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Eclipse Compiler for Java(TM)
/*******************************************************************************
* Copyright (c) 2011, 2019 GK Software AG and others.
*
* This program and the accompanying materials
* are made available under the terms of the Eclipse Public License 2.0
* which accompanies this distribution, and is available at
* https://www.eclipse.org/legal/epl-2.0/
*
* SPDX-License-Identifier: EPL-2.0
*
* Contributors:
* Stephan Herrmann - initial API and implementation
* Nikolay Metchev ([email protected]) - Contributions for
* bug 411098 - [compiler][resource] Invalid Resource Leak Warning using ternary operator inside try-with-resource
*******************************************************************************/
package org.eclipse.jdt.internal.compiler.ast;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import org.eclipse.jdt.core.compiler.CharOperation;
import org.eclipse.jdt.internal.compiler.CompilationResult;
import org.eclipse.jdt.internal.compiler.codegen.CodeStream;
import org.eclipse.jdt.internal.compiler.flow.FinallyFlowContext;
import org.eclipse.jdt.internal.compiler.flow.FlowContext;
import org.eclipse.jdt.internal.compiler.flow.FlowInfo;
import org.eclipse.jdt.internal.compiler.impl.Constant;
import org.eclipse.jdt.internal.compiler.impl.ReferenceContext;
import org.eclipse.jdt.internal.compiler.lookup.Binding;
import org.eclipse.jdt.internal.compiler.lookup.BlockScope;
import org.eclipse.jdt.internal.compiler.lookup.LocalVariableBinding;
import org.eclipse.jdt.internal.compiler.lookup.MethodBinding;
import org.eclipse.jdt.internal.compiler.lookup.MethodScope;
import org.eclipse.jdt.internal.compiler.lookup.ReferenceBinding;
import org.eclipse.jdt.internal.compiler.lookup.Scope;
import org.eclipse.jdt.internal.compiler.lookup.TagBits;
import org.eclipse.jdt.internal.compiler.lookup.TypeBinding;
import org.eclipse.jdt.internal.compiler.lookup.TypeConstants;
import org.eclipse.jdt.internal.compiler.lookup.TypeIds;
import org.eclipse.jdt.internal.compiler.problem.ProblemReporter;
import org.eclipse.jdt.internal.compiler.util.Util;
/**
* A faked local variable declaration used for keeping track of data flows of a
* special variable. Certain events will be recorded by changing the null info
* for this variable.
*
* See bug 349326 - [1.7] new warning for missing try-with-resources
*/
@SuppressWarnings({"rawtypes", "unchecked"})
public class FakedTrackingVariable extends LocalDeclaration {
private static final char[] UNASSIGNED_CLOSEABLE_NAME = "".toCharArray(); //$NON-NLS-1$
private static final char[] UNASSIGNED_CLOSEABLE_NAME_TEMPLATE = "".toCharArray(); //$NON-NLS-1$
private static final char[] TEMPLATE_ARGUMENT = "{0}".toCharArray(); //$NON-NLS-1$
// a call to close() was seen at least on one path:
private static final int CLOSE_SEEN = 1;
// the resource is shared with outside code either by
// - passing as an arg in a method call or
// - obtaining this from a method call or array reference
// Interpret that we may or may not be responsible for closing
private static final int SHARED_WITH_OUTSIDE = 2;
// the resource is likely owned by outside code (owner has responsibility to close):
// - obtained as argument of the current method, or via a field read
// - stored into a field
// - returned as the result of this method
private static final int OWNED_BY_OUTSIDE = 4;
// If close() is invoked from a nested method (inside a local type) report remaining problems only as potential:
private static final int CLOSED_IN_NESTED_METHOD = 8;
// explicit closing has been reported already against this resource:
private static final int REPORTED_EXPLICIT_CLOSE = 16;
// a location independent potential problem has been reported against this resource:
private static final int REPORTED_POTENTIAL_LEAK = 32;
// a location independent definitive problem has been reported against this resource:
private static final int REPORTED_DEFINITIVE_LEAK = 64;
// a local declarations that acts as the element variable of a foreach loop (should never suggest to use t-w-r):
private static final int FOREACH_ELEMENT_VAR = 128;
public static boolean TEST_372319 = false; // see https://bugs.eclipse.org/372319
/**
* Bitset of {@link #CLOSE_SEEN}, {@link #SHARED_WITH_OUTSIDE}, {@link #OWNED_BY_OUTSIDE}, {@link #CLOSED_IN_NESTED_METHOD}, {@link #REPORTED_EXPLICIT_CLOSE}, {@link #REPORTED_POTENTIAL_LEAK} and {@link #REPORTED_DEFINITIVE_LEAK}.
*/
private int globalClosingState = 0;
public LocalVariableBinding originalBinding; // the real local being tracked, can be null for preliminary track vars for allocation expressions
public FakedTrackingVariable innerTracker; // chained tracking variable of a chained (wrapped) resource
public FakedTrackingVariable outerTracker; // inverse of 'innerTracker'
MethodScope methodScope; // designates the method declaring this variable
private HashMap recordedLocations; // initially null, ASTNode -> Integer
// temporary storage while analyzing "res = new Res();":
private ASTNode currentAssignment; // temporarily store the assignment as the location for error reporting
// if tracking var was allocated from a finally context, record here the flow context of the corresponding try block
private FlowContext tryContext;
public FakedTrackingVariable(LocalVariableBinding original, ASTNode location, FlowInfo flowInfo, FlowContext flowContext, int nullStatus) {
super(original.name, location.sourceStart, location.sourceEnd);
this.type = new SingleTypeReference(
TypeConstants.OBJECT,
((long)this.sourceStart <<32)+this.sourceEnd);
this.methodScope = original.declaringScope.methodScope();
this.originalBinding = original;
// inside a finally block?
