runtime/hidden_api.cc - platform/art - Gitiles

 /*
  * Copyright (C) 2018 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 "hidden_api.h"

 #include <nativehelper/scoped_local_ref.h>

 #include "art_field-inl.h"
 #include "art_method-inl.h"
 #include "base/dumpable.h"
 #include "base/file_utils.h"
 #include "class_root.h"
 #include "dex/class_accessor-inl.h"
 #include "dex/dex_file_loader.h"
 #include "mirror/class_ext.h"
 #include "oat_file.h"
 #include "scoped_thread_state_change.h"
 #include "thread-inl.h"
 #include "well_known_classes.h"

 namespace art {
 namespace hiddenapi {

 // Set to true if we should always print a warning in logcat for all hidden API accesses, not just
 // dark grey and black. This can be set to true for developer preview / beta builds, but should be
 // false for public release builds.
 // Note that when flipping this flag, you must also update the expectations of test 674-hiddenapi
 // as it affects whether or not we warn for light grey APIs that have been added to the exemptions
 // list.
 static constexpr bool kLogAllAccesses = false;

 static inline std::ostream& operator<<(std::ostream& os, AccessMethod value) {
   switch (value) {
     case AccessMethod::kNone:
       LOG(FATAL) << "Internal access to hidden API should not be logged";
       UNREACHABLE();
     case AccessMethod::kReflection:
       os << "reflection";
       break;
     case AccessMethod::kJNI:
       os << "JNI";
       break;
     case AccessMethod::kLinking:
       os << "linking";
       break;
   }
   return os;
 }

 static inline std::ostream& operator<<(std::ostream& os, const AccessContext& value)
     REQUIRES_SHARED(Locks::mutator_lock_) {
   if (!value.GetClass().IsNull()) {
     std::string tmp;
     os << value.GetClass()->GetDescriptor(&tmp);
   } else if (value.GetDexFile() != nullptr) {
     os << value.GetDexFile()->GetLocation();
   } else {
     os << "<unknown_caller>";
   }
   return os;
 }

 static Domain DetermineDomainFromLocation(const std::string& dex_location,
                                           ObjPtr<mirror::ClassLoader> class_loader) {
   // If running with APEX, check `path` against known APEX locations.
   // These checks will be skipped on target buildbots where ANDROID_ART_ROOT
   // is set to "/system".
   if (ArtModuleRootDistinctFromAndroidRoot()) {
     if (LocationIsOnArtModule(dex_location.c_str()) ||
         LocationIsOnConscryptModule(dex_location.c_str())) {
       return Domain::kCorePlatform;
     }

     if (LocationIsOnApex(dex_location.c_str())) {
       return Domain::kPlatform;
     }
   }

   if (LocationIsOnSystemFramework(dex_location.c_str())) {
     return Domain::kPlatform;
   }

   if (class_loader.IsNull()) {
     LOG(WARNING) << "DexFile " << dex_location
         << " is in boot class path but is not in a known location";
     return Domain::kPlatform;
   }

   return Domain::kApplication;
 }

 void InitializeDexFileDomain(const DexFile& dex_file, ObjPtr<mirror::ClassLoader> class_loader) {
   Domain dex_domain = DetermineDomainFromLocation(dex_file.GetLocation(), class_loader);

   // Assign the domain unless a more permissive domain has already been assigned.
   // This may happen when DexFile is initialized as trusted.
   if (IsDomainMoreTrustedThan(dex_domain, dex_file.GetHiddenapiDomain())) {
     dex_file.SetHiddenapiDomain(dex_domain);
   }
 }

 namespace detail {

 // Do not change the values of items in this enum, as they are written to the
 // event log for offline analysis. Any changes will interfere with that analysis.
 enum AccessContextFlags {
   // Accessed member is a field if this bit is set, else a method
   kMemberIsField = 1 << 0,
   // Indicates if access was denied to the member, instead of just printing a warning.
   kAccessDenied  = 1 << 1,
 };

 MemberSignature::MemberSignature(ArtField* field) {
   class_name_ = field->GetDeclaringClass()->GetDescriptor(&tmp_);
   member_name_ = field->GetName();
   type_signature_ = field->GetTypeDescriptor();
   type_ = kField;
 }

 MemberSignature::MemberSignature(ArtMethod* method) {
   DCHECK(method == method->GetInterfaceMethodIfProxy(kRuntimePointerSize))
       << "Caller should have replaced proxy method with interface method";
   class_name_ = method->GetDeclaringClass()->GetDescriptor(&tmp_);
   member_name_ = method->GetName();
   type_signature_ = method->GetSignature().ToString();
   type_ = kMethod;
 }

 MemberSignature::MemberSignature(const ClassAccessor::Field& field) {
   const DexFile& dex_file = field.GetDexFile();
   const dex::FieldId& field_id = dex_file.GetFieldId(field.GetIndex());
   class_name_ = dex_file.GetFieldDeclaringClassDescriptor(field_id);
   member_name_ = dex_file.GetFieldName(field_id);
   type_signature_ = dex_file.GetFieldTypeDescriptor(field_id);
   type_ = kField;
 }

