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      1 /*
      2  * Copyright (C) 2011 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #include "reflection-inl.h"
     18 
     19 #include "class_linker.h"
     20 #include "common_throws.h"
     21 #include "dex_file-inl.h"
     22 #include "jni_internal.h"
     23 #include "method_helper-inl.h"
     24 #include "mirror/art_field-inl.h"
     25 #include "mirror/art_method-inl.h"
     26 #include "mirror/class-inl.h"
     27 #include "mirror/class.h"
     28 #include "mirror/object_array-inl.h"
     29 #include "mirror/object_array.h"
     30 #include "nth_caller_visitor.h"
     31 #include "scoped_thread_state_change.h"
     32 #include "stack.h"
     33 #include "well_known_classes.h"
     34 
     35 namespace art {
     36 
     37 class ArgArray {
     38  public:
     39   explicit ArgArray(const char* shorty, uint32_t shorty_len)
     40       : shorty_(shorty), shorty_len_(shorty_len), num_bytes_(0) {
     41     size_t num_slots = shorty_len + 1;  // +1 in case of receiver.
     42     if (LIKELY((num_slots * 2) < kSmallArgArraySize)) {
     43       // We can trivially use the small arg array.
     44       arg_array_ = small_arg_array_;
     45     } else {
     46       // Analyze shorty to see if we need the large arg array.
     47       for (size_t i = 1; i < shorty_len; ++i) {
     48         char c = shorty[i];
     49         if (c == 'J' || c == 'D') {
     50           num_slots++;
     51         }
     52       }
     53       if (num_slots <= kSmallArgArraySize) {
     54         arg_array_ = small_arg_array_;
     55       } else {
     56         large_arg_array_.reset(new uint32_t[num_slots]);
     57         arg_array_ = large_arg_array_.get();
     58       }
     59     }
     60   }
     61 
     62   uint32_t* GetArray() {
     63     return arg_array_;
     64   }
     65 
     66   uint32_t GetNumBytes() {
     67     return num_bytes_;
     68   }
     69 
     70   void Append(uint32_t value) {
     71     arg_array_[num_bytes_ / 4] = value;
     72     num_bytes_ += 4;
     73   }
     74 
     75   void Append(mirror::Object* obj) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
     76     Append(StackReference<mirror::Object>::FromMirrorPtr(obj).AsVRegValue());
     77   }
     78 
     79   void AppendWide(uint64_t value) {
     80     // For ARM and MIPS portable, align wide values to 8 bytes (ArgArray starts at offset of 4).
     81 #if defined(ART_USE_PORTABLE_COMPILER) && (defined(__arm__) || defined(__mips__))
     82     if (num_bytes_ % 8 == 0) {
     83       num_bytes_ += 4;
     84     }
     85 #endif
     86     arg_array_[num_bytes_ / 4] = value;
     87     arg_array_[(num_bytes_ / 4) + 1] = value >> 32;
     88     num_bytes_ += 8;
     89   }
     90 
     91   void AppendFloat(float value) {
     92     jvalue jv;
     93     jv.f = value;
     94     Append(jv.i);
     95   }
     96 
     97   void AppendDouble(double value) {
     98     jvalue jv;
     99     jv.d = value;
    100     AppendWide(jv.j);
    101   }
    102 
    103   void BuildArgArrayFromVarArgs(const ScopedObjectAccessAlreadyRunnable& soa,
    104                                 mirror::Object* receiver, va_list ap)
    105       SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    106     // Set receiver if non-null (method is not static)
    107     if (receiver != nullptr) {
    108       Append(receiver);
    109     }
    110     for (size_t i = 1; i < shorty_len_; ++i) {
    111       switch (shorty_[i]) {
    112         case 'Z':
    113         case 'B':
    114         case 'C':
    115         case 'S':
    116         case 'I':
    117           Append(va_arg(ap, jint));
    118           break;
    119         case 'F':
    120           AppendFloat(va_arg(ap, jdouble));
    121           break;
    122         case 'L':
    123           Append(soa.Decode<mirror::Object*>(va_arg(ap, jobject)));
    124           break;
    125         case 'D':
    126           AppendDouble(va_arg(ap, jdouble));
    127           break;
    128         case 'J':
    129           AppendWide(va_arg(ap, jlong));
    130           break;
    131 #ifndef NDEBUG
    132         default:
    133           LOG(FATAL) << "Unexpected shorty character: " << shorty_[i];
    134 #endif
    135       }
    136     }
    137   }
    138 
