java_lang_Class.cc revision 02d2f290380c6aeff5f5a089ee38fa5d55e46130 
1/*
2 * Copyright (C) 2008 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 "java_lang_Class.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 "nth_caller_visitor.h"
24#include "mirror/art_field-inl.h"
25#include "mirror/class-inl.h"
26#include "mirror/class_loader.h"
27#include "mirror/field-inl.h"
28#include "mirror/object-inl.h"
29#include "mirror/object_array-inl.h"
30#include "mirror/string-inl.h"
31#include "scoped_thread_state_change.h"
32#include "scoped_fast_native_object_access.h"
33#include "ScopedLocalRef.h"
34#include "ScopedUtfChars.h"
35#include "utf.h"
36#include "well_known_classes.h"
37
38namespace art {
39
40ALWAYS_INLINE static inline mirror::Class* DecodeClass(
41    const ScopedFastNativeObjectAccess& soa, jobject java_class)
42    SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
43  mirror::Class* c = soa.Decode<mirror::Class*>(java_class);
44  DCHECK(c != NULL);
45  DCHECK(c->IsClass());
46  // TODO: we could EnsureInitialized here, rather than on every reflective get/set or invoke .
47  // For now, we conservatively preserve the old dalvik behavior. A quick "IsInitialized" check
48  // every time probably doesn't make much difference to reflection performance anyway.
49  return c;
50}
51
52// "name" is in "binary name" format, e.g. "dalvik.system.Debug$1".
53static jclass Class_classForName(JNIEnv* env, jclass, jstring javaName, jboolean initialize,
54                                 jobject javaLoader) {
55  ScopedFastNativeObjectAccess soa(env);
56  ScopedUtfChars name(env, javaName);
57  if (name.c_str() == nullptr) {
58    return nullptr;
59  }
60
61  // We need to validate and convert the name (from x.y.z to x/y/z).  This
62  // is especially handy for array types, since we want to avoid
63  // auto-generating bogus array classes.
64  if (!IsValidBinaryClassName(name.c_str())) {
65    soa.Self()->ThrowNewExceptionF("Ljava/lang/ClassNotFoundException;",
66                                   "Invalid name: %s", name.c_str());
67    return nullptr;
68  }
69
70  std::string descriptor(DotToDescriptor(name.c_str()));
71  StackHandleScope<2> hs(soa.Self());
72  Handle<mirror::ClassLoader> class_loader(hs.NewHandle(soa.Decode<mirror::ClassLoader*>(javaLoader)));
73  ClassLinker* class_linker = Runtime::Current()->GetClassLinker();
74  Handle<mirror::Class> c(
75      hs.NewHandle(class_linker->FindClass(soa.Self(), descriptor.c_str(), class_loader)));
76  if (c.Get() == nullptr) {
77    ScopedLocalRef<jthrowable> cause(env, env->ExceptionOccurred());
78    env->ExceptionClear();
79    jthrowable cnfe = reinterpret_cast<jthrowable>(env->NewObject(WellKnownClasses::java_lang_ClassNotFoundException,
80                                                                  WellKnownClasses::java_lang_ClassNotFoundException_init,
81                                                                  javaName, cause.get()));
82    if (cnfe != nullptr) {
83      // Make sure allocation didn't fail with an OOME.
84      env->Throw(cnfe);
85    }
86    return nullptr;
87  }
88  if (initialize) {
89    class_linker->EnsureInitialized(soa.Self(), c, true, true);
90  }
91  return soa.AddLocalReference<jclass>(c.Get());
92}
93
94static jstring Class_getNameNative(JNIEnv* env, jobject javaThis) {
95  ScopedFastNativeObjectAccess soa(env);
96  StackHandleScope<1> hs(soa.Self());
97  mirror::Class* const c = DecodeClass(soa, javaThis);
98  return soa.AddLocalReference<jstring>(mirror::Class::ComputeName(hs.NewHandle(c)));
99}
100
101static jobjectArray Class_getProxyInterfaces(JNIEnv* env, jobject javaThis) {
102  ScopedFastNativeObjectAccess soa(env);
103  mirror::Class* c = DecodeClass(soa, javaThis);
104  return soa.AddLocalReference<jobjectArray>(c->GetInterfaces()->Clone(soa.Self()));
105}
106
107static mirror::ObjectArray<mirror::Field>* GetDeclaredFields(
108    Thread* self, mirror::Class* klass, bool public_only, bool force_resolve)
109      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
110  StackHandleScope<3> hs(self);
111  auto h_ifields = hs.NewHandle(klass->GetIFields());
112  auto h_sfields = hs.NewHandle(klass->GetSFields());
113  const int32_t num_ifields = h_ifields.Get() != nullptr ? h_ifields->GetLength() : 0;
114  const int32_t num_sfields = h_sfields.Get() != nullptr ? h_sfields->GetLength() : 0;
115  int32_t array_size = num_ifields + num_sfields;
116  if (public_only) {
117    // Lets go subtract all the non public fields.