 MemberSignature::MemberSignature(const ClassAccessor::Method& method) {
   const DexFile& dex_file = method.GetDexFile();
   const dex::MethodId& method_id = dex_file.GetMethodId(method.GetIndex());
   class_name_ = dex_file.GetMethodDeclaringClassDescriptor(method_id);
   member_name_ = dex_file.GetMethodName(method_id);
   type_signature_ = dex_file.GetMethodSignature(method_id).ToString();
   type_ = kMethod;
 }

 inline std::vector<const char*> MemberSignature::GetSignatureParts() const {
   if (type_ == kField) {
     return { class_name_.c_str(), "->", member_name_.c_str(), ":", type_signature_.c_str() };
   } else {
     DCHECK_EQ(type_, kMethod);
     return { class_name_.c_str(), "->", member_name_.c_str(), type_signature_.c_str() };
   }
 }

 bool MemberSignature::DoesPrefixMatch(const std::string& prefix) const {
   size_t pos = 0;
   for (const char* part : GetSignatureParts()) {
     size_t count = std::min(prefix.length() - pos, strlen(part));
     if (prefix.compare(pos, count, part, 0, count) == 0) {
       pos += count;
     } else {
       return false;
     }
   }
   // We have a complete match if all parts match (we exit the loop without
   // returning) AND we've matched the whole prefix.
   return pos == prefix.length();
 }

 bool MemberSignature::IsExempted(const std::vector<std::string>& exemptions) {
   for (const std::string& exemption : exemptions) {
     if (DoesPrefixMatch(exemption)) {
       return true;
     }
   }
   return false;
 }

 void MemberSignature::Dump(std::ostream& os) const {
   for (const char* part : GetSignatureParts()) {
     os << part;
   }
 }

 void MemberSignature::WarnAboutAccess(AccessMethod access_method,
                                       hiddenapi::ApiList list,
                                       bool access_denied) {
   LOG(WARNING) << "Accessing hidden " << (type_ == kField ? "field " : "method ")
                << Dumpable<MemberSignature>(*this) << " (" << list << ", " << access_method
                << (access_denied ? ", denied)" : ", allowed)");
 }

 bool MemberSignature::Equals(const MemberSignature& other) {
   return type_ == other.type_ &&
          class_name_ == other.class_name_ &&
          member_name_ == other.member_name_ &&
          type_signature_ == other.type_signature_;
 }

 bool MemberSignature::MemberNameAndTypeMatch(const MemberSignature& other) {
   return member_name_ == other.member_name_ && type_signature_ == other.type_signature_;
 }

 void MemberSignature::LogAccessToEventLog(uint32_t sampled_value,
                                           AccessMethod access_method,
                                           bool access_denied) {
 #ifdef ART_TARGET_ANDROID
   if (access_method == AccessMethod::kLinking || access_method == AccessMethod::kNone) {
     // Linking warnings come from static analysis/compilation of the bytecode
     // and can contain false positives (i.e. code that is never run). We choose
     // not to log these in the event log.
     // None does not correspond to actual access, so should also be ignored.
     return;
   }
   Runtime* runtime = Runtime::Current();
   if (runtime->IsAotCompiler()) {
     return;
   }
   JNIEnvExt* env = Thread::Current()->GetJniEnv();
   const std::string& package_name = Runtime::Current()->GetProcessPackageName();
   ScopedLocalRef<jstring> package_str(env, env->NewStringUTF(package_name.c_str()));
   if (env->ExceptionCheck()) {
     env->ExceptionClear();
     LOG(ERROR) << "Unable to allocate string for package name which called hidden api";
   }
   std::ostringstream signature_str;
   Dump(signature_str);
   ScopedLocalRef<jstring> signature_jstr(env,
       env->NewStringUTF(signature_str.str().c_str()));
   if (env->ExceptionCheck()) {
     env->ExceptionClear();
     LOG(ERROR) << "Unable to allocate string for hidden api method signature";
   }
   env->CallStaticVoidMethod(WellKnownClasses::dalvik_system_VMRuntime,
       WellKnownClasses::dalvik_system_VMRuntime_hiddenApiUsed,
       sampled_value,
       package_str.get(),
       signature_jstr.get(),
       static_cast<jint>(access_method),
       access_denied);
   if (env->ExceptionCheck()) {
     env->ExceptionClear();
     LOG(ERROR) << "Unable to report hidden api usage";
   }
 #else
   UNUSED(sampled_value);
   UNUSED(access_method);
   UNUSED(access_denied);
 #endif
 }

 void MemberSignature::NotifyHiddenApiListener(AccessMethod access_method) {
   if (access_method != AccessMethod::kReflection && access_method != AccessMethod::kJNI) {
     // We can only up-call into Java during reflection and JNI down-calls.
     return;
   }

   Runtime* runtime = Runtime::Current();
   if (!runtime->IsAotCompiler()) {
     ScopedObjectAccessUnchecked soa(Thread::Current());

     ScopedLocalRef<jobject> consumer_object(soa.Env(),
         soa.Env()->GetStaticObjectField(
             WellKnownClasses::dalvik_system_VMRuntime,
             WellKnownClasses::dalvik_system_VMRuntime_nonSdkApiUsageConsumer));
     // If the consumer is non-null, we call back to it to let it know that we
     // have encountered an API that's in one of our lists.
     if (consumer_object != nullptr) {
       std::ostringstream member_signature_str;
       Dump(member_signature_str);

