@Override
public Node labelCheckLHS(LabelChecker lc) throws SemanticException {
final Assign assign = (Assign) node();
Local lve = (Local) assign.left();
JifTypeSystem ts = lc.jifTypeSystem();
JifContext A = lc.jifContext();
A = (JifContext) lve.del().enterScope(A);
List throwTypes = new ArrayList(assign.del().throwTypes(ts));
final LocalInstance li = lve.localInstance();
Label L = ts.labelOfLocal(li, A.pc());
Expr rhs = (Expr) lc.context(A).labelCheck(assign.right());
PathMap Xr = rhsPathMap(lc.context(A), rhs, throwTypes);
PathMap X;
if (assign.operator() != Assign.ASSIGN) {
PathMap Xv = ts.pathMap();
Xv = Xv.N(A.pc());
Xv = Xv.NV(lc.upperBound(L, A.pc()));
if (assign.throwsArithmeticException()) {
Type arithExc = ts.ArithmeticException();
checkAndRemoveThrowType(throwTypes, arithExc);
X = Xv.join(Xr).exc(Xr.NV(), arithExc);
} else {
X = Xv.join(Xr);
}
} else {
X = Xr;
}
lc.constrain(
new NamedLabel(
"rhs.nv", "label of successful evaluation of right hand of assignment", X.NV()),
LabelConstraint.LEQ,
new NamedLabel("label of var " + li.name(), L),
A.labelEnv(),
lve.position(),
new LabelConstraintMessage() {
@Override
public String msg() {
return "Label of right hand side not less "
+ "restrictive than the label for local variable "
+ li.name();
}
@Override
public String detailMsg() {
return "More information is revealed by the successful "
+ "evaluation of the right hand side of the "
+ "assignment than is allowed to flow to "
+ "the local variable "
+ li.name()
+ ".";
}
@Override
public String technicalMsg() {
return "Invalid assignment: path NV of rhs is "
+ "not less restrictive than the declared label "
+ "of the local variable <"
+ li.name()
+ ">.";
}
});
if (JLiftOptions.getInstance().safeMutateConstraintSet) {
// also constrain PC label
lc.constrain(
new NamedLabel("pc", "program counter label for assignment", A.pc()),
LabelConstraint.LEQ,
new NamedLabel("label of var " + li.name(), L),
A.labelEnv(),
lve.position(),
new LabelConstraintMessage() {
@Override
public String msg() {
return "Program counter not less "
+ "restrictive than the label for local variable "
+ li.name();
}
});
}
Expr lhs = (Expr) updatePathMap(lve, X);
checkThrowTypes(throwTypes);
return updatePathMap(assign.right(rhs).left(lhs), X);
}