while (flowContext != null) {
if (flowContext instanceof FinallyFlowContext) {
// yes -> connect to the corresponding try block:
this.tryContext = ((FinallyFlowContext) flowContext).tryContext;
break;
}
flowContext = flowContext.parent;
}
resolve(original.declaringScope);
if (nullStatus != 0)
flowInfo.markNullStatus(this.binding, nullStatus); // mark that this flow has seen the resource
}
/* Create an unassigned tracking variable while analyzing an allocation expression: */
private FakedTrackingVariable(BlockScope scope, ASTNode location, FlowInfo flowInfo, int nullStatus) {
super(UNASSIGNED_CLOSEABLE_NAME, location.sourceStart, location.sourceEnd);
this.type = new SingleTypeReference(
TypeConstants.OBJECT,
((long)this.sourceStart <<32)+this.sourceEnd);
this.methodScope = scope.methodScope();
this.originalBinding = null;
resolve(scope);
if (nullStatus != 0)
flowInfo.markNullStatus(this.binding, nullStatus); // mark that this flow has seen the resource
}
@Override
public void generateCode(BlockScope currentScope, CodeStream codeStream)
{ /* NOP - this variable is completely dummy, ie. for analysis only. */ }
@Override
public void resolve (BlockScope scope) {
// only need the binding, which is used as reference in FlowInfo methods.
this.binding = new LocalVariableBinding(
this.name,
scope.getJavaLangObject(), // dummy, just needs to be a reference type
0,
false);
this.binding.closeTracker = this;
this.binding.declaringScope = scope;
this.binding.setConstant(Constant.NotAConstant);
this.binding.useFlag = LocalVariableBinding.USED;
// use a free slot without assigning it:
this.binding.id = scope.registerTrackingVariable(this);
}
/**
* If expression resolves to a value of type AutoCloseable answer the variable that tracks closing of that local.
* Covers two cases:
*
* - value is a local variable reference, create tracking variable it if needed.
*
- value is an allocation expression, return a preliminary tracking variable if set.
*
* @param expression
* @return a new {@link FakedTrackingVariable} or null.
*/
public static FakedTrackingVariable getCloseTrackingVariable(Expression expression, FlowInfo flowInfo, FlowContext flowContext) {
while (true) {
if (expression instanceof CastExpression)
expression = ((CastExpression) expression).expression;
else if (expression instanceof Assignment)
expression = ((Assignment) expression).expression;
else if (expression instanceof ConditionalExpression) {
FakedTrackingVariable falseTrackingVariable = getCloseTrackingVariable(((ConditionalExpression)expression).valueIfFalse, flowInfo, flowContext);
if (falseTrackingVariable != null) {
return falseTrackingVariable;
}
return getCloseTrackingVariable(((ConditionalExpression)expression).valueIfTrue, flowInfo, flowContext);
} else if (expression instanceof SwitchExpression) {
for (Expression re : ((SwitchExpression) expression).resultExpressions) {
FakedTrackingVariable fakedTrackingVariable = getCloseTrackingVariable(re, flowInfo, flowContext);
if (fakedTrackingVariable != null) {
return fakedTrackingVariable;
}
}
return null;
}
else
break;
}
if (expression instanceof SingleNameReference) {
SingleNameReference name = (SingleNameReference) expression;
if (name.binding instanceof LocalVariableBinding) {
LocalVariableBinding local = (LocalVariableBinding)name.binding;
if (local.closeTracker != null)
return local.closeTracker;
if (!isAnyCloseable(expression.resolvedType))
return null;
if ((local.tagBits & TagBits.IsResource) != 0)
return null;
// tracking var doesn't yet exist. This happens in finally block
// which is analyzed before the corresponding try block
Statement location = local.declaration;
local.closeTracker = new FakedTrackingVariable(local, location, flowInfo, flowContext, FlowInfo.UNKNOWN);
if (local.isParameter()) {
local.closeTracker.globalClosingState |= OWNED_BY_OUTSIDE;
// status of this tracker is now UNKNOWN
}
return local.closeTracker;
}
} else if (expression instanceof AllocationExpression) {
// return any preliminary tracking variable from analyseCloseableAllocation
return ((AllocationExpression) expression).closeTracker;
}
return null;
}
/**
* Before analyzing an assignment of this shape: singleName = new Allocation()
* connect any tracking variable of the LHS with the allocation on the RHS.
* Also the assignment is temporarily stored in the tracking variable in case we need to
* report errors because the assignment leaves the old LHS value unclosed.
* In this case the assignment should be used as the error location.
*
* @param location the assignment/local declaration being analyzed
* @param local the local variable being assigned to
* @param rhs the rhs of the assignment resp. the initialization of the local variable declaration.
* Precondition: client has already checked that the resolved type of this expression is either a closeable type or NULL.
