201 lines
8.2 KiB
Java
Executable File
201 lines
8.2 KiB
Java
Executable File
/*******************************************************************************
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* Copyright (c) 2013 IBM Corporation.
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* All rights reserved. This program and the accompanying materials
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* are made available under the terms of the Eclipse Public License v1.0
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* which accompanies this distribution, and is available at
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* http://www.eclipse.org/legal/epl-v10.html
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*
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* Contributors:
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* IBM Corporation - initial API and implementation
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*******************************************************************************/
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package com.ibm.wala.cast.js.ipa.callgraph;
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import java.util.Map;
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import com.ibm.wala.cast.js.ipa.summaries.JavaScriptSummarizedFunction;
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import com.ibm.wala.cast.js.ipa.summaries.JavaScriptSummary;
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import com.ibm.wala.cast.js.loader.JSCallSiteReference;
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import com.ibm.wala.cast.js.loader.JavaScriptLoader;
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import com.ibm.wala.cast.js.ssa.JSInstructionFactory;
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import com.ibm.wala.cast.js.types.JavaScriptMethods;
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import com.ibm.wala.cast.loader.AstMethod;
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import com.ibm.wala.cast.tree.CAstSourcePositionMap.Position;
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import com.ibm.wala.cast.types.AstMethodReference;
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import com.ibm.wala.classLoader.CallSiteReference;
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import com.ibm.wala.classLoader.IClass;
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import com.ibm.wala.classLoader.IMethod;
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import com.ibm.wala.ipa.callgraph.CGNode;
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import com.ibm.wala.ipa.callgraph.MethodTargetSelector;
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import com.ibm.wala.ssa.IR;
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import com.ibm.wala.ssa.SSAAbstractInvokeInstruction;
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import com.ibm.wala.types.Descriptor;
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import com.ibm.wala.types.MethodReference;
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import com.ibm.wala.types.TypeName;
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import com.ibm.wala.util.collections.HashMapFactory;
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import com.ibm.wala.util.intset.IntIterator;
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import com.ibm.wala.util.strings.Atom;
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/**
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* Generate IR to model Function.call()
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*
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* @see <a
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* href="https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Function/Call">MDN
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* Function.call() docs</a>
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*
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* @author manu
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*
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*/
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public class JavaScriptFunctionDotCallTargetSelector implements MethodTargetSelector {
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/*
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* Call graph imprecision often leads to spurious invocations of Function.prototype.call; two common
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* patterns are invocations of "new" on Function.prototype.call (which in reality would lead to a
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* type error), and self-applications of Function.prototype.call.
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*
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* While neither of these situations is a priori impossible, they are most likely due to analysis
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* imprecision. If this flag is set to true, we emit a warning when seeing them.
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*/
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public static boolean WARN_ABOUT_IMPRECISE_CALLGRAPH = true;
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public static final boolean DEBUG_SYNTHETIC_CALL_METHODS = false;
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private static final TypeName CALL_TYPE_NAME = TypeName.findOrCreate("Lprologue.js/Function_prototype_call");
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private final MethodTargetSelector base;
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public JavaScriptFunctionDotCallTargetSelector(MethodTargetSelector base) {
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this.base = base;
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}
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/*
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* (non-Javadoc)
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*
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* @see
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* com.ibm.wala.ipa.callgraph.MethodTargetSelector#getCalleeTarget(com.ibm
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* .wala.ipa.callgraph.CGNode, com.ibm.wala.classLoader.CallSiteReference,
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* com.ibm.wala.classLoader.IClass)
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*/
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public IMethod getCalleeTarget(CGNode caller, CallSiteReference site, IClass receiver) {
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IMethod method = receiver.getMethod(AstMethodReference.fnSelector);
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if (method != null) {
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TypeName tn = method.getReference().getDeclaringClass().getName();
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if (tn.equals(CALL_TYPE_NAME)) {
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/* invoking Function.prototype.call as a constructor results in a TypeError
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* see ECMA-262 5.1, 15: "None of the built-in functions described in this clause that
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* are not constructors shall implement the [[Construct]] internal method unless otherwise
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* specified" */
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if(!site.getDeclaredTarget().equals(JavaScriptMethods.ctorReference)) {
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IMethod target = getFunctionCallTarget(caller, site, receiver);
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if(target != null)
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return target;
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}
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// if we get here, we either saw an invocation of "call" as a constructor, or an invocation
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// without receiver object; in either case, this is likely due to bad call graph info
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if(WARN_ABOUT_IMPRECISE_CALLGRAPH)
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warnAboutImpreciseCallGraph(caller, site);
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}
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}
