private static MemoryBasicInformation GetMemoryInformation(ImageThunkData *thunk)
{
MemoryBasicInformation thunkMemoryInfo;
UnsafeNativeMethods.VirtualQuery(
(IntPtr)thunk,
&thunkMemoryInfo,
(IntPtr)sizeof(MemoryBasicInformation));
return(thunkMemoryInfo);
}
private static Patched <TFunction> ApplyPatch <TFunction>(
ProcessModule module,
string importedModule,
string importedName,
ThunkPredicate isCorrectFunction,
Func <TFunction, TFunction> buildReplacementFunction)
where TFunction : class
{
AssertDelegate <TFunction>("TFunction");
module.NotNull("module");
importedModule.NotEmpty("importedModule");
isCorrectFunction.NotNull("isCorrectFunction");
buildReplacementFunction.NotNull("buildReplacementFunction");
ImageImportDescriptor *descriptors = module.GetImportDescriptors();
ImageImportDescriptor *descriptor = module.FindImportedModule(descriptors, importedModule);
ImageThunkData * thunk = module.FindImportedFunction(descriptor, isCorrectFunction);
MemoryBasicInformation thunkMemory = GetMemoryInformation(thunk);
MakeWritable(thunkMemory);
try
{
TFunction originalFunction = GetDelegateForFunctionPointer <TFunction>(thunk->Function);
if (originalFunction == null)
{
throw new ArgumentException("Could not create a delegate for the original function to be patched.");
}
TFunction replacementFunction = buildReplacementFunction(originalFunction);
thunk->Function = GetFunctionPointerForDelegate(replacementFunction);
return(PatchedFunction.From(
importedModule,
importedName,
replacementFunction,
originalFunction));
}
finally
{
RestoreOriginalProtection(thunkMemory);
}
}
private static ImageThunkData *FindImportedFunction(
this ProcessModule module,
ImageImportDescriptor *descriptor,
ThunkPredicate isCorrectFunction)
{
if (descriptor->FirstThunk == 0 ||
descriptor->OriginalFirstThunk == 0)
{
throw new ArgumentException("The thunks in the specified descriptor were null.", "descriptor");
}
ImageThunkData *first = (ImageThunkData *)descriptor->FirstThunk.AsPtr(module);
ImageThunkData *original = (ImageThunkData *)descriptor->OriginalFirstThunk.AsPtr(module);
for (; original->Function != IntPtr.Zero; original++, first++)
{
if (isCorrectFunction(module, original))
{
return(first);
}
}
throw new MissingMethodException();
}