/// <summary>
/// Adds method body interception to the target method.
/// </summary>
/// <param name="IL">The <see cref="ILProcessor" /> pointing to the target method body.</param>
public void Emit(ILProcessor IL)
{
var method = IL.Body.Method;
var returnType = method.ReturnType;
var endLabel = IL.Create(OpCodes.Nop);
var executeOriginalInstructions = IL.Create(OpCodes.Nop);
// Execute the method body replacement if and only if
// interception is enabled
IL.Emit(OpCodes.Ldloc, _interceptionDisabled);
IL.Emit(OpCodes.Brtrue, executeOriginalInstructions);
var invokeReplacement = IL.Create(OpCodes.Nop);
IL.Emit(OpCodes.Ldloc, _methodReplacementProvider);
IL.Emit(OpCodes.Brtrue, invokeReplacement);
IL.Emit(OpCodes.Ldloc, _classMethodReplacementProvider);
IL.Emit(OpCodes.Brtrue, invokeReplacement);
IL.Emit(OpCodes.Br, executeOriginalInstructions);
IL.Append(invokeReplacement);
// This is equivalent to the following code:
// var replacement = provider.GetMethodReplacement(info);
var invokeMethodReplacement = new InvokeMethodReplacement(executeOriginalInstructions,
_methodReplacementProvider,
_classMethodReplacementProvider, _invocationInfo);
invokeMethodReplacement.Emit(IL);
IL.Emit(OpCodes.Br, endLabel);
IL.Append(executeOriginalInstructions);
var addOriginalInstructions = new AddOriginalInstructions(_oldInstructions, endLabel);
addOriginalInstructions.Emit(IL);
// Mark the end of the method body
IL.Append(endLabel);
var saveReturnValue = new SaveReturnValue(returnType, _returnValue);
saveReturnValue.Emit(IL);
}
public void Emit(CilWorker IL)
{
var method = IL.GetMethod();
var returnType = method.ReturnType.ReturnType;
var endLabel = IL.Create(OpCodes.Nop);
var executeOriginalInstructions = IL.Create(OpCodes.Nop);
// Execute the method body replacement if and only if
// interception is enabled
IL.Emit(OpCodes.Ldloc, _interceptionDisabled);
IL.Emit(OpCodes.Brtrue, executeOriginalInstructions);
var invokeReplacement = IL.Create(OpCodes.Nop);
IL.Emit(OpCodes.Ldloc, _methodReplacementProvider);
IL.Emit(OpCodes.Brtrue, invokeReplacement);
IL.Emit(OpCodes.Ldloc, _classMethodReplacementProvider);
IL.Emit(OpCodes.Brtrue, invokeReplacement);
IL.Emit(OpCodes.Br, executeOriginalInstructions);
IL.Append(invokeReplacement);
// This is equivalent to the following code:
// var replacement = provider.GetMethodReplacement(info);
var invokeMethodReplacement = new InvokeMethodReplacement(executeOriginalInstructions,
_methodReplacementProvider, _classMethodReplacementProvider, _invocationInfo);
invokeMethodReplacement.Emit(IL);
IL.Emit(OpCodes.Br, endLabel);
#region The original instruction block
IL.Append(executeOriginalInstructions);
var addOriginalInstructions = new AddOriginalInstructions(_oldInstructions, endLabel);
addOriginalInstructions.Emit(IL);
#endregion
// Mark the end of the method body
IL.Append(endLabel);
var saveReturnValue = new SaveReturnValue(returnType, _returnValue);
saveReturnValue.Emit(IL);
}
/// <summary>
/// Rewrites the instructions in the target method body to support dynamic exception handling.