*/
public static void preConnectTrackerAcrossAssignment(ASTNode location, LocalVariableBinding local, Expression rhs, FlowInfo flowInfo) {
FakedTrackingVariable closeTracker = null;
if (containsAllocation(rhs)) {
closeTracker = local.closeTracker;
if (closeTracker == null) {
if (rhs.resolvedType != TypeBinding.NULL) { // not NULL means valid closeable as per method precondition
closeTracker = new FakedTrackingVariable(local, location, flowInfo, null, FlowInfo.UNKNOWN);
if (local.isParameter()) {
closeTracker.globalClosingState |= OWNED_BY_OUTSIDE;
}
}
}
if (closeTracker != null) {
closeTracker.currentAssignment = location;
preConnectTrackerAcrossAssignment(location, local, flowInfo, closeTracker, rhs);
}
}
}
private static boolean containsAllocation(SwitchExpression location) {
for (Expression re : location.resultExpressions) {
if (containsAllocation(re))
return true;
}
return false;
}
private static boolean containsAllocation(ASTNode location) {
if (location instanceof AllocationExpression)
return true;
if (location instanceof ConditionalExpression) {
ConditionalExpression conditional = (ConditionalExpression) location;
return containsAllocation(conditional.valueIfTrue) || containsAllocation(conditional.valueIfFalse);
} else if (location instanceof SwitchExpression) {
return containsAllocation((SwitchExpression) location);
}
if (location instanceof CastExpression)
return containsAllocation(((CastExpression) location).expression);
return false;
}
private static void preConnectTrackerAcrossAssignment(ASTNode location, LocalVariableBinding local, FlowInfo flowInfo,
FakedTrackingVariable closeTracker, Expression expression) {
if (expression instanceof AllocationExpression) {
preConnectTrackerAcrossAssignment(location, local, flowInfo, (AllocationExpression) expression, closeTracker);
} else if (expression instanceof ConditionalExpression) {
preConnectTrackerAcrossAssignment(location, local, flowInfo, (ConditionalExpression) expression, closeTracker);
} else if (expression instanceof SwitchExpression) {
preConnectTrackerAcrossAssignment(location, local, flowInfo, (SwitchExpression) expression, closeTracker);
} else if (expression instanceof CastExpression) {
preConnectTrackerAcrossAssignment(location, local, ((CastExpression) expression).expression, flowInfo);
}
}
private static void preConnectTrackerAcrossAssignment(ASTNode location, LocalVariableBinding local, FlowInfo flowInfo,
ConditionalExpression conditional, FakedTrackingVariable closeTracker) {
preConnectTrackerAcrossAssignment(location, local, flowInfo, closeTracker, conditional.valueIfFalse);
preConnectTrackerAcrossAssignment(location, local, flowInfo, closeTracker, conditional.valueIfTrue);
}
private static void preConnectTrackerAcrossAssignment(ASTNode location, LocalVariableBinding local, FlowInfo flowInfo,
SwitchExpression se, FakedTrackingVariable closeTracker) {
for (Expression re : se.resultExpressions) {
preConnectTrackerAcrossAssignment(location, local, flowInfo, closeTracker, re);
}
}
private static void preConnectTrackerAcrossAssignment(ASTNode location, LocalVariableBinding local, FlowInfo flowInfo,
AllocationExpression allocationExpression, FakedTrackingVariable closeTracker) {
allocationExpression.closeTracker = closeTracker;
if (allocationExpression.arguments != null && allocationExpression.arguments.length > 0) {
// also push into nested allocations, see https://bugs.eclipse.org/368709
preConnectTrackerAcrossAssignment(location, local, allocationExpression.arguments[0], flowInfo);
}
}
/**
* Compute/assign a tracking variable for a freshly allocated closeable value, using information from our white lists.
* See Bug 358903 - Filter practically unimportant resource leak warnings
*/
public static void analyseCloseableAllocation(BlockScope scope, FlowInfo flowInfo, AllocationExpression allocation) {
// client has checked that the resolvedType is an AutoCloseable, hence the following cast is safe:
if (((ReferenceBinding)allocation.resolvedType).hasTypeBit(TypeIds.BitResourceFreeCloseable)) {
// remove unnecessary attempts (closeable is not relevant)
if (allocation.closeTracker != null) {
allocation.closeTracker.withdraw();
allocation.closeTracker = null;
}
} else if (((ReferenceBinding)allocation.resolvedType).hasTypeBit(TypeIds.BitWrapperCloseable)) {
boolean isWrapper = true;
if (allocation.arguments != null && allocation.arguments.length > 0) {
// find the wrapped resource represented by its tracking var:
FakedTrackingVariable innerTracker = findCloseTracker(scope, flowInfo, allocation.arguments[0]);
if (innerTracker != null) {
FakedTrackingVariable currentInner = innerTracker;
do {
if (currentInner == allocation.closeTracker)
return; // self wrap (res = new Res(res)) -> neither change (here) nor remove (below)
// also check for indirect cycles, see https://bugs.eclipse.org/368709
currentInner = currentInner.innerTracker;
} while (currentInner != null);
int newStatus = FlowInfo.NULL;
if (allocation.closeTracker == null) {
allocation.closeTracker = new FakedTrackingVariable(scope, allocation, flowInfo, FlowInfo.UNKNOWN); // no local available, closeable is unassigned
} else {
if (scope.finallyInfo != null) {
// inject results from analysing a finally block onto the newly connected wrapper
int finallyStatus = scope.finallyInfo.nullStatus(allocation.closeTracker.binding);
if (finallyStatus != FlowInfo.UNKNOWN)
newStatus = finallyStatus;
}
}
if (allocation.closeTracker.innerTracker != null) {
innerTracker = pickMoreUnsafe(allocation.closeTracker.innerTracker, innerTracker, scope, flowInfo);
}
allocation.closeTracker.innerTracker = innerTracker;
innerTracker.outerTracker = allocation.closeTracker;
flowInfo.markNullStatus(allocation.closeTracker.binding, newStatus);
if (newStatus != FlowInfo.NULL) {
// propagate results from a finally block also into nested resources:
FakedTrackingVariable currentTracker = innerTracker;
while (currentTracker != null) {
flowInfo.markNullStatus(currentTracker.binding, newStatus);
currentTracker.globalClosingState |= allocation.closeTracker.globalClosingState;
currentTracker = currentTracker.innerTracker;
}
}
return; // keep chaining wrapper (by avoiding to fall through to removeTrackingVar below)
} else {
if (!isAnyCloseable(allocation.arguments[0].resolvedType)) {
isWrapper = false; // argument is not closeable
}
}
} else {
isWrapper = false; // no argument
}
// successful wrapper detection has exited above, let's see why that failed
if (isWrapper) {
// remove unnecessary attempts (wrapper has no relevant inner)
if (allocation.closeTracker != null) {
allocation.closeTracker.withdraw();
allocation.closeTracker = null;
}
} else {
// allocation does not provide a resource as the first argument -> don't treat as a wrapper
handleRegularResource(scope, flowInfo, allocation);
}
} else { // regular resource
handleRegularResource(scope, flowInfo, allocation);
}
}
private static FakedTrackingVariable pickMoreUnsafe(FakedTrackingVariable tracker1, FakedTrackingVariable tracker2, BlockScope scope, FlowInfo info) {
// whichever of the two trackers has stronger indication to be leaking will be returned,
// the other one will be removed from the scope (considered to be merged into the former).