    139   void BuildArgArrayFromJValues(const ScopedObjectAccessAlreadyRunnable& soa,
    140                                 mirror::Object* receiver, jvalue* args)
    141       SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    142     // Set receiver if non-null (method is not static)
    143     if (receiver != nullptr) {
    144       Append(receiver);
    145     }
    146     for (size_t i = 1, args_offset = 0; i < shorty_len_; ++i, ++args_offset) {
    147       switch (shorty_[i]) {
    148         case 'Z':
    149           Append(args[args_offset].z);
    150           break;
    151         case 'B':
    152           Append(args[args_offset].b);
    153           break;
    154         case 'C':
    155           Append(args[args_offset].c);
    156           break;
    157         case 'S':
    158           Append(args[args_offset].s);
    159           break;
    160         case 'I':
    161         case 'F':
    162           Append(args[args_offset].i);
    163           break;
    164         case 'L':
    165           Append(soa.Decode<mirror::Object*>(args[args_offset].l));
    166           break;
    167         case 'D':
    168         case 'J':
    169           AppendWide(args[args_offset].j);
    170           break;
    171 #ifndef NDEBUG
    172         default:
    173           LOG(FATAL) << "Unexpected shorty character: " << shorty_[i];
    174 #endif
    175       }
    176     }
    177   }
    178 
    179   void BuildArgArrayFromFrame(ShadowFrame* shadow_frame, uint32_t arg_offset)
    180       SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    181     // Set receiver if non-null (method is not static)
    182     size_t cur_arg = arg_offset;
    183     if (!shadow_frame->GetMethod()->IsStatic()) {
    184       Append(shadow_frame->GetVReg(cur_arg));
    185       cur_arg++;
    186     }
    187     for (size_t i = 1; i < shorty_len_; ++i) {
    188       switch (shorty_[i]) {
    189         case 'Z':
    190         case 'B':
    191         case 'C':
    192         case 'S':
    193         case 'I':
    194         case 'F':
    195         case 'L':
    196           Append(shadow_frame->GetVReg(cur_arg));
    197           cur_arg++;
    198           break;
    199         case 'D':
    200         case 'J':
    201           AppendWide(shadow_frame->GetVRegLong(cur_arg));
    202           cur_arg++;
    203           cur_arg++;
    204           break;
    205 #ifndef NDEBUG
    206         default:
    207           LOG(FATAL) << "Unexpected shorty character: " << shorty_[i];
    208 #endif
    209       }
    210     }
    211   }
    212 
    213   static void ThrowIllegalPrimitiveArgumentException(const char* expected,
    214                                                      const char* found_descriptor)
    215       SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    216     ThrowIllegalArgumentException(nullptr,
    217         StringPrintf("Invalid primitive conversion from %s to %s", expected,
    218                      PrettyDescriptor(found_descriptor).c_str()).c_str());
    219   }
    220 
    221   bool BuildArgArrayFromObjectArray(const ScopedObjectAccessAlreadyRunnable& soa,
    222                                     mirror::Object* receiver,
    223                                     mirror::ObjectArray<mirror::Object>* args, MethodHelper& mh)
    224       SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    225     const DexFile::TypeList* classes = mh.GetMethod()->GetParameterTypeList();
    226     // Set receiver if non-null (method is not static)
    227     if (receiver != nullptr) {
    228       Append(receiver);
    229     }
    230     for (size_t i = 1, args_offset = 0; i < shorty_len_; ++i, ++args_offset) {
    231       mirror::Object* arg = args->Get(args_offset);
    232       if (((shorty_[i] == 'L') && (arg != nullptr)) || ((arg == nullptr && shorty_[i] != 'L'))) {
    233         mirror::Class* dst_class =
    234             mh.GetClassFromTypeIdx(classes->GetTypeItem(args_offset).type_idx_);
    235         if (UNLIKELY(arg == nullptr || !arg->InstanceOf(dst_class))) {
    236           ThrowIllegalArgumentException(nullptr,
    237               StringPrintf("method %s argument %zd has type %s, got %s",
    238                   PrettyMethod(mh.GetMethod(), false).c_str(),
    239                   args_offset + 1,  // Humans don't count from 0.
