from __future__ import annotations
import logging
import numbers
from contextlib import suppress
import claripy
from claripy import backends
from claripy.ast import Base
from claripy.errors import BackendError, ClaripyFrontendError
from .constrained_frontend import ConstrainedFrontend
log = logging.getLogger(__name__)
[docs]
class ReplacementFrontend(ConstrainedFrontend):
"""ReplacementFrontend is a frontend that allows for the replacement
symbolic constraints with concrete solutions. This is useful for
simplifying constraints and speeding up solving time.
"""
# pylint: disable=too-many-positional-arguments
[docs]
def __init__(
self,
actual_frontend,
allow_symbolic=None,
replacements=None,
replacement_cache=None,
unsafe_replacement=None,
complex_auto_replace=None,
auto_replace=None,
replace_constraints=None,
**kwargs,
):
super().__init__(**kwargs)
self._actual_frontend = actual_frontend
self._allow_symbolic = True if allow_symbolic is None else allow_symbolic
self._auto_replace = True if auto_replace is None else auto_replace
self._complex_auto_replace = False if complex_auto_replace is None else complex_auto_replace
self._replace_constraints = False if replace_constraints is None else replace_constraints
self._unsafe_replacement = False if unsafe_replacement is None else unsafe_replacement
self._replacements = replacements or {}
self._replacement_cache = replacement_cache or {}
def _blank_copy(self, c):
super()._blank_copy(c)
c._actual_frontend = self._actual_frontend.blank_copy()
c._allow_symbolic = self._allow_symbolic
c._auto_replace = self._auto_replace
c._complex_auto_replace = self._complex_auto_replace
c._replace_constraints = self._replace_constraints
c._unsafe_replacement = self._unsafe_replacement
c._replacements = {}
c._replacement_cache = {}
def _copy(self, c):
super()._copy(c)
self._actual_frontend._copy(c._actual_frontend)
c._replacements = dict(self._replacements)
c._replacement_cache = dict(self._replacement_cache)
#
# Replacements
#
[docs]
def add_replacement(self, old, new, invalidate_cache=True, replace=True, promote=True):
if not isinstance(old, Base):
return
if old is new:
return
if not replace and old.hash() in self._replacements:
return
if not promote and old.hash() in self._replacement_cache:
return
if not isinstance(new, Base):
if isinstance(new, bool):
new = claripy.BoolV(new)
elif isinstance(new, numbers.Number):
new = claripy.BVV(new, old.length)
else:
return
if invalidate_cache:
self._replacements = dict(self._replacements)
self._replacement_cache = dict(self._replacements)
self._replacements[old.hash()] = new
self._replacement_cache[old.hash()] = new
[docs]
def remove_replacements(self, old_entries):
self._replacements = {k: v for k, v in self._replacements.items() if k not in old_entries}
self._replacement_cache = dict(self._replacements)
[docs]
def clear_replacements(self):
self._replacements = {}
self._replacement_cache = dict(self._replacements)
def _replacement(self, old):
if not isinstance(old, Base):
return old
if old.hash() in self._replacement_cache:
return self._replacement_cache[old.hash()]
# not found in the cache
new = claripy.replace_dict(old, self._replacement_cache)
if new is not old:
self._replacement_cache[old.hash()] = new
return new
def _add_solve_result(self, e, er, r):
if not self._auto_replace:
return
if not isinstance(e, Base) or not e.symbolic:
return
if er.symbolic:
return
self.add_replacement(e, r, invalidate_cache=False)
#
# Storable support
#
[docs]
def downsize(self):
self._actual_frontend.downsize()
self._replacement_cache.clear()
def __getstate__(self):
return (
self._allow_symbolic,
self._unsafe_replacement,
self._complex_auto_replace,
self._auto_replace,
self._replace_constraints,
self._replacements,
self._actual_frontend,
super().__getstate__(),
)
def __setstate__(self, s):
(
self._allow_symbolic,
self._unsafe_replacement,
self._complex_auto_replace,
self._auto_replace,
self._replace_constraints,
self._replacements,
self._actual_frontend,
base_state,
) = s
super().__setstate__(base_state)
self._replacement_cache = dict(self._replacements)
#
# Replacement solving
#
def _replace_list(self, lst):
