/*
* Copyright (C) 2016 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.
*/
package com.android.tools.klint.checks;
import static com.android.SdkConstants.CLASS_CONTEXT;
import static com.android.SdkConstants.CLASS_FRAGMENT;
import static com.android.SdkConstants.CLASS_VIEW;
import com.android.annotations.NonNull;
import com.android.annotations.Nullable;
import com.android.tools.klint.detector.api.Category;
import com.android.tools.klint.detector.api.Detector;
import com.android.tools.klint.detector.api.Implementation;
import com.android.tools.klint.detector.api.Issue;
import com.android.tools.klint.detector.api.JavaContext;
import com.android.tools.klint.detector.api.Scope;
import com.android.tools.klint.detector.api.Severity;
import com.intellij.psi.PsiClass;
import com.intellij.psi.PsiClassType;
import com.intellij.psi.PsiElement;
import com.intellij.psi.PsiField;
import com.intellij.psi.PsiModifier;
import com.intellij.psi.PsiModifierList;
import com.intellij.psi.PsiType;
import com.intellij.psi.util.InheritanceUtil;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.uast.UClass;
import org.jetbrains.uast.UElement;
import org.jetbrains.uast.UField;
import org.jetbrains.uast.UVariable;
import org.jetbrains.uast.visitor.AbstractUastVisitor;
import org.jetbrains.uast.visitor.UastVisitor;
import java.util.Collections;
import java.util.List;
/**
* Looks for leaks via static fields
*/
public class LeakDetector extends Detector implements Detector.UastScanner {
/** Leaking data via static fields */
public static final Issue ISSUE = Issue.create(
"StaticFieldLeak", //$NON-NLS-1$
"Static Field Leaks",
"A static field will leak contexts.",
Category.PERFORMANCE,
6,
Severity.WARNING,
new Implementation(
LeakDetector.class,
Scope.JAVA_FILE_SCOPE));
/** Constructs a new {@link LeakDetector} check */
public LeakDetector() {
}
// ---- Implements JavaScanner ----
@Override
public List<Class<? extends PsiElement>> getApplicablePsiTypes() {
return Collections.<Class<? extends PsiElement>>singletonList(PsiField.class);
}
@Nullable
@Override
public UastVisitor createUastVisitor(@NonNull JavaContext context) {
return new FieldChecker(context);
}
private static class FieldChecker extends AbstractUastVisitor {
private final JavaContext mContext;
private FieldChecker(JavaContext context) {
mContext = context;
}
@Override
public boolean visitClass(@NotNull UClass node) {
return super.visitClass(node);
}
@Override
public boolean visitVariable(UVariable node) {
if (node instanceof UField) {
checkField((UField) node);
}
return super.visitVariable(node);
}
private void checkField(UField field) {
PsiModifierList modifierList = field.getModifierList();
if (modifierList == null || !modifierList.hasModifierProperty(PsiModifier.STATIC)) {
return;
}
PsiType type = field.getType();
if (!(type instanceof PsiClassType)) {
return;
}
String fqn = type.getCanonicalText();
if (fqn.startsWith("java.")) {
return;
}
PsiClass cls = ((PsiClassType) type).resolve();
if (cls == null) {
return;
}
if (fqn.startsWith("android.")) {
if (isLeakCandidate(cls)) {
String message = "Do not place Android context classes in static fields; "
+ "this is a memory leak (and also breaks Instant Run)";
report(field, message);
}
} else {
// User application object -- look to see if that one itself has
// static fields?
// We only check *one* level of indirection here
int count = 0;
for (PsiField referenced : cls.getAllFields()) {
// Only check a few; avoid getting bogged down on large classes
if (count++ == 20) {
break;
}
PsiType innerType = referenced.getType();
if (!(innerType instanceof PsiClassType)) {
continue;
}
fqn = innerType.getCanonicalText();
if (fqn.startsWith("java.")) {
continue;
}
PsiClass innerCls = ((PsiClassType) innerType).resolve();
if (innerCls == null) {
continue;
}
if (fqn.startsWith("android.")) {
if (isLeakCandidate(innerCls)) {
String message =
"Do not place Android context classes in static fields "
+ "(static reference to `"
+ cls.getName() + "` which has field "
+ "`" + referenced.getName() + "` pointing to `"
+ innerCls.getName() + "`); "
+ "this is a memory leak (and also breaks Instant Run)";
report(field, message);
break;
}
}
}
}
}
private void report(@NonNull UElement element, @NonNull String message) {
mContext.report(ISSUE, element, mContext.getUastLocation(element), message);
}
}
private static boolean isLeakCandidate(@NonNull PsiClass cls) {
return InheritanceUtil.isInheritor(cls, false, CLASS_CONTEXT)
|| InheritanceUtil.isInheritor(cls, false, CLASS_VIEW)
|| InheritanceUtil.isInheritor(cls, false, CLASS_FRAGMENT);
}
}