       ScopedLocalRef<jobject> signature_str(
           soa.Env(),
           soa.Env()->NewStringUTF(member_signature_str.str().c_str()));

       // Call through to Consumer.accept(String memberSignature);
       soa.Env()->CallVoidMethod(consumer_object.get(),
                                 WellKnownClasses::java_util_function_Consumer_accept,
                                 signature_str.get());
     }
   }
 }

 static ALWAYS_INLINE bool CanUpdateRuntimeFlags(ArtField*) {
   return true;
 }

 static ALWAYS_INLINE bool CanUpdateRuntimeFlags(ArtMethod* method) {
   return !method->IsIntrinsic();
 }

 template<typename T>
 static ALWAYS_INLINE void MaybeUpdateAccessFlags(Runtime* runtime, T* member, uint32_t flag)
     REQUIRES_SHARED(Locks::mutator_lock_) {
   // Update the access flags unless:
   // (a) `member` is an intrinsic
   // (b) this is AOT compiler, as we do not want the updated access flags in the boot/app image
   // (c) deduping warnings has been explicitly switched off.
   if (CanUpdateRuntimeFlags(member) &&
       !runtime->IsAotCompiler() &&
       runtime->ShouldDedupeHiddenApiWarnings()) {
     member->SetAccessFlags(member->GetAccessFlags() | flag);
   }
 }

 static ALWAYS_INLINE uint32_t GetMemberDexIndex(ArtField* field) {
   return field->GetDexFieldIndex();
 }

 static ALWAYS_INLINE uint32_t GetMemberDexIndex(ArtMethod* method)
     REQUIRES_SHARED(Locks::mutator_lock_) {
   // Use the non-obsolete method to avoid DexFile mismatch between
   // the method index and the declaring class.
   return method->GetNonObsoleteMethod()->GetDexMethodIndex();
 }

 static void VisitMembers(const DexFile& dex_file,
                          const dex::ClassDef& class_def,
                          const std::function<void(const ClassAccessor::Field&)>& fn_visit) {
   ClassAccessor accessor(dex_file, class_def, /* parse_hiddenapi_class_data= */ true);
   accessor.VisitFields(fn_visit, fn_visit);
 }

 static void VisitMembers(const DexFile& dex_file,
                          const dex::ClassDef& class_def,
                          const std::function<void(const ClassAccessor::Method&)>& fn_visit) {
   ClassAccessor accessor(dex_file, class_def, /* parse_hiddenapi_class_data= */ true);
   accessor.VisitMethods(fn_visit, fn_visit);
 }

 template<typename T>
 uint32_t GetDexFlags(T* member) REQUIRES_SHARED(Locks::mutator_lock_) {
   static_assert(std::is_same<T, ArtField>::value || std::is_same<T, ArtMethod>::value);
   constexpr bool kMemberIsField = std::is_same<T, ArtField>::value;
   using AccessorType = typename std::conditional<std::is_same<T, ArtField>::value,
       ClassAccessor::Field, ClassAccessor::Method>::type;

   ObjPtr<mirror::Class> declaring_class = member->GetDeclaringClass();
   DCHECK(!declaring_class.IsNull()) << "Attempting to access a runtime method";

   ApiList flags;
   DCHECK(!flags.IsValid());

   // Check if the declaring class has ClassExt allocated. If it does, check if
   // the pre-JVMTI redefine dex file has been set to determine if the declaring
   // class has been JVMTI-redefined.
   ObjPtr<mirror::ClassExt> ext(declaring_class->GetExtData());
   const DexFile* original_dex = ext.IsNull() ? nullptr : ext->GetPreRedefineDexFile();
   if (LIKELY(original_dex == nullptr)) {
     // Class is not redefined. Find the class def, iterate over its members and
     // find the entry corresponding to this `member`.
     const dex::ClassDef* class_def = declaring_class->GetClassDef();
     if (class_def == nullptr) {
       // ClassDef is not set for proxy classes. Only their fields can ever be inspected.
       DCHECK(declaring_class->IsProxyClass())
           << "Only proxy classes are expected not to have a class def";
       DCHECK(kMemberIsField)
           << "Interface methods should be inspected instead of proxy class methods";
       flags = ApiList::Greylist();
     } else {
       uint32_t member_index = GetMemberDexIndex(member);
       auto fn_visit = [&](const AccessorType& dex_member) {
         if (dex_member.GetIndex() == member_index) {
           flags = ApiList(dex_member.GetHiddenapiFlags());
         }
       };
       VisitMembers(declaring_class->GetDexFile(), *class_def, fn_visit);
     }
   } else {
     // Class was redefined using JVMTI. We have a pointer to the original dex file
     // and the class def index of this class in that dex file, but the field/method
     // indices are lost. Iterate over all members of the class def and find the one
     // corresponding to this `member` by name and type string comparison.
     // This is obviously very slow, but it is only used when non-exempt code tries
     // to access a hidden member of a JVMTI-redefined class.
     uint16_t class_def_idx = ext->GetPreRedefineClassDefIndex();
     DCHECK_NE(class_def_idx, DexFile::kDexNoIndex16);
     const dex::ClassDef& original_class_def = original_dex->GetClassDef(class_def_idx);
     MemberSignature member_signature(member);
     auto fn_visit = [&](const AccessorType& dex_member) {
       MemberSignature cur_signature(dex_member);
       if (member_signature.MemberNameAndTypeMatch(cur_signature)) {
         DCHECK(member_signature.Equals(cur_signature));
         flags = ApiList(dex_member.GetHiddenapiFlags());
       }
     };
     VisitMembers(*original_dex, original_class_def, fn_visit);
   }

