XSetErrorHandler(3X11) X11R5 XSetErrorHandler(3X11)NAME
XSetErrorHandler, XGetErrorText, XDisplayName, XSetIOErrorHandler,
XGetErrorDatabaseText - default error handlers
SYNTAX
int (*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;
int (*XSetIOErrorHandler(handler))()
int (*handler)(Display *);
XGetErrorDatabaseText(display, name, message, default_string, buf‐
fer_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.
DESCRIPTION
Xlib generally calls the program's supplied error handler whenever an
error is received. It is not called on errors from or protocol
requests or on errors from a 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
previous error handler is returned.
The 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 function returns the name of the display that would attempt to use.
If a NULL string is specified, looks in the environment for the display
and returns the display name that 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 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 exam‐
ple, 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 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 default_string is assumed to be in the
encoding of the current locale. The buffer_return text 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 pre‐
defined ``application names'' 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 internally by the
library.
XRequest For a core protocol request, the major request protocol num‐
ber is used for the message argument. For an extension
request, the extension name (as given by followed by a period
(.) and the minor request protocol number is used for the
message argument. If no string is found in the error data‐
base, the default_string is returned to the buffer argument.
SEE ALSOXOpenDisplay(3X11), XSynchronize(3X11)
Xlib - C Language X Interface
XSetErrorHandler(3X11)