ethereum.byzantium.vm.interpreter
Ethereum Virtual Machine (EVM) Interpreter ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
.. contents:: Table of Contents :backlinks: none :local:
Introduction
A straightforward interpreter that executes EVM code.
STACK_DEPTH_LIMIT
58 | STACK_DEPTH_LIMIT = U256(1024) |
---|
MAX_CODE_SIZE
59 | MAX_CODE_SIZE = 0x6000 |
---|
MessageCallOutput
Output of a particular message call
Contains the following:
1. `gas_left`: remaining gas after execution.
2. `refund_counter`: gas to refund after execution.
3. `logs`: list of `Log` generated during execution.
4. `accounts_to_delete`: Contracts which have self-destructed.
5. `touched_accounts`: Accounts that have been touched.
6. `error`: The error from the execution if any.
62 | @dataclass |
---|
class MessageCallOutput:
gas_left
77 | gas_left: Uint |
---|
refund_counter
78 | refund_counter: U256 |
---|
logs
79 | logs: Tuple[Log, ...] |
---|
accounts_to_delete
80 | accounts_to_delete: Set[Address] |
---|
touched_accounts
81 | touched_accounts: Iterable[Address] |
---|
error
82 | error: Optional[Exception] |
---|
process_message_call
If message.current
is empty then it creates a smart contract
else it executes a call from the message.caller
to the message.target
.
Parameters
message : Transaction specific items.
env : External items required for EVM execution.
Returns
output : MessageCallOutput
Output of the message call
def process_message_call(message: Message, env: Environment) -> MessageCallOutput:
88 | """ |
---|---|
89 | If `message.current` is empty then it creates a smart contract |
90 | else it executes a call from the `message.caller` to the `message.target`. |
91 |
|
92 | Parameters |
93 | ---------- |
94 | message : |
95 | Transaction specific items. |
96 |
|
97 | env : |
98 | External items required for EVM execution. |
99 |
|
100 | Returns |
101 | ------- |
102 | output : `MessageCallOutput` |
103 | Output of the message call |
104 | """ |
105 | if message.target == Bytes0(b""): |
106 | is_collision = account_has_code_or_nonce( |
107 | env.state, message.current_target |
108 | ) |
109 | if is_collision: |
110 | return MessageCallOutput( |
111 | Uint(0), U256(0), tuple(), set(), set(), AddressCollision() |
112 | ) |
113 | else: |
114 | evm = process_create_message(message, env) |
115 | else: |
116 | evm = process_message(message, env) |
117 | if account_exists_and_is_empty(env.state, Address(message.target)): |
118 | evm.touched_accounts.add(Address(message.target)) |
119 | |
120 | if evm.error: |
121 | logs: Tuple[Log, ...] = () |
122 | accounts_to_delete = set() |
123 | touched_accounts = set() |
124 | refund_counter = U256(0) |
125 | else: |
126 | logs = evm.logs |
127 | accounts_to_delete = evm.accounts_to_delete |
128 | touched_accounts = evm.touched_accounts |
129 | refund_counter = U256(evm.refund_counter) |
130 | |
131 | tx_end = TransactionEnd(message.gas - evm.gas_left, evm.output, evm.error) |
132 | evm_trace(evm, tx_end) |
133 | |
134 | return MessageCallOutput( |
135 | gas_left=evm.gas_left, |
136 | refund_counter=refund_counter, |
137 | logs=logs, |
138 | accounts_to_delete=accounts_to_delete, |
139 | touched_accounts=touched_accounts, |
140 | error=evm.error, |
141 | ) |
process_create_message
Executes a call to create a smart contract.
Parameters
message : Transaction specific items. env : External items required for EVM execution.
Returns
evm: :py:class:~ethereum.byzantium.vm.Evm
Items containing execution specific objects.
def process_create_message(message: Message, env: Environment) -> Evm:
145 | """ |
---|---|
146 | Executes a call to create a smart contract. |
147 |
|
148 | Parameters |
149 | ---------- |
150 | message : |
151 | Transaction specific items. |
152 | env : |
153 | External items required for EVM execution. |
154 |
|
155 | Returns |
156 | ------- |
157 | evm: :py:class:`~ethereum.byzantium.vm.Evm` |
158 | Items containing execution specific objects. |
159 | """ |
160 | # take snapshot of state before processing the message |
161 | begin_transaction(env.state) |
162 | |
163 | # If the address where the account is being created has storage, it is |
164 | # destroyed. This can only happen in the following highly unlikely |
165 | # circumstances: |
166 | # * The address created by two `CREATE` calls collide. |
167 | # * The first `CREATE` happened before Spurious Dragon and left empty |
168 | # code. |
169 | destroy_storage(env.state, message.current_target) |
170 | |
171 | increment_nonce(env.state, message.current_target) |
172 | evm = process_message(message, env) |
173 | if not evm.error: |
174 | contract_code = evm.output |
175 | contract_code_gas = len(contract_code) * GAS_CODE_DEPOSIT |
176 | try: |
177 | charge_gas(evm, contract_code_gas) |
178 | if len(contract_code) > MAX_CODE_SIZE: |
179 | raise OutOfGasError |
180 | except ExceptionalHalt as error: |
181 | rollback_transaction(env.state) |
182 | evm.gas_left = Uint(0) |
183 | evm.output = b"" |
184 | evm.error = error |
185 | else: |
186 | set_code(env.state, message.current_target, contract_code) |
187 | commit_transaction(env.state) |
188 | else: |
189 | rollback_transaction(env.state) |
190 | return evm |
process_message
Executes a call to create a smart contract.
