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// Copyright 2018-2019 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/>.
//! Environment definition of the wasm smart-contract runtime.
use crate::{Schedule, Trait, CodeHash, ComputeDispatchFee, BalanceOf};
use crate::exec::{Ext, VmExecResult, OutputBuf, EmptyOutputBuf, CallReceipt, InstantiateReceipt};
use crate::gas::{GasMeter, Token, GasMeterResult, approx_gas_for_balance};
use sandbox;
use system;
use parity_codec::{Decode, Encode};
use runtime_primitives::traits::{As, CheckedMul, Bounded};
/// Enumerates all possible *special* trap conditions.
///
/// In this runtime traps used not only for signaling about errors but also
/// to just terminate quickly in some cases.
enum SpecialTrap {
/// Signals that trap was generated in response to call `ext_return` host function.
pub(crate) struct Runtime<'a, 'data, E: Ext + 'a> {
ext: &'a mut E,
input_data: &'data [u8],
// A VM can return a result only once and only by value. So
// we wrap output buffer to make it possible to take the buffer out.
empty_output_buf: Option<EmptyOutputBuf>,
schedule: &'a Schedule<<E::T as Trait>::Gas>,
memory: sandbox::Memory,
gas_meter: &'a mut GasMeter<E::T>,
special_trap: Option<SpecialTrap>,
}
impl<'a, 'data, E: Ext + 'a> Runtime<'a, 'data, E> {
pub(crate) fn new(
ext: &'a mut E,
input_data: &'data [u8],
schedule: &'a Schedule<<E::T as Trait>::Gas>,
memory: sandbox::Memory,
gas_meter: &'a mut GasMeter<E::T>,
) -> Self {
Runtime {
ext,
input_data,
empty_output_buf: Some(empty_output_buf),
memory,
gas_meter,
special_trap: None,
}
}
fn memory(&self) -> &sandbox::Memory {
&self.memory
}
}
pub(crate) fn to_execution_result<E: Ext>(
runtime: Runtime<E>,
sandbox_err: Option<sandbox::Error>,
// Check the exact type of the error. It could be plain trap or
// special runtime trap the we must recognize.
match (sandbox_err, runtime.special_trap) {
// No traps were generated. Proceed normally.
// Special case. The trap was the result of the execution `return` host function.
(Some(sandbox::Error::Execution), Some(SpecialTrap::Return(buf))) => VmExecResult::Returned(buf),
// Any other kind of a trap should result in a failure.
(Some(_), _) => VmExecResult::Trap("during execution"),
// Any other case (such as special trap flag without actual trap) signifies
// a logic error.
_ => unreachable!(),
}
}
#[cfg_attr(test, derive(Debug, PartialEq, Eq))]
#[derive(Copy, Clone)]
/// Explicit call to the `gas` function. Charge the gas meter
/// with the value provided.
Explicit(u32),
/// The given number of bytes is read from the sandbox memory.
ReadMemory(u32),
/// The given number of bytes is written to the sandbox memory.
WriteMemory(u32),
/// The given number of bytes is read from the sandbox memory and
/// is returned as the return data buffer of the call.
ReturnData(u32),
/// Dispatch fee calculated by `T::ComputeDispatchFee`.
ComputedDispatchFee(Gas),
impl<T: Trait> Token<T> for RuntimeToken<T::Gas> {
type Metadata = Schedule<T::Gas>;
fn calculate_amount(&self, metadata: &Schedule<T::Gas>) -> T::Gas {
use self::RuntimeToken::*;
let value = match *self {
Explicit(amount) => Some(<T::Gas as As<u32>>::sa(amount)),
ReadMemory(byte_count) => metadata
.sandbox_data_read_cost
.checked_mul(&<T::Gas as As<u32>>::sa(byte_count)),
WriteMemory(byte_count) => metadata
.sandbox_data_write_cost
.checked_mul(&<T::Gas as As<u32>>::sa(byte_count)),
ReturnData(byte_count) => metadata
.return_data_per_byte_cost
.checked_mul(&<T::Gas as As<u32>>::sa(byte_count)),
ComputedDispatchFee(gas) => Some(gas),
};
value.unwrap_or_else(|| Bounded::max_value())
}
}
/// Charge the gas meter with the specified token.
/// Returns `Err(HostError)` if there is not enough gas.
fn charge_gas<T: Trait, Tok: Token<T>>(
gas_meter: &mut GasMeter<T>,
metadata: &Tok::Metadata,
token: Tok,
) -> Result<(), sandbox::HostError> {
match gas_meter.charge(metadata, token) {
GasMeterResult::Proceed => Ok(()),
GasMeterResult::OutOfGas => Err(sandbox::HostError),
}
}
/// Read designated chunk from the sandbox memory, consuming an appropriate amount of
/// gas.
