Xlib Reference Manual for Version 11 of the X Window System

B

Error Messages and Protocol Requests

This appendix contains two tables: Table B-1 describes the standard error codes (the error_code member of XErrorEvent) and what causes them, and Table B-2 describes the mapping between protocol requests and Xlib functions. Each reference page in this volume describes in more detail the errors that may occur because of that Xlib routine. Volume One, Chapter 3, Basic Window Program, describes the handling of errors in general.

A protocol request is the actual network message that is sent from Xlib to the server. Many convenience functions are provided in Xlib to make programs easier to write and more readable. When any one of several convenience routines is called it will be translated into one type of protocol request. For example, XMoveWindow and XResizeWindow are convenience routines for the more general XConfigureWindow. Both of these Xlib routines use the protocol request X_ConfigureWindow. The protocol request that causes an error, along with other information about the error is printed to the standard error output by the default error handlers. In order to find out where in your code the error ocurred, you will need to know what Xlib function to look for. Use Table B-2 to find this function.

Xlib functions that do not appear in Table B-2 do not generate protocol requests. They perform their function without affecting the display and without requiring information from the server. If errors can occur in them, the errors are reported in ...