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
       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 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
       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