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return base.getCalleeTarget(caller, site, receiver);
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}
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protected void warnAboutImpreciseCallGraph(CGNode caller, CallSiteReference site) {
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IntIterator indices = caller.getIR().getCallInstructionIndices(site).intIterator();
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IMethod callerMethod = caller.getMethod();
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Position pos = null;
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if(indices.hasNext() && callerMethod instanceof AstMethod) {
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pos = ((AstMethod)callerMethod).getSourcePosition(indices.next());
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}
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System.err.println("Detected improbable call to Function.prototype.call " +
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(pos == null ? "in function " + caller : "at position " + pos) +
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"; this is likely caused by call graph imprecision.");
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}
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private static final boolean SEPARATE_SYNTHETIC_METHOD_PER_SITE = false;
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/**
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* cache synthetic method for each arity of Function.call() invocation
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*/
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private final Map<Object, JavaScriptSummarizedFunction> callModels = HashMapFactory.make();
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/**
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* generate a synthetic method modeling the invocation of Function.call() at
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* the site
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*
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* @param caller
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* @param site
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* @param receiver
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* @return
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*/
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private IMethod getFunctionCallTarget(CGNode caller, CallSiteReference site, IClass receiver) {
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int nargs = getNumberOfArgsPassed(caller, site);
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if(nargs < 2)
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return null;
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String key = getKey(nargs, caller, site);
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if (callModels.containsKey(key)) {
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return callModels.get(key);
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}
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JSInstructionFactory insts = (JSInstructionFactory) receiver.getClassLoader().getInstructionFactory();
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MethodReference ref = genSyntheticMethodRef(receiver, nargs, key);
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JavaScriptSummary S = new JavaScriptSummary(ref, nargs);
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if(WARN_ABOUT_IMPRECISE_CALLGRAPH && caller.getMethod().getName().toString().contains(SYNTHETIC_CALL_METHOD_PREFIX))
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warnAboutImpreciseCallGraph(caller, site);
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// print information about where the method was created if desired
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if(DEBUG_SYNTHETIC_CALL_METHODS) {
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IMethod method = caller.getMethod();
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if(method instanceof AstMethod) {
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int line = ((AstMethod)method).getLineNumber(caller.getIR().getCallInstructionIndices(site).intIterator().next());
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System.err.println("creating " + ref.getName() + " at line " + line + " in " + caller);
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} else {
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System.err.println("creating " + ref.getName() + " in " + method.getName());
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}
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}
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// generate invocation instruction for the real method being invoked
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int resultVal = nargs + 2;
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CallSiteReference cs = new JSCallSiteReference(S.getNextProgramCounter());
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int[] params = new int[nargs - 2];
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for (int i = 0; i < params.length; i++) {
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// add 3 to skip v1 (which points to Function.call() itself) and v2 (the
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// real function being invoked)
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params[i] = i + 3;
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}
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// function being invoked is in v2
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S.addStatement(insts.Invoke(2, resultVal, params, resultVal + 1, cs));
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S.getNextProgramCounter();
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S.addStatement(insts.ReturnInstruction(resultVal, false));
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S.getNextProgramCounter();
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JavaScriptSummarizedFunction t = new JavaScriptSummarizedFunction(ref, S, receiver);
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callModels.put(key, t);
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return t;
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}
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public static final String SYNTHETIC_CALL_METHOD_PREFIX = "$$ call_";
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private MethodReference genSyntheticMethodRef(IClass receiver, int nargs, String key) {
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Atom atom = Atom.findOrCreateUnicodeAtom(SYNTHETIC_CALL_METHOD_PREFIX + key);
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Descriptor desc = Descriptor.findOrCreateUTF8(JavaScriptLoader.JS, "()LRoot;");
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MethodReference ref = MethodReference.findOrCreate(receiver.getReference(), atom, desc);
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return ref;
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}
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private String getKey(int nargs, CGNode caller, CallSiteReference site) {
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if (SEPARATE_SYNTHETIC_METHOD_PER_SITE) {
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return JSCallGraphUtil.getShortName(caller) + "_" + caller.getGraphNodeId() + "_" + site.getProgramCounter();
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} else {
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return ""+nargs;
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}
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}
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private int getNumberOfArgsPassed(CGNode caller, CallSiteReference site) {
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IR callerIR = caller.getIR();
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SSAAbstractInvokeInstruction callStmts[] = callerIR.getCalls(site);
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assert callStmts.length == 1;
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int nargs = callStmts[0].getNumberOfParameters();
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return nargs;
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}
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}
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