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 Michael Stapelberg and contributors (see also: LICENSE)
*
*/
#include "libi3.h"
#include <stdio.h>
#include <string.h>
#include <stdbool.h>
#include <limits.h>
#include <stdlib.h>
#include <math.h>
#include <xcb/xcb.h>
#include <xcb/xcb_aux.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.
*
* If the provided XCB connection is NULL, a new connection will be
* established.
*
* 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 *provided_conn, int screen) {
xcb_intern_atom_cookie_t atom_cookie;
xcb_intern_atom_reply_t *atom_reply;
char *content = NULL;
size_t content_max_words = 256;
xcb_connection_t *conn = provided_conn;
if (provided_conn == NULL &&
((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) {
goto out_conn;
}
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, content_max_words);
prop_reply = xcb_get_property_reply(conn, prop_cookie, NULL);
if (prop_reply == NULL) {
goto out_atom;
}
if (xcb_get_property_value_length(prop_reply) > 0 && prop_reply->bytes_after > 0) {
/* We received an incomplete value. Ask again but with a properly
* adjusted size. */
content_max_words += ceil(prop_reply->bytes_after / 4.0);
/* Repeat the request, with adjusted size */
free(prop_reply);
prop_cookie = xcb_get_property_unchecked(conn, false, root, atom_reply->atom,
XCB_GET_PROPERTY_TYPE_ANY, 0, content_max_words);
prop_reply = xcb_get_property_reply(conn, prop_cookie, NULL);
if (prop_reply == NULL) {
goto out_atom;
}
}
if (xcb_get_property_value_length(prop_reply) == 0) {
goto out;
}
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. */
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sasprintf(&content, "%u", *((unsigned int *)xcb_get_property_value(prop_reply)));
} else {
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sasprintf(&content, "%.*s", xcb_get_property_value_length(prop_reply),
(char *)xcb_get_property_value(prop_reply));
}
out:
free(prop_reply);
out_atom:
free(atom_reply);
out_conn:
if (provided_conn == NULL)
xcb_disconnect(conn);
return content;
}