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Remove unchecked arithmetic #1831

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merged 14 commits into from
Aug 28, 2023
Merged

Remove unchecked arithmetic #1831

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5ad9d0e
Remove unchecked arithmetic
athei Jul 1, 2023
9c4e59f
Remove from erc20
athei Jul 2, 2023
8ba8725
Remove from erc1155
athei Jul 2, 2023
9627c86
Remove from erc721
athei Jul 2, 2023
41bc133
Remove from incrementer
athei Jul 2, 2023
0b19225
Remove from payment-channel
athei Jul 2, 2023
526fdfd
Remove from trait-erc20
athei Jul 2, 2023
bea89ad
Remove from trait-incrementer
athei Jul 2, 2023
24da566
Remove from multi-contract-caller
athei Jul 2, 2023
ab9e040
Remove from multisig
athei Jul 2, 2023
b703b49
Remove from set-code-hash
athei Jul 2, 2023
c8e9875
cargo fmt
athei Jul 2, 2023
8675b2e
Merge branch 'master' into at/remove-unchecked-arithmetic
athei Aug 21, 2023
28175ea
Spellcheck
athei Aug 21, 2023
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1 change: 0 additions & 1 deletion crates/env/Cargo.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -26,7 +26,6 @@ derive_more = { version = "0.99", default-features = false, features = ["from",
num-traits = { version = "0.2", default-features = false, features = ["i128"] }
cfg-if = "1.0"
paste = "1.0"
arrayref = "0.3"
static_assertions = "1.1"

[target.'cfg(target_arch = "wasm32")'.dependencies]
Expand Down
8 changes: 6 additions & 2 deletions crates/env/src/call/execution_input.rs
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Expand Up @@ -184,7 +184,9 @@ where
{
#[inline]
fn size_hint(&self) -> usize {
scale::Encode::size_hint(&self.head) + scale::Encode::size_hint(&self.rest)
scale::Encode::size_hint(&self.head)
.checked_add(scale::Encode::size_hint(&self.rest))
.unwrap()
}

#[inline]
Expand All @@ -204,7 +206,9 @@ where
{
#[inline]
fn size_hint(&self) -> usize {
scale::Encode::size_hint(&self.selector) + scale::Encode::size_hint(&self.args)
scale::Encode::size_hint(&self.selector)
.checked_add(scale::Encode::size_hint(&self.args))
.unwrap()
}

#[inline]
Expand Down
21 changes: 21 additions & 0 deletions crates/env/src/engine/mod.rs
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Expand Up @@ -31,6 +31,27 @@ use ink_primitives::{
LangError,
};

/// Convert a slice into an array reference.
///
/// Creates an array reference of size $len pointing to $offset within $arr.
///
/// # Panics
///
/// - The selected range is out of bounds given the supplied slice
/// - Integer overflow on $offset + $len
macro_rules! array_mut_ref {
($arr:expr, $offset:expr, $len:expr) => {{
{
fn as_array<T>(slice: &mut [T]) -> &mut [T; $len] {
slice.try_into().unwrap()
}
let offset: usize = $offset;
let slice = &mut $arr[offset..offset.checked_add($len).unwrap()];
as_array(slice)
}
}};
}

pub trait OnInstance: EnvBackend + TypedEnvBackend {
fn on_instance<F, R>(f: F) -> R
where
Expand Down
8 changes: 4 additions & 4 deletions crates/env/src/engine/off_chain/impls.rs
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Expand Up @@ -60,7 +60,7 @@ impl CryptoHash for Blake2x128 {
<Blake2x128 as HashOutput>::Type,
OutputType
);
let output: &mut OutputType = arrayref::array_mut_ref!(output, 0, 16);
let output: &mut OutputType = array_mut_ref!(output, 0, 16);
Engine::hash_blake2_128(input, output);
}
}
Expand All @@ -72,7 +72,7 @@ impl CryptoHash for Blake2x256 {
<Blake2x256 as HashOutput>::Type,
OutputType
);
let output: &mut OutputType = arrayref::array_mut_ref!(output, 0, 32);
let output: &mut OutputType = array_mut_ref!(output, 0, 32);
Engine::hash_blake2_256(input, output);
}
}
Expand All @@ -84,7 +84,7 @@ impl CryptoHash for Sha2x256 {
<Sha2x256 as HashOutput>::Type,
OutputType
);
let output: &mut OutputType = arrayref::array_mut_ref!(output, 0, 32);
let output: &mut OutputType = array_mut_ref!(output, 0, 32);
Engine::hash_sha2_256(input, output);
}
}
Expand All @@ -96,7 +96,7 @@ impl CryptoHash for Keccak256 {
<Keccak256 as HashOutput>::Type,
OutputType
);
let output: &mut OutputType = arrayref::array_mut_ref!(output, 0, 32);
let output: &mut OutputType = array_mut_ref!(output, 0, 32);
Engine::hash_keccak_256(input, output);
}
}
Expand Down
15 changes: 8 additions & 7 deletions crates/env/src/engine/on_chain/buffer.rs
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Expand Up @@ -80,15 +80,16 @@ impl<'a> EncodeScope<'a> {
impl<'a> scale::Output for EncodeScope<'a> {
fn write(&mut self, bytes: &[u8]) {
debug_assert!(
self.len() + bytes.len() <= self.capacity(),
self.len().checked_add(bytes.len()).unwrap() <= self.capacity(),
"encode scope buffer overflowed. capacity is {} but last write index is {}",
self.capacity(),
self.len() + bytes.len(),
self.len().checked_add(bytes.len()).unwrap(),
);
let start = self.len;
let len_bytes = bytes.len();
self.buffer[start..(start + len_bytes)].copy_from_slice(bytes);
self.len += len_bytes;
self.buffer[start..(start.checked_add(len_bytes)).unwrap()]
.copy_from_slice(bytes);
self.len = self.len.checked_add(len_bytes).unwrap();
}

