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XSetErrorHandler(3)		 XLIB FUNCTIONS 	     XSetErrorHandler(3)

NAME
     XSetErrorHandler,	XGetErrorText, XDisplayName, XSetIOErrorHandler, XSetIO-
     ErrorExitHandler, 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_return,
	    int length);

ARGUMENTS
     buffer_return
	       Returns the error description.

     code      Specifies the error code for which you want to obtain a	descrip-
	       tion.

     default_string
	       Specifies the default error message if none is found in the data-
	       base.

     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, Lookup-
     Color, or AllocNamedColor protocol requests or on	BadFont  errors  from  a
     QueryFont	protocol  request.  These errors generally are reflected 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 de-
     fine 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 XOpenDis-
     play would attempt to use.  This makes it easier to report to the user pre-
     cisely which display the program attempted to open when the initial connec-
     tion 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 XSetIOErrorExitHandler 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 func-
     tion internally to look up  its  error  messages.	 The  text  in	the  de-
     fault_string  argument  is assumed to be in the encoding of the current lo-
     cale, 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  predefined  "applica-
     tion names" to report errors.  In these names, uppercase and lowercase mat-
     ter.

     XProtoError
	       The protocol error number is used as a string for the message ar-
	       gument.

     XlibMessage
	       These are the message strings that are used internally by the li-
	       brary.

     XRequest  For a core protocol request, the major request protocol number is
	       used for the message argument.  For an extension request, the ex-
	       tension name (as given by InitExtension) followed by a period (.)
	       and the minor request protocol number is used for the message ar-
	       gument.	 If  no  string  is found in the error database, the de-
	       fault_string is returned to the buffer argument.

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

X Version 11			  libX11 1.8.13 	     XSetErrorHandler(3)

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