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_VMClassLoader.h"
18
19 #include "base/zip_archive.h"
20 #include "class_linker.h"
21 #include "base/transform_iterator.h"
22 #include "base/stl_util.h"
23 #include "dex/descriptors_names.h"
24 #include "dex/dex_file_loader.h"
25 #include "dex/utf.h"
26 #include "handle_scope-inl.h"
27 #include "jni/jni_internal.h"
28 #include "mirror/class_loader.h"
29 #include "mirror/object-inl.h"
30 #include "mirror/object_array-alloc-inl.h"
31 #include "native_util.h"
32 #include "nativehelper/jni_macros.h"
33 #include "nativehelper/scoped_local_ref.h"
34 #include "nativehelper/scoped_utf_chars.h"
35 #include "obj_ptr.h"
36 #include "scoped_fast_native_object_access-inl.h"
37 #include "string_array_utils.h"
38 #include "thread-inl.h"
39 #include "well_known_classes-inl.h"
40
41 namespace art HIDDEN {
42
43 // A class so we can be friends with ClassLinker and access internal methods.
44 class VMClassLoader {
45 public:
LookupClass(ClassLinker * cl,Thread * self,std::string_view descriptor,size_t hash,ObjPtr<mirror::ClassLoader> class_loader)46 static ObjPtr<mirror::Class> LookupClass(ClassLinker* cl,
47 Thread* self,
48 std::string_view descriptor,
49 size_t hash,
50 ObjPtr<mirror::ClassLoader> class_loader)
51 REQUIRES(!Locks::classlinker_classes_lock_)
52 REQUIRES_SHARED(Locks::mutator_lock_) {
53 return cl->LookupClass(self, descriptor, hash, class_loader);
54 }
55
FindClassInPathClassLoader(ClassLinker * cl,Thread * self,const char * descriptor,size_t descriptor_length,size_t hash,Handle<mirror::ClassLoader> class_loader)56 static ObjPtr<mirror::Class> FindClassInPathClassLoader(ClassLinker* cl,
57 Thread* self,
58 const char* descriptor,
59 size_t descriptor_length,
60 size_t hash,
61 Handle<mirror::ClassLoader> class_loader)
62 REQUIRES_SHARED(Locks::mutator_lock_) {
63 ObjPtr<mirror::Class> result;
64 if (cl->FindClassInBaseDexClassLoader(
65 self, descriptor, descriptor_length, hash, class_loader, &result)) {
66 DCHECK(!self->IsExceptionPending());
67 return result;
68 }
69 if (self->IsExceptionPending()) {
70 self->ClearException();
71 }
72 return nullptr;
73 }
74 };
75
VMClassLoader_findLoadedClass(JNIEnv * env,jclass,jobject javaLoader,jstring javaName)76 static jclass VMClassLoader_findLoadedClass(JNIEnv* env, jclass, jobject javaLoader,
77 jstring javaName) {
78 ScopedFastNativeObjectAccess soa(env);
79 ObjPtr<mirror::ClassLoader> loader = soa.Decode<mirror::ClassLoader>(javaLoader);
80 ScopedUtfChars name(env, javaName);
81 if (name.c_str() == nullptr) {
82 return nullptr;
83 }
84 ClassLinker* cl = Runtime::Current()->GetClassLinker();
85
86 // Compute hash once.
87 std::string descriptor(DotToDescriptor(name.c_str()));
88 const size_t descriptor_hash = ComputeModifiedUtf8Hash(descriptor);
89
90 ObjPtr<mirror::Class> c = VMClassLoader::LookupClass(cl,
91 soa.Self(),
92 descriptor,
93 descriptor_hash,
94 loader);
95 if (c != nullptr && c->IsResolved()) {
96 return soa.AddLocalReference<jclass>(c);
97 }
98 // If class is erroneous, throw the earlier failure, wrapped in certain cases. See b/28787733.