///
/// Returns `Err` if one of the following conditions occurs:
///
/// - calculating the gas cost resulted in overflow.
/// - out of gas
/// - requested buffer is not within the bounds of the sandbox memory.
fn read_sandbox_memory<E: Ext>(
ctx: &mut Runtime<E>,
ptr: u32,
len: u32,
) -> Result<Vec<u8>, sandbox::HostError> {
charge_gas(ctx.gas_meter, ctx.schedule, RuntimeToken::ReadMemory(len))?;
let mut buf = Vec::new();
buf.resize(len as usize, 0);
ctx.memory().get(ptr, &mut buf)?;
Ok(buf)
}
/// Write the given buffer to the designated location in the sandbox memory, consuming
/// an appropriate amount of gas.
///
/// Returns `Err` if one of the following conditions occurs:
///
/// - calculating the gas cost resulted in overflow.
/// - out of gas
/// - designated area is not within the bounds of the sandbox memory.
fn write_sandbox_memory<T: Trait>(
gas_meter: &mut GasMeter<T>,
memory: &sandbox::Memory,
ptr: u32,
buf: &[u8],
) -> Result<(), sandbox::HostError> {
charge_gas(gas_meter, schedule, RuntimeToken::WriteMemory(buf.len() as u32))?;
memory.set(ptr, buf)?;
Ok(())
}
// ***********************************************************
// * AFTER MAKING A CHANGE MAKE SURE TO UPDATE COMPLEXITY.MD *
// ***********************************************************
// Define a function `fn init_env<E: Ext>() -> HostFunctionSet<E>` that returns
// a function set which can be imported by an executed contract.
// Account for used gas. Traps if gas used is greater than gas limit.
//
// NOTE: This is a implementation defined call and is NOT a part of the public API.
// This call is supposed to be called only by instrumentation injected code.
//
// - amount: How much gas is used.
gas(ctx, amount: u32) => {
charge_gas(&mut ctx.gas_meter, ctx.schedule, RuntimeToken::Explicit(amount))?;
Ok(())
// Change the value at the given key in the storage or remove the entry.
// - key_ptr: pointer into the linear
// memory where the location of the requested value is placed.
// - value_non_null: if set to 0, then the entry
// at the given location will be removed.
// - value_ptr: pointer into the linear memory
// where the value to set is placed. If `value_non_null` is set to 0, then this parameter is ignored.
// - value_len: the length of the value. If `value_non_null` is set to 0, then this parameter is ignored.
ext_set_storage(ctx, key_ptr: u32, value_non_null: u32, value_ptr: u32, value_len: u32) => {
let key = read_sandbox_memory(ctx, key_ptr, 32)?;
let value =
if value_non_null != 0 {
Some(read_sandbox_memory(ctx, value_ptr, value_len)?)
} else {
None
};
ctx.ext.set_storage(&key, value);
Ok(())
},
// Retrieve the value at the given location from the strorage and return 0.
// If there is no entry at the given location then this function will return 1 and
// clear the scratch buffer.
//
// - key_ptr: pointer into the linear memory where the key
// of the requested value is placed.
ext_get_storage(ctx, key_ptr: u32) -> u32 => {
let key = read_sandbox_memory(ctx, key_ptr, 32)?;
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if let Some(value) = ctx.ext.get_storage(&key) {
ctx.scratch_buf = value;
Ok(0)
} else {
ctx.scratch_buf.clear();
Ok(1)
}
},
// Make a call to another contract.
//
// Returns 0 on the successful execution and puts the result data returned
// by the callee into the scratch buffer. Otherwise, returns 1 and clears the scratch
// buffer.
//
// - callee_ptr: a pointer to the address of the callee contract.
// Should be decodable as an `T::AccountId`. Traps otherwise.
// - callee_len: length of the address buffer.
// - gas: how much gas to devote to the execution.
// - value_ptr: a pointer to the buffer with value, how much value to send.
// Should be decodable as a `T::Balance`. Traps otherwise.
// - value_len: length of the value buffer.
// - input_data_ptr: a pointer to a buffer to be used as input data to the callee.
// - input_data_len: length of the input data buffer.
ext_call(
ctx,
callee_ptr: u32,
callee_len: u32,
gas: u64,
value_ptr: u32,
value_len: u32,
input_data_ptr: u32,
input_data_len: u32
) -> u32 => {
let callee = {
let callee_buf = read_sandbox_memory(ctx, callee_ptr, callee_len)?;
<<E as Ext>::T as system::Trait>::AccountId::decode(&mut &callee_buf[..])
.ok_or_else(|| sandbox::HostError)?
};
let value = {
let value_buf = read_sandbox_memory(ctx, value_ptr, value_len)?;
BalanceOf::<<E as Ext>::T>::decode(&mut &value_buf[..])
