NAME

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

SYNTAX

XSetErrorHandler(handler)
      int (*handler)();

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

char *XDisplayName(string)
      char *string;

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

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 XWIN 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.

XWIN 3.0               Last change: 9/1/88                 .ie t

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 proto-
col 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 con-
dition 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 condi-
tion, 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-based 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

XWIN 3.0 Last change: 9/1/88 .ie t 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

XWIN 3.0               Last change: 9/1/88                 .ie t

XWIN 3.0               Last change: 9/1/88                 .ie t