aCompetentBean/gazprea-fuzzer-python
2
2
Fork 0
Code Issues 2 Pull requests Packages Projects Releases Wiki Activity
gazprea-fuzzer-python/ast_generator/ast_generator.py
ayrton 1da53dba48 Fixed common generation errors 
- Loops are now bound on the number of iterations by max-loop-iterations
- Names now get removed from the list of possible names when used
- Overflow errors in arithmetic are handled gracefully

Took 1 hour 13 minutes
2023-11-22 13:50:56 -07:00

776 lines
29 KiB
Python
Raw Blame History

import random
import string
import xml.etree.ElementTree as ET
from english_words import get_english_words_set
from ast_generator.utils import Variable, Argument, Routine, Scope, build_xml_element
from constants import *
import keyword
class AstGenerator:
"""
Generates an AST from a grammar based on given settings
Originally the intention was to use the ISLa library to generate
the AST, however I found that ISLa is like taking a buldozer to
a sledgehammer's job, so I decided to write a procedural generator
instead.
The way we select elements is we take all the settings in their
category and assign them a range on a number line. Then we
pick a random number in that range and whichever category it
falls into will be selected.
"""
def __init__(self, settings: dict):
"""
This class is designed to get the settings from some wrapper class that
better defines the precise constraints of the language being generated
the necessary settings are in the .yaml file and #TODO this is not generalizable yet
@param settings: settings for weights and probabilities and lengths
"""
self.settings = settings
self.symbol_table = []
global_scope = Scope(None, None)
self.symbol_table.append(global_scope) # NOTE for debug
self.current_scope = global_scope
names = get_english_words_set(['web2'], alpha=True)
possible_names = filter(lambda x: self.settings['properties']['id-length']['max'] <= len(x) <=
self.settings['properties']['id-length']['max'] and not keyword.iskeyword(x), names)
var_name_list = list(possible_names)
var_name_len = len(var_name_list)
self.variable_names = var_name_list[0:var_name_len // 2]
self.routine_names = var_name_list[var_name_len // 2:var_name_len]
self.ast: ET.Element or None = None
self.current_ast_element: ET.Element or None = None
self.current_nesting_depth = 0
self.current_control_flow_nesting_depth = 0
# Numberlines - For computing probabilities
self.int_op_options, self.int_op_cutoffs, self.int_op_numline = (
self.get_numberlines('expression-weights',
['brackets', 'arithmetic', 'unary'],
[[], [], ['not']]))
self.int_unary = ['negation', 'noop']
self.bool_op_options, self.bool_op_cutoffs, self.bool_op_numline = (
self.get_numberlines('expression-weights',
['brackets', 'comparison', 'logical', 'unary'],
excluded_values=[[], ['less-than-or-equal', 'greater-than-or-equal', 'less-than',
'greater-than'], [], ['noop', 'negation']]))
self.bool_unary = ['not']
self.float_op_options, self.float_op_cutoffs, self.float_op_numline = (
self.get_numberlines('expression-weights',
['brackets', 'arithmetic', 'unary'],
[[], [], ['not']]))
self.float_unary = ['negation', 'noop']
self.char_op_options, self.char_op_cutoffs, self.char_op_numline = (
self.get_numberlines('expression-weights',
['brackets', 'comparison'],
[[], ['less-than', 'greater-than', 'less-than-or-equal', 'greater-than-or-equal']]))
self.comp_op_options, self.comp_op_cutoffs, self.comp_op_numline = (
self.get_numberlines('expression-weights',
['brackets', 'comparison'],
[[], []]))
def get_numberlines(self, settings_section: str, subsettings: list[str], excluded_values):
assert len(subsettings) == len(excluded_values)
number_line = 0
cutoffs = []
cutoff = 0
options = {}
option = 0
settings = []
for key, value in self.settings[settings_section].items():
if key in subsettings and key not in excluded_values: # this check needs to be done recursively
if isinstance(value, int):
t = {
key: value
}
settings.append(t)
