agent.cc

/*
 * Copyright (C) 2017 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <cstdlib>
#include <sstream>
#include <cstring>
#include <cassert>
#include <cstdarg>
#include <algorithm>

#include <jni.h>

#include "jvmti.h"

#include <slicer/dex_ir.h>
#include <slicer/code_ir.h>
#include <slicer/dex_ir_builder.h>
#include <slicer/dex_utf8.h>
#include <slicer/writer.h>
#include <slicer/reader.h>
#include <slicer/instrumentation.h>

using namespace dex;
using namespace lir;

namespace com_android_dx_mockito_inline {
static jvmtiEnv* localJvmtiEnv;

static jobject sTransformer;

// Converts a class name to a type descriptor
// (ex. "java.lang.String" to "Ljava/lang/String;")
static std::string
ClassNameToDescriptor(const char* class_name) {
    std::stringstream ss;
    ss << "L";
    for (auto p = class_name; *p != '\0'; ++p) {
         ss << (*p == '.' ? '/' : *p);
    }
    ss << ";";
    return ss.str();
}

// Takes the full dex file for class 'classBeingRedefined'
// - isolates the dex code for the class out of the dex file
// - calls sTransformer.runTransformers on the isolated dex code
// - send the transformed code back to the runtime
static void
Transform(jvmtiEnv* jvmti_env,
          JNIEnv* env,
          jclass classBeingRedefined,
          jobject loader,
          const char* name,
          jobject protectionDomain,
          jint classDataLen,
          const unsigned char* classData,
          jint* newClassDataLen,
          unsigned char** newClassData) {
    if (sTransformer != NULL) {
        // Even reading the classData array is expensive as the data is only generated when the
        // memory is touched. Hence call JvmtiAgent#shouldTransform to check if we need to transform
        // the class.
        jclass cls = env->GetObjectClass(sTransformer);
        jmethodID shouldTransformMethod = env->GetMethodID(cls, "shouldTransform",
                                                           "(Ljava/lang/Class;)Z");

        jboolean shouldTransform = env->CallBooleanMethod(sTransformer, shouldTransformMethod,
                                                          classBeingRedefined);
        if (!shouldTransform) {
            return;
        }

        // Isolate byte code of class class. This is needed as Android usually gives us more
        // than the class we need.
        Reader reader(classData, classDataLen);

        u4 index = reader.FindClassIndex(ClassNameToDescriptor(name).c_str());
        reader.CreateClassIr(index);
        std::shared_ptr<ir::DexFile> ir = reader.GetIr();

        struct Allocator : public Writer::Allocator {
            virtual void* Allocate(size_t size) {return ::malloc(size);}
            virtual void Free(void* ptr) {::free(ptr);}
        };

        Allocator allocator;
        Writer writer(ir);
        size_t isolatedClassLen = 0;
        std::shared_ptr<jbyte> isolatedClass((jbyte*)writer.CreateImage(&allocator,
                                                                        &isolatedClassLen));

        // Create jbyteArray with isolated byte code of class
        jbyteArray isolatedClassArr = env->NewByteArray(isolatedClassLen);
        env->SetByteArrayRegion(isolatedClassArr, 0, isolatedClassLen,
                                isolatedClass.get());

        jstring nameStr = env->NewStringUTF(name);

        // Call JvmtiAgent#runTransformers
        jmethodID runTransformersMethod = env->GetMethodID(cls, "runTransformers",
                                                           "(Ljava/lang/ClassLoader;"
                                                           "Ljava/lang/String;"
                                                           "Ljava/lang/Class;"
                                                           "Ljava/security/ProtectionDomain;"
                                                           "[B)[B");

        jbyteArray transformedArr = (jbyteArray) env->CallObjectMethod(sTransformer,
                                                                       runTransformersMethod,
                                                                       loader, nameStr,
                                                                       classBeingRedefined,
                                                                       protectionDomain,
                                                                       isolatedClassArr);

        // Set transformed byte code
        if (!env->ExceptionOccurred() && transformedArr != NULL) {
            *newClassDataLen = env->GetArrayLength(transformedArr);

            jbyte* transformed = env->GetByteArrayElements(transformedArr, 0);

            jvmti_env->Allocate(*newClassDataLen, newClassData);
            std::memcpy(*newClassData, transformed, *newClassDataLen);

            env->ReleaseByteArrayElements(transformedArr, transformed, 0);
        }
    }
}

// Add a label before instructionAfter
static void
addLabel(CodeIr& c,
         lir::Instruction* instructionAfter,
         Label* returnTrueLabel) {
    c.instructions.InsertBefore(instructionAfter, returnTrueLabel);
}

