def memory_gas_cost(size_in_bytes: int) -> int:
size_in_words = ceil32(size_in_bytes) // 32
linear_cost = size_in_words * GAS_MEMORY
quadratic_cost = size_in_words**2 // GAS_MEMORY_QUADRATIC_DENOMINATOR
total_cost = linear_cost + quadratic_cost
return total_cost
def returndatacopy(computation: ComputationAPI) -> None:
(
mem_start_position,
returndata_start_position,
size,
) = computation.stack_pop_ints(3)
if returndata_start_position + size > len(computation.return_data):
raise OutOfBoundsRead(
"Return data length is not sufficient to satisfy request. Asked "
f"for data from index {returndata_start_position} "
f"to {returndata_start_position + size}. "
f"Return data is {len(computation.return_data)} bytes in length.")
computation.extend_memory(mem_start_position, size)
word_count = ceil32(size) // 32
copy_gas_cost = word_count * constants.GAS_COPY
computation.consume_gas(copy_gas_cost, reason="RETURNDATACOPY fee")
value = computation.return_data[
returndata_start_position:returndata_start_position + size]
computation.memory_write(mem_start_position, size, value)
def identity(computation: ComputationAPI) -> ComputationAPI:
word_count = ceil32(len(computation.msg.data)) // 32
gas_fee = constants.GAS_IDENTITY + word_count * constants.GAS_IDENTITYWORD
computation.consume_gas(gas_fee, reason="Identity Precompile")
computation.output = computation.msg.data_as_bytes
return computation
def sha256(computation: ComputationAPI) -> ComputationAPI:
word_count = ceil32(len(computation.msg.data)) // 32
gas_fee = constants.GAS_SHA256 + word_count * constants.GAS_SHA256WORD
computation.consume_gas(gas_fee, reason="SHA256 Precompile")
input_bytes = computation.msg.data
hash = hashlib.sha256(input_bytes).digest()
computation.output = hash
return computation
def ripemd160(computation: ComputationAPI) -> ComputationAPI:
word_count = ceil32(len(computation.msg.data)) // 32
gas_fee = constants.GAS_RIPEMD160 + word_count * constants.GAS_RIPEMD160WORD
computation.consume_gas(gas_fee, reason="RIPEMD160 Precompile")
# TODO: this only works if openssl is installed.
hash = hashlib.new('ripemd160', computation.msg.data).digest()
padded_hash = pad32(hash)
computation.output = padded_hash
return computation
def extend_memory(self, start_position: int, size: int) -> None:
validate_uint256(start_position, title="Memory start position")
validate_uint256(size, title="Memory size")
before_size = ceil32(len(self._memory))
after_size = ceil32(start_position + size)
before_cost = memory_gas_cost(before_size)
after_cost = memory_gas_cost(after_size)
if self.logger.show_debug2:
self.logger.debug2(
"MEMORY: size (%s -> %s) | cost (%s -> %s)",
before_size,
after_size,
before_cost,
after_cost,
)
self._memory.extend(start_position, size)
def sha3(computation: ComputationAPI) -> None:
start_position, size = computation.stack_pop_ints(2)
computation.extend_memory(start_position, size)
sha3_bytes = computation.memory_read_bytes(start_position, size)
word_count = ceil32(len(sha3_bytes)) // 32
gas_cost = constants.GAS_SHA3WORD * word_count
computation.consume_gas(gas_cost, reason="SHA3: word gas cost")
result = keccak(sha3_bytes)
computation.stack_push_bytes(result)
def calldatacopy(computation: ComputationAPI) -> None:
(
mem_start_position,
calldata_start_position,
size,
) = computation.stack_pop_ints(3)
computation.extend_memory(mem_start_position, size)
word_count = ceil32(size) // 32
copy_gas_cost = word_count * constants.GAS_COPY
computation.consume_gas(copy_gas_cost, reason="CALLDATACOPY fee")
value = computation.msg.data_as_bytes[
calldata_start_position:calldata_start_position + size]
padded_value = value.ljust(size, b'\x00')
computation.memory_write(mem_start_position, size, padded_value)
def extend(self, start_position: int, size: int) -> None:
if size == 0:
return
new_size = ceil32(start_position + size)
if new_size <= len(self):
return
size_to_extend = new_size - len(self)
try:
self._bytes.extend(itertools.repeat(0, size_to_extend))
except BufferError:
# we can't extend the buffer (which might involve relocating it) if a
# memoryview (which stores a pointer into the buffer) has been created by
# read() and not released. Callers of read() will never try to write to the
# buffer so we're not missing anything by making a new buffer and forgetting
# about the old one. We're keeping too much memory around but this is still a
# net savings over having read() return a new bytes() object every time.
self._bytes = self._bytes + bytearray(size_to_extend)
def codecopy(computation: ComputationAPI) -> None:
(
mem_start_position,
code_start_position,
size,
) = computation.stack_pop_ints(3)
computation.extend_memory(mem_start_position, size)
word_count = ceil32(size) // 32
copy_gas_cost = constants.GAS_COPY * word_count
computation.consume_gas(
copy_gas_cost,
reason="CODECOPY: word gas cost",
)
with computation.code.seek(code_start_position):
code_bytes = computation.code.read(size)
padded_code_bytes = code_bytes.ljust(size, b'\x00')
computation.memory_write(mem_start_position, size, padded_code_bytes)
def extcodecopy(computation: ComputationAPI) -> None:
account = force_bytes_to_address(computation.stack_pop1_bytes())
(
mem_start_position,
code_start_position,
size,
) = computation.stack_pop_ints(3)
computation.extend_memory(mem_start_position, size)
word_count = ceil32(size) // 32
copy_gas_cost = constants.GAS_COPY * word_count
computation.consume_gas(
copy_gas_cost,
reason='EXTCODECOPY: word gas cost',
)
code = computation.state.get_code(account)
code_bytes = code[code_start_position:code_start_position + size]
padded_code_bytes = code_bytes.ljust(size, b'\x00')
computation.memory_write(mem_start_position, size, padded_code_bytes)
def get_gas_cost(self, data: CreateOpcodeStackData) -> int:
return constants.GAS_CREATE + constants.GAS_SHA3WORD * ceil32(data.memory_length) // 32