/// </summary>
/// <param name="targetMethod">The target method.</param>
/// <param name="IL">The <see cref="CilWorker"/> instance that represents the method body.</param>
/// <param name="oldInstructions">The IL instructions of the original method body.</param>
protected override void RewriteMethodBody(MethodDefinition targetMethod, CilWorker IL,
IEnumerable <Instruction> oldInstructions)
{
var endOfOriginalInstructionBlock = IL.Create(OpCodes.Nop);
var addOriginalInstructions = new AddOriginalInstructions(oldInstructions, endOfOriginalInstructionBlock);
var endLabel = IL.Create(OpCodes.Nop);
var tryStart = IL.Emit(OpCodes.Nop);
var tryEnd = IL.Emit(OpCodes.Nop);
var catchStart = IL.Emit(OpCodes.Nop);
var catchEnd = IL.Emit(OpCodes.Nop);
var module = IL.GetModule();
var handler = new ExceptionHandler(ExceptionHandlerType.Catch);
var body = targetMethod.Body;
body.ExceptionHandlers.Add(handler);
handler.CatchType = module.ImportType <Exception>();
handler.TryStart = tryStart;
handler.TryEnd = tryEnd;
handler.HandlerStart = catchStart;
handler.HandlerEnd = catchEnd;
var emitter = new InvocationInfoEmitter(true);
var returnType = targetMethod.ReturnType.ReturnType;
// try {
IL.Append(tryStart);
addOriginalInstructions.Emit(IL);
IL.Append(endOfOriginalInstructionBlock);
if (returnType != _voidType && _returnValue != null)
{
IL.Emit(OpCodes.Stloc, _returnValue);
}
IL.Emit(OpCodes.Leave, endLabel);
// }
IL.Append(tryEnd);
// catch (Exception ex) {
IL.Append(catchStart);
IL.Emit(OpCodes.Stloc, _exception);
SaveExceptionInfo(targetMethod, emitter);
IL.Emit(OpCodes.Ldloc, _exceptionInfo);
var getHandlerMethodInfo = typeof(ExceptionHandlerRegistry).GetMethod("GetHandler");
var getHandlerMethod = module.Import(getHandlerMethodInfo);
IL.Emit(OpCodes.Call, getHandlerMethod);
IL.Emit(OpCodes.Stloc, _exceptionHandler);
// if (exceptionHandler == null)
// throw;
var doRethrow = IL.Create(OpCodes.Nop);
IL.Emit(OpCodes.Ldloc, _exceptionHandler);
IL.Emit(OpCodes.Brfalse, doRethrow);
// if (handler.CanCatch(exceptionInfo)) {
var leaveBlock = IL.Create(OpCodes.Nop);
var canCatch = module.ImportMethod <IExceptionHandler>("CanCatch");
IL.Emit(OpCodes.Ldloc, _exceptionHandler);
IL.Emit(OpCodes.Ldloc, _exceptionInfo);
IL.Emit(OpCodes.Callvirt, canCatch);
IL.Emit(OpCodes.Brfalse, doRethrow);
var catchMethod = module.ImportMethod <IExceptionHandler>("Catch");
IL.Emit(OpCodes.Ldloc, _exceptionHandler);
IL.Emit(OpCodes.Ldloc, _exceptionInfo);
IL.Emit(OpCodes.Callvirt, catchMethod);
// }
var getShouldSkipRethrow = module.ImportMethod <IExceptionHandlerInfo>("get_ShouldSkipRethrow");
IL.Emit(OpCodes.Ldloc, _exceptionInfo);
IL.Emit(OpCodes.Callvirt, getShouldSkipRethrow);
IL.Emit(OpCodes.Brfalse, doRethrow);
IL.Emit(OpCodes.Br, leaveBlock);
IL.Append(doRethrow);
IL.Emit(OpCodes.Rethrow);
IL.Append(leaveBlock);
IL.Emit(OpCodes.Leave, endLabel);
IL.Append(catchEnd);
// }
IL.Append(endLabel);
if (returnType != _voidType && _returnValue != null)
{
var returnOriginalValue = IL.Create(OpCodes.Nop);
var getReturnValue = module.ImportMethod <IExceptionHandlerInfo>("get_ReturnValue");
IL.Emit(OpCodes.Ldloc, _exceptionInfo);
IL.Emit(OpCodes.Brfalse, returnOriginalValue);
IL.Emit(OpCodes.Ldloc, _exceptionInfo);
IL.Emit(OpCodes.Callvirt, getReturnValue);
IL.Emit(OpCodes.Stloc, _returnValue);
IL.Append(returnOriginalValue);
IL.Emit(OpCodes.Ldloc, _returnValue);
}
IL.Emit(OpCodes.Ret);
}
/// <summary>
/// Rewrites the instructions in the target method body to support dynamic exception handling.