// Add a byte code before instructionAfter
static void
addInstr(CodeIr& c,
         lir::Instruction* instructionAfter,
         Opcode opcode,
         const std::list<Operand*>& operands) {
    auto instruction = c.Alloc<Bytecode>();

    instruction->opcode = opcode;

    for (auto it = operands.begin(); it != operands.end(); it++) {
        instruction->operands.push_back(*it);
    }

    c.instructions.InsertBefore(instructionAfter, instruction);
}

// Add a method call byte code before instructionAfter
static void
addCall(ir::Builder& b,
        CodeIr& c,
        lir::Instruction* instructionAfter,
        Opcode opcode,
        ir::Type* type,
        const char* methodName,
        ir::Type* returnType,
        const std::vector<ir::Type*>& types,
        const std::list<int>& regs) {
    auto proto = b.GetProto(returnType, b.GetTypeList(types));
    auto method = b.GetMethodDecl(b.GetAsciiString(methodName), proto, type);

    VRegList* param_regs = c.Alloc<VRegList>();
    for (auto it = regs.begin(); it != regs.end(); it++) {
        param_regs->registers.push_back(*it);
    }

    addInstr(c, instructionAfter, opcode, {param_regs, c.Alloc<Method>(method,
                                                                       method->orig_index)});
}

typedef struct {
    ir::Type* boxedType;
    ir::Type* scalarType;
    std::string unboxMethod;
} BoxingInfo;

// Get boxing / unboxing info for a type
static BoxingInfo
getBoxingInfo(ir::Builder &b,
              char typeCode) {
    BoxingInfo boxingInfo;

    if (typeCode != 'L' && typeCode !=  '[') {
        std::stringstream tmp;
        tmp << typeCode;
        boxingInfo.scalarType = b.GetType(tmp.str().c_str());
    }

    switch (typeCode) {
        case 'B':
            boxingInfo.boxedType = b.GetType("Ljava/lang/Byte;");
            boxingInfo.unboxMethod = "byteValue";
            break;
        case 'S':
            boxingInfo.boxedType = b.GetType("Ljava/lang/Short;");
            boxingInfo.unboxMethod = "shortValue";
            break;
        case 'I':
            boxingInfo.boxedType = b.GetType("Ljava/lang/Integer;");
            boxingInfo.unboxMethod = "intValue";
            break;
        case 'C':
            boxingInfo.boxedType = b.GetType("Ljava/lang/Character;");
            boxingInfo.unboxMethod = "charValue";
            break;
        case 'F':
            boxingInfo.boxedType = b.GetType("Ljava/lang/Float;");
            boxingInfo.unboxMethod = "floatValue";
            break;
        case 'Z':
            boxingInfo.boxedType = b.GetType("Ljava/lang/Boolean;");
            boxingInfo.unboxMethod = "booleanValue";
            break;
        case 'J':
            boxingInfo.boxedType = b.GetType("Ljava/lang/Long;");
            boxingInfo.unboxMethod = "longValue";
            break;
        case 'D':
            boxingInfo.boxedType = b.GetType("Ljava/lang/Double;");
            boxingInfo.unboxMethod = "doubleValue";
            break;
        default:
            // real object
            break;
    }

    return boxingInfo;
}

static size_t
getNumParams(ir::EncodedMethod *method) {
    if (method->decl->prototype->param_types == NULL) {
        return 0;
    }

    return method->decl->prototype->param_types->types.size();
}

static bool
canBeTransformed(ir::EncodedMethod *method) {
    std::string type = method->decl->parent->Decl();
    ir::String* methodName = method->decl->name;

    return !(((method->access_flags & (kAccAbstract | kAccPrivate | kAccBridge | kAccNative
                                       | kAccStatic)) != 0)
             || (Utf8Cmp(methodName->c_str(), "<init>") == 0)
             || (Utf8Cmp(methodName->c_str(), "<clinit>") == 0)
             || (Utf8Cmp(type.c_str(), "java.lang.Object") == 0
                 && Utf8Cmp(methodName->c_str(), "finalize") == 0
                 && getNumParams(method) == 0)
             || (strncmp(type.c_str(), "java.", 5) == 0
                 && (method->access_flags & (kAccPrivate | kAccPublic | kAccProtected)) == 0)
             // getClass is used by MockMethodAdvice.isOverridden
             || (Utf8Cmp(methodName->c_str(), "getClass") == 0));
}

static bool
isHashCode(ir::EncodedMethod *method) {
    return Utf8Cmp(method->decl->name->c_str(), "hashCode") == 0
           && getNumParams(method) == 0;
}

static bool
isEquals(ir::EncodedMethod *method) {
    return Utf8Cmp(method->decl->name->c_str(), "equals") == 0
           && getNumParams(method) == 1
           && Utf8Cmp(method->decl->prototype->param_types->types[0]->Decl().c_str(),
                      "java.lang.Object") == 0;
}

