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
60 | STACK_DEPTH_LIMIT = Uint(1024) |
---|
MAX_CODE_SIZE
61 | 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.
64 | @dataclass |
---|
class MessageCallOutput:
gas_left
79 | gas_left: Uint |
---|
refund_counter
80 | refund_counter: U256 |
---|
logs
81 | logs: Tuple[Log, ...] |
---|
accounts_to_delete
82 | accounts_to_delete: Set[Address] |
---|
touched_accounts
83 | touched_accounts: Iterable[Address] |
---|
error
84 | error: Optional[Exception] |
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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:
90 | """ |
---|---|
91 | If `message.current` is empty then it creates a smart contract |
92 | else it executes a call from the `message.caller` to the `message.target`. |
93 |
|
94 | Parameters |
95 | ---------- |
96 | message : |
97 | Transaction specific items. |
98 |
|
99 | env : |
100 | External items required for EVM execution. |
101 |
|
102 | Returns |
103 | ------- |
104 | output : `MessageCallOutput` |
105 | Output of the message call |
106 | """ |
107 | if message.target == Bytes0(b""): |
108 | is_collision = account_has_code_or_nonce( |
109 | env.state, message.current_target |
110 | ) |
111 | if is_collision: |
112 | return MessageCallOutput( |
113 | Uint(0), U256(0), tuple(), set(), set(), AddressCollision() |
114 | ) |
115 | else: |
116 | evm = process_create_message(message, env) |
117 | else: |
118 | evm = process_message(message, env) |
119 | if account_exists_and_is_empty(env.state, Address(message.target)): |
120 | evm.touched_accounts.add(Address(message.target)) |
121 | |
122 | if evm.error: |
123 | logs: Tuple[Log, ...] = () |
124 | accounts_to_delete = set() |
125 | touched_accounts = set() |
126 | refund_counter = U256(0) |
127 | else: |
128 | logs = evm.logs |
129 | accounts_to_delete = evm.accounts_to_delete |
130 | touched_accounts = evm.touched_accounts |
131 | refund_counter = U256(evm.refund_counter) |
132 | |
133 | tx_end = TransactionEnd( |
134 | int(message.gas) - int(evm.gas_left), evm.output, evm.error |
135 | ) |
136 | evm_trace(evm, tx_end) |
137 | |
138 | return MessageCallOutput( |
139 | gas_left=evm.gas_left, |
140 | refund_counter=refund_counter, |
141 | logs=logs, |
142 | accounts_to_delete=accounts_to_delete, |
143 | touched_accounts=touched_accounts, |
144 | error=evm.error, |
145 | ) |
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:
149 | """ |
---|---|
150 | Executes a call to create a smart contract. |
151 |
|
152 | Parameters |
153 | ---------- |
154 | message : |
155 | Transaction specific items. |
156 | env : |
157 | External items required for EVM execution. |
158 |
|
159 | Returns |
160 | ------- |
161 | evm: :py:class:`~ethereum.byzantium.vm.Evm` |
162 | Items containing execution specific objects. |
163 | """ |
164 | # take snapshot of state before processing the message |
165 | begin_transaction(env.state) |
166 | |
167 | # If the address where the account is being created has storage, it is |
168 | # destroyed. This can only happen in the following highly unlikely |
169 | # circumstances: |
170 | # * The address created by two `CREATE` calls collide. |
171 | # * The first `CREATE` happened before Spurious Dragon and left empty |
172 | # code. |
173 | destroy_storage(env.state, message.current_target) |
174 | |
175 | increment_nonce(env.state, message.current_target) |
176 | evm = process_message(message, env) |
177 | if not evm.error: |
178 | contract_code = evm.output |
179 | contract_code_gas = Uint(len(contract_code)) * GAS_CODE_DEPOSIT |
