Function: _permit(address owner, address spender, uint256 value, uint256 deadline, uint8 v, bytes32 r, bytes32 s)

This validates a signature for a permit and calls _approve.

Inputs

• owner

  • Control: Fully controlled by the caller.

  • Constraints: Checked that it is the recovered address from the signature in the isValidSignatureNow call.

  • Impact: The owner of the funds to be approved.

• spender

  • Control: Fully controlled by the caller.

  • Constraints: None.

  • Impact: The spender of the funds to be approved.

• value

  • Control: Fully controlled by the caller.

  • Constraints: None.

  • Impact: The amount of funds to be approved.

• deadline

  • Control: Fully controlled by the caller.

  • Constraints: Checked that it is in the future.

  • Impact: The deadline for the signature to be valid.

• v

  • Control: Fully controlled by the caller.

  • Constraints: Must recover in a valid signature.

  • Impact: The v part of the signature.

• r

  • Control: Fully controlled by the caller.

  • Constraints: Must recover in a valid signature.

  • Impact: The r part of the signature.

• s

  • Control: Fully controlled by the caller.

  • Constraints: Must recover in a valid signature.

  • Impact: The s part of the signature.

Branches and code coverage (including function calls)

Intended branches

• Check that the owner is the recovered address from the signature. That is ensured in the isValidSignatureNow call.

  Test coverage

• Check that the deadline is in the future.

  Test coverage

• Call _approve with the owner, spender, and value, so that tokens are approved.

  Test coverage

• Assure that all other aspects of the signature are valid. That is ensured in the isValidSignatureNow call.

  Test coverage

Negative behavior

• Do NOT allow reusing the signature. That is ensured through the nonce.

  Negative test