+/*
+ * vim:ts=4:sw=4:expandtab
+ *
+ * i3 - an improved dynamic tiling window manager
+ *
+ * © 2009-2011 Michael Stapelberg and contributors
+ *
+ * See file LICENSE for license information.
+ *
+ */
+#include <stdio.h>
+#include <string.h>
+#include <stdbool.h>
+#include <limits.h>
+
+#include <xcb/xcb.h>
+#include <xcb/xcb_aux.h>
+
+/*
+ * Try to get the socket path from X11 and return NULL if it doesn’t work.
+ *
+ * The memory for the socket path is dynamically allocated and has to be
+ * free()d by the caller.
+ *
+ */
+char *socket_path_from_x11() {
+ xcb_connection_t *conn;
+ xcb_intern_atom_cookie_t atom_cookie;
+ xcb_intern_atom_reply_t *atom_reply;
+ int screen;
+ char *socket_path;
+
+ if ((conn = xcb_connect(NULL, &screen)) == NULL ||
+ xcb_connection_has_error(conn))
+ return NULL;
+
+ atom_cookie = xcb_intern_atom(conn, 0, strlen("I3_SOCKET_PATH"), "I3_SOCKET_PATH");
+
+ xcb_screen_t *root_screen = xcb_aux_get_screen(conn, screen);
+ xcb_window_t root = root_screen->root;
+
+ atom_reply = xcb_intern_atom_reply(conn, atom_cookie, NULL);
+ if (atom_reply == NULL)
+ return NULL;
+
+ xcb_get_property_cookie_t prop_cookie;
+ xcb_get_property_reply_t *prop_reply;
+ prop_cookie = xcb_get_property_unchecked(conn, false, root, atom_reply->atom,
+ XCB_GET_PROPERTY_TYPE_ANY, 0, PATH_MAX);
+ prop_reply = xcb_get_property_reply(conn, prop_cookie, NULL);
+ if (prop_reply == NULL || xcb_get_property_value_length(prop_reply) == 0)
+ return NULL;
+ if (asprintf(&socket_path, "%.*s", xcb_get_property_value_length(prop_reply),
+ (char*)xcb_get_property_value(prop_reply)) == -1)
+ return NULL;
+ xcb_disconnect(conn);
+ return socket_path;
+}
+