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feat(precompiles): storage delta helpers #5605

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22 changes: 20 additions & 2 deletions crates/precompiles/src/error.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -75,6 +75,10 @@ pub enum TempoPrecompileError {
#[error("Panic({0:?})")]
Panic(PanicKind),

/// Internal storage delta underflow that carries the observed slot value for error mapping.
#[error("Storage delta underflow: current={0}")]
StorageDeltaUnderflow(U256),

/// Error from validator config
#[error("Validator config error: {0:?}")]
ValidatorConfigError(ValidatorConfigError),
Expand Down Expand Up @@ -158,7 +162,7 @@ impl TempoPrecompileError {
Self::SignatureVerifierError(e) => e.selector(),
Self::ReceivePolicyGuardError(e) => e.selector(),
Self::UnknownFunctionSelector(selector) => *selector,
Self::Panic(_) => Panic::SELECTOR,
Self::Panic(_) | Self::StorageDeltaUnderflow(_) => Panic::SELECTOR,
Self::OutOfGas | Self::Fatal(_) => [0, 0, 0, 0],
}
.into()
Expand All @@ -168,7 +172,9 @@ impl TempoPrecompileError {
/// rather than swallowed, because state may be inconsistent.
pub fn is_system_error(&self) -> bool {
match self {
Self::OutOfGas | Self::Fatal(_) | Self::Panic(_) => true,
Self::OutOfGas | Self::Fatal(_) | Self::Panic(_) | Self::StorageDeltaUnderflow(_) => {
true
}
Self::StablecoinDEX(_)
| Self::TIP20(_)
| Self::TIP20ChannelReserveError(_)
Expand All @@ -193,6 +199,11 @@ impl TempoPrecompileError {
Self::Panic(PanicKind::UnderOverflow)
}

/// Creates a storage delta underflow that carries the current slot value.
pub fn storage_delta_underflow(current: U256) -> Self {
Self::StorageDeltaUnderflow(current)
}

/// Creates an enum conversion error panic (Solidity Panic `0x21`).
pub fn enum_conversion_error() -> Self {
Self::Panic(PanicKind::EnumConversionError)
Expand Down Expand Up @@ -227,6 +238,13 @@ impl TempoPrecompileError {

panic.abi_encode().into()
}
Self::StorageDeltaUnderflow(_) => {
let panic = Panic {
code: U256::from(PanicKind::UnderOverflow as u32),
};

panic.abi_encode().into()
}
Self::ValidatorConfigError(e) => e.abi_encode().into(),
Self::ValidatorConfigV2Error(e) => e.abi_encode().into(),
Self::AccountKeychainError(e) => e.abi_encode().into(),
Expand Down
48 changes: 48 additions & 0 deletions crates/precompiles/src/storage/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -70,6 +70,30 @@ pub trait PrecompileStorageProvider {
/// Performs an SSTORE operation (persistent storage write).
fn sstore(&mut self, address: Address, key: U256, value: U256) -> Result<()>;

/// Increments a persistent storage slot by `delta`.
///
/// Intentionally returns no post-increment value, preserving `sinc` as a semantic
/// storage delta rather than an observation point that callers can branch on.
fn sinc(&mut self, address: Address, key: U256, delta: U256) -> Result<()> {
let value = self
.sload(address, key)?
.checked_add(delta)
.ok_or_else(TempoPrecompileError::under_overflow)?;
self.sstore(address, key, value)
}

/// Decrements a persistent storage slot by `delta`.
///
/// Intentionally returns no post-decrement value, preserving `sdec` as a semantic
/// storage delta rather than an observation point that callers can branch on.
fn sdec(&mut self, address: Address, key: U256, delta: U256) -> Result<()> {
let current = self.sload(address, key)?;
let value = current
.checked_sub(delta)
.ok_or_else(|| TempoPrecompileError::storage_delta_underflow(current))?;
self.sstore(address, key, value)
}

