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Annotation of 43BSDTahoe/new/X/doc/Xlib/ch13a.t, revision 1.1

1.1     ! root        1: .NH
        !             2: Error Handling
        !             3: .XS
        !             4: Error Handling
        !             5: .XE
        !             6: .PP
        !             7: .IN "Error Handlers"
        !             8: There are two default error handlers in the library, one to handle
        !             9: typically fatal conditions (for example, the connection to a display
        !            10: server
        !            11: dying due to machine crash), and one to handle error events from X.
        !            12: These error handlers can be changed to user supplied routines if you
        !            13: prefer your own error handling, and can be changed as often as you like.
        !            14: If either of these routines are passed a NULL pointer, it will
        !            15: reinvoke the default handler.
        !            16: The default action of the  supplied routine is to exit.
        !            17: .PP
        !            18: .FD
        !            19: .IN "Definitions" "XIOErrorHandler"
        !            20: .IN "XIOErrorHandler"
        !            21: XIOErrorHandler( handler )
        !            22:        int handler(Display *);
        !            23: .FN
        !            24: .PP
        !            25: The program's
        !            26: supplied error handler will be called by Xlib if any sort of system call error
        !            27: occurs, e.g. the connection to the server was lost.
        !            28: This is assumed to
        !            29: be a fatal condition, i.e., the called routine should not return.
        !            30: If the IO error handler
        !            31: does return, the client process will exit.
        !            32: .PP
        !            33: .FD
        !            34: .IN "Definitions" "XErrorHandler"
        !            35: .IN "XErrorHandler"
        !            36: XErrorHandler( handler )
        !            37:        int handler(Display *, XErrorEvent *)
        !            38: .FN
        !            39: The program's
        !            40: supplied error hander will be called by Xlib whenever an \fIXError\fP event is
        !            41: received.
        !            42: This is not assumed to be a fatal condition, i.e., it is
        !            43: acceptable for this procedure to return.
        !            44: However, the error handler should NOT
        !            45: perform any operations (directly or indirectly) on the Display.
        !            46: The
        !            47: fields of the \fIXErrorEvent\fP passed to \fIXError\fP should be interpreted as follows:
        !            48: .sp
        !            49: .DS
        !            50: .TA .5i 2.5i
        !            51: .ta .5i 2.5i
        !            52: typedef struct _XErrorEvent {
        !            53:        long pad;
        !            54:        long serial;    /* serial number of failed request */
        !            55:        char error_code;        /* error code of failed request */
        !            56:        char request_code;      /* request code of failed request */
        !            57:        char func;      /* function field of failed request */
        !            58:        char pad_b7;
        !            59:        Window window;  /* Window of failed request */
        !            60:        long pad_l3;
        !            61:        long pad_l4;
        !            62: } XErrorEvent;
        !            63: .DE
        !            64: .IN "Data Structures" "XErrorEvent"
        !            65: .IN "Serial Number"
        !            66: .sp
        !            67: The serial number is the number of requests sent over the network connection
        !            68: since it was opened, starting from one; it is the number that was the
        !            69: value of \fIdpy->request\fP immediately after the failing call was made.  The
        !            70: request code is a protocol representation of the name of the procedure
        !            71: .IN "File" "<X/X.h>"
        !            72: that failed; these are defined in \fI<X/X.h>\fP.  The error code is one of
        !            73: the following, also defined in \fI<X/X.h>\fP:
        !            74: .IN "Error Numbers"
        !            75: .LP
        !            76: .TS
        !            77: center,box;
        !            78: lcl.
        !            79: BadRequest     1       bad request code
        !            80: BadValue       2       int parameter out of range
        !            81: BadWindow      3       parameter not a Window
        !            82: BadPixmap      4       parameter not a Pixmap
        !            83: BadBitmap      5       parameter not a Bitmap
        !            84: BadCursor      6       parameter not a Cursor
        !            85: BadFont        7       parameter not a Font
        !            86: BadMatch       8       parameter mismatch
        !            87: BadTile        9       Pixmap shape invalid for tiling
        !            88: BadGrab        10      mouse/button already grabbed
        !            89: BadAccess      11      access control violation
        !            90: BadAlloc       12      insufficient resources
        !            91: BadColor       13      no such color
        !            92: .TE
        !            93: It is recommended that \fIXError\fP use the following procedure for obtaining
        !            94: textual descriptions of errors:
        !            95: .FD
        !            96: .IN "Definitions" "XErrDescrip"
        !            97: .IN "XErrDescrip"
        !            98: char *XErrDescrip (code)
        !            99:        int code;
        !           100: .FN
        !           101: Returns a null-terminated string describing the specified error code.
        !           102: The string is static in Xlib and should not be modified or freed.

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