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XSetErrorHandler(3)		XLIB FUNCTIONS		   XSetErrorHandler(3)

NAME
       XSetErrorHandler, XGetErrorText,	XDisplayName, XSetIOErrorHandler, XSe-
       tIOErrorExitHandler, XGetErrorDatabaseText - default error handlers

SYNTAX

       int (*XSetErrorHandler(int (*handler)(Display *,	XErrorEvent *)))();

       int  XGetErrorText(Display *display, int	code, char *buffer_return, int
	      length);

       char *XDisplayName(_Xconst char *string);

       int (*XSetIOErrorHandler(int (*handler)(Display *)))();

       void (*XSetIOErrorExitHandler(Display *display, void (*handler)(Display
	      *, void *), void *user_data))();

       int XGetErrorDatabaseText(Display *display, _Xconst char	*name, _Xconst
	      char *message, _Xconst char  *default_string,  char  *buffer_re-
	      turn, int	length);

ARGUMENTS
       buffer_return
		 Returns the error description.

       code	 Specifies  the	 error code for	which you want to obtain a de-
		 scription.

       default_string
		 Specifies the default error message if	none is	found  in  the
		 database.

       display	 Specifies the connection to the X server.

       handler	 Specifies the program's supplied error	handler.

       length	 Specifies the size of the buffer.

       message	 Specifies the type of the error message.

       name	 Specifies the name of the application.

       string	 Specifies the character string.

DESCRIPTION
       Xlib  generally	calls the program's supplied error handler whenever an
       error is	received.  It is not called on BadName errors  from  OpenFont,
       LookupColor,  or	AllocNamedColor	protocol requests or on	BadFont	errors
       from a QueryFont	protocol request.   These  errors  generally  are  re-
       flected	back to	the program through the	procedural interface.  Because
       this condition is not assumed to	be fatal, it is	 acceptable  for  your
       error  handler  to return; the returned value is	ignored.  However, the
       error handler should not	call any functions (directly or	indirectly) on
       the display that	will generate protocol requests	or that	will look  for
       input events.  The previous error handler is returned.

       The  XGetErrorText  function copies a null-terminated string describing
       the specified error code	into the specified buffer.  The	returned  text
       is  in  the encoding of the current locale.  It is recommended that you
       use this	function to obtain an error description	because	extensions  to
       Xlib may	define their own error codes and error strings.

       The  XDisplayName  function  returns  the  name	of  the	 display  that
       XOpenDisplay would attempt to use.  If  a  NULL	string	is  specified,
       XDisplayName  looks  in the environment for the display and returns the
       display name that XOpenDisplay would attempt to	use.   This  makes  it
       easier  to  report  to the user precisely which display the program at-
       tempted to open when the	initial	connection attempt failed.

       The XSetIOErrorHandler sets the fatal I/O error	handler.   Xlib	 calls
       the  program's  supplied	error handler if any sort of system call error
       occurs (for example, the	connection to the server was lost).   This  is
       assumed to be a fatal condition,	and the	called routine should normally
       not  return.   If the I/O error handler does return, the	client process
       exits by	default, this behavior may be altered with the	XSetIOErrorEx-
       itHandler function.

       Note that the previous error handler is returned.

       The  XGetErrorDatabaseText  function  returns a null-terminated message
       (or the default message)	from the error message	database.   Xlib  uses
       this  function  internally  to look up its error	messages.  The text in
       the default_string argument is assumed to be in	the  encoding  of  the
       current locale, and the text stored in the buffer_return	argument is in
       the encoding of the current locale.

       The  name  argument  should  generally be the name of your application.
       The message argument should indicate which type of  error  message  you
       want.   If  the name and	message	are not	in the Host Portable Character
       Encoding, the result is implementation-dependent.  Xlib uses three pre-
       defined "application names" to report errors.  In these	names,	upper-
       case and	lowercase matter.

       XProtoError
		 The protocol error number is used as a	string for the message
		 argument.

       XlibMessage
		 These are the message strings that are	used internally	by the
		 library.

       XRequest	 For  a	core protocol request, the major request protocol num-
		 ber is	used for the message argument.	For an	extension  re-
		 quest,	 the  extension	 name (as given	by InitExtension) fol-
		 lowed by a period (.) and the minor request  protocol	number
		 is  used  for the message argument.  If no string is found in
		 the error database, the default_string	 is  returned  to  the
		 buffer	argument.

SEE ALSO
       XOpenDisplay(3),	XSynchronize(3)
       Xlib - C	Language X Interface

X Version 11			 libX11	1.8.12		   XSetErrorHandler(3)

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