elif isinstance(value, dict):
settings.append(value)
else:
raise TypeError("invalid setting type. Found " + str(value) + " instead of expected int or dict")
for v in range(len(settings)):
for i in excluded_values:
for j in i:
if j in settings[v]:
settings[v].pop(j)
for v in settings:
if isinstance(v, dict):
for key, value in v.items():
number_line += value
cutoffs.append(cutoff + value)
cutoff += value
options[option] = key
option += 1
elif isinstance(v, int):
number_line += v
cutoffs.append(cutoff + v)
cutoff += v
options[option] = v
option += 1
else:
raise TypeError("invalid setting type. Found " + str(v) + " instead of expected int")
return options, cutoffs, number_line
def generate_ast(self):
"""
@brief generates an AST from a grammar
"""
self.generate_top_level_block()
def generate_top_level_block(self): # TODO add constant generation into this block
i = 0
element = build_xml_element([], name=GAZ_BLOCK_TAG)
self.current_ast_element = element
self.ast = element
# optional constants here too
self.generate_main()
while i < self.settings['generation-options']['max-number-of-routines']:
if random.random() < self.settings['block-termination-probability']:
break
self.generate_routine()
i += 1
def generate_main(self):
parent = self.current_ast_element
self.push_scope()
main_args = [ # TODO refactor these into constants
("name", "main"),
("return_type", GAZ_INT_KEY),
("args", "()"),
]
element = build_xml_element(main_args, name=GAZ_PROCEDURE_TAG)
self.current_ast_element.append(element)
self.current_ast_element = element
self.generate_block(return_stmt=True, return_value="0", return_type=GAZ_INT_KEY)
self.pop_scope()
self.current_ast_element = parent
def generate_block(self, tag=None, return_stmt=False, return_value=None, return_type=None, block_type=None,
loop_var=None):
# TODO this should be broken into many functions depending on the block requirements
if tag is None:
tag = []
parent = self.current_ast_element
self.push_scope()
element = build_xml_element(tag, name=GAZ_BLOCK_TAG)
self.current_ast_element.append(element)
self.current_ast_element = element
# Generate the loop condition increment if we are in a loop
if block_type == GAZ_LOOP_TAG:
self.generate_loop_condition_check(loop_var)
self.generate_loop_condition_increment(loop_var)
self.generate_statements()
if return_stmt:
self.generate_return(return_type=return_type, return_value=return_value)
if self.settings['generation-options']['generate-dead-code']:
self.generate_statements()
self.pop_scope()
self.current_ast_element = parent
def generate_loop_condition_check(self, loop_var: Variable):
"""
@brief generates the loop condition check
Ensures that the loop does not iterate more than max-loop-iterations times
@param loop_var:
@return:
"""
# loop var is always an int
assert loop_var.type == GAZ_INT_KEY
# create a conditional xml tag
if_stmt = build_xml_element([], name=GAZ_IF_TAG)
self.current_ast_element.append(if_stmt)
parent = self.current_ast_element
self.current_ast_element = if_stmt
# add the check 'if loop_var >= self.settings['generation_options']['max-loop-iterations']: break'
operation = build_xml_element([("op", ">=")], name=GAZ_OPERATOR_TAG)
self.current_ast_element.append(operation)
self.current_ast_element = operation
lhs = build_xml_element([], name=GAZ_LHS_TAG)
operation.append(lhs)
var = build_xml_element([("name", loop_var.name), ("type", loop_var.type)], name=GAZ_VAR_TAG)
lhs.append(var)
rhs = build_xml_element([], name=GAZ_RHS_TAG)
operation.append(rhs)
rhs.append(self.make_literal(GAZ_INT_KEY, "'" + str(self.settings['generation-options']['max-loop-iterations']) + "'"))
true_block = build_xml_element([], name=GAZ_BLOCK_TAG)
if_stmt.append(true_block)
self.current_ast_element = true_block
break_stmt = build_xml_element([], name=GAZ_BREAK_TAG)
true_block.append(break_stmt)
# return everything to normalcy
self.current_ast_element = parent
def generate_loop_condition_increment(self, loop_var):
assert loop_var.type == GAZ_INT_KEY
