9.2 Copy Hook Handler Interface: ICopyHook

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Now that we are somewhat familiar with copy hook handlers, let's talk about ICopyHook . This interface is the only interface a copy hook handler needs to implement. It contains one method, CopyCallback . Don't let the simplicity fool you, though. Implementing a copy hook handler is much more difficult than it seems at first glance (as you will soon see). As Table 9.1 shows, ICopyHook contains one method called CopyCallback . This is the only method ever called on a copy hook handler.

Table9.1. ICopyHook

Method	Description
`CopyCallback`	Determines whether the shell will be allowed to move, copy, delete, or rename a folder or printer object.

The syntax of the CopyCallback method is as follows :

 UINT CopyCallback(     HWND   hwnd   ,     UINT   wFunc   ,     UINT   wFlags   ,     LPCSTR   pszSrcFile   ,     DWORD   dwSrcAttribs   ,     LPCSTR   pszDestFile   ,     DWORD dwDestAttribs    );

Table 9.2 lists the parameters that the shell passes to the copy hook handler and their meaning.

Table9.2. CopyCallback Parameters

Parameter	Datatype	Description
`hwnd`	`HWND`	Handle to a window that the copy hook handler should use to display any user -interface elements.
`wFunc`	`UINT`	Operation to be performed (see Table 9.3).
`wFlags`	`UINT`	This value can be ignored for copy hook handlers.
`pszSrcFile`	`LPCSTR/LPCWSTR`	Address of a string that contains the name of the source folder or printer.
`dwSrcAttribs`	`DWORD`	Attributes of the source folder or printer (see Table 9.3).
`pszDestFile`	`LPCSTR/LPCWSTR`	Address of a string that contains the name of the destination folder or printer.
`dwDestAttribs`	`DWORD`	Attributes of the source folder or printer. These can be any of the file attribute flags that begin with `FILE_ATTRIBUTE_*` and are available from the API Viewer.

Table9.3. wFunc Values

Name	Description
`FO_COPY`	Copy
`FO_MOVE`	Move
`FO_DELETE`	Delete
`FO_RENAME`	Rename

CopyCallback can return one of three values:

IDYES: The operation is allowed.
IDNO: Prevents the operation on this folder. The shell can continue with any other operations that are pending.
IDCANCEL: Prevents the current operation and cancels all pending operations.

The IDL listing for both ICopyHookA and ICopyHookW is shown in Example 9.1.

Example 9.1. ICopyHook Interface

 typedef enum { FO_MOVE   = 0x0001, FO_COPY   = 0x0002, FO_DELETE = 0x0003, FO_RENAME = 0x0004 } FO; [     uuid(000214EF-0000-0000-C000-000000000046),     helpstring("ICopyHookA Interface"),     odl ] interface ICopyHookA : IUnknown {     HRESULT CopyCallback([in] HWND hwnd,                           [in] UINT wFunc,                           [in] UINT wFlags,                           [in] LPCSTRVB pszSrcFile,                           [in] DWORD dwSrcAttribs,                          [in] LPCSTRVB pszDestFile,                           [in] DWORD dwDestAttribs); } [     uuid(000214FC-0000-0000-C000-000000000046),     helpstring("ICopyHookW Interface"),     odl ] interface ICopyHookW : IUnknown {     HRESULT CopyCallback([in] HWND hwnd,                           [in] UINT wFunc,                           [in] UINT wFlags,                           [in] LPCWSTRVB pszSrcFile,   [in] DWORD dwSrcAttribs,                          [in] LPCWSTRVB pszDestFile,                           [in] DWORD dwDestAttribs); }

only for RuBoard - do not distribute or recompile