int status1 = info.nullStatus(tracker1.binding);
int status2 = info.nullStatus(tracker2.binding);
if (status1 == FlowInfo.NULL || status2 == FlowInfo.NON_NULL) return pick(tracker1, tracker2, scope);
if (status1 == FlowInfo.NON_NULL || status2 == FlowInfo.NULL) return pick(tracker2, tracker1, scope);
if ((status1 & FlowInfo.POTENTIALLY_NULL) != 0) return pick(tracker1, tracker2, scope);
if ((status2 & FlowInfo.POTENTIALLY_NULL) != 0) return pick(tracker2, tracker1, scope);
return pick(tracker1, tracker2, scope);
}
private static FakedTrackingVariable pick(FakedTrackingVariable tracker1, FakedTrackingVariable tracker2, BlockScope scope) {
tracker2.withdraw();
return tracker1;
}
private static void handleRegularResource(BlockScope scope, FlowInfo flowInfo, AllocationExpression allocation) {
FakedTrackingVariable presetTracker = allocation.closeTracker;
if (presetTracker != null && presetTracker.originalBinding != null) {
// the current assignment forgets a previous resource in the LHS, may cause a leak
// report now because handleResourceAssignment can't distinguish this from a self-wrap situation
int closeStatus = flowInfo.nullStatus(presetTracker.binding);
if (closeStatus != FlowInfo.NON_NULL // old resource was not closed
&& closeStatus != FlowInfo.UNKNOWN // old resource had some flow information
&& !flowInfo.isDefinitelyNull(presetTracker.originalBinding) // old resource was not null
&& !(presetTracker.currentAssignment instanceof LocalDeclaration)) // forgetting old val in local decl is syntactically impossible
allocation.closeTracker.recordErrorLocation(presetTracker.currentAssignment, closeStatus);
} else {
allocation.closeTracker = new FakedTrackingVariable(scope, allocation, flowInfo, FlowInfo.UNKNOWN); // no local available, closeable is unassigned
}
flowInfo.markAsDefinitelyNull(allocation.closeTracker.binding);
}
/** Find an existing tracking variable for the argument of an allocation for a resource wrapper. */
private static FakedTrackingVariable findCloseTracker(BlockScope scope, FlowInfo flowInfo, Expression arg)
{
while (arg instanceof Assignment) {
Assignment assign = (Assignment)arg;
LocalVariableBinding innerLocal = assign.localVariableBinding();
if (innerLocal != null) {
// nested assignment has already been processed
return innerLocal.closeTracker;
} else {
arg = assign.expression; // unwrap assignment and fall through
}
}
if (arg instanceof SingleNameReference) {
// is allocation arg a reference to an existing closeable?
LocalVariableBinding local = arg.localVariableBinding();
if (local != null) {
return local.closeTracker;
}
} else if (arg instanceof AllocationExpression) {
// nested allocation
return ((AllocationExpression)arg).closeTracker;
}
return null; // not a tracked expression
}
/**
* Given the rhs of an assignment or local declaration has a (Auto)Closeable type (or null), setup for leak analysis now:
* Create or re-use a tracking variable, and wire and initialize everything.
* @param scope scope containing the assignment
* @param upstreamInfo info without analysis of the rhs, use this to determine the status of a resource being disconnected
* @param flowInfo info with analysis of the rhs, use this for recording resource status because this will be passed downstream
* @param flowContext
* @param location where to report warnigs/errors against
* @param rhs the right hand side of the assignment, this expression is to be analyzed.
* The caller has already checked that the rhs is either of a closeable type or null.
* @param local the local variable into which the rhs is being assigned
*/
public static void handleResourceAssignment(BlockScope scope, FlowInfo upstreamInfo, FlowInfo flowInfo, FlowContext flowContext, ASTNode location, Expression rhs, LocalVariableBinding local)
{
// does the LHS (local) already have a tracker, indicating we may leak a resource by the assignment?
FakedTrackingVariable previousTracker = null;
FakedTrackingVariable disconnectedTracker = null;
if (local.closeTracker != null) {
// assigning to a variable already holding an AutoCloseable, has it been closed before?
previousTracker = local.closeTracker;
int nullStatus = upstreamInfo.nullStatus(local);
if (nullStatus != FlowInfo.NULL && nullStatus != FlowInfo.UNKNOWN) // only if previous value may be relevant
disconnectedTracker = previousTracker; // report error below, unless we have a self-wrap assignment
}
rhsAnalyis:
if (rhs.resolvedType != TypeBinding.NULL) {
// new value is AutoCloseable, start tracking, possibly re-using existing tracker var:
FakedTrackingVariable rhsTrackVar = getCloseTrackingVariable(rhs, flowInfo, flowContext);
if (rhsTrackVar != null) { // 1. if RHS has a tracking variable...
if (local.closeTracker == null) {
// null shouldn't occur but let's play safe:
if (rhsTrackVar.originalBinding != null)
local.closeTracker = rhsTrackVar; // a.: let fresh LHS share it
if (rhsTrackVar.currentAssignment == location) {
// pre-set tracker from lhs - passed from outside (or foreach)?
