def parse_function(code,
sigs,
origcode,
global_ctx,
is_contract_payable,
_vars=None):
"""
Parses a function and produces LLL code for the function, includes:
- Signature method if statement
- Argument handling
- Clamping and copying of arguments
- Function body
"""
if _vars is None:
_vars = {}
sig = FunctionSignature.from_definition(
code,
sigs=sigs,
custom_structs=global_ctx._structs,
)
# Validate return statements.
sig.validate_return_statement_balance()
# Create a local (per function) context.
memory_allocator = MemoryAllocator()
context = Context(
vars=_vars,
global_ctx=global_ctx,
sigs=sigs,
memory_allocator=memory_allocator,
return_type=sig.output_type,
constancy=Constancy.Constant
if sig.mutability in ("view", "pure") else Constancy.Mutable,
is_payable=sig.mutability == "payable",
origcode=origcode,
is_internal=sig.internal,
method_id=sig.method_id,
sig=sig,
)
if sig.internal:
o = parse_internal_function(
code=code,
sig=sig,
context=context,
)
else:
o = parse_external_function(code=code,
sig=sig,
context=context,
is_contract_payable=is_contract_payable)
o.context = context
o.total_gas = o.gas + calc_mem_gas(
o.context.memory_allocator.get_next_memory_position())
o.func_name = sig.name
return o
def unroll_constant(self, const, global_ctx):
ann_expr = None
expr = Expr.parse_value_expr(
const.value,
Context(vars=None,
global_ctx=global_ctx,
origcode=const.source_code,
memory_allocator=MemoryAllocator()),
)
annotation_type = global_ctx.parse_type(const.annotation.args[0], None)
fail = False
if is_instances([expr.typ, annotation_type], ByteArrayType):
if expr.typ.maxlen < annotation_type.maxlen:
return const
fail = True
elif expr.typ != annotation_type:
fail = True
# special case for literals, which can be uint256 types as well.
is_special_case_uint256_literal = (is_instances(
[expr.typ, annotation_type], BaseType)) and ([
annotation_type.typ, expr.typ.typ
] == ['uint256', 'int128']) and SizeLimits.in_bounds(
'uint256', expr.value)
is_special_case_int256_literal = (is_instances(
[expr.typ, annotation_type], BaseType)) and ([
annotation_type.typ, expr.typ.typ
] == ['int128', 'int128']) and SizeLimits.in_bounds(
'int128', expr.value)
if is_special_case_uint256_literal or is_special_case_int256_literal:
fail = False
if fail:
raise TypeMismatchException(
'Invalid value for constant type, expected %r got %r instead' %
(
annotation_type,
expr.typ,
),
const.value,
)
ann_expr = copy.deepcopy(expr)
ann_expr.typ = annotation_type
ann_expr.typ.is_literal = expr.typ.is_literal # Annotation type doesn't have literal set.
return ann_expr
def parse_func(code, sigs, origcode, global_ctx, _vars=None):
if _vars is None:
_vars = {}
sig = FunctionSignature.from_definition(
code,
sigs=sigs,
custom_units=global_ctx._custom_units,
custom_structs=global_ctx._structs,
constants=global_ctx._constants)
# Get base args for function.
total_default_args = len(code.args.defaults)
base_args = sig.args[:
-total_default_args] if total_default_args > 0 else sig.args
default_args = code.args.args[-total_default_args:]
default_values = dict(
zip([arg.arg for arg in default_args], code.args.defaults))
# __init__ function may not have defaults.
if sig.name == '__init__' and total_default_args > 0:
raise FunctionDeclarationException(
"__init__ function may not have default parameters.")
# Check for duplicate variables with globals
for arg in sig.args:
if arg.name in global_ctx._globals:
raise FunctionDeclarationException(
"Variable name duplicated between function arguments and globals: "
+ arg.name)
nonreentrant_pre = [['pass']]
nonreentrant_post = [['pass']]
if sig.nonreentrant_key:
nkey = global_ctx.get_nonrentrant_counter(sig.nonreentrant_key)
nonreentrant_pre = [[
'seq', ['assert', ['iszero', ['sload', nkey]]],
['sstore', nkey, 1]
]]
nonreentrant_post = [['sstore', nkey, 0]]
# Create a local (per function) context.
memory_allocator = MemoryAllocator()
context = Context(
vars=_vars,
global_ctx=global_ctx,
sigs=sigs,
memory_allocator=memory_allocator,
return_type=sig.output_type,
constancy=Constancy.Constant if sig.const else Constancy.Mutable,
is_payable=sig.payable,
origcode=origcode,
is_private=sig.private,
method_id=sig.method_id)
# Copy calldata to memory for fixed-size arguments
max_copy_size = sum([
32 if isinstance(arg.typ, ByteArrayLike) else
get_size_of_type(arg.typ) * 32 for arg in sig.args
])
base_copy_size = sum([
32 if isinstance(arg.typ, ByteArrayLike) else
get_size_of_type(arg.typ) * 32 for arg in base_args
])
# context.next_mem += max_copy_size
context.memory_allocator.increase_memory(max_copy_size)
clampers = []
