182 lines
6.9 KiB
Groff
182 lines
6.9 KiB
Groff
.\" Copyright \(co 1985, 1986, 1987, 1988, 1989, 1990, 1991, 1994, 1996 X Consortium
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.\"
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.\" Permission is hereby granted, free of charge, to any person obtaining
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.\" a copy of this software and associated documentation files (the
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.\" "Software"), to deal in the Software without restriction, including
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.\" without limitation the rights to use, copy, modify, merge, publish,
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.\" distribute, sublicense, and/or sell copies of the Software, and to
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.\" permit persons to whom the Software is furnished to do so, subject to
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.\" the following conditions:
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.\"
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.\" The above copyright notice and this permission notice shall be included
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.\" in all copies or substantial portions of the Software.
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.\"
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.\" THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
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.\" OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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.\" MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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.\" IN NO EVENT SHALL THE X CONSORTIUM BE LIABLE FOR ANY CLAIM, DAMAGES OR
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.\" OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
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.\" ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
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.\" OTHER DEALINGS IN THE SOFTWARE.
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.\"
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.\" Except as contained in this notice, the name of the X Consortium shall
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.\" not be used in advertising or otherwise to promote the sale, use or
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.\" other dealings in this Software without prior written authorization
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.\" from the X Consortium.
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.\"
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.\" Copyright \(co 1985, 1986, 1987, 1988, 1989, 1990, 1991 by
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.\" Digital Equipment Corporation
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.\"
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.\" Portions Copyright \(co 1990, 1991 by
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.\" Tektronix, Inc.
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.\"
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.\" Permission to use, copy, modify and distribute this documentation for
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.\" any purpose and without fee is hereby granted, provided that the above
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.\" copyright notice appears in all copies and that both that copyright notice
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.\" and this permission notice appear in all copies, and that the names of
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.\" Digital and Tektronix not be used in in advertising or publicity pertaining
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.\" to this documentation without specific, written prior permission.
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.\" Digital and Tektronix makes no representations about the suitability
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.\" of this documentation for any purpose.
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.\" It is provided "as is" without express or implied warranty.
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.\"
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.\"
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.ds xT X Toolkit Intrinsics \- C Language Interface
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.ds xW Athena X Widgets \- C Language X Toolkit Interface
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.ds xL Xlib \- C Language X Interface
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.ds xC Inter-Client Communication Conventions Manual
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.TH XSetErrorHandler __libmansuffix__ __xorgversion__ "XLIB FUNCTIONS"
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.SH NAME
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XSetErrorHandler, XGetErrorText, XDisplayName, XSetIOErrorHandler, XGetErrorDatabaseText \- default error handlers
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.SH SYNTAX
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.HP
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int (*XSetErrorHandler\^(\^int (\^*\^\fIhandler\fP\^)\^(Display *, XErrorEvent
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*)\^)\^)\^(\^);
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.HP
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int XGetErrorText\^(\^Display *\fIdisplay\fP\^, int \fIcode\fP\^, char
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*\fIbuffer_return\fP\^, int \fIlength\fP\^);
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.HP
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char *XDisplayName\^(\^char *\fIstring\fP\^);
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.HP
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int (*XSetIOErrorHandler\^(\^int (\^*\^\fIhandler\fP\^)(Display
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*)\^)\^)\^(\^);
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.HP
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int XGetErrorDatabaseText\^(\^Display *\fIdisplay\fP\^, char *\fIname\fP, char
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*\fImessage\fP\^, char *\fIdefault_string\fP\^, char *\fIbuffer_return\fP\^,
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int \fIlength\fP\^);
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.SH ARGUMENTS
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.IP \fIbuffer_return\fP 1i
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Returns the error description.
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.IP \fIcode\fP 1i
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Specifies the error code for which you want to obtain a description.
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.IP \fIdefault_string\fP 1i
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Specifies the default error message if none is found in the database.
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.IP \fIdisplay\fP 1i
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Specifies the connection to the X server.
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.IP \fIhandler\fP 1i
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Specifies the program's supplied error handler.
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.IP \fIlength\fP 1i
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Specifies the size of the buffer.
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.IP \fImessage\fP 1i
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Specifies the type of the error message.
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.IP \fIname\fP 1i
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Specifies the name of the application.
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.IP \fIstring\fP 1i
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Specifies the character string.
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.SH DESCRIPTION
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Xlib generally calls the program's
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supplied error handler whenever an error is received.
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It is not called on
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.B BadName
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errors from
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.BR OpenFont ,
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.BR LookupColor ,
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or
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.B AllocNamedColor
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protocol requests or on
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.B BadFont
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errors from a
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.B QueryFont
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protocol request.
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These errors generally are reflected back to the program through the
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procedural interface.
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Because this condition is not assumed to be fatal,
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it is acceptable for your error handler to return;
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the returned value is ignored.
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However, the error handler should not
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call any functions (directly or indirectly) on the display
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that will generate protocol requests or that will look for input events.
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The previous error handler is returned.
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.LP
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The
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.B XGetErrorText
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function copies a null-terminated string describing the specified error code
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into the specified buffer.
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The returned text is in the encoding of the current locale.
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It is recommended that you use this function to obtain an error description
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because extensions to Xlib may define their own error codes
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and error strings.
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.LP
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The
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.B XDisplayName
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function returns the name of the display that
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.B XOpenDisplay
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would attempt to use.
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If a NULL string is specified,
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.B XDisplayName
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looks in the environment for the display and returns the display name that
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.B XOpenDisplay
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would attempt to use.
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This makes it easier to report to the user precisely which display the
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program attempted to open when the initial connection attempt failed.
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.LP
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The
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.B XSetIOErrorHandler
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sets the fatal I/O error handler.
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Xlib calls the program's supplied error handler if any sort of system call
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error occurs (for example, the connection to the server was lost).
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This is assumed to be a fatal condition,
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and the called routine should not return.
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If the I/O error handler does return,
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the client process exits.
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.LP
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Note that the previous error handler is returned.
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.LP
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The
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.B XGetErrorDatabaseText
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function returns a null-terminated message
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(or the default message) from the error message
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database.
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Xlib uses this function internally to look up its error messages.
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The text in the default_string argument is assumed
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to be in the encoding of the current locale,
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and the text stored in the buffer_return argument
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is in the encoding of the current locale.
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.LP
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The name argument should generally be the name of your application.
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The message argument should indicate which type of error message you want.
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If the name and message are not in the Host Portable Character Encoding,
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the result is implementation-dependent.
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Xlib uses three predefined \*(lqapplication names\*(rq to report errors.
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In these names,
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uppercase and lowercase matter.
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.IP XProtoError 1i
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The protocol error number is used as a string for the message argument.
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.IP XlibMessage 1i
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These are the message strings that are used internally by the library.
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.IP XRequest 1i
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For a core protocol request,
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the major request protocol number is used for the message argument.
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For an extension request,
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the extension name (as given by
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.BR InitExtension )
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followed by a period (\.) and the minor request protocol number
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is used for the message argument.
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If no string is found in the error database,
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the default_string is returned to the buffer argument.
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.SH "SEE ALSO"
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XOpenDisplay(__libmansuffix__),
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XSynchronize(__libmansuffix__)
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.br
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\fI\*(xL\fP
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