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XSetErrorHandler(3) XLIB FUNCTIONS XSetErrorHandler(3)
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 condi-
tion 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 dis-
play 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 sup-
plied 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 mes-
sage) 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 encod-
ing 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(3X11), XSynchronize(3X11)
Xlib - C Language X Interface
X Version 11 libX11 1.2.1 XSetErrorHandler(3) |
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