Struct anchor_lang::accounts::interface::Interface

pub struct Interface<'info, T>(/* private fields */);

Type validating that the account is one of a set of given Programs

The Interface wraps over the Program, allowing for multiple possible program ids. Useful for any program that implements an instruction interface. For example, spl-token and spl-token-2022 both implement the spl-token interface.

Table of Contents

• Basic Functionality
• Out of the Box Types

Basic Functionality

Checks:

• expected_programs.contains(account_info.key)
• account_info.executable == true

Example

#[program]
mod my_program {
    fn set_admin_settings(...){...}
}

#[account]
#[derive(Default)]
pub struct AdminSettings {
    ...
}

#[derive(Accounts)]
pub struct SetAdminSettings<'info> {
    #[account(mut, seeds = [b"admin"], bump)]
    pub admin_settings: Account<'info, AdminSettings>,
    #[account(constraint = program.programdata_address()? == Some(program_data.key()))]
    pub program: Interface<'info, MyProgram>,
    #[account(constraint = program_data.upgrade_authority_address == Some(authority.key()))]
    pub program_data: Account<'info, ProgramData>,
    pub authority: Signer<'info>,
}

The given program has a function with which the upgrade authority can set admin settings.

The required constraints are as follows:

• program is the account of the program itself. Its constraint checks that program_data is the account that contains the program’s upgrade authority. Implicitly, this checks that program is a BPFUpgradeable program (program.programdata_address()? will be None if it’s not).
• program_data’s constraint checks that its upgrade authority is the authority account.
• Finally, authority needs to sign the transaction.

Out of the Box Types

Between the anchor_lang and anchor_spl crates, the following Interface types are provided out of the box:

• TokenInterface

Implementations

impl<'a, T> Interface<'a, T>

pub fn programdata_address(&self) -> Result<Option<Pubkey>>

Methods from Deref<Target = AccountInfo<'info>>

pub fn signer_key(&self) -> Option<&Pubkey>

pub fn unsigned_key(&self) -> &Pubkey

pub fn lamports(&self) -> u64

pub fn try_lamports(&self) -> Result<u64, ProgramError>

pub unsafe fn original_data_len(&self) -> usize

Return the account’s original data length when it was serialized for the current program invocation.

Safety

This method assumes that the original data length was serialized as a u32 integer in the 4 bytes immediately preceding the serialized account key.

pub fn data_len(&self) -> usize

pub fn try_data_len(&self) -> Result<usize, ProgramError>

pub fn data_is_empty(&self) -> bool

pub fn try_data_is_empty(&self) -> Result<bool, ProgramError>

pub fn try_borrow_lamports(&self) -> Result<Ref<'_, &mut u64>, ProgramError>

pub fn try_borrow_mut_lamports( &self ) -> Result<RefMut<'_, &'a mut u64>, ProgramError>

pub fn try_borrow_data(&self) -> Result<Ref<'_, &mut [u8]>, ProgramError>

pub fn try_borrow_mut_data( &self ) -> Result<RefMut<'_, &'a mut [u8]>, ProgramError>

pub fn realloc( &self, new_len: usize, zero_init: bool ) -> Result<(), ProgramError>

Realloc the account’s data and optionally zero-initialize the new memory.

Note: Account data can be increased within a single call by up to solana_program::entrypoint::MAX_PERMITTED_DATA_INCREASE bytes.

Note: Memory used to grow is already zero-initialized upon program entrypoint and re-zeroing it wastes compute units. If within the same call a program reallocs from larger to smaller and back to larger again the new space could contain stale data. Pass true for zero_init in this case, otherwise compute units will be wasted re-zero-initializing.

Safety

This method makes assumptions about the layout and location of memory referenced by AccountInfo fields. It should only be called for instances of AccountInfo that were created by the runtime and received in the process_instruction entrypoint of a program.

pub fn assign(&self, new_owner: &Pubkey)

pub fn deserialize_data<T>(&self) -> Result<T, Box<ErrorKind>>where T: DeserializeOwned,

pub fn serialize_data<T>(&self, state: &T) -> Result<(), Box<ErrorKind>>where T: Serialize,

Trait Implementations

impl<'info, B, T: CheckId> Accounts<'info, B> for Interface<'info, T>

fn try_accounts( _program_id: &Pubkey, accounts: &mut &'info [AccountInfo<'info>], _ix_data: &[u8], _bumps: &mut B, _reallocs: &mut BTreeSet<Pubkey> ) -> Result<Self>

Returns the validated accounts struct. What constitutes “valid” is program dependent. However, users of these types should never have to worry about account substitution attacks. For example, if a program expects a Mint account from the SPL token program in a particular field, then it should be impossible for this method to return Ok if any other account type is given–from the SPL token program or elsewhere.

impl<'info, T: AccountDeserialize> AccountsExit<'info> for Interface<'info, T>

fn exit(&self, _program_id: &Pubkey) -> Result<()>

program_id is the currently executing program.

impl<'info, T> AsRef<AccountInfo<'info>> for Interface<'info, T>

fn as_ref(&self) -> &AccountInfo<'info>

Converts this type into a shared reference of the (usually inferred) input type.

impl<'info, T: Clone> Clone for Interface<'info, T>

fn clone(&self) -> Interface<'info, T>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<'info, T> Deref for Interface<'info, T>

type Target = AccountInfo<'info>

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl<'info, T: AccountDeserialize> Key for Interface<'info, T>

fn key(&self) -> Pubkey

impl<'info, T> ToAccountInfos<'info> for Interface<'info, T>

fn to_account_infos(&self) -> Vec<AccountInfo<'info>>

impl<'info, T> ToAccountMetas for Interface<'info, T>

fn to_account_metas(&self, is_signer: Option<bool>) -> Vec<AccountMeta>

is_signer is given as an optional override for the signer meta field. This covers the edge case when a program-derived-address needs to relay a transaction from a client to another program but sign the transaction before the relay. The client cannot mark the field as a signer, and so we have to override the is_signer meta field given by the client.

impl<'a, T: CheckId> TryFrom<&'a AccountInfo<'a>> for Interface<'a, T>

fn try_from(info: &'a AccountInfo<'a>) -> Result<Self>

Deserializes the given info into a Program.

type Error = Error

The type returned in the event of a conversion error.