nimbus-eth1/nimbus/transaction/evmc_vm_glue.nim

110 lines
4.7 KiB
Nim

# Nimbus - Binary compatibility on the VM side of the EVMC API interface
#
# Copyright (c) 2019-2021 Status Research & Development GmbH
# Licensed under either of
# * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
# * MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
# at your option. This file may not be copied, modified, or distributed except according to those terms.
#{.push raises: [Defect].}
import
./host_types, evmc/evmc, stew/ranges/ptr_arith,
".."/[vm_types, vm_computation, vm_state_transactions]
proc evmcReleaseResult(result: var evmc_result) {.cdecl.} =
dealloc(result.output_data)
proc evmcExecute(vm: ptr evmc_vm, hostInterface: ptr evmc_host_interface,
hostContext: evmc_host_context, rev: evmc_revision,
msg: var evmc_message, code: ptr byte,
code_size: csize_t): evmc_result {.cdecl.} =
# TODO: Obviously we are cheating here at the moment, knowing the caller type.
# TODO: This lets the host read extra results needed for tests, but it
# means the Nimbus EVM cannot be used by a non-Nimbus host, yet.
let host = cast[TransactionHost](hostContext)
var c = host.computation
# Allocate `Computation` on demand, and leave it in `host` for that to
# extract additional results.
#if c.isNil:
# let cMsg = hostToComputationMessage(host.msg)
# # TODO: Can we avoid `seq[byte]` so we don't have to copy the code?
# let codeSeq = if code_size <= 0: @[]
# else: @(makeOpenArray(code, code_size.int))
# c = newComputation(host.vmState, cMsg, codeSeq)
# c.host.init(cast[ptr nimbus_host_interface](hostInterface), hostContext)
# host.computation = c
c.host.init(cast[ptr nimbus_host_interface](hostInterface), hostContext)
try:
execComputation(c)
except Exception as e:
c.setError("Caught error " & e.repr, true);
# When output size is zero, output data pointer may be null.
var output_data: ptr byte
var output_size: int
if c.output.len > 0:
# TODO: Don't use a copy, share the underlying data and use `GC_ref`.
# Return a copy, because reference counting is complicated across the
# shared library boundary. We could use a refcount but we don't have a
# `ref seq[byte]` to start with, so need to check `GC_ref` on a non-ref
# `seq` does what we want first.
output_size = c.output.len
# The `alloc` here matches `dealloc` in `evmcReleaseResult`.
output_data = cast[ptr byte](alloc(output_size))
copyMem(output_data, c.output[0].addr, output_size)
return evmc_result(
# Standard EVMC result, if a bit generic.
status_code: if c.isSuccess: EVMC_SUCCESS
elif not c.error.burnsGas: EVMC_REVERT
else: EVMC_FAILURE,
# Gas left is required to be zero when not `EVMC_SUCCESS` or `EVMC_REVERT`.
gas_left: if result.status_code notin {EVMC_SUCCESS, EVMC_REVERT}: 0'i64
else: c.gasMeter.gasRemaining.int64,
gas_refund: if result.status_code == EVMC_SUCCESS: c.gasMeter.gasRefunded.int64
else: 0'i64,
output_data: output_data,
output_size: output_size.csize_t,
release: if output_data.isNil: nil
else: evmcReleaseResult
# Nim defaults are fine for `create_address` and `padding`, zero bytes.
)
const evmcName = "Nimbus EVM (vm2)"
const evmcVersion = "0.0.1"
proc evmcGetCapabilities(vm: ptr evmc_vm): evmc_capabilities {.cdecl.} =
{EVMC_CAPABILITY_EVM1, EVMC_CAPABILITY_PRECOMPILES}
proc evmcSetOption(vm: ptr evmc_vm, name, value: cstring): evmc_set_option_result {.cdecl.} =
return EVMC_SET_OPTION_INVALID_NAME
proc evmcDestroy(vm: ptr evmc_vm) {.cdecl.} =
GC_unref(cast[ref evmc_vm](vm))
proc evmc_create_nimbus_evm(): ptr evmc_vm {.cdecl, exportc.} =
## Entry point to the Nimbus EVM, using an EVMC compatible interface.
## This is an exported C function. EVMC specifies the function must
## have this name format when exported from a shared library.
let vm = (ref evmc_vm)(
abi_version: EVMC_ABI_VERSION,
name: evmcName,
version: evmcVersion,
destroy: evmcDestroy,
execute: evmcExecute,
get_capabilities: evmcGetCapabilities,
set_option: evmcSetOption
)
# Keep an extra reference on this, until `evmcDestroy` is called.
GC_ref(vm)
return cast[ptr evmc_vm](vm)
# This code assumes fields, methods and types of ABI version 10, and must be
# checked for compatibility if the `import evmc/evmc` major version is updated.
when EVMC_ABI_VERSION != 10:
{.error: ("This code assumes EVMC_ABI_VERSION 10;" &
" update the code to use EVMC_ABI_VERSION " & $EVMC_ABI_VERSION).}