Hello all,
I'm trying to upgrade a VB6 project into VB.net, and the problem I had is in converting 'address of' to 'delegate'.
I had the error "Value of type 'DelegateIDccManSink_OnLogIpAddr' cannot be converted to 'integer'.",
when calling this line, ReplaceVtableEntry(.., .., callbackOnLogIpAddr).
I guess the problem is due to the VB6 expected a memory address, but the 'delegate' doesn't return an address.
Any ideas are appreciated.
- Public Delegate Function DelegateIDccManSink_OnLogIpAddr(ByVal this As KwyDccMan.IDccManSink, ByVal dwIpAddr As Integer) As Integer
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Public Sub DccManSinkInitialize(ByVal this As KwyDccMan.IDccManSink)
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Dim lObjAddress As Integer
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Dim callbackOnLogIpAddr As DelegateIDccManSink_OnLogIpAddr
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' Object Address
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lObjAddress = ObjPtr(this)
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callbackOnLogIpAddr = New DelegateIDccManSink_OnLogIpAddr(AddressOf IDccManSink_OnLogIpAddr)
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' Replace VTable Function Entries
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m_lFnOnLogIpAddr = ReplaceVtableEntry(lObjAddress, &H4S, callbackOnLogIpAddr)
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End Sub
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Private Function IDccManSink_OnLogIpAddr(ByVal this As KwyDccMan.IDccManSink, ByVal dwIpAddr As Integer) As Integer
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IDccManSink_OnLogIpAddr = SCDCallParams(ObjPtr(this), EDccManCallID.eCallIDSink_OnLogIpAddr, dwIpAddr)
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End Function
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' Put the function address (callback) directly into the object v-table
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Public Function ReplaceVtableEntry(ByVal lpObj As Integer, ByVal nEntry As Short, ByVal lpFunc As Integer) As Integer
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' lpObj - Pointer to object whose v-table will be modified
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' nEntry - Index of v-table entry to be modified
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' lpFunc - Function pointer of new v-table method
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Dim lpFuncOld As Integer, lpVTableHead As Integer, lpFuncTmp As Integer, nOldProtect As Integer
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' Object pointer contains a pointer to v-table--copy it to temporary
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CopyMemory(lpVTableHead, lpObj, 4)
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' Calculate pointer to specified entry
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lpFuncTmp = lpVTableHead + (nEntry - 1) * 4
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' Save address of previous method for return
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CopyMemory(lpFuncOld, lpFuncTmp, 4)
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' Ignore if they're already the same
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If lpFuncOld <> lpFunc Then
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' Need to change page protection to write to code
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VirtualProtect(lpFuncTmp, 4&, PAGE_EXECUTE_READWRITE, nOldProtect)
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' Write the new function address into the v-table
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CopyMemory(lpFuncTmp, lpFunc, 4) ' *lpFuncTmp = lpFunc;
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' Restore the previous page protection
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VirtualProtect(lpFuncTmp, 4, nOldProtect, nOldProtect) 'Optional
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End If
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ReplaceVtableEntry = lpFuncOld
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End Function
