Xlib Reference Manual for Version 11 of the X Window System

B

Error Messages and Protocol Requests

This appendix contains two tables: Table B-1 describes the standard error codes (the error_code member of XErrorEvent) and what causes them, and Table B-2 describes the mapping between protocol requests and Xlib functions. Each reference page in this volume describes in more detail the errors that may occur because of that Xlib routine. Volume One, Chapter 3, Basic Window Program, describes the handling of errors in general.

A protocol request is the actual network message that is sent from Xlib to the server. Many convenience functions are provided in Xlib to make programs easier to write and more readable. When any one of several convenience routines is called it will be translated into one type of protocol request. For example, XMoveWindow and XResizeWindow are convenience routines for the more general XConfigureWindow. Both of these Xlib routines use the protocol request X_ConfigureWindow. The protocol request that causes an error, along with other information about the error is printed to the standard error output by the default error handlers. In order to find out where in your code the error ocurred, you will need to know what Xlib function to look for. Use Table B-2 to find this function.

Xlib functions that do not appear in Table B-2 do not generate protocol requests. They perform their function without affecting the display and without requiring information from the server. If errors can occur in them, the errors are reported in the returned value.

Table B-1. Error Messages

Error Codes	Possible Cause
BadAccess	Client attempted to grab a key/button combination that is already grabbed by another client. Client attempted to free a colormap entry that is not allocated by the client. Client attempted to store into a read-only colormap entry. Client attempted to modify the access control list from other than the local (or otherwise authorized) host. Client attempted to select an event type that only one client can select at a time, when another client has already selected it.
BadAlloc	The server failed to allocate the requested resource.
BadAtom	A value for an Atom argument does not name a defined Atom.
BadColor	A value for a Colormap argument does not name a defined Colormap.
BadCursor	A value for a Cursor argument does not name a defined Cursor.
BadDrawable	A value for a Drawable argument does not name a defined Window or Pixmap.
BadFont	A value for a Font or GContext argument does not name a defined Font.
BadGC	A value for a GContext argument does not name a defined GContext.
BadIDChoice	The value chosen for a resource identifier is either not included in the range assigned to the client, or is already in use.
BadImplementation	The server does not implement some aspect of the request. A server that generates this error for a core request is deficient. Clients should be prepared to receive such errors and either handle or discard them.
BadLength	The length of a request is shorter or longer than that required to minimally contain the arguments. This usually indicates an internal Xlib error.
BadMatch	An InputOnly window is used as a Drawable. Some argument (or pair of arguments) has the correct type and range, but fails to “match” in some other way required by the request.
BadName	A font or color of the specified name does not exist.
BadPixmap	A value for a Pixmap argument does not name a defined Pixmap.
BadRequest	The major or minor opcode does not specify a valid request.
BadValue	Some numeric value falls outside the range of values accepted by the request. Unless a specific range is specified for an argument, the full range defined by the argument's type is accepted. Any argument defined as a set of alternatives can generate this error.
BadWindow	A value for a Window argument does not name a defined Window.

The BadAtom, BadColor, BadCursor, BadDrawable, BadFont, BadGC, BadPixmap, and Badwindow errors are also used when the argument type should be among a set of fixed alternatives (for example, a window ID, PointerRoot, or None) and some other constant or variable is used.

