hopper-native 0.4.3

//! Program entrypoint ownership for Hopper Native.
//!
//! This file is the only raw program-entry boundary owner in Hopper Native.
//! Loader input parsing lives in [`crate::raw_input`], while the public macros
//! below own the raw `entrypoint(input: *mut u8)` boundary and delegate into
//! Hopper callbacks.

use core::mem::MaybeUninit;

use crate::account_view::AccountView;
use crate::address::Address;
use crate::error::ProgramError;

/// Convert a handler's `ProgramError` into the Solana runtime's u64 return code.
///
/// Outlined `#[cold] #[inline(never)]` so an entrypoint's success tail lowers to
/// a bare `return SUCCESS` and the `ProgramError -> u64` mapping (the 25-arm
/// `From<ProgramError> for u64` match) is never inlined into the hot frame,
/// where it would add code size and stack traffic that every successful
/// invocation pays for. This mirrors Pinocchio's cold error outline.
///
/// The conversion is exactly `Into::<u64>::into(e)`, byte-for-byte identical to
/// the previous inline `error.into()`, so the runtime error codes are unchanged.
#[cold]
#[inline(never)]
pub fn err_to_u64(e: ProgramError) -> u64 {
    e.into()
}

/// Process the BPF entrypoint input.
///
/// This is the function called by the canonical Hopper Native entrypoint macro's
/// generated entrypoint.
///
/// # Safety
///
/// `input` must be the raw pointer provided by the Solana runtime.
#[inline(always)]
pub unsafe fn process_entrypoint<const MAX: usize>(
    input: *mut u8,
    process_instruction: for<'info> fn(
        &'info Address,
        &'info [AccountView<'info>],
        &'info [u8],
    ) -> crate::ProgramResult,
) -> u64 {
    const UNINIT: MaybeUninit<AccountView<'static>> = MaybeUninit::uninit();
    let mut accounts = [UNINIT; 254]; // MAX_TX_ACCOUNTS

    let (program_id, count, instruction_data) =
        // SAFETY: This block is part of Hopper's reviewed zero-copy/backend boundary; surrounding checks and caller contracts uphold the required raw-pointer, layout, and aliasing invariants.
        unsafe { crate::raw_input::deserialize_accounts::<254>(input, &mut accounts) };

    // Respect MAX: only pass up to MAX accounts to the callback.
    let effective_count = count.min(MAX);
    // SAFETY: This block is part of Hopper's reviewed zero-copy/backend boundary; surrounding checks and caller contracts uphold the required raw-pointer, layout, and aliasing invariants.
    let account_slice = unsafe {
        core::slice::from_raw_parts(accounts.as_ptr() as *const AccountView<'_>, effective_count)
    };

    match process_instruction(program_id, account_slice, instruction_data) {
        Ok(()) => crate::SUCCESS,
        Err(error) => err_to_u64(error),
    }
}

/// Declare the canonical Hopper Native program entrypoint.
///
/// Generates the `extern "C" fn entrypoint` that the Solana runtime calls.
/// `program_entrypoint!` remains available as a backward-compatible alias.
///
/// # Usage
///
/// ```ignore
/// use hopper_native::hopper_program_entrypoint;
///
/// hopper_program_entrypoint!(process_instruction);
///
/// pub fn process_instruction(
///     program_id: &Address,
///     accounts: &[AccountView],
///     instruction_data: &[u8],
/// ) -> ProgramResult {
///     Ok(())
/// }
/// ```
#[macro_export]
macro_rules! hopper_program_entrypoint {
    ( $process_instruction:expr ) => {
        $crate::hopper_program_entrypoint!($process_instruction, { $crate::MAX_TX_ACCOUNTS });
    };
    ( $process_instruction:expr, $maximum:expr ) => {
        /// # Safety
        ///
        /// Called by the Solana runtime; `input` is a valid BPF input buffer.
        #[no_mangle]
        pub unsafe extern "C" fn entrypoint(input: *mut u8) -> u64 {
            const UNINIT: core::mem::MaybeUninit<$crate::AccountView<'static>> =
                core::mem::MaybeUninit::<$crate::AccountView<'static>>::uninit();
            let mut accounts = [UNINIT; $maximum];