    240                   PrettyDescriptor(dst_class).c_str(),
    241                   PrettyTypeOf(arg).c_str()).c_str());
    242           return false;
    243         }
    244       }
    245 
    246 #define DO_FIRST_ARG(match_descriptor, get_fn, append) { \
    247           if (LIKELY(arg != nullptr && arg->GetClass<>()->DescriptorEquals(match_descriptor))) { \
    248             mirror::ArtField* primitive_field = arg->GetClass()->GetIFields()->Get(0); \
    249             append(primitive_field-> get_fn(arg));
    250 
    251 #define DO_ARG(match_descriptor, get_fn, append) \
    252           } else if (LIKELY(arg != nullptr && \
    253                             arg->GetClass<>()->DescriptorEquals(match_descriptor))) { \
    254             mirror::ArtField* primitive_field = arg->GetClass()->GetIFields()->Get(0); \
    255             append(primitive_field-> get_fn(arg));
    256 
    257 #define DO_FAIL(expected) \
    258           } else { \
    259             if (arg->GetClass<>()->IsPrimitive()) { \
    260               std::string temp; \
    261               ThrowIllegalPrimitiveArgumentException(expected, \
    262                                                      arg->GetClass<>()->GetDescriptor(&temp)); \
    263             } else { \
    264               ThrowIllegalArgumentException(nullptr, \
    265                   StringPrintf("method %s argument %zd has type %s, got %s", \
    266                       PrettyMethod(mh.GetMethod(), false).c_str(), \
    267                       args_offset + 1, \
    268                       expected, \
    269                       PrettyTypeOf(arg).c_str()).c_str()); \
    270             } \
    271             return false; \
    272           } }
    273 
    274       switch (shorty_[i]) {
    275         case 'L':
    276           Append(arg);
    277           break;
    278         case 'Z':
    279           DO_FIRST_ARG("Ljava/lang/Boolean;", GetBoolean, Append)
    280           DO_FAIL("boolean")
    281           break;
    282         case 'B':
    283           DO_FIRST_ARG("Ljava/lang/Byte;", GetByte, Append)
    284           DO_FAIL("byte")
    285           break;
    286         case 'C':
    287           DO_FIRST_ARG("Ljava/lang/Character;", GetChar, Append)
    288           DO_FAIL("char")
    289           break;
    290         case 'S':
    291           DO_FIRST_ARG("Ljava/lang/Short;", GetShort, Append)
    292           DO_ARG("Ljava/lang/Byte;", GetByte, Append)
    293           DO_FAIL("short")
    294           break;
    295         case 'I':
    296           DO_FIRST_ARG("Ljava/lang/Integer;", GetInt, Append)
    297           DO_ARG("Ljava/lang/Character;", GetChar, Append)
    298           DO_ARG("Ljava/lang/Short;", GetShort, Append)
    299           DO_ARG("Ljava/lang/Byte;", GetByte, Append)
    300           DO_FAIL("int")
    301           break;
    302         case 'J':
    303           DO_FIRST_ARG("Ljava/lang/Long;", GetLong, AppendWide)
    304           DO_ARG("Ljava/lang/Integer;", GetInt, AppendWide)
    305           DO_ARG("Ljava/lang/Character;", GetChar, AppendWide)
    306           DO_ARG("Ljava/lang/Short;", GetShort, AppendWide)
    307           DO_ARG("Ljava/lang/Byte;", GetByte, AppendWide)
    308           DO_FAIL("long")
    309           break;
    310         case 'F':
    311           DO_FIRST_ARG("Ljava/lang/Float;", GetFloat, AppendFloat)
    312           DO_ARG("Ljava/lang/Long;", GetLong, AppendFloat)
    313           DO_ARG("Ljava/lang/Integer;", GetInt, AppendFloat)
    314           DO_ARG("Ljava/lang/Character;", GetChar, AppendFloat)
    315           DO_ARG("Ljava/lang/Short;", GetShort, AppendFloat)
    316           DO_ARG("Ljava/lang/Byte;", GetByte, AppendFloat)
    317           DO_FAIL("float")
    318           break;
    319         case 'D':
    320           DO_FIRST_ARG("Ljava/lang/Double;", GetDouble, AppendDouble)
    321           DO_ARG("Ljava/lang/Float;", GetFloat, AppendDouble)
    322           DO_ARG("Ljava/lang/Long;", GetLong, AppendDouble)
    323           DO_ARG("Ljava/lang/Integer;", GetInt, AppendDouble)
    324           DO_ARG("Ljava/lang/Character;", GetChar, AppendDouble)
    325           DO_ARG("Ljava/lang/Short;", GetShort, AppendDouble)
    326           DO_ARG("Ljava/lang/Byte;", GetByte, AppendDouble)
    327           DO_FAIL("double")
    328           break;
    329 #ifndef NDEBUG
    330         default:
    331           LOG(FATAL) << "Unexpected shorty character: " << shorty_[i];
    332 #endif
    333       }
    334 #undef DO_FIRST_ARG
    335 #undef DO_ARG
    336 #undef DO_FAIL
    337     }
    338     return true;
    339   }
    340 
    341  private:
    342   enum { kSmallArgArraySize = 16 };
    343   const char* const shorty_;
    344   const uint32_t shorty_len_;
    345   uint32_t num_bytes_;
    346   uint32_t* arg_array_;
    347   uint32_t small_arg_array_[kSmallArgArraySize];
    348   std::unique_ptr<uint32_t[]> large_arg_array_;
    349 };
    350 
    351 static void CheckMethodArguments(mirror::ArtMethod* m, uint32_t* args)
    352     SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    353   const DexFile::TypeList* params = m->GetParameterTypeList();
    354   if (params == nullptr) {
    355     return;  // No arguments so nothing to check.
