XAddConnectionWatch(3) XLIB FUNCTIONS XAddConnectionWatch(3)
XAddConnectionWatch, XRemoveConnectionWatch, XProcessInternalConnection, XInternalConnec-
tionNumbers - handle Xlib internal connections
typedef void (*XConnectionWatchProc)(Display *display, XPointer client_data, int fd, Bool
opening, XPointer *watch_data);
Status XAddConnectionWatch(Display *display, XWatchProc procedure, XPointer client_data);
Status XRemoveConnectionWatch(Display *display, XWatchProc procedure, XPointer
void XProcessInternalConnection(Display *display, int fd);
Status XInternalConnectionNumbers(Display *display, int **fd_return, int *count_return);
Specifies the additional client data.
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.
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
indicating 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 connec-
tions already exist, the registered procedure will immediately be called for each of them,
before XAddConnectionWatch returns. XAddConnectionWatch returns a nonzero status if the
procedure is successfully 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 connections 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 pro-
cedure. The client_data must match the client_data used when the procedure was initially
The XProcessInternalConnection function processes input available on an internal connec-
tion. 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; oth-
erwise, the effect is not defined.
The XInternalConnectionNumbers function returns a list of the file descriptors 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 successfully allocated; otherwise, it returns zero.
Xlib - C Language X Interface
X Version 11 libX11 1.2.1 XAddConnectionWatch(3)