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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "VTableBuilder.h"
#include <stdlib.h>
static HRESULT STDMETHODCALLTYPE QueryInterfaceThunk(IUnknown* aThis,
REFIID aIid,
void** aOutInterface) {
void** table = (void**)aThis;
IUnknown* real = (IUnknown*)table[1];
return real->lpVtbl->QueryInterface(real, aIid, aOutInterface);
}
static ULONG STDMETHODCALLTYPE AddRefThunk(IUnknown* aThis) {
void** table = (void**)aThis;
IUnknown* real = (IUnknown*)table[1];
return real->lpVtbl->AddRef(real);
}
static ULONG STDMETHODCALLTYPE ReleaseThunk(IUnknown* aThis) {
void** table = (void**)aThis;
IUnknown* real = (IUnknown*)table[1];
return real->lpVtbl->Release(real);
}
IUnknown* BuildNullVTable(IUnknown* aUnk, uint32_t aVtblSize) {
void** table;
if (aVtblSize < 3) {
return NULL;
}
// We need to allocate slots for two additional pointers: The |lpVtbl|
// pointer, as well as |aUnk| which is needed to get |this| right when
// something calls through one of the IUnknown thunks.
table = calloc(aVtblSize + 2, sizeof(void*));
table[0] = &table[2]; // |lpVtbl|, points to the first entry of the vtable
table[1] = aUnk; // |this|
// Now the actual vtable entries for IUnknown
table[2] = &QueryInterfaceThunk;
table[3] = &AddRefThunk;
table[4] = &ReleaseThunk;
// Remaining entries are NULL thanks to calloc zero-initializing everything.
return (IUnknown*)table;
}
void DeleteNullVTable(IUnknown* aUnk) { free(aUnk); }
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