Table B-2. Xlib Functions and Protocol Requests

Protocol Request	Xlib Function
X_AllocColor	XAllocColor
X_AllocColorCells	XAllocColorCells
X_AllocColorPlanes	XAllocColorPlanes
X_AllocNamedColor	XAllocNamedColor
X_AllowEvents	XAllowEvents
X_Bell	XBell
X_ChangeActivePointerGrab	XChangeActivePointerGrab
X_ChangeGC	XChangeGC XSetArcMode XSetBackground XSetClipMask XSetClipOrigin XSetFillRule XSetFillStyle XSetFont XSetForeground XSetFunction XSetGraphicsExposures XSetLineAttributes XSetPlaneMask XSetState XSetStipple XSetSubwindowMode XSetTile XSetTSOrigin
X_ChangeHosts	XAddHost XAddHosts XRemoveHost XRemoveHosts
X_ChangeKeyboardControl	XAutoRepeatOff XAutoRepeatOn XChangeKeyboardControl
X_ChangeKeyboardMapping	XChangeKeyboardMapping
X_ChangePointerControl	XChangePointerControl
X_ChangeProperty	XChangeProperty XSetCommand XSetIconSizes XSetIconWindow XSetNormalHints XSetResizeHint XSetSizeHints XSetStandardProperties XSetWMHints XSetZoomHints XStoreBuffer XStoreBytes XStoreName
X_ChangeSaveSet	XAddToSaveSet XChangeSaveSet XRemoveFromSaveSet
X_ChangeWindow Attributes	XChangeWindowAttributes XDefineCursor XSelectInput XSetWindowBackground XSetWindowBackgroundPixmap XSetWindowBorder XSetWindowBorderPixmap XSetWindowColormap XUndefineCursor
X_CirculateWindow	XCirculateSubwindows XCirculateSubwindowsDown XCirculateSubwindowsUp
X_ClearArea	XClearArea XClearWindow
X_CloseFont	XFreeFont XUnloadFont
X_ConfigureWindow	XConfigureWindow XLowerWindow XMapRaised XMoveResizeWindow XMoveWindow XRaiseWindow XResizeWindow XRestackWindows XSetWindowBorderWidth
X_ConvertSelection	XConvertSelection
X_CopyArea	XCopyArea
X_CopyColormapAndFree	XCopyColormapAndFree
X_CopyGC	XCopyGC
X_CopyPlane	XCopyPlane
X_CreateColormap	XCreateColormap
X_CreateCursor	XCreatePixmapCursor
X_CreateGC	XCreateGC XOpenDisplay
X_CreateGlyphCursor	XCreateFontCursor XCreateGlyphCursor
X_CreatePixmap	XCreatePixmap
X_CreateWindow	XCreateSimpleWindow XCreateWindow
X_DeleteProperty	XDeleteProperty
X_DestroySubwindows	XDestroySubwindows
X_DestroyWindow	XDestroyWindow
X_FillPoly	XFillPolygon
X_ForceScreenSaver	XActivateScreenSaver XForceScreenSaver XResetScreensaver
X_FreeColormap	XFreeColormap
X_FreeColors	XFreeColors
X_FreeCursor	XFreeCursor
X_FreeGC	XFreeGC
X_FreePixmap	XFreePixmap
X_GetAtomName	XGetAtomName
X_GetFontPath	XGetFontPath
X_GetGeometry	XGetGeometry XGetWindowAttributes
X_GetImage	XGetImage
X_GetInputFocus	XGetInputFocus XSync
X_GetKeyboardControl	XGetKeyboardControl
X_GetKeyboardMapping	XGetKeyboardMapping
X_GetModifierMapping	XGetModifierMapping
X_GetMotionEvents	XGetMotionEvents
X_GetPointerControl	XGetPointerControl
X_GetPointerMapping	XGetPonterMapping
X_GetProperty	XClearIconWindow XFetchBytes XFetchName XGetIconSizes XGetIconWindow XGetNormalHints XGetSizeHints XGetWindowProperty XGetWMHints XGetZoomHints
X_GetScreenSaver	XGetScreensaver
X_GetSelectionOwner	XGetSelectionOwner
X_GetWindowAttributes	XGetWindowAttributes
X_GrabButton	XGrabButton
X_GrabKey	XGrabKey
X_GrabKeyboard	XGrabKeyboard
X_GrabPointer	XGrabPointer
X_GrabServer	XGrabServer
X_ImageText8	XDrawImagestring
X_ImageText16	XDrawImageString16
X_InstallColormap	XInstallColormap
X_InternAtom	XInternAtom
X_KillClient	XKillClient
X_ListExtensions	XListExtensions
X_ListFonts	XListFonts
X_ListFontsWithInfo	XListFontsWithInfo
X_ListHosts	XListHosts
X_ListInstalledColormaps	XListInstalledColormaps
X_ListProperties	XListProperties
X_LookupColor	XLookupColor XParseColor
X_MapSubwindows	XMapSubwindows
X_MapWindow	XMapRaised XMapWindow
X_NoOperation	XNoOp
X_OpenFont	XLoadFont XLoadQueryFont
X_PolyArc	XDrawArc XDrawArcs
X_PolyFillArc	XFillArc XFillArcs
X_PolyFillRectangle	XFillRectangle XFillRectangles
X_PolyLine	XDrawLines
X_PolyPoint	XDrawPoint XDrawPoints
X_PolyRectangle	XDrawRectangle XDrawRectangles
X_PolySegment	XDrawLine XDrawSegments
X_PolyText8	XDrawString XDrawText
X_PolyText16	XDrawString16 XDrawText16
X_PutImage	XPutImage
X_QueryBestSize	XQueryBestCursor XQueryBestSize XQueryBestStipple XQueryBestTile
X_QueryColors	XQueryColor XQueryColors
X_QueryExtension	XInitExtension XQueryExtension
X_QueryFont	XLoadQueryFont
X_QueryKeymap	XQueryKeymap
X_QueryPointer	XQueryPointer
X_QueryTextExtents	XQueryTextExtents XQueryTextExtents16
XQueryTree	XQueryTree
X_RecolorCursor	XRecolorCursor
X_ReparentWindow	XReparentWindow
X_RotateProperties	XRotateBuffers XRotateWindowProperties
X_SendEvent	XSendEvent
X_SetAccessControl	XDisableAccessControl XEnableAccessControl XSetAccessControl
X_SetClipRectangles	XSetClipRectangles
X_SetCloseDownMode	XSetCloseDownMode
X_SetDashes	XSetDashes
X_SetFontPath	XSetFontPath
X_SetInputFocus	XSetInputFocus
X_SetModifierMapping	XSetModifierMapping
X_SetPointerMapping	XSetPointerMapping
X_SetScreenSaver	XSetScreenSaver
X_SetSelectionOwner	XSetSelectionOwner
X_StoreColors	XStoreColor XStoreColors
X_StoreNamedColor	XStoreNamedColor
X_TranslateCoords	XTranslateCoordinates
X_UngrabButton	XUngrabButton
X_UngrabKey	XUngrabKey
X_UngrabKeyboard	XUngrabKeyboard
X_UngrabPointer	XUngrabPointer
X_UngrabServer	XUngrabServer
X_UninstallColormap	XUninstallColormap
X_UnmapSubwindows	XUnmapSubWindows
X_UnmapWindow	XUnmapWindow
X_WarpPointer	XWarpPointer