118    for (int32_t i = 0; i < num_ifields; ++i) {
119      if (!h_ifields->GetWithoutChecks(i)->IsPublic()) {
120        --array_size;
121      }
122    }
123    for (int32_t i = 0; i < num_sfields; ++i) {
124      if (!h_sfields->GetWithoutChecks(i)->IsPublic()) {
125        --array_size;
126      }
127    }
128  }
129  int32_t array_idx = 0;
130  auto object_array = hs.NewHandle(mirror::ObjectArray<mirror::Field>::Alloc(
131      self, mirror::Field::ArrayClass(), array_size));
132  if (object_array.Get() == nullptr) {
133    return nullptr;
134  }
135  for (int32_t i = 0; i < num_ifields; ++i) {
136    auto* art_field = h_ifields->GetWithoutChecks(i);
137    if (!public_only || art_field->IsPublic()) {
138      auto* field = mirror::Field::CreateFromArtField(self, art_field, force_resolve);
139      if (field == nullptr) {
140        if (kIsDebugBuild) {
141          self->AssertPendingException();
142        }
143        // Maybe null due to OOME or type resolving exception.
144        return nullptr;
145      }
146      object_array->SetWithoutChecks<false>(array_idx++, field);
147    }
148  }
149  for (int32_t i = 0; i < num_sfields; ++i) {
150    auto* art_field = h_sfields->GetWithoutChecks(i);
151    if (!public_only || art_field->IsPublic()) {
152      auto* field = mirror::Field::CreateFromArtField(self, art_field, force_resolve);
153      if (field == nullptr) {
154        if (kIsDebugBuild) {
155          self->AssertPendingException();
156        }
157        return nullptr;
158      }
159      object_array->SetWithoutChecks<false>(array_idx++, field);
160    }
161  }
162  CHECK_EQ(array_idx, array_size);
163  return object_array.Get();
164}
165
166static jobjectArray Class_getDeclaredFieldsUnchecked(JNIEnv* env, jobject javaThis,
167                                                     jboolean publicOnly) {
168  ScopedFastNativeObjectAccess soa(env);
169  return soa.AddLocalReference<jobjectArray>(
170      GetDeclaredFields(soa.Self(), DecodeClass(soa, javaThis), publicOnly != JNI_FALSE, false));
171}
172
173static jobjectArray Class_getDeclaredFields(JNIEnv* env, jobject javaThis) {
174  ScopedFastNativeObjectAccess soa(env);
175  return soa.AddLocalReference<jobjectArray>(
176      GetDeclaredFields(soa.Self(), DecodeClass(soa, javaThis), false, true));
177}
178
179static jobjectArray Class_getPublicDeclaredFields(JNIEnv* env, jobject javaThis) {
180  ScopedFastNativeObjectAccess soa(env);
181  return soa.AddLocalReference<jobjectArray>(
182      GetDeclaredFields(soa.Self(), DecodeClass(soa, javaThis), true, true));
183}
184
185// Performs a binary search through an array of fields, TODO: Is this fast enough if we don't use
186// the dex cache for lookups? I think CompareModifiedUtf8ToUtf16AsCodePointValues should be fairly
187// fast.
