openethereum/ethcore/src/evm/wasm/runtime.rs

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// Copyright 2015-2017 Parity Technologies (UK) Ltd.
// This file is part of Parity.
// Parity is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// Parity is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with Parity. If not, see <http://www.gnu.org/licenses/>.
//! Wasm evm program runtime intstance
use std::sync::Arc;
use byteorder::{LittleEndian, ByteOrder};
use evm;
use parity_wasm::interpreter;
use util::{Address, H256, U256};
use super::ptr::{WasmPtr, Error as PtrError};
use super::call_args::CallArgs;
/// Wasm runtime error
#[derive(Debug)]
pub enum Error {
/// Storage error
Storage,
/// Allocator error
Allocator,
/// Invalid gas state during the call
InvalidGasState,
/// Memory access violation
AccessViolation,
/// Interpreter runtime error
Interpreter(interpreter::Error),
}
impl From<interpreter::Error> for Error {
fn from(err: interpreter::Error) -> Self {
Error::Interpreter(err)
}
}
impl From<PtrError> for Error {
fn from(err: PtrError) -> Self {
match err {
PtrError::AccessViolation => Error::AccessViolation,
}
}
}
/// Runtime enviroment data for wasm contract execution
pub struct Runtime<'a> {
gas_counter: u64,
gas_limit: u64,
dynamic_top: u32,
ext: &'a mut evm::Ext,
memory: Arc<interpreter::MemoryInstance>,
}
impl<'a> Runtime<'a> {
/// New runtime for wasm contract with specified params
pub fn with_params<'b>(
ext: &'b mut evm::Ext,
memory: Arc<interpreter::MemoryInstance>,
stack_space: u32,
gas_limit: u64,
) -> Runtime<'b> {
Runtime {
gas_counter: 0,
gas_limit: gas_limit,
dynamic_top: stack_space,
memory: memory,
ext: ext,
}
}
/// Write to the storage from wasm memory
pub fn storage_write(&mut self, context: interpreter::CallerContext)
-> Result<Option<interpreter::RuntimeValue>, interpreter::Error>
{
let mut context = context;
let val = self.pop_h256(&mut context)?;
let key = self.pop_h256(&mut context)?;
trace!(target: "wasm", "storage_write: value {} at @{}", &val, &key);
self.ext.set_storage(key, val)
.map_err(|_| interpreter::Error::Trap("Storage update error".to_owned()))?;
Ok(Some(0i32.into()))
}
/// Read from the storage to wasm memory
pub fn storage_read(&mut self, context: interpreter::CallerContext)
-> Result<Option<interpreter::RuntimeValue>, interpreter::Error>
{
let mut context = context;
let val_ptr = context.value_stack.pop_as::<i32>()?;
let key = self.pop_h256(&mut context)?;
let val = self.ext.storage_at(&key)
.map_err(|_| interpreter::Error::Trap("Storage read error".to_owned()))?;
self.memory.set(val_ptr as u32, &*val)?;
Ok(Some(0.into()))
}
/// Pass suicide to state runtime
pub fn suicide(&mut self, context: interpreter::CallerContext)
-> Result<Option<interpreter::RuntimeValue>, interpreter::Error>
{
let mut context = context;
let refund_address = self.pop_address(&mut context)?;
self.ext.suicide(&refund_address)
.map_err(|_| interpreter::Error::Trap("Suicide error".to_owned()))?;
Ok(None)
}
/// Invoke create in the state runtime
pub fn create(&mut self, context: interpreter::CallerContext)
-> Result<Option<interpreter::RuntimeValue>, interpreter::Error>
{
//
// method signature:
// fn create(endowment: *const u8, code_ptr: *const u8, code_len: u32, result_ptr: *mut u8) -> i32;
//
trace!(target: "wasm", "runtime: create contract");
let mut context = context;
let result_ptr = context.value_stack.pop_as::<i32>()? as u32;
trace!(target: "wasm", " result_ptr: {:?}", result_ptr);
let code_len = context.value_stack.pop_as::<i32>()? as u32;
trace!(target: "wasm", " code_len: {:?}", code_len);
let code_ptr = context.value_stack.pop_as::<i32>()? as u32;
trace!(target: "wasm", " code_ptr: {:?}", code_ptr);
let endowment = self.pop_u256(&mut context)?;
trace!(target: "wasm", " val: {:?}", endowment);
let code = self.memory.get(code_ptr, code_len as usize)?;
let gas_left = self.gas_left()
.map_err(|_| interpreter::Error::Trap("Gas state error".to_owned()))?