   CHECK(flags.IsValid()) << "Could not find hiddenapi flags for "
       << Dumpable<MemberSignature>(MemberSignature(member));
   return flags.GetDexFlags();
 }

 template<typename T>
 bool HandleCorePlatformApiViolation(T* member,
                                     const AccessContext& caller_context,
                                     AccessMethod access_method,
                                     EnforcementPolicy policy) {
   DCHECK(policy != EnforcementPolicy::kDisabled)
       << "Should never enter this function when access checks are completely disabled";

   if (access_method != AccessMethod::kNone) {
     LOG(WARNING) << "Core platform API violation: "
         << Dumpable<MemberSignature>(MemberSignature(member))
         << " from " << caller_context << " using " << access_method;

     // If policy is set to just warn, add kAccCorePlatformApi to access flags of
     // `member` to avoid reporting the violation again next time.
     if (policy == EnforcementPolicy::kJustWarn) {
       MaybeUpdateAccessFlags(Runtime::Current(), member, kAccCorePlatformApi);
     }
   }

   // Deny access if enforcement is enabled.
   return policy == EnforcementPolicy::kEnabled;
 }

 template<typename T>
 bool ShouldDenyAccessToMemberImpl(T* member, ApiList api_list, AccessMethod access_method) {
   DCHECK(member != nullptr);
   Runtime* runtime = Runtime::Current();

   EnforcementPolicy policy = runtime->GetHiddenApiEnforcementPolicy();
   DCHECK(policy != EnforcementPolicy::kDisabled)
       << "Should never enter this function when access checks are completely disabled";

   const bool deny_access =
       (policy == EnforcementPolicy::kEnabled) &&
       IsSdkVersionSetAndMoreThan(runtime->GetTargetSdkVersion(),
                                  api_list.GetMaxAllowedSdkVersion());

   MemberSignature member_signature(member);

   // Check for an exemption first. Exempted APIs are treated as white list.
   if (member_signature.IsExempted(runtime->GetHiddenApiExemptions())) {
     // Avoid re-examining the exemption list next time.
     // Note this results in no warning for the member, which seems like what one would expect.
     // Exemptions effectively adds new members to the whitelist.
     MaybeUpdateAccessFlags(runtime, member, kAccPublicApi);
     return false;
   }

   if (access_method != AccessMethod::kNone) {
     // Print a log message with information about this class member access.
     // We do this if we're about to deny access, or the app is debuggable.
     if (kLogAllAccesses || deny_access || runtime->IsJavaDebuggable()) {
       member_signature.WarnAboutAccess(access_method, api_list, deny_access);
     }

     // If there is a StrictMode listener, notify it about this violation.
     member_signature.NotifyHiddenApiListener(access_method);

     // If event log sampling is enabled, report this violation.
     if (kIsTargetBuild && !kIsTargetLinux) {
       uint32_t eventLogSampleRate = runtime->GetHiddenApiEventLogSampleRate();
       // Assert that RAND_MAX is big enough, to ensure sampling below works as expected.
       static_assert(RAND_MAX >= 0xffff, "RAND_MAX too small");
       if (eventLogSampleRate != 0) {
         const uint32_t sampled_value = static_cast<uint32_t>(std::rand()) & 0xffff;
         if (sampled_value < eventLogSampleRate) {
           member_signature.LogAccessToEventLog(sampled_value, access_method, deny_access);
         }
       }
     }

     // If this access was not denied, move the member into whitelist and skip
     // the warning the next time the member is accessed.
     if (!deny_access) {
       MaybeUpdateAccessFlags(runtime, member, kAccPublicApi);
     }
   }

   return deny_access;
 }

 // Need to instantiate these.
 template uint32_t GetDexFlags<ArtField>(ArtField* member);
 template uint32_t GetDexFlags<ArtMethod>(ArtMethod* member);
 template bool HandleCorePlatformApiViolation(ArtField* member,
                                              const AccessContext& caller_context,
                                              AccessMethod access_method,
                                              EnforcementPolicy policy);
 template bool HandleCorePlatformApiViolation(ArtMethod* member,
                                              const AccessContext& caller_context,
                                              AccessMethod access_method,
                                              EnforcementPolicy policy);
 template bool ShouldDenyAccessToMemberImpl<ArtField>(ArtField* member,
                                                      ApiList api_list,
                                                      AccessMethod access_method);
 template bool ShouldDenyAccessToMemberImpl<ArtMethod>(ArtMethod* member,
                                                       ApiList api_list,
                                                       AccessMethod access_method);
 }  // namespace detail