/// Performs a TSTORE operation (transient storage write).
fn tstore(&mut self, address: Address, key: U256, value: U256) -> Result<()>;

Expand Down Expand Up @@ -169,6 +193,30 @@ pub trait StorageOps {
fn store(&mut self, slot: U256, value: U256) -> Result<()>;
/// Loads a value from the provided slot.
fn load(&self, slot: U256) -> Result<U256>;

/// Increments a value at the provided slot by `delta`.
///
/// Intentionally returns no post-increment value, preserving `sinc` as a semantic
/// storage delta rather than an observation point that callers can branch on.
fn sinc(&mut self, slot: U256, delta: U256) -> Result<()> {
let value = self
.load(slot)?
.checked_add(delta)
.ok_or_else(TempoPrecompileError::under_overflow)?;
self.store(slot, value)
}

/// Decrements a value at the provided slot by `delta`.
///
/// Intentionally returns no post-decrement value, preserving `sdec` as a semantic
/// storage delta rather than an observation point that callers can branch on.
fn sdec(&mut self, slot: U256, delta: U256) -> Result<()> {
let current = self.load(slot)?;
let value = current
.checked_sub(delta)
.ok_or_else(|| TempoPrecompileError::storage_delta_underflow(current))?;
self.store(slot, value)
}
}

/// Trait providing access to a contract's address.
Expand Down
10 changes: 10 additions & 0 deletions crates/precompiles/src/storage/thread_local.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -157,6 +157,16 @@ impl StorageCtx {
Self::try_with_storage(|s| s.sstore(address, key, value))
}

/// Increments a persistent storage slot by `delta`.
pub fn sinc(&mut self, address: Address, key: U256, delta: U256) -> Result<()> {
Self::try_with_storage(|s| s.sinc(address, key, delta))
}

/// Decrements a persistent storage slot by `delta`.
pub fn sdec(&mut self, address: Address, key: U256, delta: U256) -> Result<()> {
Self::try_with_storage(|s| s.sdec(address, key, delta))
}

/// Performs a TSTORE operation (transient storage write).
pub fn tstore(&mut self, address: Address, key: U256, value: U256) -> Result<()> {
Self::try_with_storage(|s| s.tstore(address, key, value))
Expand Down
10 changes: 10 additions & 0 deletions crates/precompiles/src/storage/types/slot.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -124,6 +124,16 @@ impl<T> StorageOps for Slot<T> {
let mut storage = StorageCtx;
storage.sstore(self.address, slot, value)
}

fn sinc(&mut self, slot: U256, delta: U256) -> Result<()> {
let mut storage = StorageCtx;
storage.sinc(self.address, slot, delta)
}

fn sdec(&mut self, slot: U256, delta: U256) -> Result<()> {
let mut storage = StorageCtx;
storage.sdec(self.address, slot, delta)
}
}

/// Wrapper that routes storage operations through transient storage (TLOAD/TSTORE).
Expand Down
161 changes: 106 additions & 55 deletions crates/precompiles/src/tip20/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -26,7 +26,7 @@ use crate::{
address_registry::AddressRegistry,
error::{Result, TempoPrecompileError},
receive_policy_guard::{InboundKind, ReceivePolicyGuard, RecoveryMode},
storage::{Handler, Mapping},
storage::{Handler, Mapping, StorageOps},
tip20::{rewards::UserRewardInfo, roles::DEFAULT_ADMIN_ROLE},
tip20_factory::TIP20Factory,
tip403_registry::{AuthRole, ITIP403Registry, TIP403Registry},
Expand Down Expand Up @@ -540,11 +540,7 @@ impl TIP20Token {
self.handle_rewards_on_mint(to.target, amount)?;

self.set_total_supply(new_supply)?;
let to_balance = self.get_balance(to.target)?;
let new_to_balance = to_balance
.checked_add(amount)
.ok_or(TempoPrecompileError::under_overflow())?;
self.set_balance(to.target, new_to_balance)?;
self.increment_balance(to.target, amount)?;

self.emit_event(to.build_transfer_event(Address::ZERO, amount))
}
Expand Down Expand Up @@ -1002,6 +998,29 @@ impl TIP20Token {
self.balances[account].write(amount)
}

fn increment_balance(&mut self, account: Address, amount: U256) -> Result<()> {
let balance = self.balances.at_mut(&account);
let slot = balance.slot();
balance.sinc(slot, amount).map_err(|err| {
if err == TempoPrecompileError::under_overflow() {
TIP20Error::supply_cap_exceeded().into()
} else {
err
}
})
Comment on lines +1002 to +1010