fn push_byte(&mut self, byte: u8) {
Expand All @@ -99,7 +100,7 @@ impl<'a> scale::Output for EncodeScope<'a> {
self.capacity(),
);
self.buffer[self.len] = byte;
self.len += 1;
self.len = self.len.checked_add(1).unwrap();
}
}

Expand Down Expand Up @@ -142,7 +143,7 @@ impl<'a> ScopedBuffer<'a> {
self.buffer = rhs;
debug_assert_eq!(lhs.len(), len);
let len_after = self.buffer.len();
debug_assert_eq!(len_before - len_after, len);
debug_assert_eq!(len_before.checked_sub(len_after).unwrap(), len);
lhs
}

Expand Down Expand Up @@ -193,7 +194,7 @@ impl<'a> ScopedBuffer<'a> {
let mut encode_scope = EncodeScope::from(&mut buffer[offset..]);
scale::Encode::encode_to(&value, &mut encode_scope);
let encode_len = encode_scope.len();
self.offset += encode_len;
self.offset = self.offset.checked_add(encode_len).unwrap();
let _ = core::mem::replace(&mut self.buffer, buffer);
}

Expand Down
8 changes: 4 additions & 4 deletions crates/env/src/engine/on_chain/impls.rs
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Expand Up @@ -57,7 +57,7 @@ impl CryptoHash for Blake2x128 {
<Blake2x128 as HashOutput>::Type,
OutputType
);
let output: &mut OutputType = arrayref::array_mut_ref!(output, 0, 16);
let output: &mut OutputType = array_mut_ref!(output, 0, 16);
ext::hash_blake2_128(input, output);
}
}
Expand All @@ -69,7 +69,7 @@ impl CryptoHash for Blake2x256 {
<Blake2x256 as HashOutput>::Type,
OutputType
);
let output: &mut OutputType = arrayref::array_mut_ref!(output, 0, 32);
let output: &mut OutputType = array_mut_ref!(output, 0, 32);
ext::hash_blake2_256(input, output);
}
}
Expand All @@ -81,7 +81,7 @@ impl CryptoHash for Sha2x256 {
<Sha2x256 as HashOutput>::Type,
OutputType
);
let output: &mut OutputType = arrayref::array_mut_ref!(output, 0, 32);
let output: &mut OutputType = array_mut_ref!(output, 0, 32);
ext::hash_sha2_256(input, output);
}
}
Expand All @@ -93,7 +93,7 @@ impl CryptoHash for Keccak256 {
<Keccak256 as HashOutput>::Type,
OutputType
);
let output: &mut OutputType = arrayref::array_mut_ref!(output, 0, 32);
let output: &mut OutputType = array_mut_ref!(output, 0, 32);
ext::hash_keccak_256(input, output);
}
}
Expand Down
5 changes: 4 additions & 1 deletion crates/env/src/topics.rs
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Expand Up @@ -228,7 +228,10 @@ where
{
#[inline]
fn size_hint(&self) -> usize {
self.prefix.size_hint() + self.value.size_hint()
self.prefix
.size_hint()
.checked_add(self.value.size_hint())
.unwrap()
}

#[inline]
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13 changes: 10 additions & 3 deletions integration-tests/erc1155/lib.rs
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Expand Up @@ -267,7 +267,10 @@ mod erc1155 {

// Given that TokenId is a `u128` the likelihood of this overflowing is pretty
// slim.
self.token_id_nonce += 1;
#[allow(clippy::arithmetic_side_effects)]
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@SkymanOne SkymanOne Jul 2, 2023 •
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I'm not fun of a this. Is there a reason we can't do checked arithmetic operation here? If the operation is not implemented for the type, then we need to implement it first before introducing the change here and in cargo contract.

