openethereum/ethcore/wasm/src/parser.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/>.
//! ActionParams parser for wasm
use vm;
use wasm_utils::{self, rules};
use parity_wasm::elements::{self, Deserialize};
use parity_wasm::peek_size;
fn gas_rules(wasm_costs: &vm::WasmCosts) -> rules::Set {
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rules::Set::new({
let mut vals = ::std::collections::HashMap::with_capacity(4);
vals.insert(rules::InstructionType::Load, wasm_costs.mem as u32);
vals.insert(rules::InstructionType::Store, wasm_costs.mem as u32);
vals.insert(rules::InstructionType::Div, wasm_costs.div as u32);
vals.insert(rules::InstructionType::Mul, wasm_costs.mul as u32);
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vals
}).with_grow_cost(wasm_costs.grow_mem)
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}
/// Splits payload to code and data according to params.params_type, also
/// loads the module instance from payload and injects gas counter according
/// to schedule.
pub fn payload<'a>(params: &'a vm::ActionParams, wasm_costs: &vm::WasmCosts)
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-> Result<(elements::Module, &'a [u8]), vm::Error>
{
let code = match params.code {
Some(ref code) => &code[..],
None => { return Err(vm::Error::Wasm("Invalid wasm call".to_owned())); }
};
let (mut cursor, data_position) = match params.params_type {
vm::ParamsType::Embedded => {
let module_size = peek_size(&*code);
(
::std::io::Cursor::new(&code[..module_size]),
module_size
)
},
vm::ParamsType::Separate => {
(::std::io::Cursor::new(&code[..]), 0)
},
};
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let deserialized_module = elements::Module::deserialize(
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&mut cursor
).map_err(|err| {
vm::Error::Wasm(format!("Error deserializing contract code ({:?})", err))
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})?;
if deserialized_module.memory_section().map_or(false, |ms| ms.entries().len() > 0) {
// According to WebAssembly spec, internal memory is hidden from embedder and should not
// be interacted with. So we disable this kind of modules at decoding level.
return Err(vm::Error::Wasm(format!("Malformed wasm module: internal memory")));
}
let contract_module = wasm_utils::inject_gas_counter(
deserialized_module,
&gas_rules(wasm_costs),
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);
let data = match params.params_type {
vm::ParamsType::Embedded => {
if data_position < code.len() { &code[data_position..] } else { &[] }
},
vm::ParamsType::Separate => {
match params.data {
Some(ref s) => &s[..],
None => &[]
}
}
};
Ok((contract_module, data))
}