99 if (c != nullptr && c->IsErroneous()) {
100 cl->ThrowEarlierClassFailure(c);
101 Thread* self = soa.Self();
102 ObjPtr<mirror::Class> exception_class = self->GetException()->GetClass();
103 if (exception_class == WellKnownClasses::java_lang_IllegalAccessError ||
104 exception_class == WellKnownClasses::java_lang_NoClassDefFoundError) {
105 self->ThrowNewWrappedException("Ljava/lang/ClassNotFoundException;",
106 c->PrettyDescriptor().c_str());
107 }
108 return nullptr;
109 }
110
111 // Hard-coded performance optimization: We know that all failed libcore calls to findLoadedClass
112 // are followed by a call to the the classloader to actually
113 // load the class.
114 if (loader != nullptr) {
115 // Try the common case.
116 StackHandleScope<1> hs(soa.Self());
117 c = VMClassLoader::FindClassInPathClassLoader(cl,
118 soa.Self(),
119 descriptor.c_str(),
120 descriptor.length(),
121 descriptor_hash,
122 hs.NewHandle(loader));
123 if (c != nullptr) {
124 return soa.AddLocalReference<jclass>(c);
125 }
126 }
127
128 // The class wasn't loaded, yet, and our fast-path did not apply (e.g., we didn't understand the
129 // classloader chain).
130 return nullptr;
131 }
132
133 /*
134 * Returns an array of entries from the boot classpath that could contain resources.
135 */
VMClassLoader_getBootClassPathEntries(JNIEnv * env,jclass)136 static jobjectArray VMClassLoader_getBootClassPathEntries(JNIEnv* env, jclass) {
137 ClassLinker* class_linker = Runtime::Current()->GetClassLinker();
138 const std::vector<const DexFile*>& path = class_linker->GetBootClassPath();
139 auto is_base_dex = [](const DexFile* dex_file) {
140 return !DexFileLoader::IsMultiDexLocation(dex_file->GetLocation());
141 };
142 size_t jar_count = std::count_if(path.begin(), path.end(), is_base_dex);
143
144 const DexFile* last_dex_file = nullptr;
145 auto dchecked_is_base_dex = [&](const DexFile* dex_file) {
146 // For multidex locations, e.g., x.jar!classes2.dex, we want to look into x.jar.
147 // But we do not need to look into the base dex file more than once so we filter
148 // out multidex locations using the fact that they follow the base location.
149 if (kIsDebugBuild) {
150 if (is_base_dex(dex_file)) {
151 CHECK_EQ(DexFileLoader::GetBaseLocation(dex_file->GetLocation().c_str()),
152 dex_file->GetLocation());
153 } else {
154 CHECK(last_dex_file != nullptr);
155 CHECK_EQ(DexFileLoader::GetBaseLocation(dex_file->GetLocation().c_str()),
156 DexFileLoader::GetBaseLocation(last_dex_file->GetLocation().c_str()));
157 }
158 last_dex_file = dex_file;
159 }
160 return is_base_dex(dex_file);
161 };
162 auto get_location = [](const DexFile* dex_file) { return dex_file->GetLocation(); };
163 ScopedObjectAccess soa(Thread::ForEnv(env));
164 return soa.AddLocalReference<jobjectArray>(CreateStringArray(
165 soa.Self(),
166 jar_count,
167 MakeTransformRange(Filter(path, dchecked_is_base_dex), get_location)));
168 }
169
170 static JNINativeMethod gMethods[] = {
171 FAST_NATIVE_METHOD(VMClassLoader, findLoadedClass, "(Ljava/lang/ClassLoader;Ljava/lang/String;)Ljava/lang/Class;"),
172 NATIVE_METHOD(VMClassLoader, getBootClassPathEntries, "()[Ljava/lang/String;"),
173 };
174
register_java_lang_VMClassLoader(JNIEnv * env)175 void register_java_lang_VMClassLoader(JNIEnv* env) {
176 REGISTER_NATIVE_METHODS("java/lang/VMClassLoader");
177 }
178
179 } // namespace art
180