stat = NULL;
+	size_t buf_size = 0;
+
+	snprintf(file_name, sizeof(file_name), "/proc/%d/stat", child);
+
+	if ((stat = fopen(file_name, "r"))) {
+		if (getline(&buffer, &buf_size, stat) != -1) {
+			strtok(buffer, sep); // pid
+			strtok(NULL, sep);   // executable name
+			strtok(NULL, sep);   // state
+			char *token = strtok(NULL, sep);   // parent pid
+			parent = strtol(token, NULL, 10);
+		}
+		free(buffer);
+		fclose(stat);
+	}
+
+	if (parent) {
+		return (parent == child) ? -1 : parent;
+	}
+
+	return -1;
+}
+
+static void pid_workspace_destroy(struct pid_workspace *pw) {
+	wl_list_remove(&pw->output_destroy.link);
+	wl_list_remove(&pw->link);
+	free(pw->workspace);
+	free(pw);
+}
+
+struct sway_workspace *root_workspace_for_pid(pid_t pid) {
+	if (!pid_workspaces.prev && !pid_workspaces.next) {
+		wl_list_init(&pid_workspaces);
+		return NULL;
+	}
+
+	struct sway_workspace *ws = NULL;
+	struct pid_workspace *pw = NULL;
+
+	sway_log(SWAY_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;
+				sway_log(SWAY_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) {
+			sway_log(SWAY_DEBUG,
+					"Creating workspace %s for pid %d because it disappeared",
+					pw->workspace, pid);
+
+			struct sway_output *output = pw->output;
+			if (pw->output && !pw->output->enabled) {
+				sway_log(SWAY_DEBUG,
+						"Workspace output %s is disabled, trying another one",
+						pw->output->wlr_output->name);
+				output = NULL;
+			}
+
+			ws = workspace_create(output, pw->workspace);
+		}
+
+		pid_workspace_destroy(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;
+	wl_list_remove(&pw->output_destroy.link);
+	wl_list_init(&pw->output_destroy.link);
+}
+
+void root_record_workspace_pid(pid_t pid) {
+	sway_log(SWAY_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();
+	struct sway_workspace *ws = seat_get_focused_workspace(seat);
+	if (!ws) {
+		sway_log(SWAY_DEBUG, "Bailing out, no workspace");
+		return;
+	}
+	struct sway_output *output = ws->output;
+	if (!output) {
+		sway_log(SWAY_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) {
+			pid_workspace_destroy(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->wlr_output->events.destroy, &pw->output_destroy);
+	wl_list_insert(&pid_workspaces, &pw->link);
+}
+
+void root_remove_workspace_pid(pid_t pid) {
+	if (!pid_workspaces.prev || !pid_workspaces.next) {
+		return;
+	}
+
+	struct pid_workspace *pw, *tmp;
+	wl_list_for_each_safe(pw, tmp, &pid_workspaces, link) {
+		if (pid == pw->pid) {
+			pid_workspace_destroy(pw);
+			return;
+		}
+	}
+}
+
+void root_rename_pid_workspaces(const char *old_name, const char *new_name) {
+	if (!pid_workspaces.prev && !pid_workspaces.next) {
+		wl_list_init(&pid_workspaces);
+	}
+
+	struct pid_workspace *pw = NULL;
+	wl_list_for_each(pw, &pid_workspaces, link) {
+		if (strcmp(pw->workspace, old_name) == 0) {
+			free(pw->workspace);
+			pw->workspace = strdup(new_name);
+		}
+	}
+}

sway/meson.build

@@ -21,6 +21,7 @@ sway_sources = files(
 	'desktop/surface.c',
 	'desktop/transaction.c',
 	'desktop/xdg_shell.c',
+	'desktop/launcher.c',
 
 	'input/input-manager.c',
 	'input/cursor.c',