SdsSetWatch - Set a watch routine to watch for events on a given SDS ID.

Function

Set a watch routine to watch for events on a given SDS ID.

Description

This feature is still somewhat experimental. It provides the ablity to watch certian happenings within SDS for a given SDS ID. For example, if a given SDS ID is being free-ed incorrectly - often caused by a double free,. then you can specify the SDS ID number to watch and arrange for the specified function to be invoked when that ID is free-ed.

You specify the ID, a routine to be invoked and the client data item.

Currently - only SdsFreeId() is watched and the "reserved" item in the call back will always be zero when invoked from SdsFreeId(). It will be some other value if this feature is extended and it is invoked from elsewhere.

Language

Declaration

void SdsSetWatch(SdsIdType id, watchRoutine, clientData, oldId, oldWatchRoutine, oldClientData, status)

Parameters

(">" input, "!" modified, "W" workspace, "<" output)

>	id	SdsIdType	Identifier to be watched. If 0, then cancel watching.
>	watchRoutine	SdsWatchRoutineType	The routine to be invoked when the watch is triggered. If not specified, then a message is written to stdout.
>	clientData	void `*`	Passed through to watchRoutine as its client data item.
<	oldId	SdsIdType `*`	If non-null, the previous id being watched is returned here. Zero if there was none.
<	oldWatchRoutine	SdsWatchRoutineType `*`	If non-null, any old watch routine address is returned here.
<	oldClientData	void `**`	If non-null, any old watch routine client data is returned here.
`!`	status	StatusType*	Modified status.

Function Prototypes Used

typedef int (*SdsWatchRoutineType)(SdsIdType id, void * client_data, int event);

Parameters

(">" input, "!" modified, "W" workspace, "<" output)

>	id	SdsIdType	The `ID` which triggered the watch event.
>	client_data	void `*`	As supplied to SdsSetWatch().
>	event	int	Indicates the event type. The following event types are supported. Others might be added later and code should allow for this. `SDS_WATCH_EVENT_FREE` (0) => SdsFree.

`SDS_WATCH_EVENT_DELETE`	SdsDelete.
`SDS_WATCH_EVENT_READFREE`	SdsReadFree.
`SDS_WATCH_EVENT_NEW`	SdsNew.
`SDS_WATCH_EVENT_COPY`	SdsCopy.
`SDS_WATCH_EVENT_INSERT`	SdsInsert.
`SDS_WATCH_EVENT_INSERT_CELL`	SdsInsertCell.
`SDS_WATCH_EVENT_EXTRACT`	SdsExtract.
`SDS_WATCH_EVENT_RESIZE`	SdsResize

Support

Tony Farrell, {AAO}

Version date

14-Sep-2004

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For more information, contact tjf@aaoepp.aao.gov.au