contract.rs

// Copyright 2018 Parity Technologies (UK) Ltd.
// This file is part of Substrate.

// Substrate 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.

// Substrate 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 Substrate.  If not, see <http://www.gnu.org/licenses/>.

//! Smart-contract execution functions.

use rstd::prelude::*;
use std::any::Any;
use {AccountDb, Trait};
use sandbox;

struct Ext<T: Trait, DB: AccountDb<T>> {
    account_db: DB,
    account: T::AccountId,
    memory: sandbox::Memory,
}

impl<T: Trait, DB: AccountDb<T>> Ext<T, DB> {
    fn memory(&self) -> &sandbox::Memory {
        &self.memory
    }
    fn account(&self) -> &T::AccountId {
        &self.account
    }
    fn account_db(&self) -> &DB {
        &self.account_db
    }
}

fn ext_stuff<T: Trait + 'static, DB: AccountDb<T> + 'static>(args: &[sandbox::TypedValue]) {
    let location_ptr = args[0].as_i32().unwrap() as u32;
    let mut location = [0; 32];

    ext::with(|e| {
        let e = e.downcast_mut::<Ext<T, DB>>().unwrap();

        e.memory().get(location_ptr, &mut location).unwrap();
        e.account_db()
            .set_storage(e.account(), location.to_vec(), None);
    });
}

environmental!(ext: Box<Any>);

pub(crate) fn execute<T: Trait + 'static, DB: AccountDb<T> + 'static>(
    code: &[u8],
    account: T::AccountId,
    account_db: DB,
) -> bool {
    let memory = sandbox::Memory::new(1, None);

    // TODO: Signatures.
    let mut imports = sandbox::EnvironmentDefinitionBuilder::new();
    imports.add_host_func("env", "ext_stuff", ext_stuff::<T, DB>);
    imports.add_memory("env", "memory", memory.clone());

    let mut instance = sandbox::Instance::new(code, &imports).unwrap();

    let mut ext_any = Box::new(Ext {
        account,
        account_db,
        memory,
    }) as Box<Any>;
    ext::using(&mut ext_any, || {
        instance.invoke(b"call", &[]);
    });

    true
}