    356   }
    357   uint32_t offset = 0;
    358   uint32_t num_params = params->Size();
    359   size_t error_count = 0;
    360   if (!m->IsStatic()) {
    361     offset = 1;
    362   }
    363   // TODO: If args contain object references, it may cause problems
    364   Thread* self = Thread::Current();
    365   StackHandleScope<1> hs(self);
    366   Handle<mirror::ArtMethod> h_m(hs.NewHandle(m));
    367   MethodHelper mh(h_m);
    368   for (uint32_t i = 0; i < num_params; i++) {
    369     uint16_t type_idx = params->GetTypeItem(i).type_idx_;
    370     mirror::Class* param_type = mh.GetClassFromTypeIdx(type_idx);
    371     if (param_type == nullptr) {
    372       CHECK(self->IsExceptionPending());
    373       LOG(ERROR) << "Internal error: unresolvable type for argument type in JNI invoke: "
    374           << h_m->GetTypeDescriptorFromTypeIdx(type_idx) << "\n"
    375           << self->GetException(nullptr)->Dump();
    376       self->ClearException();
    377       ++error_count;
    378     } else if (!param_type->IsPrimitive()) {
    379       // TODO: check primitives are in range.
    380       // TODO: There is a compaction bug here since GetClassFromTypeIdx can cause thread suspension,
    381       // this is a hard to fix problem since the args can contain Object*, we need to save and
    382       // restore them by using a visitor similar to the ones used in the trampoline entrypoints.
    383       mirror::Object* argument = reinterpret_cast<mirror::Object*>(args[i + offset]);
    384       if (argument != nullptr && !argument->InstanceOf(param_type)) {
    385         LOG(ERROR) << "JNI ERROR (app bug): attempt to pass an instance of "
    386                    << PrettyTypeOf(argument) << " as argument " << (i + 1)
    387                    << " to " << PrettyMethod(h_m.Get());
    388         ++error_count;
    389       }
    390     } else if (param_type->IsPrimitiveLong() || param_type->IsPrimitiveDouble()) {
    391       offset++;
    392     }
    393   }
    394   if (error_count > 0) {
    395     // TODO: pass the JNI function name (such as "CallVoidMethodV") through so we can call JniAbort
    396     // with an argument.
    397     JniAbortF(nullptr, "bad arguments passed to %s (see above for details)",
    398               PrettyMethod(h_m.Get()).c_str());
    399   }
    400 }
    401 
    402 static mirror::ArtMethod* FindVirtualMethod(mirror::Object* receiver,
    403                                             mirror::ArtMethod* method)
    404     SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    405   return receiver->GetClass()->FindVirtualMethodForVirtualOrInterface(method);
    406 }
    407 
    408 
    409 static void InvokeWithArgArray(const ScopedObjectAccessAlreadyRunnable& soa,
    410                                mirror::ArtMethod* method, ArgArray* arg_array, JValue* result,
    411                                const char* shorty)
    412     SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    413   uint32_t* args = arg_array->GetArray();
    414   if (UNLIKELY(soa.Env()->check_jni)) {
    415     CheckMethodArguments(method, args);
    416   }
    417   method->Invoke(soa.Self(), args, arg_array->GetNumBytes(), result, shorty);
    418 }
    419 
    420 JValue InvokeWithVarArgs(const ScopedObjectAccessAlreadyRunnable& soa, jobject obj, jmethodID mid,
    421                          va_list args)
    422     SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    423   // We want to make sure that the stack is not within a small distance from the
    424   // protected region in case we are calling into a leaf function whose stack
    425   // check has been elided.
    426   if (UNLIKELY(__builtin_frame_address(0) < soa.Self()->GetStackEnd())) {
    427     ThrowStackOverflowError(soa.Self());
    428     return JValue();
    429   }
    430 
    431   mirror::ArtMethod* method = soa.DecodeMethod(mid);
    432   mirror::Object* receiver = method->IsStatic() ? nullptr : soa.Decode<mirror::Object*>(obj);
    433   uint32_t shorty_len = 0;
    434   const char* shorty = method->GetShorty(&shorty_len);
    435   JValue result;
    436   ArgArray arg_array(shorty, shorty_len);
    437   arg_array.BuildArgArrayFromVarArgs(soa, receiver, args);
    438   InvokeWithArgArray(soa, method, &arg_array, &result, shorty);
    439   return result;
    440 }
    441 
    442 JValue InvokeWithJValues(const ScopedObjectAccessAlreadyRunnable& soa, mirror::Object* receiver,
    443                          jmethodID mid, jvalue* args) {
    444   // We want to make sure that the stack is not within a small distance from the
    445   // protected region in case we are calling into a leaf function whose stack
    446   // check has been elided.