            // SAFETY: This block is part of Hopper's reviewed zero-copy/backend boundary; surrounding checks and caller contracts uphold the required raw-pointer, layout, and aliasing invariants.
            let (program_id, count, instruction_data) = unsafe {
                $crate::raw_input::deserialize_accounts::<$maximum>(input, &mut accounts)
            };

            match $process_instruction(
                program_id,
                // SAFETY: This block is part of Hopper's reviewed zero-copy/backend boundary; surrounding checks and caller contracts uphold the required raw-pointer, layout, and aliasing invariants.
                unsafe {
                    core::slice::from_raw_parts(
                        accounts.as_ptr() as *const $crate::AccountView<'_>,
                        count,
                    )
                },
                instruction_data,
            ) {
                Ok(()) => $crate::SUCCESS,
                Err(error) => $crate::entrypoint::err_to_u64(error),
            }
        }
    };
}

/// Backward-compatible alias for `hopper_program_entrypoint!`.
#[macro_export]
macro_rules! program_entrypoint {
    ( $process_instruction:expr ) => {
        $crate::hopper_program_entrypoint!($process_instruction);
    };
    ( $process_instruction:expr, $maximum:expr ) => {
        $crate::hopper_program_entrypoint!($process_instruction, $maximum);
    };
}

/// Declare a fast two-argument Hopper Native program entrypoint.
///
/// Uses the SVM's second entrypoint register (`r2`), which carries a
/// direct pointer to instruction data under [SIMD-0321], letting the
/// entrypoint skip locating the instruction tail. Measured honestly
/// (2026-07-21, post the 2026-07-07 fused single-pass walk): the fused
/// scanning entrypoint already hops records by their `data_len` headers
/// without touching account data, so on programs whose accounts fit the
/// declared maximum the r2 path is CU-neutral (+/- 2 CU in controlled
/// A/Bs) and costs ~368 bytes for carrying both paths. The historical
/// "~30-40 CU" figure described the pre-fusion two-pass scanner. The r2
/// path earns its keep as the base of the SIMD-0449 O(1) account-pointer
/// table, and for instructions whose transaction carries many more
/// accounts than the program materializes.
///
/// # Feature gating (`simd-0321`)
///
/// SIMD-0321 is **activated on all three public clusters** (feature gate
/// `5xXZc66h4UdB6Yq7FzdBxBiRAFMMScMLwHxk2QZDaNZL`; mainnet-beta at slot
/// 410,400,000, 2026-04-01). Current agave sets `r2` unconditionally, so
/// builds may enable the feature for any cluster target; on a runtime
/// that ever leaves `r2` zero, the null-check below still falls back to
/// the scanning parse.
///
/// - **Default (feature off):** this macro expands to the standard
///   scanning entrypoint ([`hopper_program_entrypoint!`]). Identical
///   semantics, sound on every cluster today, and source-compatible:
///   when the gate activates, rebuild with the feature to claim the
///   CU savings.
/// - **`simd-0321` enabled:** the macro expands to the two-argument
///   entrypoint. As defense in depth it null-checks `r2` and falls
///   back to the scanning parse when the register is zero (current
///   SBPF VMs zero-initialize unused argument registers), so a binary
///   built with the feature degrades to the slow path instead of
///   reading garbage if it lands on a cluster without the activation.
///
/// `hopper doctor` / `hopper deploy` can check the feature-gate account
/// on the target cluster before a `simd-0321` build ships.
///
/// [SIMD-0321]: https://github.com/solana-foundation/solana-improvement-documents/blob/main/proposals/0321-vm-r2-instruction-data-pointer.md
///
/// # Usage
///
/// ```ignore
/// use hopper_native::hopper_fast_entrypoint;
///
/// hopper_fast_entrypoint!(process_instruction, 3);
///
/// pub fn process_instruction(
///     program_id: &Address,
///     accounts: &[AccountView],
///     instruction_data: &[u8],
/// ) -> ProgramResult {
///     Ok(())
/// }
/// ```
#[cfg(feature = "simd-0321")]
#[macro_export]
macro_rules! hopper_fast_entrypoint {
    ( $process_instruction:expr ) => {
        $crate::hopper_fast_entrypoint!($process_instruction, { $crate::MAX_TX_ACCOUNTS });
    };
    ( $process_instruction:expr, $maximum:expr ) => {
        /// # Safety
        ///
        /// Called by the Solana runtime; `input` is a valid BPF input buffer.
        /// When SIMD-0321 is active, `ix_data` points to the instruction data
        /// with its u64 length stored at offset -8; when it is not active the
        /// register is zero and the scanning fallback below is taken.
        #[no_mangle]
        pub unsafe extern "C" fn entrypoint(input: *mut u8, ix_data: *const u8) -> u64 {
            const UNINIT: core::mem::MaybeUninit<$crate::AccountView<'static>> =
                core::mem::MaybeUninit::<$crate::AccountView<'static>>::uninit();
            let mut accounts = [UNINIT; $maximum];

