NAME

       XSetErrorHandler, XGetErrorText, XDisplayName, XSetIOErrorHandler, XSetIOErrorExitHandler,
       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 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
       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 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  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 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 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(3), XSynchronize(3)
       Xlib - C Language X Interface