180 | try: |
181 | charge_gas(evm, contract_code_gas) |
182 | if len(contract_code) > MAX_CODE_SIZE: |
183 | raise OutOfGasError |
184 | except ExceptionalHalt as error: |
185 | rollback_transaction(env.state) |
186 | evm.gas_left = Uint(0) |
187 | evm.output = b"" |
188 | evm.error = error |
189 | else: |
190 | set_code(env.state, message.current_target, contract_code) |
191 | commit_transaction(env.state) |
192 | else: |
193 | rollback_transaction(env.state) |
194 | 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:
198 | """ |
---|---|
199 | Executes a call to create a smart contract. |
200 |
|
201 | Parameters |
202 | ---------- |
203 | message : |
204 | Transaction specific items. |
205 | env : |
206 | External items required for EVM execution. |
207 |
|
208 | Returns |
209 | ------- |
210 | evm: :py:class:`~ethereum.byzantium.vm.Evm` |
211 | Items containing execution specific objects |
212 | """ |
213 | if message.depth > STACK_DEPTH_LIMIT: |
214 | raise StackDepthLimitError("Stack depth limit reached") |
215 | |
216 | # take snapshot of state before processing the message |
217 | begin_transaction(env.state) |
218 | |
219 | touch_account(env.state, message.current_target) |
220 | |
221 | if message.should_transfer_value and message.value != 0: |
222 | move_ether( |
223 | env.state, message.caller, message.current_target, message.value |
224 | ) |
225 | |
226 | evm = execute_code(message, env) |
227 | if evm.error: |
228 | # revert state to the last saved checkpoint |
229 | # since the message call resulted in an error |
230 | rollback_transaction(env.state) |
231 | else: |
232 | commit_transaction(env.state) |
233 | 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:
237 | """ |
---|---|
238 | Executes bytecode present in the `message`. |
239 |
|
240 | Parameters |
241 | ---------- |
242 | message : |
243 | Transaction specific items. |
244 | env : |
245 | External items required for EVM execution. |
246 |
|
247 | Returns |
248 | ------- |
249 | evm: `ethereum.vm.EVM` |
250 | Items containing execution specific objects |
251 | """ |
252 | code = message.code |
253 | valid_jump_destinations = get_valid_jump_destinations(code) |
254 | |
255 | evm = Evm( |
256 | pc=Uint(0), |
257 | stack=[], |
258 | memory=bytearray(), |
259 | code=code, |
260 | gas_left=message.gas, |
261 | env=env, |
262 | valid_jump_destinations=valid_jump_destinations, |
263 | logs=(), |
264 | refund_counter=0, |
265 | running=True, |
266 | message=message, |
267 | output=b"", |
268 | accounts_to_delete=set(), |
269 | touched_accounts=set(), |
270 | return_data=b"", |
271 | error=None, |
272 | ) |
273 | try: |
274 | if evm.message.code_address in PRE_COMPILED_CONTRACTS: |
275 | evm_trace(evm, PrecompileStart(evm.message.code_address)) |
276 | PRE_COMPILED_CONTRACTS[evm.message.code_address](evm) |
277 | evm_trace(evm, PrecompileEnd()) |
278 | return evm |
279 |
|
280 | while evm.running and evm.pc < ulen(evm.code): |
281 | try: |
282 | op = Ops(evm.code[evm.pc]) |
283 | except ValueError: |
284 | raise InvalidOpcode(evm.code[evm.pc]) |
285 |
|
286 | evm_trace(evm, OpStart(op)) |
287 | op_implementation[op](evm) |
288 | evm_trace(evm, OpEnd()) |
289 |
|
290 | evm_trace(evm, EvmStop(Ops.STOP)) |
291 |
|
292 | except ExceptionalHalt as error: |
293 | evm_trace(evm, OpException(error)) |
294 | evm.gas_left = Uint(0) |
295 | evm.output = b"" |
296 | evm.error = error |
297 | except Revert as error: |
298 | evm_trace(evm, OpException(error)) |
299 | evm.error = error |
300 | return evm |