parent = self.current_ast_element
assignment = build_xml_element([], name=GAZ_ASSIGNMENT_TAG)
self.current_ast_element.append(assignment)
self.current_ast_element = assignment
# append the variable
self.current_ast_element.append(loop_var.xml)
# add the increment 'loop_var += 1'
assn_rhs = build_xml_element([], name=GAZ_RHS_TAG)
self.current_ast_element.append(assn_rhs)
self.current_ast_element = assn_rhs
operation = build_xml_element([("op", "+")], name=GAZ_OPERATOR_TAG)
self.current_ast_element.append(operation)
self.current_ast_element = operation
lhs = build_xml_element([], name=GAZ_LHS_TAG)
operation.append(lhs)
var = build_xml_element([("name", loop_var.name), ("type", loop_var.type)], name=GAZ_VAR_TAG)
lhs.append(var)
rhs = build_xml_element([], name=GAZ_RHS_TAG)
operation.append(rhs)
rhs.append(self.make_literal(GAZ_INT_KEY, '1'))
# return everything to normalcy
self.current_ast_element = parent
def generate_return(self, return_type=None, return_value=None):
if return_type is None or return_type == GAZ_VOID_TYPE:
self.current_ast_element.append(build_xml_element([], name=GAZ_RETURN_TAG))
return
else:
if return_value is None:
xml_element = build_xml_element([("type", return_type)], name=GAZ_RETURN_TAG)
self.current_ast_element.append(xml_element)
parent = self.current_ast_element
self.current_ast_element = xml_element
self.generate_expression(return_type)
self.current_ast_element = parent
return
else:
xml_element = build_xml_element([("type", return_type)], name=GAZ_RETURN_TAG)
self.current_ast_element.append(xml_element)
parent = self.current_ast_element
self.current_ast_element = xml_element
self.current_ast_element.append(self.make_literal(return_type, return_value))
self.current_ast_element = parent
return
def generate_routine(self, routine_type=None):
if routine_type is None:
routine_type = self.get_routine_type()
else:
routine_type = routine_type
args = self.generate_routine_args()
name = self.get_name(routine_type)
return_type = self.get_type(routine_type)
routine = Routine(name, routine_type, return_type, args)
routine_args = [
("name", routine.name),
("return_type", routine.return_type),
]
element = build_xml_element(routine_args, name=routine.type)
self.current_ast_element.append(element)
parent = self.current_ast_element
self.current_ast_element = element
self.push_scope()
self.define_args(routine.arguments)
self.generate_block(return_stmt=True, return_type=routine.return_type)
self.pop_scope()
self.current_ast_element = parent
def define_args(self, args):
for arg in args:
self.current_ast_element.append(arg.xml)
self.current_scope.append(arg.name, arg)
def generate_statements(self):
# Number line
number_line = 180 # TODO fix the numberline stuff to reflect the settings
cutoffs = [10, 30, 50, 80, 100, 140, 180]
options = {
0: self.generate_declaration,
1: self.generate_routine_call,
2: self.generate_conditional,
3: self.generate_loop,
4: self.generate_assignment,
5: self.generate_out_stream,
6: self.generate_in_stream,
}
while True:
if random.random() < self.settings['block-termination-probability']:
break
a = random.randint(0, number_line)
i = 0
for i in range(len(cutoffs) - 1):
if cutoffs[i] < a < cutoffs[i + 1]:
try:
options[i]()
except ValueError:
break
break
def generate_int_expr(self):
self._generate_expression([GAZ_INT_KEY],
self.int_op_numline,
self.int_op_cutoffs,
self.int_op_options,
self.int_unary)
def generate_float_expr(self):
self._generate_expression([GAZ_FLOAT_KEY, GAZ_INT_KEY],
self.float_op_numline,
self.float_op_cutoffs,
self.float_op_options,
self.float_unary)
def generate_bool_expr(self):
self._generate_expression([GAZ_BOOL_KEY],
self.bool_op_numline,
self.bool_op_cutoffs,
self.bool_op_options,
self.bool_unary)
def generate_char_expr(self):
self._generate_expression([GAZ_CHAR_KEY],
self.char_op_numline,
self.char_op_cutoffs,
self.char_op_options)
def generate_comp_expr(self):
self._generate_expression([GAZ_BOOL_KEY],
