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use std::{ops, cmp, fmt};
use util::{U128, U256, U512, Uint};
use action_params::ActionParams;
use evm::Ext;
#[derive(Debug, Clone, Copy, PartialEq)]
pub enum Error {
OutOfGas,
BadJumpDestination {
destination: usize
},
BadInstruction {
instruction: u8,
},
StackUnderflow {
instruction: &'static str,
wanted: usize,
on_stack: usize
},
OutOfStack {
instruction: &'static str,
wanted: usize,
limit: usize
},
#[allow(dead_code)]
Internal,
}
impl fmt::Display for Error {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
use self::Error::*;
let message = match *self {
OutOfGas => "Out of gas",
BadJumpDestination { .. } => "Bad jump destination",
BadInstruction { .. } => "Bad instruction",
StackUnderflow { .. } => "Stack underflow",
OutOfStack { .. } => "Out of stack",
Internal => "Internal error",
};
message.fmt(f)
}
}
pub type Result<T> = ::std::result::Result<T, Error>;
#[derive(Debug, PartialEq, Eq, PartialOrd, Ord)]
pub enum GasLeft<'a> {
Known(U256),
NeedsReturn(U256, &'a [u8]),
}
pub trait Finalize {
fn finalize<E: Ext>(self, ext: E) -> Result<U256>;
}
impl<'a> Finalize for Result<GasLeft<'a>> {
fn finalize<E: Ext>(self, ext: E) -> Result<U256> {
match self {
Ok(GasLeft::Known(gas)) => Ok(gas),
Ok(GasLeft::NeedsReturn(gas, ret_code)) => ext.ret(&gas, ret_code),
Err(err) => Err(err),
}
}
}
pub trait CostType: Sized + From<usize> + Copy
+ ops::Mul<Output=Self> + ops::Div<Output=Self> + ops::Add<Output=Self> +ops::Sub<Output=Self>
+ ops::Shr<usize, Output=Self> + ops::Shl<usize, Output=Self>
+ cmp::Ord + fmt::Debug {
fn as_u256(&self) -> U256;
fn from_u256(val: U256) -> Result<Self>;
fn as_usize(&self) -> usize;
fn overflow_add(self, other: Self) -> (Self, bool);
fn overflow_mul(self, other: Self) -> (Self, bool);
fn overflow_mul_shr(self, other: Self, shr: usize) -> (Self, bool);
}
impl CostType for U256 {
fn as_u256(&self) -> U256 {
*self
}
fn from_u256(val: U256) -> Result<Self> {
Ok(val)
}
fn as_usize(&self) -> usize {
self.as_u64() as usize
}
fn overflow_add(self, other: Self) -> (Self, bool) {
Uint::overflowing_add(self, other)
}
fn overflow_mul(self, other: Self) -> (Self, bool) {
Uint::overflowing_mul(self, other)
}
fn overflow_mul_shr(self, other: Self, shr: usize) -> (Self, bool) {
let x = self.full_mul(other);
let U512(parts) = x;
let overflow = (parts[4] | parts[5] | parts[6] | parts[7]) > 0;
let U512(parts) = x >> shr;
(
U256([parts[0], parts[1], parts[2], parts[3]]),
overflow
)
}
}
impl CostType for usize {
fn as_u256(&self) -> U256 {
U256::from(*self)
}
fn from_u256(val: U256) -> Result<Self> {
let res = val.low_u64() as usize;
if U256::from(res) != val {
return Err(Error::OutOfGas);
}
Ok(res)
}
fn as_usize(&self) -> usize {
*self
}
fn overflow_add(self, other: Self) -> (Self, bool) {
self.overflowing_add(other)
}
fn overflow_mul(self, other: Self) -> (Self, bool) {
self.overflowing_mul(other)
}
fn overflow_mul_shr(self, other: Self, shr: usize) -> (Self, bool) {
let (c, o) = U128::from(self).overflowing_mul(U128::from(other));
let U128(parts) = c;
let overflow = o | (parts[1] > 0);
let U128(parts) = c >> shr;
let result = parts[0] as usize;
let overflow = overflow | (parts[0] > result as u64);
(result, overflow)
}
}
pub trait Evm {
fn exec(&mut self, params: ActionParams, ext: &mut Ext) -> Result<GasLeft>;
}
#[cfg(test)]
mod tests {
use util::{U256, Uint};
use super::CostType;
#[test]
fn should_calculate_overflow_mul_shr_without_overflow() {
let num = 1048576;
let (res1, o1) = U256::from(num).overflow_mul_shr(U256::from(num), 20);
let (res2, o2) = num.overflow_mul_shr(num, 20);
assert_eq!(res1, U256::from(num));
assert!(!o1);
assert_eq!(res2, num);
assert!(!o2);
}
#[test]
fn should_calculate_overflow_mul_shr_with_overflow() {
let max = u64::max_value();
let num1 = U256([max, max, max, max]);
let num2 = usize::max_value();
let (res1, o1) = num1.overflow_mul_shr(num1, 256);
let (res2, o2) = num2.overflow_mul_shr(num2, 64);
assert_eq!(res2, num2 - 1);
assert!(o2);
assert_eq!(res1, !U256::zero() - U256::one());
assert!(o1);
}
#[test]
fn should_validate_u256_to_usize_conversion() {
let v = U256::from(usize::max_value()) + U256::from(1);
let res = usize::from_u256(v);
assert!(res.is_err());
}
}