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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, XWatchProc procedure,
              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 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
       descriptors for all internal connections currently open for the speci-
       fied 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 1.1.5           XAddConnectionWatch(3)