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interprocedural_cfg.py
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interprocedural_cfg.py
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import ast
import os.path
from collections import namedtuple
from .alias_helper import (
as_alias_handler,
handle_aliases_in_calls,
handle_aliases_in_init_files,
handle_fdid_aliases,
not_as_alias_handler,
retrieve_import_alias_mapping
)
from .ast_helper import Arguments, generate_ast, get_call_names_as_string
from .base_cfg import (
AssignmentNode,
CALL_IDENTIFIER,
CFG,
ConnectToExitNode,
EntryOrExitNode,
IgnoredNode,
Node,
RestoreNode,
ReturnNode,
Visitor
)
from .label_visitor import LabelVisitor
from .module_definitions import (
LocalModuleDefinition,
ModuleDefinition,
ModuleDefinitions
)
from .project_handler import get_directory_modules
from .right_hand_side_visitor import RHSVisitor
SavedVariable = namedtuple('SavedVariable', 'LHS RHS')
NOT_A_BLACKBOX = set(['Flask',
'run',
'get',
'replace',
'read',
'set_cookie',
'make_response',
'SQLAlchemy',
'Column',
'execute',
'sessionmaker',
'Session',
'filter',
'execute',
'call',
'render_template',
'redirect',
'url_for',
'flash',
'jsonify'])
class InterproceduralVisitor(Visitor):
def __init__(self, node, project_modules, local_modules,
filename, module_definitions=None):
"""Create an empty CFG."""
self.project_modules = project_modules
self.local_modules = local_modules
self.filenames = [filename]
self.blackbox_assignments = set()
self.blackbox_calls = set()
self.nodes = list()
self.function_index = 0
self.undecided = False
self.function_names = list()
self.function_return_stack = list()
self.module_definitions_stack = list()
self.use_prev_node = list()
# Are we already in a module?
if module_definitions:
self.init_function_cfg(node, module_definitions)
else:
self.init_cfg(node)
def init_cfg(self, node):
self.module_definitions_stack.append(ModuleDefinitions(filename=self.filenames[-1]))
entry_node = self.append_node(EntryOrExitNode("Entry module"))
module_statements = self.visit(node)
if not module_statements:
raise Exception('Empty module. It seems that your file is empty,' +
'there is nothing to analyse.')
if not isinstance(module_statements, IgnoredNode):
first_node = module_statements.first_statement
if CALL_IDENTIFIER not in first_node.label:
entry_node.connect(first_node)
exit_node = self.append_node(EntryOrExitNode("Exit module"))
last_nodes = module_statements.last_statements
exit_node.connect_predecessors(last_nodes)
else:
exit_node = self.append_node(EntryOrExitNode("Exit module"))
entry_node.connect(exit_node)
def init_function_cfg(self, node, module_definitions):
self.module_definitions_stack.append(module_definitions)
self.function_names.append(node.name)
self.function_return_stack.append(node.name)
entry_node = self.append_node(EntryOrExitNode("Entry function"))
module_statements = self.stmt_star_handler(node.body)
first_node = module_statements.first_statement
if CALL_IDENTIFIER not in first_node.label:
entry_node.connect(first_node)
exit_node = self.append_node(EntryOrExitNode("Exit function"))
last_nodes = module_statements.last_statements
exit_node.connect_predecessors(last_nodes)
def visit_ClassDef(self, node):
self.add_to_definitions(node)
local_definitions = self.module_definitions_stack[-1]
local_definitions.classes.append(node.name)
parent_definitions = self.get_parent_definitions()
if parent_definitions:
parent_definitions.classes.append(node.name)
self.stmt_star_handler(node.body)
local_definitions.classes.pop()
if parent_definitions:
parent_definitions.classes.pop()
return IgnoredNode()
def get_parent_definitions(self):
parent_definitions = None
if len(self.module_definitions_stack) > 1:
parent_definitions = self.module_definitions_stack[-2]
return parent_definitions
def visit_FunctionDef(self, node):
self.add_to_definitions(node)
return IgnoredNode()
def add_to_definitions(self, node):
local_definitions = self.module_definitions_stack[-1]
parent_definitions = self.get_parent_definitions()
if parent_definitions:
parent_qualified_name = '.'.join(parent_definitions.classes +
[node.name])
parent_definition = ModuleDefinition(parent_definitions,
parent_qualified_name,
local_definitions.module_name,
self.filenames[-1])
parent_definition.node = node
parent_definitions.append_if_local_or_in_imports(parent_definition)
local_qualified_name = '.'.join(local_definitions.classes +
[node.name])
local_definition = LocalModuleDefinition(local_definitions,
local_qualified_name,
None,
self.filenames[-1])
local_definition.node = node
local_definitions.append_if_local_or_in_imports(local_definition)
self.function_names.append(node.name)
def return_connection_handler(self, nodes, exit_node):
"""Connect all return statements to the Exit node."""