// Transforms the classes to add the mockito hooks
// - equals and hashcode are handled in a special way
extern "C" JNIEXPORT jbyteArray JNICALL
Java_com_android_dx_mockito_inline_ClassTransformer_nativeRedefine(JNIEnv* env,
                                                                   jobject generator,
                                                                   jstring idStr,
                                                                   jbyteArray originalArr) {
    unsigned char* original = (unsigned char*)env->GetByteArrayElements(originalArr, 0);

    Reader reader(original, env->GetArrayLength(originalArr));
    reader.CreateClassIr(0);
    std::shared_ptr<ir::DexFile> dex_ir = reader.GetIr();
    ir::Builder b(dex_ir);

    ir::Type* booleanScalarT = b.GetType("Z");
    ir::Type* intScalarT = b.GetType("I");
    ir::Type* objectT = b.GetType("Ljava/lang/Object;");
    ir::Type* objectArrayT = b.GetType("[Ljava/lang/Object;");
    ir::Type* stringT = b.GetType("Ljava/lang/String;");
    ir::Type* methodT = b.GetType("Ljava/lang/reflect/Method;");
    ir::Type* systemT = b.GetType("Ljava/lang/System;");
    ir::Type* callableT = b.GetType("Ljava/util/concurrent/Callable;");
    ir::Type* dispatcherT = b.GetType("Lcom/android/dx/mockito/inline/MockMethodDispatcher;");

    // Add id to dex file
    const char* idNative = env->GetStringUTFChars(idStr, 0);
    ir::String* id = b.GetAsciiString(idNative);
    env->ReleaseStringUTFChars(idStr, idNative);

    for (auto& method : dex_ir->encoded_methods) {
        if (!canBeTransformed(method.get())) {
            continue;
        }

        if (isEquals(method.get())) {
            /*
            equals_original(Object other) {
                T t = foo(other);
                return bar(t);
            }

            equals_transformed(params) {
                // MockMethodDispatcher dispatcher = MockMethodDispatcher.get(idStr, this);
                const-string v0, "65463hg34t"
                move-objectfrom16 v1, THIS
                invoke-static {v0, v1}, MockMethodDispatcher.get(String, Object):MockMethodDispatcher
                move-result-object v2

                // if (dispatcher == null || ) {
                //     goto original_method;
                // }
                if-eqz v2, original_method

                // if (!dispatcher.isMock(this)) {
                //     goto original_method;
                // }
                invoke-virtual {v2, v1}, MockMethodDispatcher.isMock(Object):Method
                move-result v2
                if-eqz v2, original_method

                // return self == other
                move-objectfrom16 v0, ARG1
                if-eq v0, v1, return_true

                const v0, 0
                return v0

            return true:
                const v0, 1
                return v0

            original_method:
                // Move all method arguments down so that they match what the original code expects.
                move-object16 v4, v5      # THIS
                move-object16 v5, v6      # ARG1

                T t = foo(other);
                return bar(t);
            }
            */

            CodeIr c(method.get(), dex_ir);

            // Make sure there are at least 5 local registers to use
            int originalNumRegisters = method->code->registers - method->code->ins_count;
            int numAdditionalRegs = std::max(0, 3 - originalNumRegisters);
            int thisReg = numAdditionalRegs + method->code->registers
                          - method->code->ins_count;

            if (numAdditionalRegs > 0) {
                c.ir_method->code->registers += numAdditionalRegs;
            }

            lir::Instruction* fi = *(c.instructions.begin());