.into();
match self.ext.create(&gas_left, &endowment, &code, evm::CreateContractAddress::FromSenderAndCodeHash) {
evm::ContractCreateResult::Created(address, gas_left) => {
self.memory.set(result_ptr, &*address)?;
self.gas_counter = self.gas_limit - gas_left.low_u64();
trace!(target: "wasm", "runtime: create contract success (@{:?})", address);
Ok(Some(0i32.into()))
},
evm::ContractCreateResult::Failed => {
trace!(target: "wasm", "runtime: create contract fail");
Ok(Some((-1i32).into()))
}
}
}
/// Allocate memory using the wasm stack params
pub fn malloc(&mut self, context: interpreter::CallerContext)
-> Result<Option<interpreter::RuntimeValue>, interpreter::Error>
{
let amount = context.value_stack.pop_as::<i32>()? as u32;
let previous_top = self.dynamic_top;
self.dynamic_top = previous_top + amount;
Ok(Some((previous_top as i32).into()))
}
/// Allocate memory in wasm memory instance
pub fn alloc(&mut self, amount: u32) -> Result<u32, Error> {
let previous_top = self.dynamic_top;
self.dynamic_top = previous_top + amount;
Ok(previous_top.into())
}
/// Report gas cost with the params passed in wasm stack
fn gas(&mut self, context: interpreter::CallerContext)
-> Result<Option<interpreter::RuntimeValue>, interpreter::Error>
{
let amount = context.value_stack.pop_as::<i32>()? as u64;
if self.charge_gas(amount) {
Ok(None)
} else {
Err(interpreter::Error::Trap(format!("Gas exceeds limits of {}", self.gas_limit)))
}
}
fn charge_gas(&mut self, amount: u64) -> bool {
let prev = self.gas_counter;
if prev + amount > self.gas_limit {
// exceeds gas
false
} else {
self.gas_counter = prev + amount;
true
}
}
fn h256_at(&self, ptr: WasmPtr) -> Result<H256, interpreter::Error> {
Ok(H256::from_slice(&ptr.slice(32, &*self.memory)
.map_err(|_| interpreter::Error::Trap("Memory access violation".to_owned()))?
))
}
fn pop_h256(&self, context: &mut interpreter::CallerContext) -> Result<H256, interpreter::Error> {
let ptr = WasmPtr::from_i32(context.value_stack.pop_as::<i32>()?)
.map_err(|_| interpreter::Error::Trap("Memory access violation".to_owned()))?;
self.h256_at(ptr)
}
fn pop_u256(&self, context: &mut interpreter::CallerContext) -> Result<U256, interpreter::Error> {
let ptr = WasmPtr::from_i32(context.value_stack.pop_as::<i32>()?)
.map_err(|_| interpreter::Error::Trap("Memory access violation".to_owned()))?;
self.h256_at(ptr).map(Into::into)
}
fn address_at(&self, ptr: WasmPtr) -> Result<Address, interpreter::Error> {
Ok(Address::from_slice(&ptr.slice(20, &*self.memory)
.map_err(|_| interpreter::Error::Trap("Memory access violation".to_owned()))?
))
}
fn pop_address(&self, context: &mut interpreter::CallerContext) -> Result<Address, interpreter::Error> {
let ptr = WasmPtr::from_i32(context.value_stack.pop_as::<i32>()?)