    447   if (UNLIKELY(__builtin_frame_address(0) < soa.Self()->GetStackEnd())) {
    448     ThrowStackOverflowError(soa.Self());
    449     return JValue();
    450   }
    451 
    452   mirror::ArtMethod* method = soa.DecodeMethod(mid);
    453   uint32_t shorty_len = 0;
    454   const char* shorty = method->GetShorty(&shorty_len);
    455   JValue result;
    456   ArgArray arg_array(shorty, shorty_len);
    457   arg_array.BuildArgArrayFromJValues(soa, receiver, args);
    458   InvokeWithArgArray(soa, method, &arg_array, &result, shorty);
    459   return result;
    460 }
    461 
    462 JValue InvokeVirtualOrInterfaceWithJValues(const ScopedObjectAccessAlreadyRunnable& soa,
    463                                            mirror::Object* receiver, jmethodID mid, jvalue* args) {
    464   // We want to make sure that the stack is not within a small distance from the
    465   // protected region in case we are calling into a leaf function whose stack
    466   // check has been elided.
    467   if (UNLIKELY(__builtin_frame_address(0) < soa.Self()->GetStackEnd())) {
    468     ThrowStackOverflowError(soa.Self());
    469     return JValue();
    470   }
    471 
    472   mirror::ArtMethod* method = FindVirtualMethod(receiver, soa.DecodeMethod(mid));
    473   uint32_t shorty_len = 0;
    474   const char* shorty = method->GetShorty(&shorty_len);
    475   JValue result;
    476   ArgArray arg_array(shorty, shorty_len);
    477   arg_array.BuildArgArrayFromJValues(soa, receiver, args);
    478   InvokeWithArgArray(soa, method, &arg_array, &result, shorty);
    479   return result;
    480 }
    481 
    482 JValue InvokeVirtualOrInterfaceWithVarArgs(const ScopedObjectAccessAlreadyRunnable& soa,
    483                                            jobject obj, jmethodID mid, va_list args) {
    484   // We want to make sure that the stack is not within a small distance from the
    485   // protected region in case we are calling into a leaf function whose stack
    486   // check has been elided.
    487   if (UNLIKELY(__builtin_frame_address(0) < soa.Self()->GetStackEnd())) {
    488     ThrowStackOverflowError(soa.Self());
    489     return JValue();
    490   }
    491 
    492   mirror::Object* receiver = soa.Decode<mirror::Object*>(obj);
    493   mirror::ArtMethod* method = FindVirtualMethod(receiver, soa.DecodeMethod(mid));
    494   uint32_t shorty_len = 0;
    495   const char* shorty = method->GetShorty(&shorty_len);
    496   JValue result;
    497   ArgArray arg_array(shorty, shorty_len);
    498   arg_array.BuildArgArrayFromVarArgs(soa, receiver, args);
    499   InvokeWithArgArray(soa, method, &arg_array, &result, shorty);
    500   return result;
    501 }
    502 
    503 void InvokeWithShadowFrame(Thread* self, ShadowFrame* shadow_frame, uint16_t arg_offset,
    504                            MethodHelper& mh, JValue* result) {
    505   // We want to make sure that the stack is not within a small distance from the
    506   // protected region in case we are calling into a leaf function whose stack
    507   // check has been elided.
    508   if (UNLIKELY(__builtin_frame_address(0) < self->GetStackEnd())) {
    509     ThrowStackOverflowError(self);
    510     return;
    511   }
    512 
    513   ArgArray arg_array(mh.GetShorty(), mh.GetShortyLength());
    514   arg_array.BuildArgArrayFromFrame(shadow_frame, arg_offset);
    515   shadow_frame->GetMethod()->Invoke(self, arg_array.GetArray(), arg_array.GetNumBytes(), result,
    516                                     mh.GetShorty());
    517 }
    518 
    519 jobject InvokeMethod(const ScopedObjectAccessAlreadyRunnable& soa, jobject javaMethod,
    520                      jobject javaReceiver, jobject javaArgs, bool accessible) {
    521   // We want to make sure that the stack is not within a small distance from the
    522   // protected region in case we are calling into a leaf function whose stack
    523   // check has been elided.
