XAddConnectionWatch(3X11)XLIB FUNCTIONS XAddConnectionWatch(3X11)
NAME
XAddConnectionWatch, XRemoveConnectionWatch, XProcessInter-
nalConnection, 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, XWatchProc pro-
cedure, XPointer client_data);
Status XRemoveConnectionWatch(Display *display, XWatchProc
procedure, 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 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 connections already exist, the
registered procedure will immediately be called for each of
XFree86 Version 4.5.0 1
XAddConnectionWatch(3X11)XLIB FUNCTIONS XAddConnectionWatch(3X11)
them, before XAddConnectionWatch returns. XAddConnec-
tionWatch 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 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 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 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 allo-
cated; otherwise, it returns zero.
SEE ALSO
Xlib - C Language X Interface
XFree86 Version 4.5.0 2