/// </summary>
/// <param name="targetMethod">The target method.</param>
/// <param name="IL">The <see cref="CilWorker"/> instance that represents the method body.</param>
/// <param name="oldInstructions">The IL instructions of the original method body.</param>
protected override void RewriteMethodBody(MethodDefinition targetMethod, CilWorker IL,
IEnumerable<Instruction> oldInstructions)
{
var endOfOriginalInstructionBlock = IL.Create(OpCodes.Nop);
var addOriginalInstructions = new AddOriginalInstructions(oldInstructions, endOfOriginalInstructionBlock);
var endLabel = IL.Create(OpCodes.Nop);
var tryStart = IL.Emit(OpCodes.Nop);
var tryEnd = IL.Emit(OpCodes.Nop);
var catchStart = IL.Emit(OpCodes.Nop);
var catchEnd = IL.Emit(OpCodes.Nop);
var module = IL.GetModule();
var handler = new ExceptionHandler(ExceptionHandlerType.Catch);
var body = targetMethod.Body;
body.ExceptionHandlers.Add(handler);
handler.CatchType = module.ImportType<Exception>();
handler.TryStart = tryStart;
handler.TryEnd = tryEnd;
handler.HandlerStart = catchStart;
handler.HandlerEnd = catchEnd;
var emitter = new InvocationInfoEmitter(true);
var returnType = targetMethod.ReturnType.ReturnType;
// try {
IL.Append(tryStart);
addOriginalInstructions.Emit(IL);
IL.Append(endOfOriginalInstructionBlock);
if (returnType != _voidType && _returnValue != null)
{
IL.Emit(OpCodes.Stloc, _returnValue);
}
IL.Emit(OpCodes.Leave, endLabel);
// }
IL.Append(tryEnd);
// catch (Exception ex) {
IL.Append(catchStart);
IL.Emit(OpCodes.Stloc, _exception);
SaveExceptionInfo(targetMethod, emitter);
IL.Emit(OpCodes.Ldloc, _exceptionInfo);
var getHandlerMethodInfo = typeof (ExceptionHandlerRegistry).GetMethod("GetHandler");
var getHandlerMethod = module.Import(getHandlerMethodInfo);
IL.Emit(OpCodes.Call, getHandlerMethod);
IL.Emit(OpCodes.Stloc, _exceptionHandler);
// if (exceptionHandler == null)
// throw;
var doRethrow = IL.Create(OpCodes.Nop);
IL.Emit(OpCodes.Ldloc, _exceptionHandler);
IL.Emit(OpCodes.Brfalse, doRethrow);
// if (handler.CanCatch(exceptionInfo)) {
var leaveBlock = IL.Create(OpCodes.Nop);
var canCatch = module.ImportMethod<IExceptionHandler>("CanCatch");
IL.Emit(OpCodes.Ldloc, _exceptionHandler);
IL.Emit(OpCodes.Ldloc, _exceptionInfo);
IL.Emit(OpCodes.Callvirt, canCatch);
IL.Emit(OpCodes.Brfalse, doRethrow);
var catchMethod = module.ImportMethod<IExceptionHandler>("Catch");
IL.Emit(OpCodes.Ldloc, _exceptionHandler);
IL.Emit(OpCodes.Ldloc, _exceptionInfo);
IL.Emit(OpCodes.Callvirt, catchMethod);
// }
var getShouldSkipRethrow = module.ImportMethod<IExceptionHandlerInfo>("get_ShouldSkipRethrow");
IL.Emit(OpCodes.Ldloc, _exceptionInfo);
IL.Emit(OpCodes.Callvirt, getShouldSkipRethrow);
IL.Emit(OpCodes.Brfalse, doRethrow);
IL.Emit(OpCodes.Br, leaveBlock);
IL.Append(doRethrow);
IL.Emit(OpCodes.Rethrow);
IL.Append(leaveBlock);
IL.Emit(OpCodes.Leave, endLabel);
IL.Append(catchEnd);
// }
IL.Append(endLabel);
if (returnType != _voidType && _returnValue != null)
{
var returnOriginalValue = IL.Create(OpCodes.Nop);
var getReturnValue = module.ImportMethod<IExceptionHandlerInfo>("get_ReturnValue");
IL.Emit(OpCodes.Ldloc, _exceptionInfo);
IL.Emit(OpCodes.Brfalse, returnOriginalValue);
IL.Emit(OpCodes.Ldloc, _exceptionInfo);
IL.Emit(OpCodes.Callvirt, getReturnValue);
IL.Emit(OpCodes.Stloc, _returnValue);
IL.Append(returnOriginalValue);
IL.Emit(OpCodes.Ldloc, _returnValue);
}
IL.Emit(OpCodes.Ret);
}