for function_body_node in nodes:
if isinstance(function_body_node, ConnectToExitNode):
if exit_node not in function_body_node.outgoing:
function_body_node.connect(exit_node)
def visit_Return(self, node):
label = LabelVisitor()
label.visit(node)
this_function_name = self.function_return_stack[-1]
try:
rhs_visitor = RHSVisitor()
rhs_visitor.visit(node.value)
except AttributeError:
rhs_visitor.result = 'EmptyReturn'
LHS = 'ret_' + this_function_name
return self.append_node(ReturnNode(LHS + ' = ' + label.result,
LHS, rhs_visitor.result,
node, line_number=node.lineno,
path=self.filenames[-1]))
def visit_Yield(self, node):
label = LabelVisitor()
label.visit(node)
this_function_name = self.function_return_stack[-1]
try:
rhs_visitor = RHSVisitor()
rhs_visitor.visit(node.value)
except AttributeError:
rhs_visitor.result = 'EmptyYield'
LHS = 'yield_' + this_function_name
return self.append_node(ReturnNode(LHS + ' = ' + label.result,
LHS, rhs_visitor.result,
node, line_number=node.lineno,
path=self.filenames[-1]))
def save_local_scope(self, line_number, original_previous_node):
"""Save the local scope before entering a function call."""
saved_variables = list()
saved_variables_so_far = set()
for assignment in [node for node in self.nodes
if type(node) == AssignmentNode]:
if isinstance(assignment, RestoreNode):
continue
if assignment.left_hand_side in saved_variables_so_far:
continue
saved_variables_so_far.add(assignment.left_hand_side)
save_name = 'save_' + str(self.function_index) + '_' +\
assignment.left_hand_side
previous_node = self.nodes[-1]
r = RestoreNode(save_name + ' = ' + assignment.left_hand_side,
save_name, [assignment.left_hand_side],
line_number=line_number, path=self.filenames[-1])
saved_scope_node = self.append_node(r)
saved_variables.append(SavedVariable(LHS=save_name,
RHS=assignment.left_hand_side))
if self.use_prev_node[-1] or previous_node is not original_previous_node:
previous_node.connect(saved_scope_node)
return saved_variables
def save_actual_parameters_in_temp(self, args, arguments, line_number, original_previous_node):
"""Save the actual parameters of a function call."""
parameters = dict()
for i, parameter in enumerate(args):
temp_name = 'temp_' + str(self.function_index) + '_' + arguments[i]
label_visitor = LabelVisitor()
label_visitor.visit(parameter)
rhs_visitor = RHSVisitor()
rhs_visitor.visit(parameter)
restore_node = RestoreNode(temp_name + ' = ' + label_visitor.result,
temp_name,
rhs_visitor.result,
line_number=line_number,
path=self.filenames[-1])
if self.use_prev_node[-1] or self.nodes[-1] is not original_previous_node:
self.nodes[-1].connect(restore_node)
self.nodes.append(restore_node)
parameters[label_visitor.result] = arguments[i]
return parameters
def create_local_scope_from_actual_parameters(self, args, arguments,
line_number):
"""Create the local scope before entering
the body of a function call.
Note: We do not need a check of original_previous_node because of the
preceding call to save_actual_parameters_in_temp.