// now it's a fresh resource
rhsTrackVar.globalClosingState &= ~(SHARED_WITH_OUTSIDE|OWNED_BY_OUTSIDE|FOREACH_ELEMENT_VAR);
}
} else {
if (rhs instanceof AllocationExpression || rhs instanceof ConditionalExpression || rhs instanceof SwitchExpression) {
if (rhsTrackVar == disconnectedTracker)
return; // b.: self wrapper: res = new Wrap(res); -> done!
if (local.closeTracker == rhsTrackVar
&& ((rhsTrackVar.globalClosingState & OWNED_BY_OUTSIDE) != 0)) {
// c.: assigning a fresh resource (pre-connected alloc)
// to a local previously holding an alien resource -> start over
local.closeTracker = new FakedTrackingVariable(local, location, flowInfo, flowContext, FlowInfo.NULL);
// still check disconnectedTracker below
break rhsAnalyis;
}
}
local.closeTracker = rhsTrackVar; // d.: conflicting LHS and RHS, proceed with recordErrorLocation below
}
// keep close-status of RHS unchanged across this assignment
} else if (previousTracker != null) { // 2. re-use tracking variable from the LHS?
FlowContext currentFlowContext = flowContext;
checkReuseTracker : {
if (previousTracker.tryContext != null) {
while (currentFlowContext != null) {
if (previousTracker.tryContext == currentFlowContext) {
// "previous" location was the finally block of the current try statement.
// -> This is not a re-assignment.
// see https://bugs.eclipse.org/388996
break checkReuseTracker;
}
currentFlowContext = currentFlowContext.parent;
}
}
// re-assigning from a fresh value, mark as not-closed again:
if ((previousTracker.globalClosingState & (SHARED_WITH_OUTSIDE|OWNED_BY_OUTSIDE|FOREACH_ELEMENT_VAR)) == 0
&& flowInfo.hasNullInfoFor(previousTracker.binding)) // avoid spilling info into a branch that doesn't see the corresponding resource
flowInfo.markAsDefinitelyNull(previousTracker.binding);
local.closeTracker = analyseCloseableExpression(flowInfo, flowContext, local, location, rhs, previousTracker);
}
} else { // 3. no re-use, create a fresh tracking variable:
rhsTrackVar = analyseCloseableExpression(flowInfo, flowContext, local, location, rhs, null);
if (rhsTrackVar != null) {
local.closeTracker = rhsTrackVar;
// a fresh resource, mark as not-closed:
if ((rhsTrackVar.globalClosingState & (SHARED_WITH_OUTSIDE|OWNED_BY_OUTSIDE|FOREACH_ELEMENT_VAR)) == 0)
flowInfo.markAsDefinitelyNull(rhsTrackVar.binding);
// TODO(stephan): this might be useful, but I could not find a test case for it:
// if (flowContext.initsOnFinally != null)
// flowContext.initsOnFinally.markAsDefinitelyNonNull(trackerBinding);
}
}
}
if (disconnectedTracker != null) {
if (disconnectedTracker.innerTracker != null && disconnectedTracker.innerTracker.binding.declaringScope == scope) {
// discard tracker for the wrapper but keep the inner:
disconnectedTracker.innerTracker.outerTracker = null;
scope.pruneWrapperTrackingVar(disconnectedTracker);
} else {
int upstreamStatus = upstreamInfo.nullStatus(disconnectedTracker.binding);
if (upstreamStatus != FlowInfo.NON_NULL)
disconnectedTracker.recordErrorLocation(location, upstreamStatus);
}
}
}
/**
* Analyze structure of a closeable expression, matching (chained) resources against our white lists.
* @param flowInfo where to record close status
* @param local local variable to which the closeable is being assigned
* @param location where to flag errors/warnings against
* @param expression expression to be analyzed
* @param previousTracker when analyzing a re-assignment we may already have a tracking variable for local,
* which we should then re-use
* @return a tracking variable associated with local or null if no need to track
*/
private static FakedTrackingVariable analyseCloseableExpression(FlowInfo flowInfo, FlowContext flowContext, LocalVariableBinding local,
ASTNode location, Expression expression, FakedTrackingVariable previousTracker)
{
// unwrap uninteresting nodes:
while (true) {
if (expression instanceof Assignment)
expression = ((Assignment)expression).expression;
else if (expression instanceof CastExpression)
expression = ((CastExpression) expression).expression;
else
break;
}
boolean isResourceProducer = false;
if (expression.resolvedType instanceof ReferenceBinding) {
ReferenceBinding resourceType = (ReferenceBinding) expression.resolvedType;
if (resourceType.hasTypeBit(TypeIds.BitResourceFreeCloseable)) {
if (isBlacklistedMethod(expression))
isResourceProducer = true;
else
return null; // (a) resource-free closeable: -> null
}
}
// analyze by node type:
if (expression instanceof AllocationExpression) {
// allocation expressions already have their tracking variables analyzed by analyseCloseableAllocation(..)