            let (program_id, count, instruction_data) = if ix_data.is_null() {
                // SIMD-0321 not active on this cluster: r2 is zero. Fall back
                // to the full scanning parse so the program stays correct.
                // SAFETY: `input` is the loader-provided input buffer; the
                // scanning parser owns all bounds/duplicate-marker checks.
                unsafe { $crate::raw_input::deserialize_accounts::<$maximum>(input, &mut accounts) }
            } else {
                // Instruction data length is the u64 immediately before the
                // data pointer (per SIMD-0321's serialization contract).
                // SAFETY: SIMD-0321 ix_data points at instruction-data bytes
                // with u64 length prefix at `ix_data - 8`.
                let ix_len =
                    unsafe { core::ptr::read_unaligned(ix_data.sub(8) as *const u64) as usize };
                let instruction_data: &'static [u8] =
                    unsafe { core::slice::from_raw_parts(ix_data, ix_len) };

                // SAFETY: program id trails the instruction data per the
                // loader serialization layout; `Address` is a transparent
                // `[u8; 32]`, so a reference into the buffer is valid at any
                // offset and lives as long as the invocation.
                let program_id: &'static $crate::Address =
                    unsafe { &*(ix_data.add(ix_len) as *const $crate::Address) };

                if $crate::raw_input::SIMD_0449_TABLE_ENABLED {
                    // SIMD-0449 build: consume the runtime's appended
                    // pre-deduplicated account-pointer table, O(1)
                    // resolution plus one pointer copy per account. The
                    // gate is a `const`, so the untaken branch folds
                    // away entirely.
                    // SAFETY: the `simd-0449` feature asserts the SIMD
                    // is active on the target cluster (table present);
                    // `instruction_data`/`program_id` were derived from
                    // the SIMD-0321 r2 register above.
                    unsafe {
                        $crate::raw_input::deserialize_accounts_0449_into::<$maximum>(
                            input,
                            &mut accounts,
                            instruction_data,
                            program_id,
                        )
                    }
                } else {
                    // SAFETY: `input` is the loader input buffer; account-slot
                    // framing is validated by `deserialize_accounts_fast`.
                    unsafe {
                        $crate::raw_input::deserialize_accounts_fast::<$maximum>(
                            input,
                            &mut accounts,
                            instruction_data,
                            program_id,
                        )
                    }
                }
            };

            match $process_instruction(
                program_id,
                // SAFETY: the first `count` slots were initialized by the
                // parser above; `AccountView` is repr(C) over the slot data.
                unsafe {
                    core::slice::from_raw_parts(
                        accounts.as_ptr() as *const $crate::AccountView<'_>,
                        count,
                    )
                },
                instruction_data,
            ) {
                Ok(()) => $crate::SUCCESS,
                Err(error) => $crate::entrypoint::err_to_u64(error),
            }
        }
    };
}

