Function process_update

programs/asset/program/src/processor/update.rs:41–380

(
    program_id: &Pubkey,
    ctx: Context<Update>,
    args: UpdateInput,
)

///   3. `[optional]` system_program
#[inline(always)]
pub fn process_update(
    program_id: &Pubkey,
    ctx: Context<Update>,
    args: UpdateInput,
) -> ProgramResult {
    // account validation

    require!(
        ctx.accounts.authority.is_signer(),
        ProgramError::MissingRequiredSignature,
        "authority"
    );

    require!(
        ctx.accounts.asset.owner() == program_id,
        ProgramError::IllegalOwner,
        "asset"
    );

    let mut account_data = ctx.accounts.asset.try_borrow_mut_data()?;

    require!(
        account_data.len() >= Asset::LEN && account_data[0] == Discriminator::Asset.into(),
        AssetError::Uninitialized,
        "asset"
    );

    let asset = Asset::load_mut(&mut account_data);

    require!(
        asset.authority == *ctx.accounts.authority.key(),
        AssetError::InvalidAuthority,
        "authority"
    );

    require!(
        <PodBool as Into<bool>>::into(asset.mutable),
        AssetError::ImmutableAsset,
        "asset"
    );

    // updates the asset:
    //
    //   1. name
    //   2. mutable flag
    //   3. extension

    if let Some(name) = args.name {
        asset.name = name.into();
    }

    if let Some(mutable) = args.mutable {
        asset.mutable = mutable.into();
    }

    // creating/updating an extension is a multi-step process:
    //
    //   1. find the extension to update or determine that it is a new one