            Label* originalMethodLabel = c.Alloc<Label>(0);
            Label* returnTrueLabel = c.Alloc<Label>(0);
            CodeLocation* originalMethod = c.Alloc<CodeLocation>(originalMethodLabel);
            VReg* v0 = c.Alloc<VReg>(0);
            VReg* v1 = c.Alloc<VReg>(1);
            VReg* v2 = c.Alloc<VReg>(2);
            VReg* thiz = c.Alloc<VReg>(thisReg);

            addInstr(c, fi, OP_CONST_STRING, {v0, c.Alloc<String>(id, id->orig_index)});
            addInstr(c, fi, OP_MOVE_OBJECT_FROM16, {v1, thiz});
            addCall(b, c, fi, OP_INVOKE_STATIC, dispatcherT, "get", dispatcherT,
                    {stringT, objectT}, {0, 1});
            addInstr(c, fi, OP_MOVE_RESULT_OBJECT, {v2});
            addInstr(c, fi, OP_IF_EQZ, {v2, originalMethod});
            addCall(b, c, fi, OP_INVOKE_VIRTUAL, dispatcherT, "isMock", booleanScalarT, {objectT},
                    {2, 1});
            addInstr(c, fi, OP_MOVE_RESULT, {v2});
            addInstr(c, fi, OP_IF_EQZ, {v2, originalMethod});
            addInstr(c, fi, OP_MOVE_OBJECT_FROM16, {v0, c.Alloc<VReg>(thisReg + 1)});
            addInstr(c, fi, OP_IF_EQ, {v0, v1, c.Alloc<CodeLocation>(returnTrueLabel)});
            addInstr(c, fi, OP_CONST, {v0, c.Alloc<Const32>(0)});
            addInstr(c, fi, OP_RETURN, {v0});
            addLabel(c, fi, returnTrueLabel);
            addInstr(c, fi, OP_CONST, {v0, c.Alloc<Const32>(1)});
            addInstr(c, fi, OP_RETURN, {v0});
            addLabel(c, fi, originalMethodLabel);
            addInstr(c, fi, OP_MOVE_OBJECT_16, {c.Alloc<VReg>(thisReg - numAdditionalRegs), thiz});
            addInstr(c, fi, OP_MOVE_OBJECT_16, {c.Alloc<VReg>(thisReg - numAdditionalRegs + 1),
                     c.Alloc<VReg>(thisReg + 1)});

            c.Assemble();
        } else if (isHashCode(method.get())) {
            /*
            hashCode_original(Object other) {
                T t = foo(other);
                return bar(t);
            }

            hashCode_transformed(params) {
                // MockMethodDispatcher dispatcher = MockMethodDispatcher.get(idStr, this);
                const-string v0, "65463hg34t"
                move-objectfrom16 v1, THIS
                invoke-static {v0, v1}, MockMethodDispatcher.get(String, Object):MockMethodDispatcher
                move-result-object v2

                // if (dispatcher == null || ) {
                //     goto original_method;
                // }
                if-eqz v2, original_method

                // if (!dispatcher.isMock(this)) {
                //     goto original_method;
                // }
                invoke-interface {v2, v1}, MockMethodDispatcher.isMock(Object):Method
                move-result v2
                if-eqz v2, original_method

                // return System.identityHashCode(this);
                invoke-static {v1}, System.identityHashCode(Object):int
                move-result v2
                return v2

            original_method:
                // Move all method arguments down so that they match what the original code expects.
                move-object16 v4, v5      # THIS

                T t = foo(other);
                return bar(t);
            }
            */

            CodeIr c(method.get(), dex_ir);

            // Make sure there are at least 5 local registers to use
            int originalNumRegisters = method->code->registers - method->code->ins_count;
            int numAdditionalRegs = std::max(0, 3 - originalNumRegisters);
            int thisReg = numAdditionalRegs + method->code->registers - method->code->ins_count;

            if (numAdditionalRegs > 0) {
                c.ir_method->code->registers += numAdditionalRegs;
            }

            lir::Instruction* fi = *(c.instructions.begin());

            Label* originalMethodLabel = c.Alloc<Label>(0);
            CodeLocation* originalMethod = c.Alloc<CodeLocation>(originalMethodLabel);
            VReg* v0 = c.Alloc<VReg>(0);
            VReg* v1 = c.Alloc<VReg>(1);
            VReg* v2 = c.Alloc<VReg>(2);
            VReg* thiz = c.Alloc<VReg>(thisReg);