.ok_or_else(|| sandbox::HostError)?
};
let input_data = read_sandbox_memory(ctx, input_data_ptr, input_data_len)?;
// Grab the scratch buffer and put in its' place an empty one.
// We will use it for creating `EmptyOutputBuf` container for the call.
let scratch_buf = mem::replace(&mut ctx.scratch_buf, Vec::new());
let empty_output_buf = EmptyOutputBuf::from_spare_vec(scratch_buf);
let nested_gas_limit = if gas == 0 {
ctx.gas_meter.gas_left()
} else {
<<E::T as Trait>::Gas as As<u64>>::sa(gas)
};
let ext = &mut ctx.ext;
let call_outcome = ctx.gas_meter.with_nested(nested_gas_limit, |nested_meter| {
match nested_meter {
Some(nested_meter) => {
ext.call(
&callee,
value,
nested_meter,
&input_data,
empty_output_buf
)
.map_err(|_| ())
}
// there is not enough gas to allocate for the nested call.
None => Err(()),
}
});
match call_outcome {
Ok(CallReceipt { output_data }) => {
ctx.scratch_buf = output_data;
Ok(0)
},
// Instantiate a contract with code returned by the specified initializer code.
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//
// This function creates an account and executes initializer code. After the execution,
// the returned buffer is saved as the code of the created account.
//
// Returns 0 on the successful contract creation and puts the address
// of the created contract into the scratch buffer.
// Otherwise, returns 1 and clears the scratch buffer.
//
// - init_code_ptr: a pointer to the buffer that contains the initializer code.
// - init_code_len: length of the initializer code buffer.
// - gas: how much gas to devote to the execution of the initializer code.
// - value_ptr: a pointer to the buffer with value, how much value to send.
// Should be decodable as a `T::Balance`. Traps otherwise.
// - value_len: length of the value buffer.
// - input_data_ptr: a pointer to a buffer to be used as input data to the initializer code.
// - input_data_len: length of the input data buffer.
ext_create(
ctx,
init_code_ptr: u32,
init_code_len: u32,
gas: u64,
value_ptr: u32,
value_len: u32,
input_data_ptr: u32,
input_data_len: u32
) -> u32 => {
let code_hash = {
let code_hash_buf = read_sandbox_memory(ctx, init_code_ptr, init_code_len)?;
<CodeHash<<E as Ext>::T>>::decode(&mut &code_hash_buf[..]).ok_or_else(|| sandbox::HostError)?
};
let value = {
let value_buf = read_sandbox_memory(ctx, value_ptr, value_len)?;
BalanceOf::<<E as Ext>::T>::decode(&mut &value_buf[..])
.ok_or_else(|| sandbox::HostError)?
};
let input_data = read_sandbox_memory(ctx, input_data_ptr, input_data_len)?;
// Clear the scratch buffer in any case.
ctx.scratch_buf.clear();
let nested_gas_limit = if gas == 0 {
ctx.gas_meter.gas_left()
} else {
<<E::T as Trait>::Gas as As<u64>>::sa(gas)
let instantiate_outcome = ctx.gas_meter.with_nested(nested_gas_limit, |nested_meter| {
Some(nested_meter) => {
ext.instantiate(
&code_hash,
value,
nested_meter,
&input_data
)
.map_err(|_| ())
}
// there is not enough gas to allocate for the nested call.
None => Err(()),
}
});
match instantiate_outcome {
Ok(InstantiateReceipt { address }) => {
// Write the address to the scratch buffer.
address.encode_to(&mut ctx.scratch_buf);
Ok(0)
},
Err(_) => Ok(1),
}
},
// Save a data buffer as a result of the execution, terminate the execution and return a
// successful result to the caller.
ext_return(ctx, data_ptr: u32, data_len: u32) => {
match ctx
.gas_meter
.charge(
ctx.schedule,
RuntimeToken::ReturnData(data_len)
)
{
GasMeterResult::Proceed => (),
GasMeterResult::OutOfGas => return Err(sandbox::HostError),
}
let empty_output_buf = ctx
.empty_output_buf
.take()
.expect(
"`empty_output_buf` is taken only here;
`ext_return` traps;
`Runtime` can only be used only for one execution;
qed"
);
let output_buf = empty_output_buf.fill(
data_len as usize,
|slice_mut| {
// Read the memory at the specified pointer to the provided slice.
ctx.memory.get(data_ptr, slice_mut)
}
)?;
ctx.special_trap = Some(SpecialTrap::Return(output_buf));
// The trap mechanism is used to immediately terminate the execution.
// This trap should be handled appropriately before returning the result
// to the user of this crate.
Err(sandbox::HostError)
},
// Stores the address of the caller into the scratch buffer.