/// Without the `simd-0321` feature the "fast" entrypoint is an alias for
/// the standard scanning entrypoint. The SIMD-0321 gate is live on every
/// public cluster (mainnet-beta 2026-04-01); the r2 form is sound to build
/// and stays opt-in only because it measured CU-neutral against the fused
/// scanning walk for ~368 bytes of extra `.text`. The two-argument r2 form
/// also null-checks the register and falls back to scanning, so it is safe
/// even where the gate is somehow inactive.
#[cfg(not(feature = "simd-0321"))]
#[macro_export]
macro_rules! hopper_fast_entrypoint {
    ( $process_instruction:expr ) => {
        $crate::hopper_program_entrypoint!($process_instruction);
    };
    ( $process_instruction:expr, $maximum:expr ) => {
        $crate::hopper_program_entrypoint!($process_instruction, $maximum);
    };
}

/// Backward-compatible alias for `hopper_fast_entrypoint!`.
#[macro_export]
macro_rules! fast_entrypoint {
    ( $process_instruction:expr ) => {
        $crate::hopper_fast_entrypoint!($process_instruction);
    };
    ( $process_instruction:expr, $maximum:expr ) => {
        $crate::hopper_fast_entrypoint!($process_instruction, $maximum);
    };
}

/// Declare the canonical lazy program entrypoint that defers account parsing.
#[macro_export]
macro_rules! hopper_lazy_entrypoint {
    ( $process:expr ) => {
        /// # Safety
        ///
        /// Called by the Solana runtime; `input` is a valid BPF input buffer.
        #[no_mangle]
        pub unsafe extern "C" fn entrypoint(input: *mut u8) -> u64 {
            // SAFETY: This block is part of Hopper's reviewed zero-copy/backend boundary; surrounding checks and caller contracts uphold the required raw-pointer, layout, and aliasing invariants.
            let mut ctx = unsafe { $crate::lazy::lazy_deserialize(input) };
            match $process(&mut ctx) {
                Ok(()) => $crate::SUCCESS,
                Err(error) => $crate::entrypoint::err_to_u64(error),
            }
        }
    };
}

/// Backward-compatible alias for `hopper_lazy_entrypoint!`.
#[macro_export]
macro_rules! lazy_entrypoint {
    ( $process:expr ) => {
        $crate::hopper_lazy_entrypoint!($process);
    };
}

/// Set up a no-op global allocator that aborts on allocation.
///
/// Useful for `no_std` programs that must not allocate. Any attempt to
/// allocate immediately aborts the invocation through the SVM's abort syscall.
/// No experimental inline assembly is required. Returning null would also be
/// valid for `GlobalAlloc`; this allocator deliberately fails immediately.
#[macro_export]
macro_rules! no_allocator {
    () => {
        #[cfg(target_os = "solana")]
        mod __hopper_allocator {
            struct NoAlloc;

            unsafe impl core::alloc::GlobalAlloc for NoAlloc {
                unsafe fn alloc(&self, _layout: core::alloc::Layout) -> *mut u8 {
                    // SAFETY: abort accepts no pointers and never returns.
                    unsafe { $crate::syscalls::abort() }
                }
                unsafe fn dealloc(&self, _ptr: *mut u8, _layout: core::alloc::Layout) {}
            }

            #[global_allocator]
            static ALLOCATOR: NoAlloc = NoAlloc;
        }
    };
}

/// Canonical Solana heap region start address (`0x3_0000_0000`).
pub const HEAP_START_ADDRESS: usize = 0x3_0000_0000;

/// Default Solana heap region length (32 KiB).
pub const HEAP_LENGTH: usize = 32 * 1024;

