1XSetErrorHandler(3)             XLIB FUNCTIONS             XSetErrorHandler(3)
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NAME

6       XSetErrorHandler, XGetErrorText, XDisplayName, XSetIOErrorHandler,
7       XGetErrorDatabaseText - default error handlers
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SYNTAX

10       int (*XSetErrorHandler(int (*handler)(Display *, XErrorEvent *)))();
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12       int XGetErrorText(Display *display, int code, char *buffer_return, int
13              length);
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15       char *XDisplayName(char *string);
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17       int (*XSetIOErrorHandler(int (*handler)(Display *)))();
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19       int XGetErrorDatabaseText(Display *display, char *name, char *message,
20              char *default_string, char *buffer_return, int length);
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ARGUMENTS

23       buffer_return
24                 Returns the error description.
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26       code      Specifies the error code for which you want to obtain a
27                 description.
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29       default_string
30                 Specifies the default error message if none is found in the
31                 database.
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33       display   Specifies the connection to the X server.
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35       handler   Specifies the program's supplied error handler.
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37       length    Specifies the size of the buffer.
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39       message   Specifies the type of the error message.
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41       name      Specifies the name of the application.
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43       string    Specifies the character string.
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DESCRIPTION

46       Xlib generally calls the program's supplied error handler whenever an
47       error is received.  It is not called on BadName errors from OpenFont,
48       LookupColor, or AllocNamedColor protocol requests or on BadFont errors
49       from a QueryFont protocol request.  These errors generally are
50       reflected back to the program through the procedural interface.
51       Because this condition is not assumed to be fatal, it is acceptable for
52       your error handler to return; the returned value is ignored.  However,
53       the error handler should not call any functions (directly or indi‐
54       rectly) on the display that will generate protocol requests or that
55       will look for input events.  The previous error handler is returned.
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57       The XGetErrorText function copies a null-terminated string describing
58       the specified error code into the specified buffer.  The returned text
59       is in the encoding of the current locale.  It is recommended that you
60       use this function to obtain an error description because extensions to
61       Xlib may define their own error codes and error strings.
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63       The XDisplayName function returns the name of the display that
64       XOpenDisplay would attempt to use.  If a NULL string is specified,
65       XDisplayName looks in the environment for the display and returns the
66       display name that XOpenDisplay would attempt to use.  This makes it
67       easier to report to the user precisely which display the program
68       attempted to open when the initial connection attempt failed.
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70       The XSetIOErrorHandler sets the fatal I/O error handler.  Xlib calls
71       the program's supplied error handler if any sort of system call error
72       occurs (for example, the connection to the server was lost).  This is
73       assumed to be a fatal condition, and the called routine should not
74       return.  If the I/O error handler does return, the client process
75       exits.
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77       Note that the previous error handler is returned.
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79       The XGetErrorDatabaseText function returns a null-terminated message
80       (or the default message) from the error message database.  Xlib uses
81       this function internally to look up its error messages.  The text in
82       the default_string argument is assumed to be in the encoding of the
83       current locale, and the text stored in the buffer_return argument is in
84       the encoding of the current locale.
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86       The name argument should generally be the name of your application.
87       The message argument should indicate which type of error message you
88       want.  If the name and message are not in the Host Portable Character
89       Encoding, the result is implementation-dependent.  Xlib uses three pre‐
90       defined ``application names'' to report errors.  In these names, upper‐
91       case and lowercase matter.
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93       XProtoError
94                 The protocol error number is used as a string for the message
95                 argument.
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97       XlibMessage
98                 These are the message strings that are used internally by the
99                 library.
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101       XRequest  For a core protocol request, the major request protocol num‐
102                 ber is used for the message argument.  For an extension
103                 request, the extension name (as given by InitExtension) fol‐
104                 lowed by a period (.) and the minor request protocol number
105                 is used for the message argument.  If no string is found in
106                 the error database, the default_string is returned to the
107                 buffer argument.
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SEE ALSO

110       XOpenDisplay(3), XSynchronize(3)
111       Xlib - C Language X Interface
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115X Version 11                     libX11 1.6.4              XSetErrorHandler(3)
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