    524   if (UNLIKELY(__builtin_frame_address(0) <
    525                soa.Self()->GetStackEndForInterpreter(true))) {
    526     ThrowStackOverflowError(soa.Self());
    527     return nullptr;
    528   }
    529 
    530   mirror::ArtMethod* m = mirror::ArtMethod::FromReflectedMethod(soa, javaMethod);
    531 
    532   mirror::Class* declaring_class = m->GetDeclaringClass();
    533   if (UNLIKELY(!declaring_class->IsInitialized())) {
    534     StackHandleScope<1> hs(soa.Self());
    535     Handle<mirror::Class> h_class(hs.NewHandle(declaring_class));
    536     if (!Runtime::Current()->GetClassLinker()->EnsureInitialized(h_class, true, true)) {
    537       return nullptr;
    538     }
    539     declaring_class = h_class.Get();
    540   }
    541 
    542   mirror::Object* receiver = nullptr;
    543   if (!m->IsStatic()) {
    544     // Check that the receiver is non-null and an instance of the field's declaring class.
    545     receiver = soa.Decode<mirror::Object*>(javaReceiver);
    546     if (!VerifyObjectIsClass(receiver, declaring_class)) {
    547       return NULL;
    548     }
    549 
    550     // Find the actual implementation of the virtual method.
    551     m = receiver->GetClass()->FindVirtualMethodForVirtualOrInterface(m);
    552   }
    553 
    554   // Get our arrays of arguments and their types, and check they're the same size.
    555   mirror::ObjectArray<mirror::Object>* objects =
    556       soa.Decode<mirror::ObjectArray<mirror::Object>*>(javaArgs);
    557   const DexFile::TypeList* classes = m->GetParameterTypeList();
    558   uint32_t classes_size = (classes == nullptr) ? 0 : classes->Size();
    559   uint32_t arg_count = (objects != nullptr) ? objects->GetLength() : 0;
    560   if (arg_count != classes_size) {
    561     ThrowIllegalArgumentException(NULL,
    562                                   StringPrintf("Wrong number of arguments; expected %d, got %d",
    563                                                classes_size, arg_count).c_str());
    564     return NULL;
    565   }
    566 
    567   // If method is not set to be accessible, verify it can be accessed by the caller.
    568   if (!accessible && !VerifyAccess(soa.Self(), receiver, declaring_class, m->GetAccessFlags())) {
    569     ThrowIllegalAccessException(nullptr, StringPrintf("Cannot access method: %s",
    570                                                       PrettyMethod(m).c_str()).c_str());
    571     return nullptr;
    572   }
    573 
    574   // Invoke the method.
    575   JValue result;
    576   uint32_t shorty_len = 0;
    577   const char* shorty = m->GetShorty(&shorty_len);
    578   ArgArray arg_array(shorty, shorty_len);
    579   StackHandleScope<1> hs(soa.Self());
    580   MethodHelper mh(hs.NewHandle(m));
    581   if (!arg_array.BuildArgArrayFromObjectArray(soa, receiver, objects, mh)) {
    582     CHECK(soa.Self()->IsExceptionPending());
    583     return nullptr;
    584   }
    585 
    586   InvokeWithArgArray(soa, m, &arg_array, &result, shorty);
    587 
    588   // Wrap any exception with "Ljava/lang/reflect/InvocationTargetException;" and return early.
    589   if (soa.Self()->IsExceptionPending()) {
    590     jthrowable th = soa.Env()->ExceptionOccurred();
    591     soa.Env()->ExceptionClear();
    592     jclass exception_class = soa.Env()->FindClass("java/lang/reflect/InvocationTargetException");
    593     jmethodID mid = soa.Env()->GetMethodID(exception_class, "<init>", "(Ljava/lang/Throwable;)V");
    594     jobject exception_instance = soa.Env()->NewObject(exception_class, mid, th);
    595     soa.Env()->Throw(reinterpret_cast<jthrowable>(exception_instance));
    596     return NULL;
    597   }
    598 
    599   // Box if necessary and return.
    600   return soa.AddLocalReference<jobject>(BoxPrimitive(mh.GetReturnType()->GetPrimitiveType(),
    601                                                      result));
    602 }
    603 
    604 bool VerifyObjectIsClass(mirror::Object* o, mirror::Class* c) {
    605   if (o == NULL) {
    606     ThrowNullPointerException(NULL, "null receiver");
    607     return false;
    608   } else if (!o->InstanceOf(c)) {
    609     std::string expected_class_name(PrettyDescriptor(c));
    610     std::string actual_class_name(PrettyTypeOf(o));
    611     ThrowIllegalArgumentException(NULL,
    612                                   StringPrintf("Expected receiver of type %s, but got %s",
    613                                                expected_class_name.c_str(),
    614                                                actual_class_name.c_str()).c_str());
    615     return false;
    616   }
    617   return true;
    618 }
    619 
    620 mirror::Object* BoxPrimitive(Primitive::Type src_class, const JValue& value) {
    621   if (src_class == Primitive::kPrimNot) {
    622     return value.GetL();
    623   }
    624   if (src_class == Primitive::kPrimVoid) {
    625     // There's no such thing as a void field, and void methods invoked via reflection return null.
