1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
|
// Copyright 2017 The Bazel Authors. All rights reserved.
//
// 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.
package com.google.devtools.build.android.desugar;
import static com.google.common.base.Preconditions.checkNotNull;
import static org.objectweb.asm.Opcodes.ASM5;
import static org.objectweb.asm.Opcodes.INVOKESTATIC;
import static org.objectweb.asm.Opcodes.INVOKEVIRTUAL;
import com.google.common.base.Function;
import com.google.common.collect.FluentIterable;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableMultimap;
import com.google.common.collect.ImmutableSet;
import java.util.Collections;
import java.util.Set;
import java.util.concurrent.atomic.AtomicInteger;
import org.objectweb.asm.ClassVisitor;
import org.objectweb.asm.Label;
import org.objectweb.asm.MethodVisitor;
/**
* Desugar try-with-resources. This class visitor intercepts calls to the following methods, and
* redirect them to ThrowableExtension.
* <li>{@code Throwable.addSuppressed(Throwable)}
* <li>{@code Throwable.getSuppressed()}
* <li>{@code Throwable.printStackTrace()}
* <li>{@code Throwable.printStackTrace(PrintStream)}
* <li>{@code Throwable.printStackTrace(PringWriter)}
*/
public class TryWithResourcesRewriter extends ClassVisitor {
private static final String RUNTIME_PACKAGE_INTERNAL_NAME =
"com/google/devtools/build/android/desugar/runtime";
static final String THROWABLE_EXTENSION_INTERNAL_NAME =
RUNTIME_PACKAGE_INTERNAL_NAME + '/' + "ThrowableExtension";
/** The extension classes for java.lang.Throwable. */
static final ImmutableSet<String> THROWABLE_EXT_CLASS_INTERNAL_NAMES =
ImmutableSet.of(
THROWABLE_EXTENSION_INTERNAL_NAME,
THROWABLE_EXTENSION_INTERNAL_NAME + "$AbstractDesugaringStrategy",
THROWABLE_EXTENSION_INTERNAL_NAME + "$ConcurrentWeakIdentityHashMap",
THROWABLE_EXTENSION_INTERNAL_NAME + "$ConcurrentWeakIdentityHashMap$WeakKey",
THROWABLE_EXTENSION_INTERNAL_NAME + "$MimicDesugaringStrategy",
THROWABLE_EXTENSION_INTERNAL_NAME + "$NullDesugaringStrategy",
THROWABLE_EXTENSION_INTERNAL_NAME + "$ReuseDesugaringStrategy");
/** The extension classes for java.lang.Throwable. All the names end with ".class" */
static final ImmutableSet<String> THROWABLE_EXT_CLASS_INTERNAL_NAMES_WITH_CLASS_EXT =
FluentIterable.from(THROWABLE_EXT_CLASS_INTERNAL_NAMES)
.transform(
new Function<String, String>() {
@Override
public String apply(String s) {
return s + ".class";
}
})
.toSet();
static final ImmutableMultimap<String, String> TARGET_METHODS =
ImmutableMultimap.<String, String>builder()
.put("addSuppressed", "(Ljava/lang/Throwable;)V")
.put("getSuppressed", "()[Ljava/lang/Throwable;")
.put("printStackTrace", "()V")
.put("printStackTrace", "(Ljava/io/PrintStream;)V")
.put("printStackTrace", "(Ljava/io/PrintWriter;)V")
.build();
static final ImmutableMap<String, String> METHOD_DESC_MAP =
ImmutableMap.<String, String>builder()
.put("(Ljava/lang/Throwable;)V", "(Ljava/lang/Throwable;Ljava/lang/Throwable;)V")
.put("()[Ljava/lang/Throwable;", "(Ljava/lang/Throwable;)[Ljava/lang/Throwable;")
.put("()V", "(Ljava/lang/Throwable;)V")
.put("(Ljava/io/PrintStream;)V", "(Ljava/lang/Throwable;Ljava/io/PrintStream;)V")
.put("(Ljava/io/PrintWriter;)V", "(Ljava/lang/Throwable;Ljava/io/PrintWriter;)V")
.build();
private final ClassLoader classLoader;
private final Set<String> visitedExceptionTypes;
private final AtomicInteger numOfTryWithResourcesInvoked;
/**
* Indicate whether the current class being desugared should be ignored. If the current class is
* one of the runtime extension classes, then it should be ignored.
*/
private boolean shouldCurrentClassBeIgnored;
public TryWithResourcesRewriter(
ClassVisitor classVisitor,
ClassLoader classLoader,
Set<String> visitedExceptionTypes,
AtomicInteger numOfTryWithResourcesInvoked) {
super(ASM5, classVisitor);
this.classLoader = classLoader;
this.visitedExceptionTypes = visitedExceptionTypes;
this.numOfTryWithResourcesInvoked = numOfTryWithResourcesInvoked;
}
@Override
public void visit(
int version,
int access,
String name,
String signature,
String superName,
String[] interfaces) {
super.visit(version, access, name, signature, superName, interfaces);
shouldCurrentClassBeIgnored = THROWABLE_EXT_CLASS_INTERNAL_NAMES.contains(name);
}
@Override
public MethodVisitor visitMethod(
int access, String name, String desc, String signature, String[] exceptions) {
if (exceptions != null && exceptions.length > 0) {
// collect exception types.
Collections.addAll(visitedExceptionTypes, exceptions);
}
MethodVisitor visitor = super.cv.visitMethod(access, name, desc, signature, exceptions);
return visitor == null || shouldCurrentClassBeIgnored
? visitor
: new TryWithResourceVisitor(name + desc, visitor, classLoader);
}
private class TryWithResourceVisitor extends MethodVisitor {
private final ClassLoader classLoader;
/** For debugging purpose. Enrich exception information. */
private final String methodSignature;
public TryWithResourceVisitor(
String methodSignature, MethodVisitor methodVisitor, ClassLoader classLoader) {
super(ASM5, methodVisitor);
this.classLoader = classLoader;
this.methodSignature = methodSignature;
}
@Override
public void visitTryCatchBlock(Label start, Label end, Label handler, String type) {
if (type != null) {
visitedExceptionTypes.add(type); // type in a try-catch block must extend Throwable.
}
super.visitTryCatchBlock(start, end, handler, type);
}
@Override
public void visitMethodInsn(int opcode, String owner, String name, String desc, boolean itf) {
if (!isMethodCallTargeted(opcode, owner, name, desc)) {
super.visitMethodInsn(opcode, owner, name, desc, itf);
return;
}
numOfTryWithResourcesInvoked.incrementAndGet();
visitedExceptionTypes.add(checkNotNull(owner)); // owner extends Throwable.
super.visitMethodInsn(
INVOKESTATIC, THROWABLE_EXTENSION_INTERNAL_NAME, name, METHOD_DESC_MAP.get(desc), false);
}
private boolean isMethodCallTargeted(int opcode, String owner, String name, String desc) {
if (opcode != INVOKEVIRTUAL) {
return false;
}
if (!TARGET_METHODS.containsEntry(name, desc)) {
return false;
}
if (visitedExceptionTypes.contains(owner)) {
return true; // The owner is an exception that has been visited before.
}
try {
Class<?> throwableClass = classLoader.loadClass("java.lang.Throwable");
Class<?> klass = classLoader.loadClass(owner.replace('/', '.'));
return throwableClass.isAssignableFrom(klass);
} catch (ClassNotFoundException e) {
throw new AssertionError(
"Failed to load class when desugaring method " + methodSignature, e);
}
}
}
}
|
