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 1.8.10 XAddConnectionWatch(3)