XAddConnectionWatch(3) XLIB FUNCTIONS XAddConnectionWatch(3)
NAME
XAddConnectionWatch, XRemoveConnectionWatch, XProcessInternalConnec-
tion, XInternalConnectionNumbers - handle Xlib internal connections
SYNTAX
typedef void (*XConnectionWatchProc)(Display *display, XPointer
client_data, int fd, Bool opening, XPointer *watch_data);
Status XAddConnectionWatch(Display *display, XConnectionWatchProc pro-
cedure, XPointer client_data);
void XRemoveConnectionWatch(Display *display, XConnectionWatchProc pro-
cedure, XPointer client_data);
void XProcessInternalConnection(Display *display, int fd);
Status XInternalConnectionNumbers(Display *display, int **fd_return,
int *count_return);
ARGUMENTS
client_data
Specifies the additional client data.
count_return
Returns the number of file descriptors.
display Specifies the connection to the X server.
fd Specifies the file descriptor.
fd_return Returns the file descriptors.
procedure Specifies the procedure to be called.
DESCRIPTION
The XAddConnectionWatch function registers a procedure to be called
each time Xlib opens or closes an internal connection for the specified
display. The procedure is passed the display, the specified
client_data, the file descriptor for the connection, a Boolean indicat-
ing whether the connection is being opened or closed, and a pointer to
a location for private watch data. If opening is True, the procedure
can store a pointer to private data in the location pointed to by
watch_data; when the procedure is later called for this same connection
and opening is False, the location pointed to by watch_data will hold
this same private data pointer.
This function can be called at any time after a display is opened. If
internal connections already exist, the registered procedure will imme-
diately be called for each of them, before XAddConnectionWatch returns.
XAddConnectionWatch returns a nonzero status if the procedure is suc-
cessfully registered; otherwise, it returns zero.
The registered procedure should not call any Xlib functions. If the
procedure directly or indirectly causes the state of internal connec-
tions or watch procedures to change, the result is not defined. If
Xlib has been initialized for threads, the procedure is called with the
display locked and the result of a call by the procedure to any Xlib
function that locks the display is not defined unless the executing
thread has externally locked the display using XLockDisplay.
The XRemoveConnectionWatch function removes a previously registered
connection watch procedure. The client_data must match the client_data
used when the procedure was initially registered.
The XProcessInternalConnection function processes input available on an
internal connection. This function should be called for an internal
connection only after an operating system facility (for example, select
or poll) has indicated that input is available; otherwise, the effect
is not defined.
The XInternalConnectionNumbers function returns a list of the file de-
scriptors for all internal connections currently open for the specified
display. When the allocated list is no longer needed, free it by using
XFree. This functions returns a nonzero status if the list is success-
fully allocated; otherwise, it returns zero.
SEE ALSO
Xlib - C Language X Interface
X Version 11 libX11 1.8.4 XAddConnectionWatch(3)
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