feature gate: init program

feature-gate/README.md

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+# Feature Gate Program
+
+This program serves to manage new features on Solana.
+
+It serves two main purposes: activating new features and revoking features that
+are pending activation.
+
+More information & documentation will follow as this program matures, but you
+can follow the discussions
+[here](https://github.com/solana-labs/solana/issues/32780)!

feature-gate/program/Cargo.toml

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+[package]
+name = "spl-feature-gate"
+version = "0.1.0"
+description = "Solana Program Library Feature Gate Program"
+authors = ["Solana Labs Maintainers <[email protected]>"]
+repository = "https://github.com/solana-labs/solana-program-library"
+license = "Apache-2.0"
+edition = "2021"
+
+[features]
+no-entrypoint = []
+test-sbf = []
+
+[dependencies]
+solana-program = "1.16.16"
+spl-program-error = { version = "0.3.0", path = "../../libraries/program-error" }
+
+[dev-dependencies]
+solana-program-test = "1.16.16"
+solana-sdk = "1.16.16"
+
+[lib]
+crate-type = ["cdylib", "lib"]
+
+[package.metadata.docs.rs]
+targets = ["x86_64-unknown-linux-gnu"]

feature-gate/program/src/entrypoint.rs

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+//! Program entrypoint
+
+use {
+    crate::processor,
+    solana_program::{
+        account_info::AccountInfo, entrypoint, entrypoint::ProgramResult, pubkey::Pubkey,
+    },
+};
+
+entrypoint!(process_instruction);
+fn process_instruction(
+    program_id: &Pubkey,
+    accounts: &[AccountInfo],
+    input: &[u8],
+) -> ProgramResult {
+    processor::process(program_id, accounts, input)
+}

feature-gate/program/src/error.rs

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+//! Program error types
+
+use spl_program_error::*;
+
+/// Program specific errors
+#[spl_program_error]
+pub enum FeatureGateError {
+    /// Operation overflowed
+    #[error("Operation overflowed")]
+    Overflow,
+    /// Feature account must be a system account
+    #[error("Feature account must be a system account")]
+    FeatureNotSystemAccount,
+    /// Feature not inactive
+    #[error("Feature not inactive")]
+    FeatureNotInactive,
+}

feature-gate/program/src/instruction.rs

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+//! Program instructions
+
+use solana_program::{
+    feature::Feature,
+    instruction::{AccountMeta, Instruction},
+    program_error::ProgramError,
+    pubkey::Pubkey,
+    rent::Rent,
+    system_instruction, system_program,
+};
+
+/// Feature Gate program instructions
+#[derive(Clone, Debug, PartialEq)]
+pub enum FeatureGateInstruction {
+    /// Submit a feature for activation.
+    ///
+    /// Note: This instruction expects the account to exist and be owned by the
+    /// system program. The account should also have enough rent-exempt lamports
+    /// to cover the cost of the account creation for a
+    /// `solana_program::feature::Feature` state prior to invoking this
+    /// instruction.
+    ///
+    /// Accounts expected by this instruction:
+    ///
+    ///   0. `[w+s]` Feature account (must be a system account)
+    ///   1. `[]` System program
+    Activate,
+    /// Revoke a pending feature activation.
+    ///
+    /// Accounts expected by this instruction:
+    ///
+    ///   0. `[w+s]` Feature account
+    ///   1. `[w]` Destination (for rent lamports)
+    RevokePendingActivation,
+}
+impl FeatureGateInstruction {
+    /// Unpacks a byte buffer into a
+    /// [FeatureGateInstruction](enum.FeatureGateInstruction.html).
+    pub fn unpack(input: &[u8]) -> Result<Self, ProgramError> {
+        if input.is_empty() {
+            return Err(ProgramError::InvalidInstructionData);
+        }
+        match input[0] {
+            0 => Ok(Self::Activate),
+            1 => Ok(Self::RevokePendingActivation),
+            _ => Err(ProgramError::InvalidInstructionData),
+        }
+    }
+
+    /// Packs a [FeatureGateInstruction](enum.FeatureGateInstruction.html) into
+    /// a byte buffer.
+    pub fn pack(&self) -> Vec<u8> {
+        match self {
+            Self::Activate => vec![0],
+            Self::RevokePendingActivation => vec![1],
+        }
+    }
+}
+
+/// Creates an 'Activate' instruction.
+pub fn activate(program_id: &Pubkey, feature: &Pubkey) -> Instruction {
+    let accounts = vec![
+        AccountMeta::new(*feature, true),
+        AccountMeta::new_readonly(system_program::id(), false),
+    ];
+
+    let data = FeatureGateInstruction::Activate.pack();
+
+    Instruction {
+        program_id: *program_id,
+        accounts,
+        data,
+    }
+}
+
+/// Creates a set of two instructions:
+///   * One to fund the feature account with rent-exempt lamports
+///   * Another is the Feature Gate Program's 'Activate' instruction
+pub fn activate_with_rent_transfer(
+    program_id: &Pubkey,
+    feature: &Pubkey,
+    payer: &Pubkey,
+) -> [Instruction; 2] {
+    let lamports = Rent::default().minimum_balance(Feature::size_of());
+    [
+        system_instruction::transfer(payer, feature, lamports),
+        activate(program_id, feature),
+    ]
+}
+
+/// Creates a 'RevokePendingActivation' instruction.
+pub fn revoke(program_id: &Pubkey, feature: &Pubkey, destination: &Pubkey) -> Instruction {
+    let accounts = vec![
+        AccountMeta::new(*feature, true),
+        AccountMeta::new(*destination, false),
+    ];
+
+    let data = FeatureGateInstruction::RevokePendingActivation.pack();
+
+    Instruction {
+        program_id: *program_id,
+        accounts,
+        data,
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    fn test_pack_unpack(instruction: &FeatureGateInstruction) {
+        let packed = instruction.pack();
+        let unpacked = FeatureGateInstruction::unpack(&packed).unwrap();
+        assert_eq!(instruction, &unpacked);
+    }
+
+    #[test]
+    fn test_pack_unpack_activate() {
+        test_pack_unpack(&FeatureGateInstruction::Activate);
+    }
+
+    #[test]
+    fn test_pack_unpack_revoke() {
+        test_pack_unpack(&FeatureGateInstruction::RevokePendingActivation);
+    }
+}