Parameters
message : Transaction specific items. env : External items required for EVM execution.
Returns
evm: :py:class:~ethereum.byzantium.vm.Evm
Items containing execution specific objects
def process_message(message: Message, env: Environment) -> Evm:
194 | """ |
---|---|
195 | Executes a call to create a smart contract. |
196 |
|
197 | Parameters |
198 | ---------- |
199 | message : |
200 | Transaction specific items. |
201 | env : |
202 | External items required for EVM execution. |
203 |
|
204 | Returns |
205 | ------- |
206 | evm: :py:class:`~ethereum.byzantium.vm.Evm` |
207 | Items containing execution specific objects |
208 | """ |
209 | if message.depth > STACK_DEPTH_LIMIT: |
210 | raise StackDepthLimitError("Stack depth limit reached") |
211 | |
212 | # take snapshot of state before processing the message |
213 | begin_transaction(env.state) |
214 | |
215 | touch_account(env.state, message.current_target) |
216 | |
217 | if message.should_transfer_value and message.value != 0: |
218 | move_ether( |
219 | env.state, message.caller, message.current_target, message.value |
220 | ) |
221 | |
222 | evm = execute_code(message, env) |
223 | if evm.error: |
224 | # revert state to the last saved checkpoint |
225 | # since the message call resulted in an error |
226 | rollback_transaction(env.state) |
227 | else: |
228 | commit_transaction(env.state) |
229 | return evm |
execute_code
Executes bytecode present in the message
.
Parameters
message : Transaction specific items. env : External items required for EVM execution.
Returns
evm: ethereum.vm.EVM
Items containing execution specific objects
def execute_code(message: Message, env: Environment) -> Evm:
233 | """ |
---|---|
234 | Executes bytecode present in the `message`. |
235 |
|
236 | Parameters |
237 | ---------- |
238 | message : |
239 | Transaction specific items. |
240 | env : |
241 | External items required for EVM execution. |
242 |
|
243 | Returns |
244 | ------- |
245 | evm: `ethereum.vm.EVM` |
246 | Items containing execution specific objects |
247 | """ |
248 | code = message.code |
249 | valid_jump_destinations = get_valid_jump_destinations(code) |
250 | |
251 | evm = Evm( |
252 | pc=Uint(0), |
253 | stack=[], |
254 | memory=bytearray(), |
255 | code=code, |
256 | gas_left=message.gas, |
257 | env=env, |
258 | valid_jump_destinations=valid_jump_destinations, |
259 | logs=(), |
260 | refund_counter=U256(0), |
261 | running=True, |
262 | message=message, |
263 | output=b"", |
264 | accounts_to_delete=set(), |
265 | touched_accounts=set(), |
266 | return_data=b"", |
267 | error=None, |
268 | ) |
269 | try: |
270 | if evm.message.code_address in PRE_COMPILED_CONTRACTS: |
271 | evm_trace(evm, PrecompileStart(evm.message.code_address)) |
272 | PRE_COMPILED_CONTRACTS[evm.message.code_address](evm) |
273 | evm_trace(evm, PrecompileEnd()) |
274 | return evm |
275 |
|
276 | while evm.running and evm.pc < len(evm.code): |
277 | try: |
278 | op = Ops(evm.code[evm.pc]) |
279 | except ValueError: |
280 | raise InvalidOpcode(evm.code[evm.pc]) |
281 |
|
282 | evm_trace(evm, OpStart(op)) |
283 | op_implementation[op](evm) |
284 | evm_trace(evm, OpEnd()) |
285 |
|
286 | evm_trace(evm, EvmStop(Ops.STOP)) |
287 |
|
288 | except ExceptionalHalt as error: |
289 | evm_trace(evm, OpException(error)) |
290 | evm.gas_left = Uint(0) |
291 | evm.output = b"" |
292 | evm.error = error |
293 | except Revert as error: |
294 | evm_trace(evm, OpException(error)) |
295 | evm.error = error |
296 | return evm |