"""
for i in range(len(args)):
temp_name = 'temp_' + str(self.function_index) + '_' + arguments[i]
local_name = arguments[i]
previous_node = self.nodes[-1]
r = RestoreNode(local_name + ' = ' + temp_name,
local_name, [temp_name],
line_number=line_number,
path=self.filenames[-1])
local_scope_node = self.append_node(r)
previous_node.connect(local_scope_node)
def restore_saved_local_scope(self, saved_variables, parameters,
line_number):
"""Restore the previously saved variables to their original values.
Args:
saved_variables(list[SavedVariable]).
"""
restore_nodes = list()
for var in saved_variables:
if var.RHS in parameters:
restore_nodes.append(RestoreNode(var.RHS + ' = ' +
parameters[var.RHS],
var.RHS, [var.LHS],
line_number=line_number,
path=self.filenames[-1]))
else:
restore_nodes.append(RestoreNode(var.RHS + ' = ' + var.LHS,
var.RHS, [var.LHS],
line_number=line_number,
path=self.filenames[-1]))
for n, successor in zip(restore_nodes, restore_nodes[1:]):
n.connect(successor)
if restore_nodes:
self.nodes[-1].connect(restore_nodes[0])
self.nodes.extend(restore_nodes)
return restore_nodes
def return_handler(self, node, function_nodes):
"""Handle the return from a function during a function call."""
call_node = None
for n in function_nodes:
if isinstance(n, ConnectToExitNode):
LHS = CALL_IDENTIFIER + 'call_' + str(self.function_index)
previous_node = self.nodes[-1]
if not call_node:
RHS = 'ret_' + get_call_names_as_string(node.func)
r = RestoreNode(LHS + ' = ' + RHS, LHS, [RHS],
line_number=node.lineno,
path=self.filenames[-1])
call_node = self.append_node(r)
previous_node.connect(call_node)
else:
# lave rigtig kobling
pass
def add_function(self, call_node, definition):
try:
self.function_index += 1
def_node = definition.node
original_previous_node = self.nodes[-1]
saved_variables = self.save_local_scope(def_node.lineno, original_previous_node)
parameters = self.save_actual_parameters_in_temp(call_node.args,
Arguments(def_node.args),
call_node.lineno,
original_previous_node)
self.filenames.append(definition.path)
self.create_local_scope_from_actual_parameters(call_node.args,
Arguments(def_node.args),
def_node.lineno)
function_nodes = self.get_function_nodes(definition, original_previous_node)
self.filenames.pop() # Maybe move after restore nodes
self.restore_saved_local_scope(saved_variables, parameters, def_node.lineno)
self.return_handler(call_node, function_nodes)
self.function_return_stack.pop()
except IndexError:
error_call = get_call_names_as_string(call_node.func)
print('Error: Possible nameclash in "{}".' +
' Call omitted!\n'.format(error_call))
return self.nodes[-1]
def get_function_nodes(self, definition, original_previous_node):
length = len(self.nodes)
previous_node = self.nodes[-1]
entry_node = self.append_node(EntryOrExitNode("Function Entry " +
definition.name))
if self.use_prev_node[-1] or previous_node is not original_previous_node:
previous_node.connect(entry_node)
function_body_connect_statements = self.stmt_star_handler(definition.node.body)
entry_node.connect(function_body_connect_statements.first_statement)
exit_node = self.append_node(EntryOrExitNode("Exit " + definition.name))
exit_node.connect_predecessors(function_body_connect_statements.last_statements)
self.return_connection_handler(self.nodes[length:], exit_node)
return self.nodes[length:]
def visit_Call(self, node):
_id = get_call_names_as_string(node.func)
local_definitions = self.module_definitions_stack[-1]
alias = handle_aliases_in_calls(_id, local_definitions.import_alias_mapping)
if alias:
definition = local_definitions.get_definition(alias)
else:
definition = local_definitions.get_definition(_id)
# e.g. "request.args.get" -> "get"
last_attribute = _id.rpartition('.')[-1]
if definition:
if isinstance(definition.node, ast.ClassDef):
self.add_builtin(node)
elif isinstance(definition.node, ast.FunctionDef):
self.undecided = False
self.function_return_stack.append(_id)
return self.add_function(node, definition)
else:
raise Exception('Definition was neither FunctionDef or ' +
'ClassDef, cannot add the function ')
elif last_attribute not in NOT_A_BLACKBOX:
return self.add_blackbox_call(node)
return self.add_builtin(node)
def add_class(self, call_node, def_node):
label_visitor = LabelVisitor()
label_visitor.visit(call_node)
previous_node = self.nodes[-1]
entry_node = self.append_node(EntryOrExitNode("Class Entry " + def_node.name))
previous_node.connect(entry_node)
function_body_connect_statements = self.stmt_star_handler(def_node.body)
entry_node.connect(function_body_connect_statements.first_statement)
exit_node = self.append_node(EntryOrExitNode("Exit " + def_node.name))
exit_node.connect_predecessors(function_body_connect_statements.last_statements)
return Node(label_visitor.result, call_node,
line_number=call_node.lineno,
path=self.filenames[-1])
def add_module(self, module, module_or_package_name, local_names, import_alias_mapping, is_init=False, from_from=False, from_fdid=False):
"""
Returns:
The ExitNode that gets attached to the CFG of the class.