            addInstr(c, fi, OP_CONST_STRING, {v0, c.Alloc<String>(id, id->orig_index)});
            addInstr(c, fi, OP_MOVE_OBJECT_FROM16, {v1, thiz});
            addCall(b, c, fi, OP_INVOKE_STATIC, dispatcherT, "get", dispatcherT,
                    {stringT, objectT}, {0, 1});
            addInstr(c, fi, OP_MOVE_RESULT_OBJECT, {v2});
            addInstr(c, fi, OP_IF_EQZ, {v2, originalMethod});
            addCall(b, c, fi, OP_INVOKE_VIRTUAL, dispatcherT, "isMock", booleanScalarT, {objectT},
                    {2, 1});
            addInstr(c, fi, OP_MOVE_RESULT, {v2});
            addInstr(c, fi, OP_IF_EQZ, {v2, originalMethod});
            addCall(b, c, fi, OP_INVOKE_STATIC, systemT, "identityHashCode", intScalarT, {objectT},
                    {1});
            addInstr(c, fi, OP_MOVE_RESULT, {v2});
            addInstr(c, fi, OP_RETURN, {v2});
            addLabel(c, fi, originalMethodLabel);
            addInstr(c, fi, OP_MOVE_OBJECT_16, {c.Alloc<VReg>(thisReg - numAdditionalRegs), thiz});

            c.Assemble();
        } else {
            /*
            long method_original(int param1, long param2, String param3) {
                foo();
                return bar();
            }

            long method_transformed(int param1, long param2, String param3) {
                // MockMethodDispatcher dispatcher = MockMethodDispatcher.get(idStr, this);
                const-string v0, "65463hg34t"
                move-objectfrom16 v1, THIS       # this is necessary as invoke-static cannot deal
                                                 # with medium or high registers and THIS might not
                                                 # be low
                invoke-static {v0, v1}, MockMethodDispatcher.get(String, Object):MockMethodDispatcher
                move-result-object v0

                // if (dispatcher == null) {
                //    goto original_method;
                // }
                if-eqz v0, original_method

                // Method origin = dispatcher.getOrigin(this, methodDesc);
                const-string v1 "fully.qualified.ClassName#original_method(int, long, String)"
                move-objectfrom16 v2, THIS       # this is necessary as invoke-static cannot deal
                                                 # with medium or high registers and THIS might not
                                                 # be low
                invoke-virtual {v0, v2, v1}, MockMethodDispatcher.getOrigin(Object, String):Method
                move-result-object v1

                // if (origin == null) {
                //     goto original_method;
                // }
                if-eqz v1, original_method

                // Create an array with Objects of all parameters.

                //     Object[] arguments = new Object[3]
                const v3, 3
                new-array v2, v3, Object[]

                //     Integer param1Integer = Integer.valueOf(param1)
                move-from16 v3, ARG1     # this is necessary as invoke-static cannot deal with high
                                         # registers and ARG1 might be high
                invoke-static {v3}, Integer.valueOf(int):Integer
                move-result-object v3

                //     arguments[0] = param1Integer
                const v4, 0
                aput-object v3, v2, v4

                //     Long param2Long = Long.valueOf(param2)
                move-widefrom16 v3:v4, ARG2.1:ARG2.2 # this is necessary as invoke-static cannot
                                                     # deal with high registers and ARG2 might be
                                                     # high
                invoke-static {v3, v4}, Long.valueOf(long):Long
                move-result-object v3

                //     arguments[1] = param2Long
                const v4, 1
                aput-object v3, v2, v4

                //     arguments[2] = param3
                const v4, 2
                move-objectfrom16 v3, ARG3     # this is necessary as aput-object cannot deal with
                                               # high registers and ARG3 might be high
                aput-object v3, v2, v4

                // Callable<?> mocked = dispatcher.handle(this, origin, arguments);
                move-objectfrom16 v3, THIS       # this is necessary as invoke-virtual cannot deal
                                                 # with medium or high registers and THIS might not
                                                 # be low
                invoke-virtual {v0,v3,v1,v2}, MockMethodDispatcher.handle(Object, Method,
                                                                          Object[]):Callable
                move-result-object v0

                //  if (mocked != null) {
                if-eqz v0, original_method

                //      Object ret = mocked.call();
                invoke-interface {v0}, Callable.call():Object
                move-result-object v0

                //      Long retLong = (Long)ret
                check-cast v0, Long

                //      long retlong = retLong.longValue();
                invoke-virtual {v0}, Long.longValue():long
                move-result-wide v0:v1

                //      return retlong;
                return-wide v0:v1

                //  }

            original_method:
                // Move all method arguments down so that they match what the original code expects.
                // Let's assume three arguments, one int, one long, one String and the and used to
                // use 4 registers
                move-object16 v4, v5      # THIS
                move16 v5, v6             # ARG1
                move-wide16 v6:v7, v7:v8  # ARG2 (overlapping moves are allowed)
                move-object16 v8, v9      # ARG3

                // foo();
                // return bar();
                unmodified original byte code
            }
            */

            CodeIr c(method.get(), dex_ir);