return tuple(self._replacement(c) for c in lst)
[docs]
def eval(self, e, n, extra_constraints=(), exact=None):
er = self._replacement(e)
ecr = self._replace_list(extra_constraints)
r = self._actual_frontend.eval(er, n, extra_constraints=ecr, exact=exact)
if self._unsafe_replacement:
self._add_solve_result(e, er, r[0])
return r
[docs]
def batch_eval(self, exprs, n, extra_constraints=(), exact=None):
er = self._replace_list(exprs)
ecr = self._replace_list(extra_constraints)
r = self._actual_frontend.batch_eval(er, n, extra_constraints=ecr, exact=exact)
if self._unsafe_replacement:
for i, original in enumerate(exprs):
self._add_solve_result(original, er[i], r[0][i])
return r
[docs]
def max(self, e, extra_constraints=(), signed=False, exact=None):
er = self._replacement(e)
ecr = self._replace_list(extra_constraints)
r = self._actual_frontend.max(er, extra_constraints=ecr, signed=signed, exact=exact)
if self._unsafe_replacement:
self._add_solve_result(e, er, r)
return r
[docs]
def min(self, e, extra_constraints=(), signed=False, exact=None):
er = self._replacement(e)
ecr = self._replace_list(extra_constraints)
r = self._actual_frontend.min(er, extra_constraints=ecr, signed=signed, exact=exact)
if self._unsafe_replacement:
self._add_solve_result(e, er, r)
return r
[docs]
def solution(self, e, v, extra_constraints=(), exact=None):
er = self._replacement(e)
vr = self._replacement(v)
ecr = self._replace_list(extra_constraints)
r = self._actual_frontend.solution(er, vr, extra_constraints=ecr, exact=exact)
if self._unsafe_replacement and r and (not isinstance(vr, Base) or not vr.symbolic):
self._add_solve_result(e, er, vr)
return r
[docs]
def is_true(self, e, extra_constraints=(), exact=None):
er = self._replacement(e)
ecr = self._replace_list(extra_constraints)
return self._actual_frontend.is_true(er, extra_constraints=ecr, exact=exact)
[docs]
def is_false(self, e, extra_constraints=(), exact=None):
er = self._replacement(e)
ecr = self._replace_list(extra_constraints)
return self._actual_frontend.is_false(er, extra_constraints=ecr, exact=exact)
[docs]
def satisfiable(self, extra_constraints=(), exact=None):
ecr = self._replace_list(extra_constraints)
return self._actual_frontend.satisfiable(extra_constraints=ecr, exact=exact)
def _concrete_value(self, e):
c = super()._concrete_value(e)
if c is not None:
return c
cr = self._replacement(e)
with suppress(BackendError):
return backends.concrete.eval(cr, 1)[0]
return None
def _concrete_constraint(self, e):
c = super()._concrete_value(e)
if c is not None:
return c
# if er.is_false():
# raise UnsatError("Replacement frontend received False constraint after replacement.")
if self._replace_constraints:
er = self._replacement(e)
return super()._concrete_constraint(er)
return super()._concrete_constraint(e)
def _add(self, constraints, invalidate_cache=True):
if self._auto_replace:
for c in constraints:
# the badass thing here would be to use the *replaced* constraint, but
# we don't currently support chains of replacements, so we'll do a
# less effective flat-replacement with the original constraint
# rc = self._replacement(c)
rc = c
if not isinstance(rc, Base) or not rc.symbolic:
continue
if not self._complex_auto_replace:
if rc.op == "Not":
self.add_replacement(
c.args[0], claripy.false(), replace=False, promote=True, invalidate_cache=True
)
elif rc.op == "__eq__" and rc.args[0].symbolic ^ rc.args[1].symbolic:
old, new = rc.args if rc.args[0].symbolic else rc.args[::-1]
self.add_replacement(old, new, replace=False, promote=True, invalidate_cache=True)
else:
satisfiable, replacements = backends.vsa.constraint_to_si(rc)
if not satisfiable:
self.add_replacement(rc, claripy.false())
for old, new in replacements:
if old.cardinality == 1:
continue
rold = self._replacement(old)
if rold.cardinality == 1:
continue
self.add_replacement(old, rold.intersection(new))
added = super()._add(constraints)
cr = self._replace_list(added)
if not self._allow_symbolic and any(c.symbolic for c in cr):
raise ClaripyFrontendError(
"symbolic constraints made it into ReplacementFrontend with allow_symbolic=False"
)
self._actual_frontend.add(cr)
return added