 }  // namespace hiddenapi
 }  // namespace art
	/*
	* Copyright (C) 2018 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 "hidden_api.h"

	#include <nativehelper/scoped_local_ref.h>

	#include "art_field-inl.h"
	#include "art_method-inl.h"
	#include "base/dumpable.h"
	#include "base/file_utils.h"
	#include "class_root.h"
	#include "dex/class_accessor-inl.h"
	#include "dex/dex_file_loader.h"
	#include "mirror/class_ext.h"
	#include "oat_file.h"
	#include "scoped_thread_state_change.h"
	#include "thread-inl.h"
	#include "well_known_classes.h"

	namespace art {
	namespace hiddenapi {

	// Set to true if we should always print a warning in logcat for all hidden API accesses, not just
	// dark grey and black. This can be set to true for developer preview / beta builds, but should be
	// false for public release builds.
	// Note that when flipping this flag, you must also update the expectations of test 674-hiddenapi
	// as it affects whether or not we warn for light grey APIs that have been added to the exemptions
	// list.
	static constexpr bool kLogAllAccesses = false;

	static inline std::ostream& operator<<(std::ostream& os, AccessMethod value) {
	switch (value) {
	case AccessMethod::kNone:
	LOG(FATAL) << "Internal access to hidden API should not be logged";
	UNREACHABLE();
	case AccessMethod::kReflection:
	os << "reflection";
	break;
	case AccessMethod::kJNI:
	os << "JNI";
	break;
	case AccessMethod::kLinking:
	os << "linking";
	break;
	}
	return os;
	}

	static inline std::ostream& operator<<(std::ostream& os, const AccessContext& value)
	REQUIRES_SHARED(Locks::mutator_lock_) {
	if (!value.GetClass().IsNull()) {
	std::string tmp;
	os << value.GetClass()->GetDescriptor(&tmp);
	} else if (value.GetDexFile() != nullptr) {
	os << value.GetDexFile()->GetLocation();
	} else {
	os << "<unknown_caller>";
	}
	return os;
	}

	static Domain DetermineDomainFromLocation(const std::string& dex_location,
	ObjPtr<mirror::ClassLoader> class_loader) {
	// If running with APEX, check `path` against known APEX locations.
	// These checks will be skipped on target buildbots where ANDROID_ART_ROOT
	// is set to "/system".
	if (ArtModuleRootDistinctFromAndroidRoot()) {
	if (LocationIsOnArtModule(dex_location.c_str()) \|\|
	LocationIsOnConscryptModule(dex_location.c_str())) {
	return Domain::kCorePlatform;
	}

	if (LocationIsOnApex(dex_location.c_str())) {
	return Domain::kPlatform;
	}
	}

	if (LocationIsOnSystemFramework(dex_location.c_str())) {
	return Domain::kPlatform;
	}

	if (class_loader.IsNull()) {
	LOG(WARNING) << "DexFile " << dex_location
	<< " is in boot class path but is not in a known location";
	return Domain::kPlatform;
	}

	return Domain::kApplication;
	}

	void InitializeDexFileDomain(const DexFile& dex_file, ObjPtr<mirror::ClassLoader> class_loader) {
	Domain dex_domain = DetermineDomainFromLocation(dex_file.GetLocation(), class_loader);

	// Assign the domain unless a more permissive domain has already been assigned.
	// This may happen when DexFile is initialized as trusted.
	if (IsDomainMoreTrustedThan(dex_domain, dex_file.GetHiddenapiDomain())) {
	dex_file.SetHiddenapiDomain(dex_domain);
	}
	}

	namespace detail {

	// Do not change the values of items in this enum, as they are written to the
	// event log for offline analysis. Any changes will interfere with that analysis.
	enum AccessContextFlags {
	// Accessed member is a field if this bit is set, else a method
	kMemberIsField = 1 << 0,
	// Indicates if access was denied to the member, instead of just printing a warning.
	kAccessDenied = 1 << 1,
	};

	MemberSignature::MemberSignature(ArtField* field) {
	class_name_ = field->GetDeclaringClass()->GetDescriptor(&tmp_);
	member_name_ = field->GetName();
	type_signature_ = field->GetTypeDescriptor();
	type_ = kField;
	}

	MemberSignature::MemberSignature(ArtMethod* method) {
	DCHECK(method == method->GetInterfaceMethodIfProxy(kRuntimePointerSize))
	<< "Caller should have replaced proxy method with interface method";
	class_name_ = method->GetDeclaringClass()->GetDescriptor(&tmp_);
	member_name_ = method->GetName();
	type_signature_ = method->GetSignature().ToString();
	type_ = kMethod;
	}

	MemberSignature::MemberSignature(const ClassAccessor::Field& field) {
	const DexFile& dex_file = field.GetDexFile();
	const dex::FieldId& field_id = dex_file.GetFieldId(field.GetIndex());
	class_name_ = dex_file.GetFieldDeclaringClassDescriptor(field_id);
	member_name_ = dex_file.GetFieldName(field_id);
	type_signature_ = dex_file.GetFieldTypeDescriptor(field_id);
	type_ = kField;
	}