# Create callback_ptr, this stores a destination in the bytecode for a private
# function to jump to after a function has executed.
_post_callback_ptr = "{}_{}_post_callback_ptr".format(
sig.name, sig.method_id)
if sig.private:
context.callback_ptr = context.new_placeholder(typ=BaseType('uint256'))
clampers.append(
LLLnode.from_list(
['mstore', context.callback_ptr, 'pass'],
annotation='pop callback pointer',
))
if total_default_args > 0:
clampers.append(['label', _post_callback_ptr])
# private functions without return types need to jump back to
# the calling function, as there is no return statement to handle the
# jump.
stop_func = [['stop']]
if sig.output_type is None and sig.private:
stop_func = [['jump', ['mload', context.callback_ptr]]]
if not len(base_args):
copier = 'pass'
elif sig.name == '__init__':
copier = [
'codecopy', MemoryPositions.RESERVED_MEMORY, '~codelen',
base_copy_size
]
else:
copier = get_arg_copier(sig=sig,
total_size=base_copy_size,
memory_dest=MemoryPositions.RESERVED_MEMORY)
clampers.append(copier)
# Add asserts for payable and internal
# private never gets payable check.
if not sig.payable and not sig.private:
clampers.append(['assert', ['iszero', 'callvalue']])
# Fill variable positions
for i, arg in enumerate(sig.args):
if i < len(base_args) and not sig.private:
clampers.append(
make_clamper(
arg.pos,
context.memory_allocator.get_next_memory_position(),
arg.typ,
sig.name == '__init__',
))
if isinstance(arg.typ, ByteArrayLike):
mem_pos, _ = context.memory_allocator.increase_memory(
32 * get_size_of_type(arg.typ))
context.vars[arg.name] = VariableRecord(arg.name, mem_pos, arg.typ,
False)
else:
context.vars[arg.name] = VariableRecord(
arg.name,
MemoryPositions.RESERVED_MEMORY + arg.pos,
arg.typ,
False,
)
# Private function copiers. No clamping for private functions.
dyn_variable_names = [
a.name for a in base_args if isinstance(a.typ, ByteArrayLike)
]
if sig.private and dyn_variable_names:
i_placeholder = context.new_placeholder(typ=BaseType('uint256'))
unpackers = []
for idx, var_name in enumerate(dyn_variable_names):
var = context.vars[var_name]
ident = "_load_args_%d_dynarg%d" % (sig.method_id, idx)
o = make_unpacker(ident=ident,
i_placeholder=i_placeholder,
begin_pos=var.pos)
unpackers.append(o)
if not unpackers:
unpackers = ['pass']
clampers.append(
LLLnode.from_list(
# [0] to complete full overarching 'seq' statement, see private_label.
['seq_unchecked'] + unpackers + [0],
typ=None,
annotation='dynamic unpacker',
pos=getpos(code),
))
# Create "clampers" (input well-formedness checkers)
# Return function body
if sig.name == '__init__':
o = LLLnode.from_list(
['seq'] + clampers + [parse_body(code.body, context)],
pos=getpos(code),
)
elif is_default_func(sig):
if len(sig.args) > 0:
raise FunctionDeclarationException(
'Default function may not receive any arguments.', code)
if sig.private:
raise FunctionDeclarationException(
'Default function may only be public.',
code,
)
o = LLLnode.from_list(
['seq'] + clampers + [parse_body(code.body, context)],
pos=getpos(code),
)
else:
if total_default_args > 0: # Function with default parameters.
