def preconstrain(self, value, variable):
"""
Add a preconstraint that ``variable == value`` to the state.
:param value: The concrete value. Can be a bitvector or a bytestring or an integer.
:param variable: The BVS to preconstrain.
"""
if not isinstance(value, claripy.ast.Base):
value = self.state.solver.BVV(value, len(variable))
elif value.op != 'BVV':
raise ValueError("Passed a value to preconstrain that was not a BVV or a string")
if variable.op not in claripy.operations.leaf_operations:
l.warning("The variable %s to preconstrain is not a leaf AST. This may cause replacement failures in the "
"claripy replacement backend.", variable)
l.warning("Please use a leaf AST as the preconstraining variable instead.")
# Add the constraint with a simplification avoidance tag. If
# this is not added, claripy may simplify new constraints if
# they are redundant with respect to the preconstraints. This
# is problematic when the preconstraints are removed.
constraint = (variable == value).annotate(claripy.SimplificationAvoidanceAnnotation())
l.debug("Preconstraint: %s", constraint)
# add the constraint for reconstraining later
if next(iter(variable.variables)) in self.variable_map:
l.warning("%s is already preconstrained. Are you misusing preconstrainer?", next(iter(variable.variables)))
self.variable_map[next(iter(variable.variables))] = constraint
self.preconstraints.append(constraint)
if o.REPLACEMENT_SOLVER in self.state.options:
self.state.solver._solver.add_replacement(variable, value, invalidate_cache=False)
else:
self.state.add_constraints(constraint)
if not self.state.satisfiable():
l.warning("State went unsat while adding preconstraints")
def test_simplification_annotations():
s = claripy.Solver()
x = claripy.BVS("x", 32)
s.add(x > 10)
s.add(x > 11)
s.add((x > 12).annotate(claripy.SimplificationAvoidanceAnnotation()))
assert len(s.constraints) == 3
s.simplify()
assert len(s.constraints) == 2