188ALWAYS_INLINE static inline mirror::ArtField* FindFieldByName(
189    Thread* self ATTRIBUTE_UNUSED, mirror::String* name,
190    mirror::ObjectArray<mirror::ArtField>* fields)
191    SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
192  uint32_t low = 0;
193  uint32_t high = fields->GetLength();
194  const uint16_t* const data = name->GetCharArray()->GetData() + name->GetOffset();
195  const size_t length = name->GetLength();
196  while (low < high) {
197    auto mid = (low + high) / 2;
198    mirror::ArtField* const field = fields->GetWithoutChecks(mid);
199    int result = CompareModifiedUtf8ToUtf16AsCodePointValues(field->GetName(), data, length);
200    // Alternate approach, only a few % faster at the cost of more allocations.
201    // int result = field->GetStringName(self, true)->CompareTo(name);
202    if (result < 0) {
203      low = mid + 1;
204    } else if (result > 0) {
205      high = mid;
206    } else {
207      return field;
208    }
209  }
210  if (kIsDebugBuild) {
211    for (int32_t i = 0; i < fields->GetLength(); ++i) {
212      CHECK_NE(fields->GetWithoutChecks(i)->GetName(), name->ToModifiedUtf8());
213    }
214  }
215  return nullptr;
216}
217
218ALWAYS_INLINE static inline mirror::Field* GetDeclaredField(
219    Thread* self, mirror::Class* c, mirror::String* name)
220    SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
221  auto* instance_fields = c->GetIFields();
222  if (instance_fields != nullptr) {
223    auto* art_field = FindFieldByName(self, name, instance_fields);
224    if (art_field != nullptr) {
225      return mirror::Field::CreateFromArtField(self, art_field, true);
226    }
227  }
228  auto* static_fields = c->GetSFields();
229  if (static_fields != nullptr) {
230    auto* art_field = FindFieldByName(self, name, static_fields);
231    if (art_field != nullptr) {
232      return mirror::Field::CreateFromArtField(self, art_field, true);
233    }
234  }
235  return nullptr;
236}
237
238static jobject Class_getDeclaredFieldInternal(JNIEnv* env, jobject javaThis, jstring name) {
239  ScopedFastNativeObjectAccess soa(env);
240  auto* name_string = soa.Decode<mirror::String*>(name);
241  return soa.AddLocalReference<jobject>(
242      GetDeclaredField(soa.Self(), DecodeClass(soa, javaThis), name_string));
243}
244
245static jobject Class_getDeclaredField(JNIEnv* env, jobject javaThis, jstring name) {
246  ScopedFastNativeObjectAccess soa(env);
247  auto* name_string = soa.Decode<mirror::String*>(name);
248  if (name == nullptr) {
249    ThrowNullPointerException("name == null");
250    return nullptr;
251  }
252  auto* klass = DecodeClass(soa, javaThis);
253  mirror::Field* result = GetDeclaredField(soa.Self(), klass, name_string);
254  if (result == nullptr) {
255    std::string name_str = name_string->ToModifiedUtf8();
256    // We may have a pending exception if we failed to resolve.
257    if (!soa.Self()->IsExceptionPending()) {
258      soa.Self()->ThrowNewException("Ljava/lang/NoSuchFieldException;", name_str.c_str());
259    }
260    return nullptr;
261  }
262  return soa.AddLocalReference<jobject>(result);
263}
264
265static JNINativeMethod gMethods[] = {
266  NATIVE_METHOD(Class, classForName, "!(Ljava/lang/String;ZLjava/lang/ClassLoader;)Ljava/lang/Class;"),
267  NATIVE_METHOD(Class, getNameNative, "!()Ljava/lang/String;"),
268  NATIVE_METHOD(Class, getProxyInterfaces, "!()[Ljava/lang/Class;"),
269  NATIVE_METHOD(Class, getDeclaredFields, "!()[Ljava/lang/reflect/Field;"),
270  NATIVE_METHOD(Class, getPublicDeclaredFields, "!()[Ljava/lang/reflect/Field;"),
271  NATIVE_METHOD(Class, getDeclaredFieldsUnchecked, "!(Z)[Ljava/lang/reflect/Field;"),
272  NATIVE_METHOD(Class, getDeclaredFieldInternal, "!(Ljava/lang/String;)Ljava/lang/reflect/Field;"),
273  NATIVE_METHOD(Class, getDeclaredField, "!(Ljava/lang/String;)Ljava/lang/reflect/Field;"),
274};
275
276void register_java_lang_Class(JNIEnv* env) {
277  REGISTER_NATIVE_METHODS("java/lang/Class");
278}
279
280}  // namespace art
281