self.comp_op_numline,
self.comp_op_cutoffs,
self.comp_op_options,
comparison=True)
def _generate_expression(self, expr_type: list[str], number_line,
cutoffs, options, unary=None, comparison: bool = False):
if unary is None:
unary = []
parent = self.current_ast_element
self.current_nesting_depth += 1
if self.current_nesting_depth > self.settings['generation-options']['max-nesting-depth'] or random.random() < \
self.settings['block-termination-probability']:
self.generate_literal(random.choice(expr_type))
self.current_nesting_depth -= 1
return
op = ""
a = random.randint(0, number_line - 1)
i = 0
for i in range(len(cutoffs) - 1):
if i == 0:
if a < cutoffs[i]:
op = options[i]
break
if cutoffs[i] <= a < cutoffs[i + 1]:
op = options[i]
break
if op in unary:
self.generate_unary(op, random.choice(expr_type))
elif op == GAZ_BRACKET_TAG:
self.generate_bracket(random.choice(expr_type))
elif comparison:
if op in ['equality', 'inequality']:
self.generate_binary(op, random.choice([GAZ_INT_KEY, GAZ_FLOAT_KEY, GAZ_CHAR_KEY]))
else:
self.generate_binary(op, random.choice([GAZ_INT_KEY, GAZ_FLOAT_KEY]))
else:
self.generate_binary(op, random.choice(expr_type))
self.current_nesting_depth -= 1
self.current_ast_element = parent
def generate_declaration(self, mut=None):
parent = self.current_ast_element
decl_type = self.get_type(GAZ_VAR_TAG)
decl_args = [
("type", decl_type),
]
element = build_xml_element(decl_args, name=GAZ_DECLARATION_TAG)
self.current_ast_element.append(element)
self.current_ast_element = element
variable = self.generate_variable(decl_type, mut=mut)
self.current_ast_element.append(variable.xml)
self.current_scope.append(variable.name, variable)
self.generate_xhs(GAZ_RHS_TAG, decl_type) # TODO add real type (decl_type)
self.current_ast_element = parent
def generate_binary(self, op, op_type):
parent = self.current_ast_element
if op == "":
raise ValueError("op is empty!")
args = [
("op", op),
("type", op_type),
]
element = build_xml_element(args, name=GAZ_OPERATOR_TAG)
self.current_ast_element.append(element)
self.current_ast_element = element
self.generate_xhs(GAZ_LHS_TAG, op_type)
self.generate_xhs(GAZ_RHS_TAG, op_type)
self.current_ast_element = parent
def generate_bracket(self, op_type):
parent = self.current_ast_element
args = [
("type", op_type),
]
element = build_xml_element(args, name=GAZ_BRACKET_TAG)
self.current_ast_element.append(element)
self.current_ast_element = element
self.generate_xhs(GAZ_RHS_TAG, op_type)
self.current_ast_element = parent
def generate_xhs(self, handedness, op_type, is_zero=False):
element = build_xml_element([], name=handedness)
parent = self.current_ast_element
self.current_ast_element.append(element)
self.current_ast_element = element
self.generate_expression(op_type, is_zero=is_zero)
self.current_ast_element = parent
def generate_unary(self, op, op_type=ANY_TYPE):
parent = self.current_ast_element
args = [
("op", op),
("type", op_type),
]
element = build_xml_element(args, name=GAZ_UNARY_OPERATOR_TAG)
self.current_ast_element.append(element)
self.current_ast_element = element
self.generate_xhs(GAZ_RHS_TAG, op_type)
self.current_ast_element = parent
def generate_routine_call(self):
pass
def generate_conditional(self):
if self.current_control_flow_nesting_depth >= self.settings['generation-options']['max-nesting-depth']:
return
if self.current_control_flow_nesting_depth > 0 and random.random() < self.settings[
'block-termination-probability']:
return
element = build_xml_element([], name=GAZ_IF_TAG)
self.current_ast_element.append(element)
parent = self.current_ast_element
self.current_ast_element = element
self.current_control_flow_nesting_depth += 1
self.push_scope()
self.generate_expression(GAZ_BOOL_KEY)
self.generate_block(tag=[("type", GAZ_TRUE_BLOCK_TAG)])
self.generate_block(tag=[("type", GAZ_FALSE_BLOCK_TAG)])
self.pop_scope()
self.current_ast_element = parent
def generate_loop(self): # fixme generation of infinite loops happens too often...