Open Question:
Are there times when the return value doesn't matter?
"""
module_path = module[1]
parent_definitions = self.module_definitions_stack[-1]
# The only place the import_alias_mapping is updated
parent_definitions.import_alias_mapping.update(import_alias_mapping)
parent_definitions.import_names = local_names
new_module_definitions = ModuleDefinitions(local_names, module_or_package_name)
new_module_definitions.is_init = is_init
self.module_definitions_stack.append(new_module_definitions)
# Analyse the file
self.filenames.append(module_path)
self.local_modules = get_directory_modules(module_path)
tree = generate_ast(module_path)
# module[0] is None during e.g. "from . import foo", so we must str()
self.append_node(EntryOrExitNode('Module Entry ' + str(module[0])))
self.visit(tree)
exit_node = self.append_node(EntryOrExitNode('Module Exit ' + str(module[0])))
# Done analysing, pop the module off
self.module_definitions_stack.pop()
self.filenames.pop()
if new_module_definitions.is_init:
for def_ in new_module_definitions.definitions:
module_def_alias = handle_aliases_in_init_files(def_.name,
new_module_definitions.import_alias_mapping)
parent_def_alias = handle_aliases_in_init_files(def_.name,
parent_definitions.import_alias_mapping)
# They should never both be set
assert not (module_def_alias and parent_def_alias)
def_name = def_.name
if parent_def_alias:
def_name = parent_def_alias
if module_def_alias:
def_name = module_def_alias
local_definitions = self.module_definitions_stack[-1]
if local_definitions != parent_definitions:
raise
if not isinstance(module_or_package_name, str):
module_or_package_name = module_or_package_name.name
if module_or_package_name:
if from_from:
qualified_name = def_name
if from_fdid:
alias = handle_fdid_aliases(module_or_package_name, import_alias_mapping)
if alias:
module_or_package_name = alias
parent_definition = ModuleDefinition(parent_definitions,
qualified_name,
module_or_package_name,
self.filenames[-1])
else:
parent_definition = ModuleDefinition(parent_definitions,
qualified_name,
None,
self.filenames[-1])
else:
qualified_name = '.'.join([module_or_package_name,
def_name])
parent_definition = ModuleDefinition(parent_definitions,
qualified_name,
parent_definitions.module_name,
self.filenames[-1])
parent_definition.node = def_.node
parent_definitions.definitions.append(parent_definition)
else:
parent_definition = ModuleDefinition(parent_definitions,
def_name,
parent_definitions.module_name,
self.filenames[-1])
parent_definition.node = def_.node
parent_definitions.definitions.append(parent_definition)
return exit_node
def from_directory_import(self, module, real_names, local_names, import_alias_mapping, skip_init=False):
"""
Directories don't need to be packages.