            // Make sure there are at least 5 local registers to use
            int originalNumRegisters = method->code->registers - method->code->ins_count;
            int numAdditionalRegs = std::max(0, 5 - originalNumRegisters);
            int thisReg = originalNumRegisters + numAdditionalRegs;

            if (numAdditionalRegs > 0) {
                c.ir_method->code->registers += numAdditionalRegs;
            }

            lir::Instruction* fi = *(c.instructions.begin());

            // Add methodDesc to dex file
            std::stringstream ss;
            ss << method->decl->parent->Decl() << "#" << method->decl->name->c_str() << "(" ;
            bool first = true;
            if (method->decl->prototype->param_types != NULL) {
                 for (const auto& type : method->decl->prototype->param_types->types) {
                     if (first) {
                         first = false;
                     } else {
                         ss << ",";
                     }

                     ss << type->Decl().c_str();
                 }
            }
            ss << ")";
            std::string methodDescStr = ss.str();
            ir::String* methodDesc = b.GetAsciiString(methodDescStr.c_str());

            size_t numParams = getNumParams(method.get());

            Label* originalMethodLabel = c.Alloc<Label>(0);
            CodeLocation* originalMethod = c.Alloc<CodeLocation>(originalMethodLabel);
            VReg* v0 = c.Alloc<VReg>(0);
            VReg* v1 = c.Alloc<VReg>(1);
            VReg* v2 = c.Alloc<VReg>(2);
            VReg* v3 = c.Alloc<VReg>(3);
            VReg* v4 = c.Alloc<VReg>(4);
            VReg* thiz = c.Alloc<VReg>(thisReg);

            addInstr(c, fi, OP_CONST_STRING, {v0, c.Alloc<String>(id, id->orig_index)});
            addInstr(c, fi, OP_MOVE_OBJECT_FROM16, {v1, thiz});
            addCall(b, c, fi, OP_INVOKE_STATIC, dispatcherT, "get", dispatcherT, {stringT, objectT},
                    {0, 1});
            addInstr(c, fi, OP_MOVE_RESULT_OBJECT, {v0});
            addInstr(c, fi, OP_IF_EQZ, {v0, originalMethod});
            addInstr(c, fi, OP_CONST_STRING,
                     {v1, c.Alloc<String>(methodDesc, methodDesc->orig_index)});
            addInstr(c, fi, OP_MOVE_OBJECT_FROM16, {v2, thiz});
            addCall(b, c, fi, OP_INVOKE_VIRTUAL, dispatcherT, "getOrigin", methodT,
                    {objectT, stringT}, {0, 2, 1});
            addInstr(c, fi, OP_MOVE_RESULT_OBJECT, {v1});
            addInstr(c, fi, OP_IF_EQZ, {v1, originalMethod});
            addInstr(c, fi, OP_CONST, {v3, c.Alloc<Const32>(numParams)});
            addInstr(c, fi, OP_NEW_ARRAY, {v2, v3, c.Alloc<Type>(objectArrayT,
                                                                 objectArrayT->orig_index)});

            if (numParams > 0) {
                int argReg = thisReg + 1;

                for (int argNum = 0; argNum < numParams; argNum++) {
                    const auto& type = method->decl->prototype->param_types->types[argNum];
                    BoxingInfo boxingInfo = getBoxingInfo(b, type->descriptor->c_str()[0]);

                    switch (type->GetCategory()) {
                        case ir::Type::Category::Scalar:
                            addInstr(c, fi, OP_MOVE_FROM16, {v3, c.Alloc<VReg>(argReg)});
                            addCall(b, c, fi, OP_INVOKE_STATIC, boxingInfo.boxedType, "valueOf",
                                    boxingInfo.boxedType, {type}, {3});
                            addInstr(c, fi, OP_MOVE_RESULT_OBJECT, {v3});

                            argReg++;
                            break;
                        case ir::Type::Category::WideScalar: {
                            VRegPair* v3v4 = c.Alloc<VRegPair>(3);
                            VRegPair* argRegPair = c.Alloc<VRegPair>(argReg);

                            addInstr(c, fi, OP_MOVE_WIDE_FROM16, {v3v4, argRegPair});
                            addCall(b, c, fi, OP_INVOKE_STATIC, boxingInfo.boxedType, "valueOf",
                                    boxingInfo.boxedType, {type}, {3, 4});
                            addInstr(c, fi, OP_MOVE_RESULT_OBJECT, {v3});

