private static void MakeWritable(MemoryBasicInformation thunkMemoryInfo)
{
if (!UnsafeNativeMethods.VirtualProtect(
thunkMemoryInfo.BaseAddress,
thunkMemoryInfo.RegionSize,
MemoryProtectionOptions.ExecuteReadWrite,
&thunkMemoryInfo.Protect))
{
throw new Win32Exception();
}
}
private static void RestoreOriginalProtection(MemoryBasicInformation thunkMemoryInfo)
{
MemoryProtectionOptions ignore;
if (!UnsafeNativeMethods.VirtualProtect(
thunkMemoryInfo.BaseAddress,
thunkMemoryInfo.RegionSize,
thunkMemoryInfo.Protect,
&ignore))
{
throw new Win32Exception();
}
}
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);
}
}