	MemberSignature::MemberSignature(const ClassAccessor::Method& method) {
	const DexFile& dex_file = method.GetDexFile();
	const dex::MethodId& method_id = dex_file.GetMethodId(method.GetIndex());
	class_name_ = dex_file.GetMethodDeclaringClassDescriptor(method_id);
	member_name_ = dex_file.GetMethodName(method_id);
	type_signature_ = dex_file.GetMethodSignature(method_id).ToString();
	type_ = kMethod;
	}

	inline std::vector<const char*> MemberSignature::GetSignatureParts() const {
	if (type_ == kField) {
	return { class_name_.c_str(), "->", member_name_.c_str(), ":", type_signature_.c_str() };
	} else {
	DCHECK_EQ(type_, kMethod);
	return { class_name_.c_str(), "->", member_name_.c_str(), type_signature_.c_str() };
	}
	}

	bool MemberSignature::DoesPrefixMatch(const std::string& prefix) const {
	size_t pos = 0;
	for (const char* part : GetSignatureParts()) {
	size_t count = std::min(prefix.length() - pos, strlen(part));
	if (prefix.compare(pos, count, part, 0, count) == 0) {
	pos += count;
	} else {
	return false;
	}
	}
	// We have a complete match if all parts match (we exit the loop without
	// returning) AND we've matched the whole prefix.
	return pos == prefix.length();
	}

	bool MemberSignature::IsExempted(const std::vector<std::string>& exemptions) {
	for (const std::string& exemption : exemptions) {
	if (DoesPrefixMatch(exemption)) {
	return true;
	}
	}
	return false;
	}

	void MemberSignature::Dump(std::ostream& os) const {
	for (const char* part : GetSignatureParts()) {
	os << part;
	}
	}

	void MemberSignature::WarnAboutAccess(AccessMethod access_method,
	hiddenapi::ApiList list,
	bool access_denied) {
	LOG(WARNING) << "Accessing hidden " << (type_ == kField ? "field " : "method ")
	<< Dumpable<MemberSignature>(*this) << " (" << list << ", " << access_method
	<< (access_denied ? ", denied)" : ", allowed)");
	}

	bool MemberSignature::Equals(const MemberSignature& other) {
	return type_ == other.type_ &&
	class_name_ == other.class_name_ &&
	member_name_ == other.member_name_ &&
	type_signature_ == other.type_signature_;
	}

	bool MemberSignature::MemberNameAndTypeMatch(const MemberSignature& other) {
	return member_name_ == other.member_name_ && type_signature_ == other.type_signature_;
	}

	void MemberSignature::LogAccessToEventLog(uint32_t sampled_value,
	AccessMethod access_method,
	bool access_denied) {
	#ifdef ART_TARGET_ANDROID
	if (access_method == AccessMethod::kLinking \|\| access_method == AccessMethod::kNone) {
	// Linking warnings come from static analysis/compilation of the bytecode
	// and can contain false positives (i.e. code that is never run). We choose
	// not to log these in the event log.
	// None does not correspond to actual access, so should also be ignored.
	return;
	}
	Runtime* runtime = Runtime::Current();
	if (runtime->IsAotCompiler()) {
	return;
	}
	JNIEnvExt* env = Thread::Current()->GetJniEnv();
	const std::string& package_name = Runtime::Current()->GetProcessPackageName();
	ScopedLocalRef<jstring> package_str(env, env->NewStringUTF(package_name.c_str()));
	if (env->ExceptionCheck()) {
	env->ExceptionClear();
	LOG(ERROR) << "Unable to allocate string for package name which called hidden api";
	}
	std::ostringstream signature_str;
	Dump(signature_str);
	ScopedLocalRef<jstring> signature_jstr(env,
	env->NewStringUTF(signature_str.str().c_str()));
	if (env->ExceptionCheck()) {
	env->ExceptionClear();
	LOG(ERROR) << "Unable to allocate string for hidden api method signature";
	}
	env->CallStaticVoidMethod(WellKnownClasses::dalvik_system_VMRuntime,
	WellKnownClasses::dalvik_system_VMRuntime_hiddenApiUsed,
	sampled_value,
	package_str.get(),
	signature_jstr.get(),
	static_cast<jint>(access_method),
	access_denied);
	if (env->ExceptionCheck()) {
	env->ExceptionClear();
	LOG(ERROR) << "Unable to report hidden api usage";
	}
	#else
	UNUSED(sampled_value);
	UNUSED(access_method);
	UNUSED(access_denied);
	#endif
	}

	void MemberSignature::NotifyHiddenApiListener(AccessMethod access_method) {
	if (access_method != AccessMethod::kReflection && access_method != AccessMethod::kJNI) {
	// We can only up-call into Java during reflection and JNI down-calls.
	return;
	}

	Runtime* runtime = Runtime::Current();
	if (!runtime->IsAotCompiler()) {
	ScopedObjectAccessUnchecked soa(Thread::Current());

	ScopedLocalRef<jobject> consumer_object(soa.Env(),
	soa.Env()->GetStaticObjectField(
	WellKnownClasses::dalvik_system_VMRuntime,
	WellKnownClasses::dalvik_system_VMRuntime_nonSdkApiUsageConsumer));
	// If the consumer is non-null, we call back to it to let it know that we
	// have encountered an API that's in one of our lists.
	if (consumer_object != nullptr) {
	std::ostringstream member_signature_str;
	Dump(member_signature_str);