/// Bytes of the heap's BOTTOM reserved as Hopper runtime scratch, starting
/// right after the [`BumpAllocator`] cursor word: the byte range
/// `[HEAP_START + 8, HEAP_START + 8 + HEAP_RUNTIME_RESERVED)`.
///
/// Why this exists: deployed SBF programs cannot carry writable sections,
/// the loader rejects `.bss`/`.data` outright (`WritableSectionNotSupported`),
/// so a `static mut` is not merely costly, it makes the program FAIL TO
/// LOAD. The only writable, per-invocation, zero-initialized memory a
/// program owns is this VM heap region. Hopper's instruction-scoped
/// runtime state (today: the lamport gate in
/// `hopper_runtime::write_policy`) therefore lives at the heap bottom,
/// which works precisely because the VM zeroes the region on every
/// invocation and every such structure is valid all-zero.
///
/// The [`BumpAllocator`] treats this range as out of bounds (its floor sits
/// above it), so `alloc` can never hand it out. Programs that install a
/// custom allocator over the heap must honor the same reservation if they
/// link any hopper-runtime feature that uses it.
pub const HEAP_RUNTIME_RESERVED: usize = 20 * 1024;

/// A bump allocator over the SVM heap region.
///
/// This is the same single-pass, never-frees design the Solana SDK and
/// Pinocchio use: the first word of the heap stores the current cursor,
/// allocations bump it downward from the top of the region, and
/// `dealloc` is a no-op. It is the right allocator for the cold paths of
/// a program that wants `alloc` (e.g. a `Vec` while building a CPI) while
/// keeping the hot path zero-allocation. For programs that must never
/// allocate, prefer [`no_allocator!`] so any stray allocation traps.
///
/// Install it with `default_allocator!`.
pub struct BumpAllocator {
    /// Heap region start address.
    pub start: usize,
    /// Heap region length in bytes.
    pub len: usize,
}

// SAFETY: Solana program execution is single-threaded, so the cursor word
// at `start` is never accessed concurrently.
unsafe impl core::alloc::GlobalAlloc for BumpAllocator {
    #[inline]
    unsafe fn alloc(&self, layout: core::alloc::Layout) -> *mut u8 {
        // The cursor is stored in the first word of the heap region.
        let pos_ptr = self.start as *mut usize;
        // SAFETY: `pos_ptr` is the reserved cursor word; single-threaded.
        let mut pos = unsafe { *pos_ptr };
        if pos == 0 {
            // First allocation: start at the top of the region.
            pos = self.start + self.len;
        }
        pos = pos.saturating_sub(layout.size());
        pos &= !(layout.align().wrapping_sub(1));
        // Floor: the cursor word plus the Hopper runtime scratch region
        // ([`HEAP_RUNTIME_RESERVED`], heap bottom). Bumping into either
        // would corrupt the allocator state or the instruction-scoped
        // runtime state (e.g. the lamport gate), so exhaust instead.
        if pos < self.start + core::mem::size_of::<usize>() + HEAP_RUNTIME_RESERVED {
            return core::ptr::null_mut();
        }
        // SAFETY: `pos_ptr` is the reserved cursor word; single-threaded.
        unsafe { *pos_ptr = pos };
        pos as *mut u8
    }

    #[inline]
    unsafe fn dealloc(&self, _ptr: *mut u8, _layout: core::alloc::Layout) {
        // Bump allocator: memory is reclaimed when the instruction ends.
    }
}

/// Install the default bump allocator over the SVM heap region.
///
/// Opt-in counterpart to [`no_allocator!`]: use this when a program needs
/// `alloc` (e.g. heap `Vec`/`String` on a cold path) while keeping the
/// zero-copy hot path allocation-free. Never frees within an instruction;
/// the whole heap is reclaimed when the instruction returns.
#[macro_export]
macro_rules! default_allocator {
    () => {
        #[cfg(target_os = "solana")]
        #[global_allocator]
        static ALLOCATOR: $crate::BumpAllocator = $crate::BumpAllocator {
            start: $crate::HEAP_START_ADDRESS,
            len: $crate::HEAP_LENGTH,
        };
    };
}