                            argReg += 2;
                            break;
                        }
                        case ir::Type::Category::Reference:
                            addInstr(c, fi, OP_MOVE_OBJECT_FROM16, {v3, c.Alloc<VReg>(argReg)});

                            argReg++;
                            break;
                        case ir::Type::Category::Void:
                            assert(false);
                    }

                    addInstr(c, fi, OP_CONST, {v4, c.Alloc<Const32>(argNum)});
                    addInstr(c, fi, OP_APUT_OBJECT, {v3, v2, v4});
                }
            }

            addInstr(c, fi, OP_MOVE_OBJECT_FROM16, {v3, thiz});
            addCall(b, c, fi, OP_INVOKE_VIRTUAL, dispatcherT, "handle", callableT,
                    {objectT, methodT, objectArrayT}, {0, 3, 1, 2});
            addInstr(c, fi, OP_MOVE_RESULT_OBJECT, {v0});
            addInstr(c, fi, OP_IF_EQZ, {v0, originalMethod});
            addCall(b, c, fi, OP_INVOKE_INTERFACE, callableT, "call", objectT, {}, {0});
            addInstr(c, fi, OP_MOVE_RESULT_OBJECT, {v0});

            ir::Type *returnType = method->decl->prototype->return_type;
            BoxingInfo boxingInfo = getBoxingInfo(b, returnType->descriptor->c_str()[0]);

            switch (returnType->GetCategory()) {
                case ir::Type::Category::Scalar:
                    addInstr(c, fi, OP_CHECK_CAST, {v0,
                            c.Alloc<Type>(boxingInfo.boxedType, boxingInfo.boxedType->orig_index)});
                    addCall(b, c, fi, OP_INVOKE_VIRTUAL, boxingInfo.boxedType,
                            boxingInfo.unboxMethod.c_str(), returnType, {}, {0});
                    addInstr(c, fi, OP_MOVE_RESULT, {v0});
                    addInstr(c, fi, OP_RETURN, {v0});
                    break;
                case ir::Type::Category::WideScalar: {
                    VRegPair* v0v1 = c.Alloc<VRegPair>(0);

                    addInstr(c, fi, OP_CHECK_CAST, {v0,
                            c.Alloc<Type>(boxingInfo.boxedType, boxingInfo.boxedType->orig_index)});
                    addCall(b, c, fi, OP_INVOKE_VIRTUAL, boxingInfo.boxedType,
                            boxingInfo.unboxMethod.c_str(), returnType, {}, {0});
                    addInstr(c, fi, OP_MOVE_RESULT_WIDE, {v0v1});
                    addInstr(c, fi, OP_RETURN_WIDE, {v0v1});
                    break;
                }
                case ir::Type::Category::Reference:
                    addInstr(c, fi, OP_CHECK_CAST, {v0, c.Alloc<Type>(returnType,
                                                                      returnType->orig_index)});
                    addInstr(c, fi, OP_RETURN_OBJECT, {v0});
                    break;
                case ir::Type::Category::Void:
                    addInstr(c, fi, OP_RETURN_VOID, {});
                    break;
            }

            addLabel(c, fi, originalMethodLabel);
            addInstr(c, fi, OP_MOVE_OBJECT_16, {c.Alloc<VReg>(thisReg - numAdditionalRegs), thiz});

            if (numParams > 0) {
                int argReg = thisReg + 1;

                for (int argNum = 0; argNum < numParams; argNum++) {
                    const auto& type = method->decl->prototype->param_types->types[argNum];
                    int origReg = argReg - numAdditionalRegs;
                    switch (type->GetCategory()) {
                        case ir::Type::Category::Scalar:
                            addInstr(c, fi, OP_MOVE_16, {c.Alloc<VReg>(origReg),
                                     c.Alloc<VReg>(argReg)});
                            argReg++;
                            break;
                        case ir::Type::Category::WideScalar:
                            addInstr(c, fi, OP_MOVE_WIDE_16,{c.Alloc<VRegPair>(origReg),
                                     c.Alloc<VRegPair>(argReg)});
                            argReg +=2;
                            break;
                        case ir::Type::Category::Reference:
                            addInstr(c, fi, OP_MOVE_OBJECT_16, {c.Alloc<VReg>(origReg),
                                     c.Alloc<VReg>(argReg)});
                            argReg++;
                            break;
                    }
                }
            }

            c.Assemble();
        }
    }

    struct Allocator : public Writer::Allocator {
        virtual void* Allocate(size_t size) {return ::malloc(size);}
        virtual void Free(void* ptr) {::free(ptr);}
    };

