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Remove increaseAllowance and decreaseAllowance #52

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Remove increaseAllowance and decreaseAllowance #52

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49 changes: 1 addition & 48 deletions contracts/lending/Vault.vy
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Original file line number Diff line number Diff line change
Expand Up @@ -600,61 +600,14 @@ def transfer(_to: address, _value: uint256) -> bool:
def approve(_spender: address, _value: uint256) -> bool:
"""
@notice Allow `_spender` to transfer up to `_value` amount of tokens from the caller's account.
@dev Non-zero to non-zero approvals are allowed, but should be used cautiously. The methods
increaseAllowance + decreaseAllowance are available to prevent any front-running that
may occur.
@dev Non-zero to non-zero approvals are allowed, but should be used cautiously.
@param _spender The account permitted to spend up to `_value` amount of caller's funds.
@param _value The amount of tokens `_spender` is allowed to spend.
"""
self._approve(msg.sender, _spender, _value)
return True


@external
def increaseAllowance(_spender: address, _add_value: uint256) -> bool:
"""
@notice Increase the allowance granted to `_spender`.
@dev This function will never overflow, and instead will bound
allowance to MAX_UINT256. This has the potential to grant an
infinite approval.
@param _spender The account to increase the allowance of.
@param _add_value The amount to increase the allowance by.
"""
cached_allowance: uint256 = self.allowance[msg.sender][_spender]
allowance: uint256 = unsafe_add(cached_allowance, _add_value)

# check for an overflow
if allowance < cached_allowance:
allowance = max_value(uint256)

if allowance != cached_allowance:
self._approve(msg.sender, _spender, allowance)

return True


@external
def decreaseAllowance(_spender: address, _sub_value: uint256) -> bool:
"""
@notice Decrease the allowance granted to `_spender`.
@dev This function will never underflow, and instead will bound
allowance to 0.
@param _spender The account to decrease the allowance of.
@param _sub_value The amount to decrease the allowance by.
"""
cached_allowance: uint256 = self.allowance[msg.sender][_spender]
allowance: uint256 = unsafe_sub(cached_allowance, _sub_value)

# check for an underflow
if cached_allowance < allowance:
allowance = 0

if allowance != cached_allowance:
self._approve(msg.sender, _spender, allowance)

return True


@external
@view
def admin() -> address:
Expand Down