xcb_query_extension(3) XCB Requests xcb_query_extension(3)
NAME
xcb_query_extension - check if extension is present
SYNOPSIS
#include <xcb/xproto.h>
Request function
xcb_query_extension_cookie_t xcb_query_extension(xcb_connection_t *conn,
uint16_t name_len, const char *name);
Reply datastructure
typedef struct xcb_query_extension_reply_t {
uint8_t response_type;
uint8_t pad0;
uint16_t sequence;
uint32_t length;
uint8_t present;
uint8_t major_opcode;
uint8_t first_event;
uint8_t first_error;
} xcb_query_extension_reply_t;
Reply function
xcb_query_extension_reply_t
*xcb_query_extension_reply(xcb_connection_t *conn,
xcb_query_extension_cookie_t cookie, xcb_generic_error_t **e);
REQUEST ARGUMENTS
conn The XCB connection to X11.
name_len The length of name in bytes.
name The name of the extension to query, for example "RANDR". This
is case sensitive!
REPLY FIELDS
response_type
The type of this reply, in this case XCB_QUERY_EXTENSION. This
field is also present in the xcb_generic_reply_t and can be
used to tell replies apart from each other.
sequence The sequence number of the last request processed by the X11
server.
length The length of the reply, in words (a word is 4 bytes).
present Whether the extension is present on this X11 server.
major_opcode
The major opcode for requests.
first_event
The first event code, if any.
first_error
The first error code, if any.
DESCRIPTION
Determines if the specified extension is present on this X11 server.
Every extension has a unique major_opcode to identify requests, the mi-
nor opcodes and request formats are extension-specific. If the extension
provides events and errors, the first_event and first_error fields in
the reply are set accordingly.
There should rarely be a need to use this request directly, XCB provides
the xcb_get_extension_data function instead.
RETURN VALUE
Returns an xcb_query_extension_cookie_t. Errors have to be handled when
calling the reply function xcb_query_extension_reply.
If you want to handle errors in the event loop instead, use
xcb_query_extension_unchecked. See xcb-requests(3) for details.
ERRORS
This request does never generate any errors.
SEE ALSO
xcb-requests(3), xcb_get_extension_data(3), xdpyinfo(1)
AUTHOR
Generated from xproto.xml. Contact xcb@lists.freedesktop.org for correc-
tions and improvements.
X Version 11 libxcb 1.17.0 xcb_query_extension(3)
Generated by dwww version 1.16 on Sat Oct 3 07:34:52 CEST 2026.