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X11R7.4 - man page for xdisplayname (x11r4 section 3)

XSetErrorHandler(3)			  XLIB FUNCTIONS		      XSetErrorHandler(3)

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

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

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

       char *XDisplayName(char *string);

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

       int XGetErrorDatabaseText(Display *display, char *name, char *message, 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 description.

       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 reflected back to the program through the procedural interface.  Because this condi-
       tion 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 dis-
       play 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 attempted to open when
       the initial connection attempt failed.

       The XSetIOErrorHandler sets the fatal I/O error handler.  Xlib calls the program's sup-
       plied 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 not return.  If the I/O error handler does return, the client process exits.

       Note that the previous error handler is returned.

       The XGetErrorDatabaseText function returns a null-terminated message (or the default mes-
       sage) 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 encod-
       ing 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 ``application names'' to report errors.  In these names, uppercase 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 number is used for the
		 message argument.  For an extension request, the extension name (as given by
		 InitExtension) followed 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(3X11), XSynchronize(3X11)
       Xlib - C Language X Interface

X Version 11				   libX11 1.2.1 		      XSetErrorHandler(3)


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