    626     return nullptr;
    627   }
    628 
    629   jmethodID m = nullptr;
    630   const char* shorty;
    631   switch (src_class) {
    632   case Primitive::kPrimBoolean:
    633     m = WellKnownClasses::java_lang_Boolean_valueOf;
    634     shorty = "LZ";
    635     break;
    636   case Primitive::kPrimByte:
    637     m = WellKnownClasses::java_lang_Byte_valueOf;
    638     shorty = "LB";
    639     break;
    640   case Primitive::kPrimChar:
    641     m = WellKnownClasses::java_lang_Character_valueOf;
    642     shorty = "LC";
    643     break;
    644   case Primitive::kPrimDouble:
    645     m = WellKnownClasses::java_lang_Double_valueOf;
    646     shorty = "LD";
    647     break;
    648   case Primitive::kPrimFloat:
    649     m = WellKnownClasses::java_lang_Float_valueOf;
    650     shorty = "LF";
    651     break;
    652   case Primitive::kPrimInt:
    653     m = WellKnownClasses::java_lang_Integer_valueOf;
    654     shorty = "LI";
    655     break;
    656   case Primitive::kPrimLong:
    657     m = WellKnownClasses::java_lang_Long_valueOf;
    658     shorty = "LJ";
    659     break;
    660   case Primitive::kPrimShort:
    661     m = WellKnownClasses::java_lang_Short_valueOf;
    662     shorty = "LS";
    663     break;
    664   default:
    665     LOG(FATAL) << static_cast<int>(src_class);
    666     shorty = nullptr;
    667   }
    668 
    669   ScopedObjectAccessUnchecked soa(Thread::Current());
    670   DCHECK_EQ(soa.Self()->GetState(), kRunnable);
    671 
    672   ArgArray arg_array(shorty, 2);
    673   JValue result;
    674   if (src_class == Primitive::kPrimDouble || src_class == Primitive::kPrimLong) {
    675     arg_array.AppendWide(value.GetJ());
    676   } else {
    677     arg_array.Append(value.GetI());
    678   }
    679 
    680   soa.DecodeMethod(m)->Invoke(soa.Self(), arg_array.GetArray(), arg_array.GetNumBytes(),
    681                               &result, shorty);
    682   return result.GetL();
    683 }
    684 
    685 static std::string UnboxingFailureKind(mirror::ArtField* f)
    686     SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    687   if (f != nullptr) {
    688     return "field " + PrettyField(f, false);
    689   }
    690   return "result";
    691 }
    692 
    693 static bool UnboxPrimitive(const ThrowLocation* throw_location, mirror::Object* o,
    694                            mirror::Class* dst_class, mirror::ArtField* f,
    695                            JValue* unboxed_value)
    696     SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
    697   bool unbox_for_result = (f == nullptr);
    698   if (!dst_class->IsPrimitive()) {
    699     if (UNLIKELY(o != nullptr && !o->InstanceOf(dst_class))) {
    700       if (!unbox_for_result) {
    701         ThrowIllegalArgumentException(throw_location,
    702                                       StringPrintf("%s has type %s, got %s",
    703                                                    UnboxingFailureKind(f).c_str(),
    704                                                    PrettyDescriptor(dst_class).c_str(),
    705                                                    PrettyTypeOf(o).c_str()).c_str());
    706       } else {
    707         ThrowClassCastException(throw_location,
    708                                 StringPrintf("Couldn't convert result of type %s to %s",
    709                                              PrettyTypeOf(o).c_str(),
    710                                              PrettyDescriptor(dst_class).c_str()).c_str());
    711       }
    712       return false;
    713     }
    714     unboxed_value->SetL(o);
    715     return true;
    716   }
    717   if (UNLIKELY(dst_class->GetPrimitiveType() == Primitive::kPrimVoid)) {
    718     ThrowIllegalArgumentException(throw_location,
    719                                   StringPrintf("Can't unbox %s to void",
    720                                                UnboxingFailureKind(f).c_str()).c_str());
    721     return false;
    722   }
    723   if (UNLIKELY(o == nullptr)) {
    724     if (!unbox_for_result) {
    725       ThrowIllegalArgumentException(throw_location,
    726                                     StringPrintf("%s has type %s, got null",
    727                                                  UnboxingFailureKind(f).c_str(),
    728                                                  PrettyDescriptor(dst_class).c_str()).c_str());
    729     } else {