FakedTrackingVariable tracker = ((AllocationExpression) expression).closeTracker;
if (tracker != null && tracker.originalBinding == null) {
// tracker without original binding (unassigned closeable) shouldn't reach here but let's play safe
return null;
}
return tracker;
} else if (expression instanceof MessageSend
|| expression instanceof ArrayReference)
{
// we *might* be responsible for the resource obtained
FakedTrackingVariable tracker = new FakedTrackingVariable(local, location, flowInfo, flowContext, FlowInfo.POTENTIALLY_NULL); // shed some doubt
if (!isResourceProducer)
tracker.globalClosingState |= SHARED_WITH_OUTSIDE;
return tracker;
} else if (
(expression.bits & RestrictiveFlagMASK) == Binding.FIELD
||((expression instanceof QualifiedNameReference)
&& ((QualifiedNameReference) expression).isFieldAccess()))
{
// responsibility for this resource probably lies at a higher level
FakedTrackingVariable tracker = new FakedTrackingVariable(local, location, flowInfo, flowContext, FlowInfo.UNKNOWN);
tracker.globalClosingState |= OWNED_BY_OUTSIDE;
// leave state as UNKNOWN, the bit OWNED_BY_OUTSIDE will prevent spurious warnings
return tracker;
}
if (local.closeTracker != null)
// (c): inner has already been analyzed: -> re-use track var
return local.closeTracker;
FakedTrackingVariable newTracker = new FakedTrackingVariable(local, location, flowInfo, flowContext, FlowInfo.UNKNOWN);
LocalVariableBinding rhsLocal = expression.localVariableBinding();
if (rhsLocal != null && rhsLocal.isParameter()) {
newTracker.globalClosingState |= OWNED_BY_OUTSIDE;
}
return newTracker;
}
private static boolean isBlacklistedMethod(Expression expression) {
if (expression instanceof MessageSend) {
MethodBinding method = ((MessageSend) expression).binding;
if (method != null && method.isValidBinding())
// for all methods in java.nio.file.Files that return a resource (Stream) it really needs closing
return CharOperation.equals(method.declaringClass.compoundName, TypeConstants.JAVA_NIO_FILE_FILES);
}
return false;
}
public static void cleanUpAfterAssignment(BlockScope currentScope, int lhsBits, Expression expression) {
// remove all remaining track vars with no original binding
// unwrap uninteresting nodes:
while (true) {
if (expression instanceof Assignment)
expression = ((Assignment)expression).expression;
else if (expression instanceof CastExpression)
expression = ((CastExpression) expression).expression;
else
break;
}
if (expression instanceof AllocationExpression) {
FakedTrackingVariable tracker = ((AllocationExpression) expression).closeTracker;
if (tracker != null && tracker.originalBinding == null) {
tracker.withdraw();
((AllocationExpression) expression).closeTracker = null;
}
} else {
// assignment passing a local into a field?
LocalVariableBinding local = expression.localVariableBinding();
if (local != null && local.closeTracker != null && ((lhsBits & Binding.FIELD) != 0))
local.closeTracker.withdraw(); // TODO: may want to use local.closeTracker.markPassedToOutside(..,true)
}
}
/** Answer wither the given type binding is a subtype of java.lang.AutoCloseable. */
public static boolean isAnyCloseable(TypeBinding typeBinding) {
return typeBinding instanceof ReferenceBinding
&& ((ReferenceBinding)typeBinding).hasTypeBit(TypeIds.BitAutoCloseable|TypeIds.BitCloseable);
}
public int findMostSpecificStatus(FlowInfo flowInfo, BlockScope currentScope, BlockScope locationScope) {
int status = FlowInfo.UNKNOWN;
FakedTrackingVariable currentTracker = this;
// loop as to consider wrappers (per white list) encapsulating an inner resource.
while (currentTracker != null) {
LocalVariableBinding currentVar = currentTracker.binding;
int currentStatus = getNullStatusAggressively(currentVar, flowInfo);
if (locationScope != null) // only check at method exit points
currentStatus = mergeCloseStatus(locationScope, currentStatus, currentVar, currentScope);
if (currentStatus == FlowInfo.NON_NULL) {
status = currentStatus;
break; // closed -> stop searching
} else if (status == FlowInfo.NULL || status == FlowInfo.UNKNOWN) {
status = currentStatus; // improved although not yet safe -> keep searching for better
}
currentTracker = currentTracker.innerTracker;
}
return status;
}
/**
* Get the null status looking even into unreachable flows
* @param local
* @param flowInfo
* @return one of the constants FlowInfo.{NULL,POTENTIALLY_NULL,POTENTIALLY_NON_NULL,NON_NULL}.
*/
private int getNullStatusAggressively(LocalVariableBinding local, FlowInfo flowInfo) {
if (flowInfo == FlowInfo.DEAD_END) {
return FlowInfo.UNKNOWN;
}
int reachMode = flowInfo.reachMode();
int status = 0;
try {
// unreachable flowInfo is too shy in reporting null-issues, temporarily forget reachability:
if (reachMode != FlowInfo.REACHABLE)
flowInfo.tagBits &= ~FlowInfo.UNREACHABLE;
status = flowInfo.nullStatus(local);
if (TEST_372319) { // see https://bugs.eclipse.org/372319
try {
Thread.sleep(5); // increase probability of concurrency bug
} catch (InterruptedException e) { /* nop */ }
}
} finally {
// reset
flowInfo.tagBits |= reachMode;
}
// at this point some combinations are not useful so flatten to a single bit:
if ((status & FlowInfo.NULL) != 0) {
if ((status & (FlowInfo.NON_NULL | FlowInfo.POTENTIALLY_NON_NULL)) != 0)
return FlowInfo.POTENTIALLY_NULL; // null + doubt = pot null
return FlowInfo.NULL;
} else if ((status & FlowInfo.NON_NULL) != 0) {
if ((status & FlowInfo.POTENTIALLY_NULL) != 0)
return FlowInfo.POTENTIALLY_NULL; // non-null + doubt = pot null
return FlowInfo.NON_NULL;
} else if ((status & FlowInfo.POTENTIALLY_NULL) != 0)
return FlowInfo.POTENTIALLY_NULL;
return status;
}
public int mergeCloseStatus(BlockScope currentScope, int status, LocalVariableBinding local, BlockScope outerScope) {
// get the most suitable null status representing whether resource 'binding' has been closed
// start at 'currentScope' and potentially travel out until 'outerScope'
// at each scope consult any recorded 'finallyInfo'.