feature-gate/program/src/lib.rs

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+//! Feature Gate program
+
+#![deny(missing_docs)]
+#![cfg_attr(not(test), forbid(unsafe_code))]
+
+mod entrypoint;
+pub mod error;
+pub mod instruction;
+pub mod processor;
+
+// Export current SDK types for downstream users building with a different SDK
+// version
+pub use solana_program;
+
+solana_program::declare_id!("Feature111111111111111111111111111111111111");

feature-gate/program/src/processor.rs

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+//! Program state processor
+
+use {
+    crate::{error::FeatureGateError, instruction::FeatureGateInstruction},
+    solana_program::{
+        account_info::{next_account_info, AccountInfo},
+        entrypoint::ProgramResult,
+        feature::Feature,
+        msg,
+        program::invoke,
+        program_error::ProgramError,
+        pubkey::Pubkey,
+        system_instruction, system_program,
+    },
+};
+
+/// Processes an [Activate](enum.FeatureGateInstruction.html) instruction.
+pub fn process_activate(program_id: &Pubkey, accounts: &[AccountInfo]) -> ProgramResult {
+    let account_info_iter = &mut accounts.iter();
+
+    let feature_info = next_account_info(account_info_iter)?;
+    let _system_program_info = next_account_info(account_info_iter)?;
+
+    if !feature_info.is_signer {
+        return Err(ProgramError::MissingRequiredSignature);
+    }
+
+    if feature_info.owner != &system_program::id() {
+        return Err(FeatureGateError::FeatureNotSystemAccount.into());
+    }
+
+    invoke(
+        &system_instruction::allocate(feature_info.key, Feature::size_of() as u64),
+        &[feature_info.clone()],
+    )?;
+    invoke(
+        &system_instruction::assign(feature_info.key, program_id),
+        &[feature_info.clone()],
+    )?;
+
+    Ok(())
+}
+
+/// Processes an [revoke](enum.FeatureGateInstruction.html) instruction.
+pub fn process_revoke(program_id: &Pubkey, accounts: &[AccountInfo]) -> ProgramResult {
+    let account_info_iter = &mut accounts.iter();
+
+    let feature_info = next_account_info(account_info_iter)?;
+    let destination_info = next_account_info(account_info_iter)?;
+
+    if !feature_info.is_signer {
+        return Err(ProgramError::MissingRequiredSignature);
+    }
+
+    if feature_info.owner != program_id {
+        return Err(ProgramError::IllegalOwner);
+    }
+
+    if Feature::from_account_info(feature_info)?
+        .activated_at
+        .is_some()
+    {
+        return Err(FeatureGateError::FeatureNotInactive.into());
+    }
+
+    let new_destination_lamports = feature_info
+        .lamports()
+        .checked_add(destination_info.lamports())
+        .ok_or::<ProgramError>(FeatureGateError::Overflow.into())?;
+
+    **feature_info.try_borrow_mut_lamports()? = 0;
+    **destination_info.try_borrow_mut_lamports()? = new_destination_lamports;
+
+    feature_info.realloc(0, true)?;
+    feature_info.assign(&system_program::id());
+
+    Ok(())
+}
+
+/// Processes an [Instruction](enum.Instruction.html).
+pub fn process(program_id: &Pubkey, accounts: &[AccountInfo], input: &[u8]) -> ProgramResult {
+    let instruction = FeatureGateInstruction::unpack(input)?;
+    match instruction {
+        FeatureGateInstruction::Activate => {
+            msg!("Instruction: Activate");
+            process_activate(program_id, accounts)
+        }
+        FeatureGateInstruction::RevokePendingActivation => {
+            msg!("Instruction: RevokePendingActivation");
+            process_revoke(program_id, accounts)
+        }
+    }
+}