Otherwise we are breaking the arithmetic safety guarantees.

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We can. But it is not necessary here. Overflowing a u128 is impossible by incrementing by 1 per extrinsic.

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Do I understand correctly that we won't be able to use arithmetic operators (i.e. +, -, /, *) on numbers at all? I am just thinking of what impact it will have on the developer experience if we have to tell everyone knows that they need to use checked_ operations specifically.

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Do I understand correctly that we won't be able to use arithmetic operators (i.e. +, -, /, *) on numbers at all?

Correct.

I am just thinking of what impact it will have on the developer experience if we have to tell everyone knows that they need to use checked_ operations specifically.

Or saturating or wrapping. Developers should express the overflow behaviour in-code instead of leaving it open to a compile time switch. We should have done that from the beginning. People have to think about this anyways.

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Or saturating or wrapping.

Or use Wrapping and Saturating, so then the arithmetic itself wouldn't become an unreadable soup of function calls, e.g. this compiles:

#![deny(clippy::arithmetic_side_effects)]
use core::num::Wrapping;

fn foo(a: Wrapping<u32>, b: Wrapping<u32>) -> Wrapping<u32> {
    a + b
}

(Saturating is still unstable though, but we could just provide our own wrapper for the time being.)

{
self.token_id_nonce += 1;
}
self.balances.insert((caller, self.token_id_nonce), &value);

// Emit transfer event but with mint semantics
Expand Down Expand Up @@ -329,11 +332,15 @@ mod erc1155 {
.balances
.get((from, token_id))
.expect("Caller should have ensured that `from` holds `token_id`.");
sender_balance -= value;
// checks that sender_balance >= value were performed by caller
#[allow(clippy::arithmetic_side_effects)]
{
sender_balance -= value;
}
self.balances.insert((from, token_id), &sender_balance);

let mut recipient_balance = self.balances.get((to, token_id)).unwrap_or(0);
recipient_balance += value;
recipient_balance = recipient_balance.checked_add(value).unwrap();
self.balances.insert((to, token_id), &recipient_balance);

let caller = self.env().caller();
Expand Down
8 changes: 6 additions & 2 deletions integration-tests/erc20/lib.rs
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Expand Up @@ -178,6 +178,8 @@ mod erc20 {
return Err(Error::InsufficientAllowance)
}
self.transfer_from_to(&from, &to, value)?;
// We checked that allowance >= value
#[allow(clippy::arithmetic_side_effects)]
self.allowances
.insert((&from, &caller), &(allowance - value));
Ok(())
Expand All @@ -201,10 +203,12 @@ mod erc20 {
if from_balance < value {
return Err(Error::InsufficientBalance)
}

// We checked that from_balance >= value
#[allow(clippy::arithmetic_side_effects)]
self.balances.insert(from, &(from_balance - value));
let to_balance = self.balance_of_impl(to);
self.balances.insert(to, &(to_balance + value));
self.balances
.insert(to, &(to_balance.checked_add(value).unwrap()));
self.env().emit_event(Transfer {
from: Some(*from),
to: Some(*to),
Expand Down
9 changes: 6 additions & 3 deletions integration-tests/erc721/lib.rs
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Expand Up @@ -227,7 +227,7 @@ mod erc721 {

let count = owned_tokens_count
.get(caller)
.map(|c| c - 1)
.map(|c| c.checked_sub(1).unwrap())
.ok_or(Error::CannotFetchValue)?;
owned_tokens_count.insert(caller, &count);
token_owner.remove(id);
Expand Down Expand Up @@ -284,7 +284,7 @@ mod erc721 {

let count = owned_tokens_count
.get(from)
.map(|c| c - 1)
.map(|c| c.checked_sub(1).unwrap())
.ok_or(Error::CannotFetchValue)?;
owned_tokens_count.insert(from, &count);
token_owner.remove(id);
Expand All @@ -308,7 +308,10 @@ mod erc721 {
return Err(Error::NotAllowed)
};

let count = owned_tokens_count.get(to).map(|c| c + 1).unwrap_or(1);
let count = owned_tokens_count
.get(to)
.map(|c| c.checked_add(1).unwrap())
.unwrap_or(1);

owned_tokens_count.insert(to, &count);
token_owner.insert(id, to);
Expand Down
2 changes: 1 addition & 1 deletion integration-tests/incrementer/lib.rs
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Expand Up @@ -20,7 +20,7 @@ mod incrementer {

#[ink(message)]
pub fn inc(&mut self, by: i32) {
self.value += by;
self.value = self.value.checked_add(by).unwrap();
}

#[ink(message)]
Expand Down
2 changes: 1 addition & 1 deletion integration-tests/multi-contract-caller/accumulator/lib.rs
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Expand Up @@ -23,7 +23,7 @@ pub mod accumulator {
/// Mutates the internal value.
#[ink(message)]
pub fn inc(&mut self, by: i32) {
self.value += by;
self.value = self.value.checked_add(by).unwrap();
}