if (status != FlowInfo.NON_NULL) {
if (currentScope.finallyInfo != null) {
int finallyStatus = currentScope.finallyInfo.nullStatus(local);
if (finallyStatus == FlowInfo.NON_NULL)
return finallyStatus;
if (finallyStatus != FlowInfo.NULL && currentScope.finallyInfo.hasNullInfoFor(local)) // neither is NON_NULL, but not both are NULL => call it POTENTIALLY_NULL
status = FlowInfo.POTENTIALLY_NULL;
}
if (currentScope != outerScope && currentScope.parent instanceof BlockScope)
return mergeCloseStatus(((BlockScope) currentScope.parent), status, local, outerScope);
}
return status;
}
/** Mark that this resource is closed locally. */
public void markClose(FlowInfo flowInfo, FlowContext flowContext) {
FakedTrackingVariable current = this;
do {
flowInfo.markAsDefinitelyNonNull(current.binding);
current.globalClosingState |= CLOSE_SEEN;
flowContext.markFinallyNullStatus(current.binding, FlowInfo.NON_NULL);
current = current.innerTracker;
} while (current != null);
}
/** Mark that this resource is closed from a nested method (inside a local class). */
public void markClosedInNestedMethod() {
this.globalClosingState |= CLOSED_IN_NESTED_METHOD;
}
/**
* Mark that this resource is passed to some outside code
* (as argument to a method/ctor call or as a return value from the current method),
* and thus should be considered as potentially closed.
* @param owned should the resource be considered owned by some outside?
*/
public static FlowInfo markPassedToOutside(BlockScope scope, Expression expression, FlowInfo flowInfo, FlowContext flowContext, boolean owned) {
FakedTrackingVariable trackVar = getCloseTrackingVariable(expression, flowInfo, flowContext);
if (trackVar != null) {
// insert info that the tracked resource *may* be closed (by the target method, i.e.)
FlowInfo infoResourceIsClosed = owned ? flowInfo : flowInfo.copy();
int flag = owned ? OWNED_BY_OUTSIDE : SHARED_WITH_OUTSIDE;
do {
trackVar.globalClosingState |= flag;
if (scope.methodScope() != trackVar.methodScope)
trackVar.globalClosingState |= CLOSED_IN_NESTED_METHOD;
infoResourceIsClosed.markAsDefinitelyNonNull(trackVar.binding);
} while ((trackVar = trackVar.innerTracker) != null);
if (owned) {
return infoResourceIsClosed; // don't let downstream signal any problems on this flow
} else {
return FlowInfo.conditional(flowInfo, infoResourceIsClosed); // only report potential problems on this flow
}
}
return flowInfo;
}
public static void markForeachElementVar(LocalDeclaration local) {
if (local.binding != null && local.binding.closeTracker != null) {
local.binding.closeTracker.globalClosingState |= FOREACH_ELEMENT_VAR;
}
}
/**
* Iterator for a set of FakedTrackingVariable, which dispenses the elements
* according to the priorities defined by enum {@link Stage}.
* Resources whose outer is owned by an enclosing scope are never answered,
* unless we are analysing on behalf of an exit (return/throw).
*/
public static class IteratorForReporting implements Iterator {
private final Set varSet;
private final Scope scope;
private final boolean atExit;
private Stage stage;
private Iterator iterator;
private FakedTrackingVariable next;
enum Stage {
/** 1. prio: all top-level resources, ie., resources with no outer. */
OuterLess,
/** 2. prio: resources whose outer has already been processed (element of the same varSet). */
InnerOfProcessed,
/** 3. prio: resources whose outer is not owned by any enclosing scope. */
InnerOfNotEnclosing,
/** 4. prio: when analysing on behalf of an exit point: anything not picked before. */
AtExit
}
public IteratorForReporting(List variables, Scope scope, boolean atExit) {
this.varSet = new HashSet<>(variables);
this.scope = scope;
this.atExit = atExit;
setUpForStage(Stage.OuterLess);
}
@Override
public boolean hasNext() {
FakedTrackingVariable trackingVar;
switch (this.stage) {
case OuterLess:
while (this.iterator.hasNext()) {
trackingVar = this.iterator.next();
if (trackingVar.outerTracker == null)
return found(trackingVar);
}
setUpForStage(Stage.InnerOfProcessed);
//$FALL-THROUGH$
case InnerOfProcessed:
while (this.iterator.hasNext()) {
trackingVar = this.iterator.next();
FakedTrackingVariable outer = trackingVar.outerTracker;
if (outer.binding.declaringScope == this.scope && !this.varSet.contains(outer))
return found(trackingVar);
}
setUpForStage(Stage.InnerOfNotEnclosing);
//$FALL-THROUGH$
case InnerOfNotEnclosing:
searchAlien: while (this.iterator.hasNext()) {
trackingVar = this.iterator.next();
FakedTrackingVariable outer = trackingVar.outerTracker;
if (!this.varSet.contains(outer)) {
Scope outerTrackerScope = outer.binding.declaringScope;
Scope currentScope = this.scope;
while ((currentScope = currentScope.parent) instanceof BlockScope) {
if (outerTrackerScope == currentScope)
break searchAlien;
}
return found(trackingVar);
}
}
setUpForStage(Stage.AtExit);
//$FALL-THROUGH$
case AtExit:
if (this.atExit && this.iterator.hasNext())
return found(this.iterator.next());
return false;
default: throw new IllegalStateException("Unexpected Stage "+this.stage); //$NON-NLS-1$
}
}
private boolean found(FakedTrackingVariable trackingVar) {
this.iterator.remove();
this.next = trackingVar;
return true;
}
private void setUpForStage(Stage nextStage) {
this.iterator = this.varSet.iterator();
this.stage = nextStage;
}
@Override
public FakedTrackingVariable next() {
return this.next;
}
@Override
public void remove() {
throw new UnsupportedOperationException();
}
}
/**
* Answer true if we know for sure that no resource is bound to this variable
* at the point of 'flowInfo'.