function_routine = "{}_{}".format(sig.name, sig.method_id)
default_sigs = sig_utils.generate_default_arg_sigs(
code, sigs, global_ctx)
sig_chain = ['seq']
for default_sig in default_sigs:
sig_compare, private_label = get_sig_statements(
default_sig, getpos(code))
# Populate unset default variables
populate_arg_count = len(sig.args) - len(default_sig.args)
set_defaults = []
if populate_arg_count > 0:
current_sig_arg_names = {x.name for x in default_sig.args}
missing_arg_names = [
arg.arg for arg in default_args
if arg.arg not in current_sig_arg_names
]
for arg_name in missing_arg_names:
value = Expr(default_values[arg_name],
context).lll_node
var = context.vars[arg_name]
left = LLLnode.from_list(var.pos,
typ=var.typ,
location='memory',
pos=getpos(code),
mutable=var.mutable)
set_defaults.append(
make_setter(left,
value,
'memory',
pos=getpos(code)))
current_sig_arg_names = {x.name for x in default_sig.args}
base_arg_names = {arg.name for arg in base_args}
if sig.private:
# Load all variables in default section, if private,
# because the stack is a linear pipe.
copier_arg_count = len(default_sig.args)
copier_arg_names = current_sig_arg_names
else:
copier_arg_count = len(default_sig.args) - len(base_args)
copier_arg_names = current_sig_arg_names - base_arg_names
# Order copier_arg_names, this is very important.
copier_arg_names = [
x.name for x in default_sig.args
if x.name in copier_arg_names
]
# Variables to be populated from calldata/stack.
default_copiers = []
if copier_arg_count > 0:
# Get map of variables in calldata, with thier offsets
offset = 4
calldata_offset_map = {}
for arg in default_sig.args:
calldata_offset_map[arg.name] = offset
offset += (32 if isinstance(arg.typ, ByteArrayLike)
else get_size_of_type(arg.typ) * 32)
# Copy set default parameters from calldata
dynamics = []
for arg_name in copier_arg_names:
var = context.vars[arg_name]
calldata_offset = calldata_offset_map[arg_name]
if sig.private:
_offset = calldata_offset
if isinstance(var.typ, ByteArrayLike):
_size = 32
dynamics.append(var.pos)
else:
_size = var.size * 32
default_copiers.append(
get_arg_copier(
sig=sig,
memory_dest=var.pos,
total_size=_size,
offset=_offset,
))
else:
# Add clampers.
default_copiers.append(
make_clamper(
calldata_offset - 4,
var.pos,
var.typ,
))
# Add copying code.
if isinstance(var.typ, ByteArrayLike):
_offset = [
'add', 4,
['calldataload', calldata_offset]
]
else:
_offset = calldata_offset
default_copiers.append(
get_arg_copier(
sig=sig,
memory_dest=var.pos,
total_size=var.size * 32,
offset=_offset,
))
# Unpack byte array if necessary.
if dynamics:
i_placeholder = context.new_placeholder(
typ=BaseType('uint256'))
for idx, var_pos in enumerate(dynamics):
ident = 'unpack_default_sig_dyn_%d_arg%d' % (
default_sig.method_id, idx)
default_copiers.append(
make_unpacker(
ident=ident,
i_placeholder=i_placeholder,
begin_pos=var_pos,
))
default_copiers.append(0) # for over arching seq, POP
sig_chain.append([
'if', sig_compare,
[
'seq', private_label, ['pass'] if not sig.private else
LLLnode.from_list([
'mstore',
context.callback_ptr,
'pass',
],
annotation='pop callback pointer',
pos=getpos(code)),
['seq'] + set_defaults if set_defaults else ['pass'],
['seq_unchecked'] +
default_copiers if default_copiers else ['pass'],
[
'goto', _post_callback_ptr
if sig.private else function_routine
]
]
])
# With private functions all variable loading occurs in the default
# function sub routine.
if sig.private:
_clampers = [['label', _post_callback_ptr]]
else:
_clampers = clampers
# Function with default parameters.
o = LLLnode.from_list(
[
'seq',
sig_chain,
[
'if',
0, # can only be jumped into
[
'seq', ['label', function_routine]
if not sig.private else ['pass'],
['seq'] + nonreentrant_pre + _clampers +
[parse_body(c, context) for c in code.body] +
nonreentrant_post + stop_func
],
],
],
typ=None,
pos=getpos(code))
else:
# Function without default parameters.
sig_compare, private_label = get_sig_statements(sig, getpos(code))
o = LLLnode.from_list([
'if', sig_compare,
['seq'] + [private_label] + nonreentrant_pre + clampers +
[parse_body(c, context)
for c in code.body] + nonreentrant_post + stop_func
],
typ=None,
pos=getpos(code))
# Check for at leasts one return statement if necessary.
if context.return_type and context.function_return_count == 0:
raise FunctionDeclarationException(
"Missing return statement in function '%s' " % sig.name, code)
o.context = context
o.total_gas = o.gas + calc_mem_gas(
o.context.memory_allocator.get_next_memory_position())
o.func_name = sig.name
return o