# FIXME make sure that loop conditions are evaluated at least once (assert true or make a config param)
if self.current_control_flow_nesting_depth >= self.settings['generation-options']['max-nesting-depth']:
return
if self.current_control_flow_nesting_depth > 0 and random.random() < self.settings[
'block-termination-probability']:
return
init_var = self.generate_zero_declaration()
parent = self.current_ast_element
element = build_xml_element([], name=GAZ_LOOP_TAG)
self.current_ast_element.append(element)
self.current_ast_element = element
self.current_control_flow_nesting_depth += 1
self.push_scope()
self.generate_expression(GAZ_BOOL_KEY)
self.generate_block(block_type=GAZ_LOOP_TAG,
loop_var=init_var) # append a variable increment and prepend a break statement if var is > max loop iterations
self.pop_scope()
self.current_ast_element = parent
def generate_zero_declaration(self):
parent = self.current_ast_element
element = build_xml_element([], name=GAZ_DECLARATION_TAG)
self.current_ast_element.append(element)
self.current_ast_element = element
variable = self.generate_variable(GAZ_INT_KEY, 'var')
self.current_ast_element.append(variable.xml)
self.current_scope.append(variable.name, variable)
self.generate_xhs(GAZ_RHS_TAG, variable.type, is_zero=True)
self.current_ast_element = parent
return variable
def generate_assignment(self):
possible_vars = self.current_scope.get_all_defined_mutable_vars()
if len(possible_vars) == 0:
raise ValueError("No possible variables to assign to!")
# same structure as a declaration
parent = self.current_ast_element
element = build_xml_element([], name=GAZ_ASSIGNMENT_TAG)
self.current_ast_element.append(element)
self.current_ast_element = element
variable = random.choice(possible_vars)
self.current_ast_element.append(variable.xml)
self.generate_xhs(GAZ_RHS_TAG, variable.type)
self.current_ast_element = parent
def generate_out_stream(self):
self.generate_stream(GAZ_OUT_STREAM)
def generate_in_stream(self):
self.generate_stream(GAZ_IN_STREAM)
def generate_stream(self, stream_type):
parent = self.current_ast_element
args = [
("type", stream_type),
]
element = build_xml_element(args, name=GAZ_STREAM_TAG)
self.current_ast_element.append(element)
self.current_ast_element = element
self.generate_expression(ANY_TYPE)
self.current_ast_element = parent
def generate_variable(self, var_type: str, mut=None):
if mut is None:
return Variable(self.get_name(GAZ_VAR_TAG), var_type, self.get_qualifier())
else:
return Variable(self.get_name(GAZ_VAR_TAG), var_type, mut)
def generate_literal(self, var_type: str, value=None):
if value is None:
value = self.get_value(var_type)
else:
value = value
args = [
("type", var_type),
("value", str(value)),
]
element = build_xml_element(args, name=GAZ_LIT_TAG)
self.current_ast_element.append(element)
def make_literal(self, type, value):
args = [
("type", type),
("value", value),
]
element = build_xml_element(args, name=GAZ_LIT_TAG)
return element
def generate_global(self):
current_scope = self.current_scope
current_element = self.current_ast_element
self.current_scope = self.current_scope.get_top_scope()
self.current_ast_element = self.ast
self.generate_declaration(mut='const')
self.current_scope = current_scope
self.current_ast_element = current_element
def generate_expression(self, expr_type: str, is_zero=False):
if is_zero:
self.generate_literal(expr_type, value=0)
return
elif expr_type == GAZ_INT_KEY or expr_type == GAZ_FLOAT_KEY:
self.generate_int_expr()
elif expr_type == GAZ_BOOL_KEY:
if random.random() < 0.5:
self.generate_bool_expr()
else:
self.generate_comp_expr()
elif expr_type == GAZ_CHAR_KEY:
self.generate_char_expr()
elif expr_type == ANY_TYPE: # TODO implement the choice of any type
self.generate_int_expr()
else:
raise NotImplementedError(f"Expression type {expr_type} not implemented")
def generate_routine_args(self):
number = random.randint(self.settings['properties']['number-of-arguments']['min'],
self.settings['properties']['number-of-arguments']['max'])
args = []
for i in range(number):
arg = self.generate_arg()
args.append(arg)
self.current_scope.append(arg.name, arg)
return args
def generate_arg(self):
return Argument(self.get_name(GAZ_VAR_TAG), self.get_type(GAZ_VAR_TAG))
def push_scope(self, xml_element: ET.Element = None):
scope = Scope(self.current_scope)
self.symbol_table.append(scope)
self.current_scope = scope
def pop_scope(self):
self.current_scope = self.current_scope.enclosing_scope
# TODO revamp the random value generations
def get_qualifier(self):
"""
@brief get a random qualifier from the list of possible qualifiers
@return a qualifier as a string
"""
number_line = (self.settings["misc-weights"]["type-qualifier-weights"]["const"] +
self.settings["misc-weights"]["type-qualifier-weights"]["var"] - 1)
res = random.randint(0, number_line)
if res in range(0, self.settings["misc-weights"]["type-qualifier-weights"]["const"]):
return 'const'
elif res in range(self.settings["misc-weights"]["type-qualifier-weights"]["const"],
self.settings["misc-weights"]["type-qualifier-weights"]["const"] +
self.settings["misc-weights"]["type-qualifier-weights"]["var"]):
return 'var'
else:
raise ValueError("Internal Error, please report the stack trace to me")
def get_routine_type(self):
cutoffs = []
values = []
ops = []
for key, value in self.settings["routine-weights"].items():
cutoffs.append(value + sum(cutoffs))
values.append(value)
ops.append(key)
res = random.randint(0, sum(values))
for i in range(len(cutoffs)):
if res < cutoffs[i]:
return ops[i] # TODO everything should be fast faied
def get_value(self, type):
if type == GAZ_INT_KEY:
if self.settings["properties"]["generate-max-int"]:
return random.randint(-2147483648, 2147483647)
else:
return random.randint(-1000, 1000)
elif type == GAZ_FLOAT_KEY:
return random.uniform(-1000, 1000)
elif type == GAZ_BOOL_KEY:
return random.choice([True, False])
elif type == GAZ_CHAR_KEY:
return "'" + random.choice(string.ascii_letters) + "'"
else:
raise TypeError("Unimplemented generator for type: " + type)
def get_name(self, name_type):
"""
@brief get a random name from the list of possible names and add it to the current scope
@param name_type:
@return:
"""
if not self.settings['properties']['use-english-words']:
length = random.randint(self.settings['properties']['id-length']['min'],
self.settings['properties']['id-length']['max'])
name = ''.join(random.choices(string.ascii_letters, k=length))
return name
else:
if name_type == GAZ_VAR_TAG:
choice = random.choice(self.variable_names)
self.variable_names.remove(choice)
return choice
else:
choice = random.choice(self.routine_names)
self.routine_names.remove(choice)
return choice
def get_type(self, tag): # TODO Add support for composite types
return 'int' # TODO Add support for all types
if tag in [GAZ_PROCEDURE_TAG, GAZ_FUNCTION_TAG, GAZ_VAR_TAG]:
cutoffs = []
values = []
types = []
for key, value in self.settings["type-weights"]["value-types"].items():
if key == GAZ_VOID_TYPE and tag != GAZ_PROCEDURE_TAG:
continue
cutoffs.append(value + sum(cutoffs))
values.append(value)
types.append(key)
res = random.randint(0, sum(values))
for i in range(len(cutoffs)):
if res < cutoffs[i]:
return types[i]
Reference in a new issue View git blame Copy permalink