*/
public boolean hasDefinitelyNoResource(FlowInfo flowInfo) {
if (this.originalBinding == null) return false; // shouldn't happen but keep quiet.
if (flowInfo.isDefinitelyNull(this.originalBinding)) {
return true;
}
if (!(flowInfo.isDefinitelyAssigned(this.originalBinding)
|| flowInfo.isPotentiallyAssigned(this.originalBinding))) {
return true;
}
return false;
}
public boolean isClosedInFinallyOfEnclosing(BlockScope scope) {
BlockScope currentScope = scope;
while (true) {
if (currentScope.finallyInfo != null
&& currentScope.finallyInfo.isDefinitelyNonNull(this.binding)) {
return true; // closed in enclosing finally
}
if (!(currentScope.parent instanceof BlockScope)) {
return false;
}
currentScope = (BlockScope) currentScope.parent;
}
}
/**
* If current is the same as 'returnedResource' or a wrapper thereof,
* mark as reported and return true, otherwise false.
*/
public boolean isResourceBeingReturned(FakedTrackingVariable returnedResource) {
FakedTrackingVariable current = this;
do {
if (current == returnedResource) {
this.globalClosingState |= REPORTED_DEFINITIVE_LEAK;
return true;
}
current = current.innerTracker;
} while (current != null);
return false;
}
public void withdraw() {
// must unregister at the declaringScope, note that twr resources are owned by the scope enclosing the twr
this.binding.declaringScope.removeTrackingVar(this);
}
public void recordErrorLocation(ASTNode location, int nullStatus) {
if ((this.globalClosingState & OWNED_BY_OUTSIDE) != 0) {
return;
}
if (this.recordedLocations == null)
this.recordedLocations = new HashMap();
this.recordedLocations.put(location, Integer.valueOf(nullStatus));
}
public boolean reportRecordedErrors(Scope scope, int mergedStatus, boolean atDeadEnd) {
FakedTrackingVariable current = this;
while (current.globalClosingState == 0) {
current = current.innerTracker;
if (current == null) {
// no relevant state found -> report:
if (atDeadEnd && neverClosedAtLocations())
mergedStatus = FlowInfo.NULL;
if ((mergedStatus & (FlowInfo.NULL|FlowInfo.POTENTIALLY_NULL|FlowInfo.POTENTIALLY_NON_NULL)) != 0) {
reportError(scope.problemReporter(), null, mergedStatus);
return true;
} else {
break;
}
}
}
boolean hasReported = false;
if (this.recordedLocations != null) {
Iterator locations = this.recordedLocations.entrySet().iterator();
int reportFlags = 0;
while (locations.hasNext()) {
Map.Entry entry = (Entry) locations.next();
reportFlags |= reportError(scope.problemReporter(), (ASTNode)entry.getKey(), ((Integer)entry.getValue()).intValue());
hasReported = true;
}
if (reportFlags != 0) {
// after all locations have been reported, mark as reported to prevent duplicate report via an outer wrapper
current = this;
do {
current.globalClosingState |= reportFlags;
} while ((current = current.innerTracker) != null);
}
}
return hasReported;
}
private boolean neverClosedAtLocations() {
if (this.recordedLocations != null) {
for (Object value : this.recordedLocations.values())
if (!value.equals(FlowInfo.NULL))
return false;
}
return true;
}
public int reportError(ProblemReporter problemReporter, ASTNode location, int nullStatus) {
if ((this.globalClosingState & OWNED_BY_OUTSIDE) != 0) {
return 0; // TODO: should we still propagate some flags??
}
// which degree of problem?
boolean isPotentialProblem = false;
if (nullStatus == FlowInfo.NULL) {
if ((this.globalClosingState & CLOSED_IN_NESTED_METHOD) != 0)
isPotentialProblem = true;
} else if ((nullStatus & (FlowInfo.POTENTIALLY_NULL|FlowInfo.POTENTIALLY_NON_NULL)) != 0) {
isPotentialProblem = true;
}
// report:
if (isPotentialProblem) {
if ((this.globalClosingState & (REPORTED_POTENTIAL_LEAK|REPORTED_DEFINITIVE_LEAK)) != 0)
return 0;
problemReporter.potentiallyUnclosedCloseable(this, location);
} else {
if ((this.globalClosingState & (REPORTED_DEFINITIVE_LEAK)) != 0)
return 0;
problemReporter.unclosedCloseable(this, location);
}
// propagate flag to inners:
int reportFlag = isPotentialProblem ? REPORTED_POTENTIAL_LEAK : REPORTED_DEFINITIVE_LEAK;
if (location == null) { // if location != null flags will be set after the loop over locations
FakedTrackingVariable current = this;
do {
current.globalClosingState |= reportFlag;
} while ((current = current.innerTracker) != null);
}
return reportFlag;
}
public void reportExplicitClosing(ProblemReporter problemReporter) {
if ((this.globalClosingState & (OWNED_BY_OUTSIDE|REPORTED_EXPLICIT_CLOSE|FOREACH_ELEMENT_VAR)) == 0) { // can't use t-w-r for OWNED_BY_OUTSIDE
this.globalClosingState |= REPORTED_EXPLICIT_CLOSE;
problemReporter.explicitlyClosedAutoCloseable(this);
}
}
public String nameForReporting(ASTNode location, ReferenceContext referenceContext) {
if (this.name == UNASSIGNED_CLOSEABLE_NAME) {
if (location != null && referenceContext != null) {
CompilationResult compResult = referenceContext.compilationResult();
if (compResult != null) {
int[] lineEnds = compResult.getLineSeparatorPositions();
int resourceLine = Util.getLineNumber(this.sourceStart, lineEnds , 0, lineEnds.length-1);
int reportLine = Util.getLineNumber(location.sourceStart, lineEnds , 0, lineEnds.length-1);
if (resourceLine != reportLine) {
char[] replacement = Integer.toString(resourceLine).toCharArray();
return String.valueOf(CharOperation.replace(UNASSIGNED_CLOSEABLE_NAME_TEMPLATE, TEMPLATE_ARGUMENT, replacement));
}
}
}
}
return String.valueOf(this.name);
}
}