/// Returns the current state.
Expand Down
2 changes: 1 addition & 1 deletion integration-tests/multi-contract-caller/subber/lib.rs
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Expand Up @@ -26,7 +26,7 @@ mod subber {
/// Decreases the `accumulator` value by some amount.
#[ink(message)]
pub fn dec(&mut self, by: i32) {
self.accumulator.inc(-by)
self.accumulator.inc(0i32.checked_sub(by).unwrap())
}
}
}
18 changes: 14 additions & 4 deletions integration-tests/multisig/lib.rs
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Expand Up @@ -379,7 +379,10 @@ mod multisig {
pub fn add_owner(&mut self, new_owner: AccountId) {
self.ensure_from_wallet();
self.ensure_no_owner(&new_owner);
ensure_requirement_is_valid(self.owners.len() as u32 + 1, self.requirement);
ensure_requirement_is_valid(
(self.owners.len() as u32).checked_add(1).unwrap(),
self.requirement,
);
self.is_owner.insert(new_owner, &());
self.owners.push(new_owner);
self.env().emit_event(OwnerAddition { owner: new_owner });
Expand All @@ -398,6 +401,8 @@ mod multisig {
pub fn remove_owner(&mut self, owner: AccountId) {
self.ensure_from_wallet();
self.ensure_owner(&owner);
// If caller is an owner the len has to be > 0
#[allow(clippy::arithmetic_side_effects)]
let len = self.owners.len() as u32 - 1;
let requirement = u32::min(len, self.requirement);
ensure_requirement_is_valid(len, requirement);
Expand Down Expand Up @@ -522,7 +527,10 @@ mod multisig {
"There is a entry in `self.confirmations`. Hence a count must exit.",
);
// Will not underflow as there is at least one confirmation
confirmation_count -= 1;
#[allow(clippy::arithmetic_side_effects)]
{
confirmation_count -= 1;
}
self.confirmation_count
.insert(trans_id, &confirmation_count);
self.env().emit_event(Revocation {
Expand Down Expand Up @@ -618,14 +626,16 @@ mod multisig {
let key = (transaction, confirmer);
let new_confirmation = !self.confirmations.contains(key);
if new_confirmation {
count += 1;
count = count.checked_add(1).unwrap();
self.confirmations.insert(key, &());
self.confirmation_count.insert(transaction, &count);
}
let status = {
if count >= self.requirement {
ConfirmationStatus::Confirmed
} else {
// We checked that count < self.requirement
#[allow(clippy::arithmetic_side_effects)]
ConfirmationStatus::ConfirmationsNeeded(self.requirement - count)
}
};
Expand Down Expand Up @@ -677,7 +687,7 @@ mod multisig {
if self.confirmations.contains(key) {
self.confirmations.remove(key);
let mut count = self.confirmation_count.get(trans_id).unwrap_or(0);
count -= 1;
count = count.saturating_sub(1);
self.confirmation_count.insert(trans_id, &count);
}
}
Expand Down
8 changes: 6 additions & 2 deletions integration-tests/payment-channel/lib.rs
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Expand Up @@ -138,6 +138,8 @@ mod payment_channel {
return Err(Error::InvalidSignature)
}

// We checked that amount >= self.withdrawn
#[allow(clippy::arithmetic_side_effects)]
self.env()
.transfer(self.recipient, amount - self.withdrawn)
.map_err(|_| Error::TransferFailed)?;
Expand All @@ -157,7 +159,7 @@ mod payment_channel {
}

let now = self.env().block_timestamp();
let expiration = now + self.close_duration;
let expiration = now.checked_add(self.close_duration).unwrap();

self.env().emit_event(SenderCloseStarted {
expiration,
Expand Down Expand Up @@ -207,8 +209,10 @@ mod payment_channel {
return Err(Error::AmountIsLessThanWithdrawn)
}

// We checked that amount >= self.withdrawn
#[allow(clippy::arithmetic_side_effects)]
let amount_to_withdraw = amount - self.withdrawn;
self.withdrawn += amount_to_withdraw;
self.withdrawn.checked_add(amount_to_withdraw).unwrap();

self.env()
.transfer(self.recipient, amount_to_withdraw)
Expand Down
2 changes: 1 addition & 1 deletion integration-tests/set-code-hash/lib.rs
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Expand Up @@ -36,7 +36,7 @@ pub mod incrementer {
/// Increments the counter value which is stored in the contract's storage.
#[ink(message)]
pub fn inc(&mut self) {
self.count += 1;
self.count = self.count.checked_add(1).unwrap();
ink::env::debug_println!(
"The new count is {}, it was modified using the original contract code.",
self.count
Expand Down