nimbus-eth1/nimbus/transaction/evmc_host_glue.nim

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# Nimbus - Binary compatibility on the host 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].}
when not declaredInScope(included_from_host_services):
{.error: "Do not import this file directly, import host_services instead".}
import evmc/evmc
template toHost(p: evmc_host_context): TransactionHost =
cast[TransactionHost](p)
proc accountExists(p: evmc_host_context, address: var evmc_address): c99bool {.cdecl.} =
toHost(p).accountExists(address.fromEvmc)
proc getStorage(p: evmc_host_context, address: var evmc_address,
key: var evmc_bytes32): evmc_bytes32 {.cdecl.} =
toHost(p).getStorage(address.fromEvmc, key.fromEvmc).toEvmc
proc setStorage(p: evmc_host_context, address: var evmc_address,
key, value: var evmc_bytes32): evmc_storage_status {.cdecl.} =
toHost(p).setStorage(address.fromEvmc, key.fromEvmc, value.fromEvmc)
proc getBalance(p: evmc_host_context,
address: var evmc_address): evmc_uint256be {.cdecl.} =
toHost(p).getBalance(address.fromEvmc).toEvmc
proc getCodeSize(p: evmc_host_context,
address: var evmc_address): csize_t {.cdecl.} =
toHost(p).getCodeSize(address.fromEvmc)
proc getCodeHash(p: evmc_host_context,
address: var evmc_address): evmc_bytes32 {.cdecl.} =
toHost(p).getCodeHash(address.fromEvmc).toEvmc
proc copyCode(p: evmc_host_context, address: var evmc_address, code_offset: csize_t,
buffer_data: ptr byte, buffer_size: csize_t): csize_t {.cdecl.} =
toHost(p).copyCode(address.fromEvmc, code_offset, buffer_data, buffer_size)
proc selfDestruct(p: evmc_host_context, address,
beneficiary: var evmc_address) {.cdecl.} =
toHost(p).selfDestruct(address.fromEvmc, beneficiary.fromEvmc)
proc call(p: evmc_host_context, msg: var evmc_message): evmc_result {.cdecl.} =
toHost(p).call(msg)
proc getTxContext(p: evmc_host_context): evmc_tx_context {.cdecl.} =
toHost(p).getTxContext()
proc getBlockHash(p: evmc_host_context, number: int64): evmc_bytes32 {.cdecl.} =
# TODO: `HostBlockNumber` is 256-bit unsigned. It should be changed to match
# EVMC which is more sensible.
toHost(p).getBlockHash(number.uint64.u256).toEvmc
proc emitLog(p: evmc_host_context, address: var evmc_address,
data: ptr byte, data_size: csize_t,
topics: ptr evmc_bytes32, topics_count: csize_t) {.cdecl.} =
toHost(p).emitLog(address.fromEvmc, data, data_size,
cast[ptr HostTopic](topics), topics_count)
proc accessAccount(p: evmc_host_context,
address: var evmc_address): evmc_access_status {.cdecl.} =
toHost(p).accessAccount(address.fromEvmc)
proc accessStorage(p: evmc_host_context, address: var evmc_address,
key: var evmc_bytes32): evmc_access_status {.cdecl.} =
toHost(p).accessStorage(address.fromEvmc, key.fromEvmc)
let hostInterface = evmc_host_interface(
account_exists: accountExists,
get_storage: getStorage,
set_storage: setStorage,
get_balance: getBalance,
get_code_size: getCodeSize,
get_code_hash: getCodeHash,
copy_code: copyCode,
selfdestruct: selfDestruct,
call: call,
get_tx_context: getTxContext,
get_block_hash: getBlockHash,
emit_log: emitLog,
access_account: accessAccount,
access_storage: accessStorage,
)
# The built-in Nimbus EVM, via imported C function.
proc evmc_create_nimbus_evm(): ptr evmc_vm {.cdecl, importc.}
# Pull in the definition of the above function because we're not building it as
# a separate library yet.
import ./evmc_vm_glue
proc evmcExecComputation*(host: TransactionHost): EvmcResult {.inline.} =
host.showCallEntry(host.msg)
let vm = evmc_create_nimbus_evm()
if vm.isNil:
echo "Warning: No EVM"
# Nim defaults are fine for all other fields in the result object.
result = EvmcResult(status_code: EVMC_INTERNAL_ERROR)
host.showCallReturn(result)
return
let hostContext = cast[evmc_host_context](host)
host.hostInterface = hostInterface.unsafeAddr
# Without `{.gcsafe.}:` here, the call via `vm.execute` results in a Nim
# compile-time error in a far away function. Starting here, a cascade of
# warnings takes place: "Warning: '...' is not GC-safe as it performs an
# indirect call here [GCUnsafe2]", then a list of "Warning: '...' is not
# GC-safe as it calls '...'" at each function up the call stack, to a high
# level function `persistBlocks` where it terminates compilation as an error
# instead of a warning.
#
# It is tempting to annotate all EVMC API functions with `{.cdecl, gcsafe.}`,
# overriding the function signatures from the Nim EVMC module. Perhaps we
# will do that, though it's conceptually dubious, as the two sides of the
# EVMC ABI live in different GC worlds (when loaded as a shared library with
# its own Nim runtime), very similar to calling between threads.
#
# TODO: But wait: Why does the Nim EVMC test program compile fine without
# any `gcsafe`, even with `--threads:on`?
{.gcsafe.}:
result = vm.execute(vm, hostInterface.unsafeAddr, hostContext,
evmc_revision(host.vmState.fork), host.msg,
if host.code.len > 0: host.code[0].unsafeAddr else: nil,
host.code.len.csize_t)
host.showCallReturn(result)