@klkvr klkvr Jun 10, 2026

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same here

}

fn decrement_balance(&mut self, account: Address, amount: U256) -> Result<()> {
let balance = self.balances.at_mut(&account);
let slot = balance.slot();
balance.sdec(slot, amount).map_err(|err| match err {
TempoPrecompileError::StorageDeltaUnderflow(current) => {
TIP20Error::insufficient_balance(current, amount, self.address).into()
}
err => err,
})
}

fn get_allowance(&self, owner: Address, spender: Address) -> Result<U256> {
self.allowances[owner][spender].read()
}
Expand Down Expand Up @@ -1148,29 +1167,13 @@ impl TIP20Token {
/// For virtual recipients the event address is the virtual alias; the balance update always
/// targets `to.target` (the resolved master).
pub(crate) fn _transfer(&mut self, from: Address, to: &Recipient, amount: U256) -> Result<()> {
let from_balance = self.get_balance(from)?;
if amount > from_balance {
return Err(
TIP20Error::insufficient_balance(from_balance, amount, self.address).into(),
);
}

self.handle_rewards_on_transfer(from, to.target, amount)?;

// Adjust balances
let new_from_balance = from_balance
.checked_sub(amount)
.ok_or(TempoPrecompileError::under_overflow())?;

self.set_balance(from, new_from_balance)?;
self.decrement_balance(from, amount)?;

@legion2002 legion2002 Jun 11, 2026

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⚠️ [LOW] _transfer balance pre-check removal lets rewards accounting turn insufficient balance into a Panic

The PR removes the up-front from balance check and now relies on decrement_balance to map storage underflow back into TIP20Error::insufficient_balance. That mapping happens only here, after handle_rewards_on_transfer(from, to.target, amount) has already run. For an opted-in sender that transfers more than its balance to a non-opted-in recipient, rewards accounting can subtract amount from opted_in_supply first; when amount exceeds the opted-in supply, that path returns TempoPrecompileError::under_overflow(), which is encoded as Solidity Panic(0x11) and treated as a system error instead of the expected TIP20 insufficient-balance error.

Recommended Fix:
Restore an explicit balance check before handle_rewards_on_transfer, or make handle_rewards_on_transfer receive the already-validated sender balance / post-debit amount so insufficient-balance transfers fail with TIP20Error::insufficient_balance before reward accounting can underflow.


if to.target != Address::ZERO {
let to_balance = self.get_balance(to.target)?;
let new_to_balance = to_balance
.checked_add(amount)
.ok_or(TempoPrecompileError::under_overflow())?;

self.set_balance(to.target, new_to_balance)?;
self.increment_balance(to.target, amount)?;
}

self.emit_event(to.build_transfer_event(from, amount))
Expand Down Expand Up @@ -1295,22 +1298,10 @@ impl TIP20Token {
)?;
}

let new_from_balance =
from_balance
.checked_sub(amount)
.ok_or(TIP20Error::insufficient_balance(
from_balance,
amount,
self.address,
))?;

self.set_balance(from, new_from_balance)?;
self.decrement_balance(from, amount)?;
self.increment_balance(TIP_FEE_MANAGER_ADDRESS, amount)?;

let to_balance = self.get_balance(TIP_FEE_MANAGER_ADDRESS)?;
let new_to_balance = to_balance
.checked_add(amount)
.ok_or(TIP20Error::supply_cap_exceeded())?;
self.set_balance(TIP_FEE_MANAGER_ADDRESS, new_to_balance)
Ok(())
}