//
// If this is a top-level call (i.e. initiated by an extrinsic) the origin address of the extrinsic
// will be returned. Otherwise, if this call is initiated by another contract then the address
// of the contract will be returned.
ext_caller(ctx) => {
ctx.scratch_buf = ctx.ext.caller().encode();
Ok(())
},
// Stores the address of the current contract into the scratch buffer.
ext_address(ctx) => {
ctx.scratch_buf = ctx.ext.address().encode();
Ok(())
},
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// Stores the gas price for the current transaction into the scratch buffer.
//
// The data is encoded as T::Balance. The current contents of the scratch buffer are overwritten.
ext_gas_price(ctx) => {
ctx.scratch_buf = ctx.gas_meter.gas_price().encode();
Ok(())
},
// Stores the amount of gas left into the scratch buffer.
//
// The data is encoded as T::Balance. The current contents of the scratch buffer are overwritten.
ext_gas_left(ctx) => {
ctx.scratch_buf = ctx.gas_meter.gas_left().encode();
Ok(())
},
// Stores the balance of the current account into the scratch buffer.
//
// The data is encoded as T::Balance. The current contents of the scratch buffer are overwritten.
ext_balance(ctx) => {
ctx.scratch_buf = ctx.ext.balance().encode();
Ok(())
},
// Stores the value transferred along with this call or as endowment into the scratch buffer.
//
// The data is encoded as T::Balance. The current contents of the scratch buffer are overwritten.
ext_value_transferred(ctx) => {
ctx.scratch_buf = ctx.ext.value_transferred().encode();
Ok(())
},
// Load the latest block RNG seed into the scratch buffer
ext_random_seed(ctx) => {
ctx.scratch_buf = ctx.ext.random_seed().encode();
Ok(())
},
// Load the latest block timestamp into the scratch buffer
ext_now(ctx) => {
let now: u64 = As::as_(ctx.ext.now().clone());
ctx.scratch_buf = now.encode();
Ok(())
},
// Decodes the given buffer as a `T::Call` and adds it to the list
// of to-be-dispatched calls.
//
// All calls made it to the top-level context will be dispatched before
// finishing the execution of the calling extrinsic.
ext_dispatch_call(ctx, call_ptr: u32, call_len: u32) => {
let call = {
let call_buf = read_sandbox_memory(ctx, call_ptr, call_len)?;
<<<E as Ext>::T as Trait>::Call>::decode(&mut &call_buf[..])
.ok_or_else(|| sandbox::HostError)?
};
// Charge gas for dispatching this call.
let fee = {
let balance_fee = <<E as Ext>::T as Trait>::ComputeDispatchFee::compute_dispatch_fee(&call);
approx_gas_for_balance::<<E as Ext>::T>(ctx.gas_meter.gas_price(), balance_fee)
};
charge_gas(&mut ctx.gas_meter, ctx.schedule, RuntimeToken::ComputedDispatchFee(fee))?;
ctx.ext.note_dispatch_call(call);
Ok(())
},
// Returns the size of the input buffer.
ext_input_size(ctx) -> u32 => {
Ok(ctx.input_data.len() as u32)
},
// Copy data from the input buffer starting from `offset` with length `len` into the contract memory.
// The region at which the data should be put is specified by `dest_ptr`.
ext_input_copy(ctx, dest_ptr: u32, offset: u32, len: u32) => {
let offset = offset as usize;
if offset > ctx.input_data.len() {
// Offset can't be larger than input buffer length.
return Err(sandbox::HostError);
}
// This can't panic since `offset <= ctx.input_data.len()`.
let src = &ctx.input_data[offset..];
if src.len() != len as usize {
return Err(sandbox::HostError);
}
// Finally, perform the write.
write_sandbox_memory(
ctx.gas_meter,
&ctx.memory,
dest_ptr,
src,
)?;
Ok(())
},
// Returns the size of the scratch buffer.
ext_scratch_size(ctx) -> u32 => {
Ok(ctx.scratch_buf.len() as u32)
},
// Copy data from the scratch buffer starting from `offset` with length `len` into the contract memory.
// The region at which the data should be put is specified by `dest_ptr`.
ext_scratch_copy(ctx, dest_ptr: u32, offset: u32, len: u32) => {
let offset = offset as usize;
if offset > ctx.scratch_buf.len() {
// Offset can't be larger than scratch buffer length.
return Err(sandbox::HostError);
}
// This can't panic since `offset <= ctx.scratch_buf.len()`.
let src = &ctx.scratch_buf[offset..];
if src.len() != len as usize {
return Err(sandbox::HostError);
}
// Finally, perform the write.
write_sandbox_memory(
ctx.gas_meter,
&ctx.memory,
dest_ptr,
src,
)?;