    730       ThrowNullPointerException(throw_location,
    731                                 StringPrintf("Expected to unbox a '%s' primitive type but was returned null",
    732                                              PrettyDescriptor(dst_class).c_str()).c_str());
    733     }
    734     return false;
    735   }
    736 
    737   JValue boxed_value;
    738   mirror::Class* klass = o->GetClass();
    739   mirror::Class* src_class = nullptr;
    740   ClassLinker* class_linker = Runtime::Current()->GetClassLinker();
    741   mirror::ArtField* primitive_field = o->GetClass()->GetIFields()->Get(0);
    742   if (klass->DescriptorEquals("Ljava/lang/Boolean;")) {
    743     src_class = class_linker->FindPrimitiveClass('Z');
    744     boxed_value.SetZ(primitive_field->GetBoolean(o));
    745   } else if (klass->DescriptorEquals("Ljava/lang/Byte;")) {
    746     src_class = class_linker->FindPrimitiveClass('B');
    747     boxed_value.SetB(primitive_field->GetByte(o));
    748   } else if (klass->DescriptorEquals("Ljava/lang/Character;")) {
    749     src_class = class_linker->FindPrimitiveClass('C');
    750     boxed_value.SetC(primitive_field->GetChar(o));
    751   } else if (klass->DescriptorEquals("Ljava/lang/Float;")) {
    752     src_class = class_linker->FindPrimitiveClass('F');
    753     boxed_value.SetF(primitive_field->GetFloat(o));
    754   } else if (klass->DescriptorEquals("Ljava/lang/Double;")) {
    755     src_class = class_linker->FindPrimitiveClass('D');
    756     boxed_value.SetD(primitive_field->GetDouble(o));
    757   } else if (klass->DescriptorEquals("Ljava/lang/Integer;")) {
    758     src_class = class_linker->FindPrimitiveClass('I');
    759     boxed_value.SetI(primitive_field->GetInt(o));
    760   } else if (klass->DescriptorEquals("Ljava/lang/Long;")) {
    761     src_class = class_linker->FindPrimitiveClass('J');
    762     boxed_value.SetJ(primitive_field->GetLong(o));
    763   } else if (klass->DescriptorEquals("Ljava/lang/Short;")) {
    764     src_class = class_linker->FindPrimitiveClass('S');
    765     boxed_value.SetS(primitive_field->GetShort(o));
    766   } else {
    767     std::string temp;
    768     ThrowIllegalArgumentException(throw_location,
    769         StringPrintf("%s has type %s, got %s", UnboxingFailureKind(f).c_str(),
    770             PrettyDescriptor(dst_class).c_str(),
    771             PrettyDescriptor(o->GetClass()->GetDescriptor(&temp)).c_str()).c_str());
    772     return false;
    773   }
    774 
    775   return ConvertPrimitiveValue(throw_location, unbox_for_result,
    776                                src_class->GetPrimitiveType(), dst_class->GetPrimitiveType(),
    777                                boxed_value, unboxed_value);
    778 }
    779 
    780 bool UnboxPrimitiveForField(mirror::Object* o, mirror::Class* dst_class, mirror::ArtField* f,
    781                             JValue* unboxed_value) {
    782   DCHECK(f != nullptr);
    783   return UnboxPrimitive(nullptr, o, dst_class, f, unboxed_value);
    784 }
    785 
    786 bool UnboxPrimitiveForResult(const ThrowLocation& throw_location, mirror::Object* o,
    787                              mirror::Class* dst_class, JValue* unboxed_value) {
    788   return UnboxPrimitive(&throw_location, o, dst_class, nullptr, unboxed_value);
    789 }
    790 
    791 bool VerifyAccess(Thread* self, mirror::Object* obj, mirror::Class* declaring_class, uint32_t access_flags) {
    792   if ((access_flags & kAccPublic) != 0) {
    793     return true;
    794   }
    795   NthCallerVisitor visitor(self, 2);
    796   visitor.WalkStack();
    797   if (UNLIKELY(visitor.caller == nullptr)) {
    798     // The caller is an attached native thread.
    799     return false;
    800   }
    801   mirror::Class* caller_class = visitor.caller->GetDeclaringClass();
    802   if (caller_class == declaring_class) {
    803     return true;
    804   }
    805   if ((access_flags & kAccPrivate) != 0) {
    806     return false;
    807   }
    808   if ((access_flags & kAccProtected) != 0) {
    809     if (obj != nullptr && !obj->InstanceOf(caller_class) &&
    810         !declaring_class->IsInSamePackage(caller_class)) {
    811       return false;
    812     } else if (declaring_class->IsAssignableFrom(caller_class)) {
    813       return true;
    814     }
    815   }
    816   return declaring_class->IsInSamePackage(caller_class);
    817 }
    818 
    819 }  // namespace art
    820