.map_err(|_| interpreter::Error::Trap("Memory access violation".to_owned()))?;
self.address_at(ptr)
}
fn user_trap(&mut self, _context: interpreter::CallerContext)
-> Result<Option<interpreter::RuntimeValue>, interpreter::Error>
{
Err(interpreter::Error::Trap("unknown trap".to_owned()))
}
fn user_noop(&mut self,
_context: interpreter::CallerContext
) -> Result<Option<interpreter::RuntimeValue>, interpreter::Error> {
Ok(None)
}
/// Write call descriptor to wasm memory
pub fn write_descriptor(&mut self, call_args: CallArgs) -> Result<WasmPtr, Error> {
let d_ptr = self.alloc(16)?;
let args_len = call_args.len();
let args_ptr = self.alloc(args_len)?;
// write call descriptor
// call descriptor is [args_ptr, args_len, return_ptr, return_len]
// all are 4 byte length, last 2 are zeroed
let mut d_buf = [0u8; 16];
LittleEndian::write_u32(&mut d_buf[0..4], args_ptr);
LittleEndian::write_u32(&mut d_buf[4..8], args_len);
self.memory.set(d_ptr, &d_buf)?;
// write call args to memory
self.memory.set(args_ptr, &call_args.address)?;
self.memory.set(args_ptr+20, &call_args.sender)?;
self.memory.set(args_ptr+40, &call_args.origin)?;
self.memory.set(args_ptr+60, &call_args.value)?;
self.memory.set(args_ptr+92, &call_args.data)?;
Ok(d_ptr.into())
}
fn debug_log(&mut self, context: interpreter::CallerContext)
-> Result<Option<interpreter::RuntimeValue>, interpreter::Error>
{
let msg_len = context.value_stack.pop_as::<i32>()? as u32;
let msg_ptr = context.value_stack.pop_as::<i32>()? as u32;
let msg = String::from_utf8(self.memory.get(msg_ptr, msg_len as usize)?)
.map_err(|_| interpreter::Error::Trap("Debug log utf-8 decoding error".to_owned()))?;
trace!(target: "wasm", "Contract debug message: {}", msg);
Ok(None)
}
/// Query current gas left for execution
pub fn gas_left(&self) -> Result<u64, Error> {
if self.gas_counter > self.gas_limit { return Err(Error::InvalidGasState); }
Ok(self.gas_limit - self.gas_counter)
}
/// Shared memory reference
pub fn memory(&self) -> &interpreter::MemoryInstance {
&*self.memory
}
fn mem_copy(&self, context: interpreter::CallerContext)
-> Result<Option<interpreter::RuntimeValue>, interpreter::Error>
{
let len = context.value_stack.pop_as::<i32>()? as u32;
let dst = context.value_stack.pop_as::<i32>()? as u32;
let src = context.value_stack.pop_as::<i32>()? as u32;
let mem = self.memory().get(src, len as usize)?;
self.memory().set(dst, &mem)?;
Ok(Some(0i32.into()))
}
}
impl<'a> interpreter::UserFunctionExecutor for Runtime<'a> {
fn execute(&mut self, name: &str, context: interpreter::CallerContext)
-> Result<Option<interpreter::RuntimeValue>, interpreter::Error>
{
match name {
"_malloc" => {
self.malloc(context)
},
"_free" => {
// Since it is arena allocator, free does nothing
// todo: update if changed
self.user_noop(context)
},
"_storage_read" => {
self.storage_read(context)
},
"_storage_write" => {
self.storage_write(context)
},
"_suicide" => {
self.suicide(context)
},
"_create" => {
self.create(context)
},
"_debug" => {
self.debug_log(context)
},
"gas" => {
self.gas(context)
},
"_emscripten_memcpy_big" => {
self.mem_copy(context)
},
_ => {
trace!("Unknown env func: '{}'", name);
self.user_trap(context)
}
}
}
}