"""
module_path = module[1]
init_file_location = os.path.join(module_path, '__init__.py')
init_exists = os.path.isfile(init_file_location)
if init_exists and not skip_init:
package_name = os.path.split(module_path)[1]
return self.add_module((module[0], init_file_location),
package_name,
local_names,
import_alias_mapping,
is_init=True,
from_from=True)
for real_name in real_names:
full_name = os.path.join(module_path, real_name)
if os.path.isdir(full_name):
new_init_file_location = os.path.join(full_name, '__init__.py')
if os.path.isfile(new_init_file_location):
self.add_module((real_name, new_init_file_location),
real_name,
local_names,
import_alias_mapping,
is_init=True,
from_from=True,
from_fdid=True)
else:
raise Exception("from anything import directory needs an __init__.py file in directory")
else:
file_module = (real_name, full_name + '.py')
self.add_module(file_module, real_name, local_names, import_alias_mapping, from_from=True)
def import_package(self, module, module_name, local_name, import_alias_mapping):
module_path = module[1]
init_file_location = os.path.join(module_path, '__init__.py')
init_exists = os.path.isfile(init_file_location)
if init_exists:
return self.add_module((module[0], init_file_location),
module_name,
local_name,
import_alias_mapping,
is_init=True)
else:
raise Exception("import directory needs an __init__.py file")
def visit_Import(self, node):
for name in node.names:
for module in self.local_modules:
if name.name == module[0]:
if os.path.isdir(module[1]):
return self.import_package(module,
name,
name.asname,
retrieve_import_alias_mapping(node.names))
return self.add_module(module,
name.name,
name.asname,
retrieve_import_alias_mapping(node.names))
for module in self.project_modules:
if name.name == module[0]:
if os.path.isdir(module[1]):
return self.import_package(module,
name,
name.asname,
retrieve_import_alias_mapping(node.names))
return self.add_module(module,
name.name,
name.asname,
retrieve_import_alias_mapping(node.names))
return IgnoredNode()
def handle_relative_import(self, node):
"""
from A means node.level == 0
from . import B means node.level == 1
from .A means node.level == 1
"""
no_file = os.path.abspath(os.path.join(self.filenames[-1], os.pardir))
skip_init = False
if node.level == 1:
# Same directory as current file
if node.module:
name_with_dir = os.path.join(no_file, node.module.replace('.', '/'))
if not os.path.isdir(name_with_dir):
name_with_dir = name_with_dir + '.py'
# e.g. from . import X
else:
name_with_dir = no_file
# We do not want to analyse the init file of the current directory
skip_init = True
else:
parent = os.path.abspath(os.path.join(no_file, os.pardir))
if node.level > 2:
# Perform extra `cd ..` however many times
for _ in range(0, node.level - 2):
parent = os.path.abspath(os.path.join(parent, os.pardir))
if node.module:
name_with_dir = os.path.join(parent, node.module.replace('.', '/'))
if not os.path.isdir(name_with_dir):
name_with_dir = name_with_dir + '.py'
# e.g. from .. import X
else:
name_with_dir = parent
# Is it a file?
if name_with_dir.endswith('.py'):
return self.add_module((node.module, name_with_dir), None,
as_alias_handler(node.names),
retrieve_import_alias_mapping(node.names),
from_from=True)
return self.from_directory_import((node.module, name_with_dir),
not_as_alias_handler(node.names),
as_alias_handler(node.names),
retrieve_import_alias_mapping(node.names),
skip_init=skip_init)
def visit_ImportFrom(self, node):
# Is it relative?
if node.level > 0:
return self.handle_relative_import(node)
else:
for module in self.local_modules:
if node.module == module[0]:
if os.path.isdir(module[1]):
return self.from_directory_import(module,
not_as_alias_handler(node.names),
as_alias_handler(node.names))
return self.add_module(module, None,
as_alias_handler(node.names),
retrieve_import_alias_mapping(node.names),
from_from=True)
for module in self.project_modules:
name = module[0]
if node.module == name:
if os.path.isdir(module[1]):
return self.from_directory_import(module,
not_as_alias_handler(node.names),
as_alias_handler(node.names),
retrieve_import_alias_mapping(node.names))
return self.add_module(module, None,
as_alias_handler(node.names),
retrieve_import_alias_mapping(node.names),
from_from=True)
return IgnoredNode()
def interprocedural(node, project_modules, local_modules, filename,
module_definitions=None):
visitor = InterproceduralVisitor(node,
project_modules,
local_modules, filename,
module_definitions)
return CFG(visitor.nodes, visitor.blackbox_assignments)