	ScopedLocalRef<jobject> signature_str(
	soa.Env(),
	soa.Env()->NewStringUTF(member_signature_str.str().c_str()));

	// Call through to Consumer.accept(String memberSignature);
	soa.Env()->CallVoidMethod(consumer_object.get(),
	WellKnownClasses::java_util_function_Consumer_accept,
	signature_str.get());
	}
	}
	}

	static ALWAYS_INLINE bool CanUpdateRuntimeFlags(ArtField*) {
	return true;
	}

	static ALWAYS_INLINE bool CanUpdateRuntimeFlags(ArtMethod* method) {
	return !method->IsIntrinsic();
	}

	template<typename T>
	static ALWAYS_INLINE void MaybeUpdateAccessFlags(Runtime* runtime, T* member, uint32_t flag)
	REQUIRES_SHARED(Locks::mutator_lock_) {
	// Update the access flags unless:
	// (a) `member` is an intrinsic
	// (b) this is AOT compiler, as we do not want the updated access flags in the boot/app image
	// (c) deduping warnings has been explicitly switched off.
	if (CanUpdateRuntimeFlags(member) &&
	!runtime->IsAotCompiler() &&
	runtime->ShouldDedupeHiddenApiWarnings()) {
	member->SetAccessFlags(member->GetAccessFlags() \| flag);
	}
	}

	static ALWAYS_INLINE uint32_t GetMemberDexIndex(ArtField* field) {
	return field->GetDexFieldIndex();
	}

	static ALWAYS_INLINE uint32_t GetMemberDexIndex(ArtMethod* method)
	REQUIRES_SHARED(Locks::mutator_lock_) {
	// Use the non-obsolete method to avoid DexFile mismatch between
	// the method index and the declaring class.
	return method->GetNonObsoleteMethod()->GetDexMethodIndex();
	}

	static void VisitMembers(const DexFile& dex_file,
	const dex::ClassDef& class_def,
	const std::function<void(const ClassAccessor::Field&)>& fn_visit) {
	ClassAccessor accessor(dex_file, class_def, /* parse_hiddenapi_class_data= */ true);
	accessor.VisitFields(fn_visit, fn_visit);
	}

	static void VisitMembers(const DexFile& dex_file,
	const dex::ClassDef& class_def,
	const std::function<void(const ClassAccessor::Method&)>& fn_visit) {
	ClassAccessor accessor(dex_file, class_def, /* parse_hiddenapi_class_data= */ true);
	accessor.VisitMethods(fn_visit, fn_visit);
	}

	template<typename T>
	uint32_t GetDexFlags(T* member) REQUIRES_SHARED(Locks::mutator_lock_) {
	static_assert(std::is_same<T, ArtField>::value \|\| std::is_same<T, ArtMethod>::value);
	constexpr bool kMemberIsField = std::is_same<T, ArtField>::value;
	using AccessorType = typename std::conditional<std::is_same<T, ArtField>::value,
	ClassAccessor::Field, ClassAccessor::Method>::type;

	ObjPtr<mirror::Class> declaring_class = member->GetDeclaringClass();
	DCHECK(!declaring_class.IsNull()) << "Attempting to access a runtime method";

	ApiList flags;
	DCHECK(!flags.IsValid());

	// Check if the declaring class has ClassExt allocated. If it does, check if
	// the pre-JVMTI redefine dex file has been set to determine if the declaring
	// class has been JVMTI-redefined.
	ObjPtr<mirror::ClassExt> ext(declaring_class->GetExtData());
	const DexFile* original_dex = ext.IsNull() ? nullptr : ext->GetPreRedefineDexFile();
	if (LIKELY(original_dex == nullptr)) {
	// Class is not redefined. Find the class def, iterate over its members and
	// find the entry corresponding to this `member`.
	const dex::ClassDef* class_def = declaring_class->GetClassDef();
	if (class_def == nullptr) {
	// ClassDef is not set for proxy classes. Only their fields can ever be inspected.
	DCHECK(declaring_class->IsProxyClass())
	<< "Only proxy classes are expected not to have a class def";
	DCHECK(kMemberIsField)
	<< "Interface methods should be inspected instead of proxy class methods";
	flags = ApiList::Greylist();
	} else {
	uint32_t member_index = GetMemberDexIndex(member);
	auto fn_visit = [&](const AccessorType& dex_member) {
	if (dex_member.GetIndex() == member_index) {
	flags = ApiList(dex_member.GetHiddenapiFlags());
	}
	};
	VisitMembers(declaring_class->GetDexFile(), *class_def, fn_visit);
	}
	} else {
	// Class was redefined using JVMTI. We have a pointer to the original dex file
	// and the class def index of this class in that dex file, but the field/method
	// indices are lost. Iterate over all members of the class def and find the one
	// corresponding to this `member` by name and type string comparison.
	// This is obviously very slow, but it is only used when non-exempt code tries
	// to access a hidden member of a JVMTI-redefined class.
	uint16_t class_def_idx = ext->GetPreRedefineClassDefIndex();
	DCHECK_NE(class_def_idx, DexFile::kDexNoIndex16);
	const dex::ClassDef& original_class_def = original_dex->GetClassDef(class_def_idx);
	MemberSignature member_signature(member);
	auto fn_visit = [&](const AccessorType& dex_member) {
	MemberSignature cur_signature(dex_member);
	if (member_signature.MemberNameAndTypeMatch(cur_signature)) {
	DCHECK(member_signature.Equals(cur_signature));
	flags = ApiList(dex_member.GetHiddenapiFlags());
	}
	};
	VisitMembers(*original_dex, original_class_def, fn_visit);
	}

