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Fix compilation of expressions using instanceof and primitives

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Prior to this commit the SpEL compiler would generate bad bytecode
if the left hand operand of an instanceof was a primitive or
if the right hand operand was a primitive type reference.
With the fixes primitives on the left hand side are now
correctly boxed and special handling is in place for when the
right hand side is a primitive type reference. Using a primitive
type reference on the right always causes the instanceof
check to return false.

Additionally a guard has been added such that compilation is
not allowed when the right hand side of an expression
is not a type reference. If it is, for example, a variable
reference that evaluates to a type reference then that
cannot be expressed in bytecode so compilation is not performed.

Issue: SPR-14250
This commit is contained in:
Andy Clement
2016-05-05 09:57:15 -07:00
parent 3c92ddc94b
commit a31f0bb3c0
2 changed files with 66 additions and 5 deletions
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22
spring-expression/src/main/java/org/springframework/expression/spel/ast/OperatorInstanceof.java
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@@ -1,5 +1,5 @@
/*
* Copyright 2002-2014 the original author or authors.
* Copyright 2002-2016 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
@@ -53,8 +53,9 @@ public class OperatorInstanceof extends Operator {
*/
@Override
public BooleanTypedValue getValueInternal(ExpressionState state) throws EvaluationException {
SpelNodeImpl rightOperand = getRightOperand();
TypedValue left = getLeftOperand().getValueInternal(state);
TypedValue right = getRightOperand().getValueInternal(state);
TypedValue right = rightOperand.getValueInternal(state);
Object leftValue = left.getValue();
Object rightValue = right.getValue();
BooleanTypedValue result = null;
@@ -71,7 +72,11 @@ public class OperatorInstanceof extends Operator {
result = BooleanTypedValue.forValue(rightClass.isAssignableFrom(leftValue.getClass()));
}
this.type = rightClass;
this.exitTypeDescriptor = "Z";
if (rightOperand instanceof TypeReference) {
// Can only generate bytecode where the right operand is a direct type reference,
// not if it is indirect (for example when right operand is a variable reference)
this.exitTypeDescriptor = "Z";
}
return result;
}
@@ -83,7 +88,16 @@ public class OperatorInstanceof extends Operator {
@Override
public void generateCode(MethodVisitor mv, CodeFlow cf) {
getLeftOperand().generateCode(mv, cf);
mv.visitTypeInsn(INSTANCEOF,Type.getInternalName(this.type));
CodeFlow.insertBoxIfNecessary(mv, cf.lastDescriptor());
if (this.type.isPrimitive()) {
// always false - but left operand code always driven
// in case it had side effects
mv.visitInsn(POP);
mv.visitInsn(ICONST_0); // value of false
}
else {
mv.visitTypeInsn(INSTANCEOF,Type.getInternalName(this.type));
}
cf.pushDescriptor(this.exitTypeDescriptor);
}