XSetIOErrorHandler(3)

1XSetErrorHandler(3)             XLIB FUNCTIONS             XSetErrorHandler(3)
2
3
4

NAME

6       XSetErrorHandler,   XGetErrorText,   XDisplayName,  XSetIOErrorHandler,
7       XGetErrorDatabaseText - default error handlers
8

SYNTAX

10       int (*XSetErrorHandler(int (*handler)(Display *, XErrorEvent *)))();
11
12       int XGetErrorText(Display *display, int code, char *buffer_return,  int
13              length);
14
15       char *XDisplayName(_Xconst char *string);
16
17       int (*XSetIOErrorHandler(int (*handler)(Display *)))();
18
19       int XGetErrorDatabaseText(Display *display, _Xconst char *name, _Xconst
20              char  *message,  _Xconst  char   *default_string,   char   *buf‐
21              fer_return, int length);
22

ARGUMENTS

24       buffer_return
25                 Returns the error description.
26
27       code      Specifies  the  error  code  for  which  you want to obtain a
28                 description.
29
30       default_string
31                 Specifies the default error message if none is found  in  the
32                 database.
33
34       display   Specifies the connection to the X server.
35
36       handler   Specifies the program's supplied error handler.
37
38       length    Specifies the size of the buffer.
39
40       message   Specifies the type of the error message.
41
42       name      Specifies the name of the application.
43
44       string    Specifies the character string.
45

DESCRIPTION

47       Xlib  generally  calls the program's supplied error handler whenever an
48       error is received.  It is not called on BadName errors  from  OpenFont,
49       LookupColor,  or AllocNamedColor protocol requests or on BadFont errors
50       from  a  QueryFont  protocol  request.   These  errors  generally   are
51       reflected  back  to  the  program  through  the  procedural  interface.
52       Because this condition is not assumed to be fatal, it is acceptable for
53       your  error handler to return; the returned value is ignored.  However,
54       the error handler should not call  any  functions  (directly  or  indi‐
55       rectly)  on  the  display  that will generate protocol requests or that
56       will look for input events.  The previous error handler is returned.
57
58       The XGetErrorText function copies a null-terminated  string  describing
59       the  specified error code into the specified buffer.  The returned text
60       is in the encoding of the current locale.  It is recommended  that  you
61       use  this function to obtain an error description because extensions to
62       Xlib may define their own error codes and error strings.
63
64       The  XDisplayName  function  returns  the  name  of  the  display  that
65       XOpenDisplay  would  attempt  to  use.   If a NULL string is specified,
66       XDisplayName looks in the environment for the display and  returns  the
67       display  name  that  XOpenDisplay  would attempt to use.  This makes it
68       easier to report to  the  user  precisely  which  display  the  program
69       attempted to open when the initial connection attempt failed.
70
71       The  XSetIOErrorHandler  sets  the fatal I/O error handler.  Xlib calls
72       the program's supplied error handler if any sort of system  call  error
73       occurs  (for  example, the connection to the server was lost).  This is
74       assumed to be a fatal condition, and  the  called  routine  should  not
75       return.   If  the  I/O  error  handler  does return, the client process
76       exits.
77
78       Note that the previous error handler is returned.
79
80       The XGetErrorDatabaseText function returns  a  null-terminated  message
81       (or  the  default  message) from the error message database.  Xlib uses
82       this function internally to look up its error messages.   The  text  in
83       the  default_string  argument  is  assumed to be in the encoding of the
84       current locale, and the text stored in the buffer_return argument is in
85       the encoding of the current locale.
86
87       The  name  argument  should  generally be the name of your application.
88       The message argument should indicate which type of  error  message  you
89       want.   If  the name and message are not in the Host Portable Character
90       Encoding, the result is implementation-dependent.  Xlib uses three pre‐
91       defined  “application  names” to report errors.  In these names, upper‐
92       case and lowercase matter.
93
94       XProtoError
95                 The protocol error number is used as a string for the message
96                 argument.
97
98       XlibMessage
99                 These are the message strings that are used internally by the
100                 library.
101
102       XRequest  For a core protocol request, the major request protocol  num‐
103                 ber  is  used  for  the  message  argument.  For an extension
104                 request, the extension name (as given by InitExtension)  fol‐
105                 lowed  by  a period (.) and the minor request protocol number
106                 is used for the message argument.  If no string is  found  in
107                 the  error  database,  the  default_string is returned to the
108                 buffer argument.
109

NAME

SYNTAX

ARGUMENTS

DESCRIPTION

SEE ALSO