	CHECK(flags.IsValid()) << "Could not find hiddenapi flags for "
	<< Dumpable<MemberSignature>(MemberSignature(member));
	return flags.GetDexFlags();
	}

	template<typename T>
	bool HandleCorePlatformApiViolation(T* member,
	const AccessContext& caller_context,
	AccessMethod access_method,
	EnforcementPolicy policy) {
	DCHECK(policy != EnforcementPolicy::kDisabled)
	<< "Should never enter this function when access checks are completely disabled";

	if (access_method != AccessMethod::kNone) {
	LOG(WARNING) << "Core platform API violation: "
	<< Dumpable<MemberSignature>(MemberSignature(member))
	<< " from " << caller_context << " using " << access_method;

	// If policy is set to just warn, add kAccCorePlatformApi to access flags of
	// `member` to avoid reporting the violation again next time.
	if (policy == EnforcementPolicy::kJustWarn) {
	MaybeUpdateAccessFlags(Runtime::Current(), member, kAccCorePlatformApi);
	}
	}

	// Deny access if enforcement is enabled.
	return policy == EnforcementPolicy::kEnabled;
	}

	template<typename T>
	bool ShouldDenyAccessToMemberImpl(T* member, ApiList api_list, AccessMethod access_method) {
	DCHECK(member != nullptr);
	Runtime* runtime = Runtime::Current();

	EnforcementPolicy policy = runtime->GetHiddenApiEnforcementPolicy();
	DCHECK(policy != EnforcementPolicy::kDisabled)
	<< "Should never enter this function when access checks are completely disabled";

	const bool deny_access =
	(policy == EnforcementPolicy::kEnabled) &&
	IsSdkVersionSetAndMoreThan(runtime->GetTargetSdkVersion(),
	api_list.GetMaxAllowedSdkVersion());

	MemberSignature member_signature(member);

	// Check for an exemption first. Exempted APIs are treated as white list.
	if (member_signature.IsExempted(runtime->GetHiddenApiExemptions())) {
	// Avoid re-examining the exemption list next time.
	// Note this results in no warning for the member, which seems like what one would expect.
	// Exemptions effectively adds new members to the whitelist.
	MaybeUpdateAccessFlags(runtime, member, kAccPublicApi);
	return false;
	}

	if (access_method != AccessMethod::kNone) {
	// Print a log message with information about this class member access.
	// We do this if we're about to deny access, or the app is debuggable.
	if (kLogAllAccesses \|\| deny_access \|\| runtime->IsJavaDebuggable()) {
	member_signature.WarnAboutAccess(access_method, api_list, deny_access);
	}

	// If there is a StrictMode listener, notify it about this violation.
	member_signature.NotifyHiddenApiListener(access_method);

	// If event log sampling is enabled, report this violation.
	if (kIsTargetBuild && !kIsTargetLinux) {
	uint32_t eventLogSampleRate = runtime->GetHiddenApiEventLogSampleRate();
	// Assert that RAND_MAX is big enough, to ensure sampling below works as expected.
	static_assert(RAND_MAX >= 0xffff, "RAND_MAX too small");
	if (eventLogSampleRate != 0) {
	const uint32_t sampled_value = static_cast<uint32_t>(std::rand()) & 0xffff;
	if (sampled_value < eventLogSampleRate) {
	member_signature.LogAccessToEventLog(sampled_value, access_method, deny_access);
	}
	}
	}

	// If this access was not denied, move the member into whitelist and skip
	// the warning the next time the member is accessed.
	if (!deny_access) {
	MaybeUpdateAccessFlags(runtime, member, kAccPublicApi);
	}
	}

	return deny_access;
	}

	// Need to instantiate these.
	template uint32_t GetDexFlags<ArtField>(ArtField* member);
	template uint32_t GetDexFlags<ArtMethod>(ArtMethod* member);
	template bool HandleCorePlatformApiViolation(ArtField* member,
	const AccessContext& caller_context,
	AccessMethod access_method,
	EnforcementPolicy policy);
	template bool HandleCorePlatformApiViolation(ArtMethod* member,
	const AccessContext& caller_context,
	AccessMethod access_method,
	EnforcementPolicy policy);
	template bool ShouldDenyAccessToMemberImpl<ArtField>(ArtField* member,
	ApiList api_list,
	AccessMethod access_method);
	template bool ShouldDenyAccessToMemberImpl<ArtMethod>(ArtMethod* member,
	ApiList api_list,
	AccessMethod access_method);
	} // namespace detail

	} // namespace hiddenapi
	} // namespace art