Static Analyzer for Solidity
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slither/utils/slither_format/format_external_function.py

59 lines
3.4 KiB

import re
class FormatExternalFunction:
@staticmethod
def format (slither, patches, elements):
for element in elements:
Found = False
for contract in slither.contracts:
if not Found and contract.name == element['contract']['name']:
for function in contract.functions:
if function.name == element['name']:
# If function parameters are written to in function body then we cannot convert this function
# to external because external function parameters are allocated in calldata region which is
# non-modifiable. See https://solidity.readthedocs.io/en/develop/types.html#data-location
if not FormatExternalFunction.function_parameters_written(function):
FormatExternalFunction.create_patch(slither, patches, element['source_mapping']['filename_absolute'], "public", "external", int(function.parameters_src.split(':')[0]), int(function.returns_src.split(':')[0]))
Found = True
break
@staticmethod
def create_patch(slither, patches, in_file, match_text, replace_text, modify_loc_start, modify_loc_end):
in_file_str = slither.source_code[in_file]
old_str_of_interest = in_file_str[modify_loc_start:modify_loc_end]
old_str_of_interest_beyond_parameters = ')'.join(old_str_of_interest.split(')')[1:])
s = old_str_of_interest_beyond_parameters.split('(')
if len(s) == 1:
account_for_return = 0
else:
account_for_return = 1
old_str_of_interest_beyond_parameters_before_modifier_return = old_str_of_interest_beyond_parameters.split('(')[0]
m = re.search("public", old_str_of_interest_beyond_parameters_before_modifier_return)
if m is None:
# No visibility specifier exists; public by default.
(new_str_of_interest, _) = re.subn(" ", " external ", old_str_of_interest_beyond_parameters_before_modifier_return, 1)
patches[in_file].append({
"detector" : "external-function",
"start" : modify_loc_start + len(old_str_of_interest.split(')')[0]) + 1,
"end" : modify_loc_end - len('('.join(old_str_of_interest_beyond_parameters.split('(')[1:])) - account_for_return,
"old_string" : old_str_of_interest_beyond_parameters_before_modifier_return,
"new_string" : new_str_of_interest
})
else:
(new_str_of_interest, _) = re.subn(match_text, replace_text, old_str_of_interest_beyond_parameters_before_modifier_return, 1)
patches[in_file].append({
"detector" : "external-function",
"start" : modify_loc_start + len(old_str_of_interest.split(')')[0]) + 1 + m.span()[0],
"end" : modify_loc_end - len('('.join(old_str_of_interest_beyond_parameters.split('(')[1:])) - account_for_return,
"old_string" : old_str_of_interest_beyond_parameters_before_modifier_return,
"new_string" : new_str_of_interest
})
@staticmethod
def function_parameters_written(function):
for node in function.nodes:
if any (var.name == parameter.name for var in node.local_variables_written for parameter in function.parameters):
return True
return False