Contract Syscalls

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Contract syscalls handle cross-contract invocation and account creation.

Syscall Name	Gas Cost	Description	Devpack Wrapper
System.Contract.Call	10	Cross-contract call	Syscalls.contractCall(hash, method, params)
System.Contract.GetCallFlags	10	Get current call flags	Syscalls.getCallFlags()
System.Contract.CreateStandardAccount	10	Create account from public key	Syscalls.createStandardAccount(pubkey)
System.Contract.CreateMultisigAccount	10	Create multisig account	Syscalls.createMultisigAccount(m, pubkeys)

import "devpack/contracts/Syscalls.sol";

contract Bridge {
    address constant GAS_CONTRACT = 0xd2a4cff31913016155e38e474a2c06d08be276cf;

    function checkBalance(address account) external returns (bytes memory) {
        // Cross-contract call to the GAS native contract (10 GAS units)
        bytes memory params = abi.encode(account);
        return Syscalls.contractCall(GAS_CONTRACT, "balanceOf", params);
    }

    function createMultisig(uint256 threshold, bytes[] memory pubkeys)
        external
        returns (address)
    {
        // Create a multisig account requiring `threshold` of `pubkeys`
        return Syscalls.createMultisigAccount(threshold, pubkeys);
    }
}

CallFlags

The System.Contract.GetCallFlags syscall returns the permission flags for the current execution context. These flags control what operations the called contract is allowed to perform.

Flag	Value	Description
None	0x00	No permissions
ReadStates	0x01	Can read storage and call other contracts
WriteStates	0x02	Can write to storage
AllowCall	0x04	Can make cross-contract calls
AllowNotify	0x08	Can emit notifications
All	0x0F	Full permissions (default for direct calls)

TIP

When calling another contract, you can restrict its permissions by passing specific call flags. This is a defense-in-depth mechanism — a called contract with ReadStates only cannot modify your storage even if it contains malicious code.