XSetErrorHandler(3X11)  COMMAND REFERENCE  XSetErrorHandler(3X11)



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

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

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

     char *XDisplayName(string)
           char *string;

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

     XGetErrorDatabaseText(display, name, message,
     default_string, buffer_return, length)
           Display *display;
           char *name, *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.




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XSetErrorHandler(3X11)  COMMAND REFERENCE  XSetErrorHandler(3X11)



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 condition is not assumed to be fatal, it is acceptable
     for your error handler to return.  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 XGetErrorText function copies a null-terminated string
     describing the specified error code into the specified
     buffer.  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 attempted 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 not return.  If the
     I/O error handler does return, the client process exits.

     The XGetErrorDatabaseText function returns a message (or the
     default message) from the error message database.  Xlib uses
     this function internally to look up its error messages.  On
     a UNIX* operating system, the error message database is
     /usr/lib/X11/XErrorDB.

     The name argument should generally be the name of your
     application.  The message argument should indicate which
     type of error message you want.  Xlib uses three predefined
     message types to report errors (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



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XSetErrorHandler(3X11)  COMMAND REFERENCE  XSetErrorHandler(3X11)



               internally by the library.

     XRequest  The major 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
     XSynchronize(3x11)
     Xlib - C Language X Interface

*UNIX is a registered trademark of AT&T.











































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