128 lines
4.6 KiB
Nim
128 lines
4.6 KiB
Nim
# Nimbus - Dynamic loader for EVM modules as shared libraries / DLLs
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#
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# Copyright (c) 2019-2021 Status Research & Development GmbH
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# Licensed under either of
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# * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
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# * MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
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# at your option. This file may not be copied, modified, or distributed except according to those terms.
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{.push raises: [].}
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import
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std/[dynlib, strformat, strutils, os],
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chronicles,
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evmc/evmc, ../config
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# The built-in Nimbus EVM, via imported C function.
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proc evmc_create_nimbus_evm(): ptr evmc_vm {.cdecl, importc.}
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# Import this module to link in the definition of `evmc_create_nimbus_evm`.
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# Nim thinks the module is unused because the function is only called via
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# `.exportc` -> `.importc`.
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{.warning[UnusedImport]: off.}:
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import ./evmc_vm_glue
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var evmcLibraryPath {.threadvar.}: string
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## Library path set by `--evm` command line option.
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## Like the loaded EVMs themselves, this is thread-local for Nim simplicity.
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proc evmcSetLibraryPath*(path: string) =
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evmcLibraryPath = path
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proc evmcLoadVMGetCreateFn(): (evmc_create_vm_name_fn, string) =
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var path = evmcLibraryPath
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if path.len == 0:
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path = getEnv("NIMBUS_EVM")
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# Use built-in EVM if no other is specified.
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if path.len == 0:
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return (evmc_create_nimbus_evm, "built-in")
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# The steps below match the EVMC Loader documentation, copied here:
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#
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# - The filename is used to guess the EVM name and the name of the create
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# function. The create function name is constructed by the following
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# rules. Consider example path: "/ethereum/libexample-interpreter.so.1.0".
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# - The filename is taken from the path: "libexample-interpreter.so.1.0".
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# - The "lib" prefix and all file extensions are stripped from the name:
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# "example-interpreter".
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# - All "-" are replaced with "_" to construct base name:
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# "example_interpreter"
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# - The function name "evmc_create_" + base name is searched in the library:
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# "evmc_create_example_interpreter",
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# - If the function is not found, the function name "evmc_create" is searched
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# in the library.
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# Load the library.
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let lib = loadLib(path, false)
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if lib.isNil:
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warn "Error loading EVM library", path
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return (nil, "")
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# Find filename in the path.
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var symbolName = os.extractFilename(path)
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# Skip "lib" prefix if present. Note, `removePrefix` only removes at the
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# start despite its documentation.
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symbolName.removePrefix("lib")
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# Trim all file extesnsions. (`os.splitFile` only removes the last.)
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symbolName = symbolName.split('.', 1)[0]
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# Replace all "-" with "_".
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symbolName = symbolName.replace('-', '_')
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# Search for the built function name.
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symbolName = "evmc_create_" & symbolName
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var sym = symAddr(lib, symbolName)
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if sym.isNil:
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const fallback = "evmc_create"
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sym = symAddr(lib, fallback)
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if sym.isNil:
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warn "EVMC create function not found in library", path
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warn "Tried this library symbol", symbol=symbolName
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warn "Tried this library symbol", symbol=fallback
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return (nil, "")
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return (cast[evmc_create_vm_name_fn](sym), path)
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proc evmcLoadVMShowDetail(): ptr evmc_vm {.raises: [CatchableError].} =
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let (vmCreate, vmDescription) = evmcLoadVMGetCreateFn()
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if vmCreate.isNil:
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return nil
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var vm: ptr evmc_vm
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try:
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{.gcsafe.}:
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vm = vmCreate()
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except CatchableError as e:
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raise e
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except Exception as e:
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{.warning: "Kludge(BareExcept): `evmc_create_nimbus_evm()` in vendor package needs to be double checked and updated".}
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raiseAssert "Ooops evmcLoadVMShowDetail(): name=" &
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$e.name & " msg=" & e.msg
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if vm.isNil:
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warn "The loaded EVM did not create a VM when requested",
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`from`=vmDescription
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return nil
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if vm.abi_version != EVMC_ABI_VERSION:
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warn "The loaded EVM is for an incompatible EVMC ABI",
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requireABI=EVMC_ABI_VERSION, loadedABI=vm.abi_version,
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`from`=vmDescription
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warn "The loaded EVM will not be used", `from`=vmDescription
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return nil
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let name = if vm.name.isNil: "<nil>" else: $vm.name
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let version = if vm.version.isNil: "<nil>" else: $vm.version
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info "Using EVM", name=name, version=version, `from`=vmDescription
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return vm
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proc evmcLoadVMCached*(): ptr evmc_vm {.raises: [CatchableError].} =
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# TODO: Make this open the VM library once per process. Currently it does
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# so once per thread, but at least this is thread-safe.
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var vm {.threadvar.}: ptr evmc_vm
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var triedLoading {.threadvar.}: bool
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if not triedLoading:
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triedLoading = true
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vm = evmcLoadVMShowDetail()
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return vm
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