gri3-wm/libi3/root_atom_contents.c

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/*
* vim:ts=4:sw=4:expandtab
*
* i3 - an improved dynamic tiling window manager
* © 2009-2011 Michael Stapelberg and contributors (see also: LICENSE)
*
*/
#include <stdio.h>
#include <string.h>
#include <stdbool.h>
#include <limits.h>
#include <xcb/xcb.h>
#include <xcb/xcb_aux.h>
#include "libi3.h"
/*
* Try to get the contents of the given atom (for example I3_SOCKET_PATH) from
* the X11 root window and return NULL if it doesnt work.
*
* The memory for the contents is dynamically allocated and has to be
* free()d by the caller.
*
*/
char *root_atom_contents(const char *atomname) {
xcb_connection_t *conn;
xcb_intern_atom_cookie_t atom_cookie;
xcb_intern_atom_reply_t *atom_reply;
int screen;
char *content;
if ((conn = xcb_connect(NULL, &screen)) == NULL ||
xcb_connection_has_error(conn))
return NULL;
atom_cookie = xcb_intern_atom(conn, 0, strlen(atomname), atomname);
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 (prop_reply->type == XCB_ATOM_CARDINAL) {
/* We treat a CARDINAL as a >= 32-bit unsigned int. The only CARDINAL
* we query is I3_PID, which is 32-bit. */
if (asprintf(&content, "%u", *((unsigned int*)xcb_get_property_value(prop_reply))) == -1)
return NULL;
} else {
if (asprintf(&content, "%.*s", xcb_get_property_value_length(prop_reply),
(char*)xcb_get_property_value(prop_reply)) == -1)
return NULL;
}
xcb_disconnect(conn);
return content;
}