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XAddConnectionWatch(3)          XLIB FUNCTIONS          XAddConnectionWatch(3)


NAME

       XAddConnectionWatch, XRemoveConnectionWatch,
       XProcessInternalConnection, 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
              procedure, XPointer client_data);

       void XRemoveConnectionWatch(Display *display, XConnectionWatchProc
              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 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 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 allocated; otherwise, it returns zero.


SEE ALSO

       Xlib - C Language X Interface

X Version 11                     libX11 1.8.6           XAddConnectionWatch(3)

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