    Allocator allocator;
    Writer writer(dex_ir);
    size_t transformedLen = 0;
    std::shared_ptr<jbyte> transformed((jbyte*)writer.CreateImage(&allocator, &transformedLen));

    jbyteArray transformedArr = env->NewByteArray(transformedLen);
    env->SetByteArrayRegion(transformedArr, 0, transformedLen, transformed.get());

    return transformedArr;
}

// Initializes the agent
extern "C" jint Agent_OnAttach(JavaVM* vm,
                               char* options,
                               void* reserved) {
    jint jvmError = vm->GetEnv(reinterpret_cast<void**>(&localJvmtiEnv), JVMTI_VERSION_1_2);
    if (jvmError != JNI_OK) {
        return jvmError;
    }

    jvmtiCapabilities caps;
    memset(&caps, 0, sizeof(caps));
    caps.can_retransform_classes = 1;

    jvmtiError error = localJvmtiEnv->AddCapabilities(&caps);
    if (error != JVMTI_ERROR_NONE) {
        return error;
    }

    jvmtiEventCallbacks cb;
    memset(&cb, 0, sizeof(cb));
    cb.ClassFileLoadHook = Transform;

    error = localJvmtiEnv->SetEventCallbacks(&cb, sizeof(cb));
    if (error != JVMTI_ERROR_NONE) {
        return error;
    }

    error = localJvmtiEnv->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_CLASS_FILE_LOAD_HOOK,
                                                    NULL);
    if (error != JVMTI_ERROR_NONE) {
        return error;
    }

    return JVMTI_ERROR_NONE;
}

// Throw runtime exception
static void throwRuntimeExpection(JNIEnv* env, const char* fmt, ...) {
    char msgBuf[512];

    va_list args;
    va_start (args, fmt);
    vsnprintf(msgBuf, sizeof(msgBuf), fmt, args);
    va_end (args);

    jclass exceptionClass = env->FindClass("java/lang/RuntimeException");
    env->ThrowNew(exceptionClass, msgBuf);
}

// Register transformer hook
extern "C" JNIEXPORT void JNICALL
Java_com_android_dx_mockito_inline_JvmtiAgent_nativeRegisterTransformerHook(JNIEnv* env,
                                                                            jobject thiz) {
    sTransformer = env->NewGlobalRef(thiz);
}

// Unregister transformer hook
extern "C" JNIEXPORT void JNICALL
Java_com_android_dx_mockito_inline_JvmtiAgent_nativeUnregisterTransformerHook(JNIEnv* env,
                                                                              jobject thiz) {
    env->DeleteGlobalRef(sTransformer);
    sTransformer = NULL;
}

// Triggers retransformation of classes via this file's Transform method
extern "C" JNIEXPORT void JNICALL
Java_com_android_dx_mockito_inline_JvmtiAgent_nativeRetransformClasses(JNIEnv* env,
                                                                       jobject thiz,
                                                                       jobjectArray classes) {
    jsize numTransformedClasses = env->GetArrayLength(classes);
    jclass *transformedClasses = (jclass*) malloc(numTransformedClasses * sizeof(jclass));
    for (int i = 0; i < numTransformedClasses; i++) {
        transformedClasses[i] = (jclass) env->NewGlobalRef(env->GetObjectArrayElement(classes, i));
    }

    jvmtiError error = localJvmtiEnv->RetransformClasses(numTransformedClasses,
                                                         transformedClasses);

    for (int i = 0; i < numTransformedClasses; i++) {
        env->DeleteGlobalRef(transformedClasses[i]);
    }
    free(transformedClasses);

    if (error != JVMTI_ERROR_NONE) {
        throwRuntimeExpection(env, "Could not retransform classes: %d", error);
    }
}

// Adds a jar file to the bootstrap class loader
extern "C" JNIEXPORT void JNICALL
Java_com_android_dx_mockito_inline_JvmtiAgent_nativeAppendToBootstrapClassLoaderSearch(JNIEnv* env,
                                                                                  jclass klass,
                                                                                  jstring jarFile) {
    const char *jarFileNative = env->GetStringUTFChars(jarFile, 0);
    jvmtiError error = localJvmtiEnv->AddToBootstrapClassLoaderSearch(jarFileNative);

    if (error != JVMTI_ERROR_NONE) {
        throwRuntimeExpection(env, "Could not add %s to bootstrap class path: %d", jarFileNative,
                              error);
    }

    env->ReleaseStringUTFChars(jarFile, jarFileNative);
}
}  // namespace com_android_dx_mockito_inline