XSetErrorHandler(3X11) MIT X11R4 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, 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.
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. 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 supplied 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 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
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 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 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(3X11), XSynchronize(3X11)
X Window System: The Complete Reference, Second Edition, Robert W. Scheifler and James Gettys
XSetErrorHandler(3X11)