/// Refunds unused fee tokens from the fee manager back to `to` and emits a transfer event for
Expand Down Expand Up @@ -1353,23 +1344,10 @@ impl TIP20Token {
)?;
}

let from_balance = self.get_balance(TIP_FEE_MANAGER_ADDRESS)?;
let new_from_balance =
from_balance
.checked_sub(refund)
.ok_or(TIP20Error::insufficient_balance(
from_balance,
refund,
self.address,
))?;
self.decrement_balance(TIP_FEE_MANAGER_ADDRESS, refund)?;
self.increment_balance(to, refund)?;

self.set_balance(TIP_FEE_MANAGER_ADDRESS, new_from_balance)?;

let to_balance = self.get_balance(to)?;
let new_to_balance = to_balance
.checked_add(refund)
.ok_or(TIP20Error::supply_cap_exceeded())?;
self.set_balance(to, new_to_balance)
Ok(())
}
}

Expand Down Expand Up @@ -2311,6 +2289,30 @@ pub(crate) mod tests {
})
}

#[test]
fn test_transfer_fee_pre_tx_fee_manager_overflow() -> eyre::Result<()> {
let mut storage = HashMapStorageProvider::new(1);
let admin = Address::random();
let user = Address::random();
let fee_amount = U256::ONE;

StorageCtx::enter(&mut storage, || {
let mut token = TIP20Setup::create("Test", "TST", admin)
.with_issuer(admin)
.with_mint(user, fee_amount)
.apply()?;
token.set_balance(TIP_FEE_MANAGER_ADDRESS, U256::MAX)?;

assert_eq!(
token.transfer_fee_pre_tx(user, fee_amount),
Err(TempoPrecompileError::TIP20(
TIP20Error::supply_cap_exceeded()
))
);
Ok(())
})
}

#[test]
fn test_transfer_fee_pre_tx_paused() -> eyre::Result<()> {
let mut storage = HashMapStorageProvider::new(1);
Expand Down Expand Up @@ -2369,6 +2371,55 @@ pub(crate) mod tests {
})
}

#[test]
fn test_transfer_fee_post_tx_insufficient_fee_manager_balance() -> eyre::Result<()> {
let mut storage = HashMapStorageProvider::new(1);
let admin = Address::random();
let user = Address::random();
let initial_fee = U256::from(10);
let refund_amount = U256::from(30);

StorageCtx::enter(&mut storage, || {
let mut token = TIP20Setup::create("Test", "TST", admin)
.with_issuer(admin)
.with_mint(TIP_FEE_MANAGER_ADDRESS, initial_fee)
.apply()?;

assert_eq!(
token.transfer_fee_post_tx(user, refund_amount, U256::ZERO),
Err(TempoPrecompileError::TIP20(
TIP20Error::insufficient_balance(initial_fee, refund_amount, token.address)
))
);

Ok(())
})
}

#[test]
fn test_transfer_fee_post_tx_recipient_overflow() -> eyre::Result<()> {
let mut storage = HashMapStorageProvider::new(1);
let admin = Address::random();
let user = Address::random();
let refund_amount = U256::ONE;

StorageCtx::enter(&mut storage, || {
let mut token = TIP20Setup::create("Test", "TST", admin)
.with_issuer(admin)
.apply()?;
token.set_balance(TIP_FEE_MANAGER_ADDRESS, refund_amount)?;
token.set_balance(user, U256::MAX)?;

assert_eq!(
token.transfer_fee_post_tx(user, refund_amount, U256::ZERO),
Err(TempoPrecompileError::TIP20(
TIP20Error::supply_cap_exceeded()
))
);
Ok(())
})
}

#[test]
fn test_transfer_fee_post_tx_refunds_spending_limit() -> eyre::Result<()> {
let mut storage = HashMapStorageProvider::new_with_spec(1, TempoHardfork::T1C);
Expand Down
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