/// Default no_std panic handler that aborts immediately.
///
/// Uses the SVM abort syscall, without experimental inline assembly or a
/// compute-consuming spin loop. The runtime rolls back the failed instruction.
#[macro_export]
macro_rules! nostd_panic_handler {
    () => {
        #[cfg(target_os = "solana")]
        #[panic_handler]
        fn panic(_info: &core::panic::PanicInfo) -> ! {
            // SAFETY: abort accepts no pointers and never returns.
            unsafe { $crate::syscalls::abort() }
        }
    };
}

#[cfg(test)]
mod entrypoint_tail_tests {
    extern crate std;

    use std::vec;
    use std::vec::Vec;

    use super::*;

    /// Serialize a zero-account loader frame: `u64` account count (0), then the
    /// `u64` ix-data length prefix, the ix-data bytes, and the 32-byte program
    /// id. Returns an 8-aligned `u64` backing (matching `MM_INPUT_START`).
    fn build_zero_account_frame(ix_data: &[u8], program_id: [u8; 32]) -> Vec<u64> {
        let mut buf: Vec<u8> = Vec::new();
        buf.extend_from_slice(&0u64.to_le_bytes()); // account_count = 0
        buf.extend_from_slice(&(ix_data.len() as u64).to_le_bytes());
        buf.extend_from_slice(ix_data);
        buf.extend_from_slice(&program_id);
        let mut words = vec![0u64; buf.len().div_ceil(8)];
        // SAFETY: `words` has at least `buf.len()` bytes of capacity and the
        // regions do not overlap.
        unsafe {
            core::ptr::copy_nonoverlapping(buf.as_ptr(), words.as_mut_ptr() as *mut u8, buf.len());
        }
        words
    }

    fn ok_handler<'a>(
        _: &'a Address,
        _: &'a [AccountView<'a>],
        _: &'a [u8],
    ) -> crate::ProgramResult {
        Ok(())
    }

    fn custom_err_handler<'a>(
        _: &'a Address,
        _: &'a [AccountView<'a>],
        _: &'a [u8],
    ) -> crate::ProgramResult {
        Err(ProgramError::Custom(4242))
    }

    fn builtin_err_handler<'a>(
        _: &'a Address,
        _: &'a [AccountView<'a>],
        _: &'a [u8],
    ) -> crate::ProgramResult {
        Err(ProgramError::MissingRequiredSignature)
    }

    #[test]
    fn ok_returns_bare_success_zero() {
        let mut frame = build_zero_account_frame(&[1, 2, 3], [7u8; 32]);
        // SAFETY: `frame` is a well-formed, 8-aligned zero-account loader frame.
        let code = unsafe { process_entrypoint::<4>(frame.as_mut_ptr() as *mut u8, ok_handler) };
        assert_eq!(code, 0);
        assert_eq!(code, crate::SUCCESS);
    }

    #[test]
    fn custom_err_maps_through_cold_outline_unchanged() {
        let mut frame = build_zero_account_frame(&[], [0u8; 32]);
        // SAFETY: well-formed, 8-aligned zero-account loader frame.
        let code =
            unsafe { process_entrypoint::<4>(frame.as_mut_ptr() as *mut u8, custom_err_handler) };
        // Cold outline must equal the direct `From<ProgramError> for u64` mapping.
        assert_eq!(code, u64::from(ProgramError::Custom(4242)));
        assert_eq!(code, err_to_u64(ProgramError::Custom(4242)));
        assert_eq!(code, 4242);
    }

    #[test]
    fn builtin_err_maps_through_cold_outline_unchanged() {
        let mut frame = build_zero_account_frame(&[], [0u8; 32]);
        // SAFETY: well-formed, 8-aligned zero-account loader frame.
        let code =
            unsafe { process_entrypoint::<4>(frame.as_mut_ptr() as *mut u8, builtin_err_handler) };
        assert_eq!(code, u64::from(ProgramError::MissingRequiredSignature));
        assert_eq!(code, err_to_u64(ProgramError::MissingRequiredSignature));
    }

    /// The cold outline is a byte-for-byte alias of `From<ProgramError> for u64`
    /// across the full variant space (custom-zero, custom, and builtins).
    #[test]
    fn err_to_u64_matches_from_impl_for_all_variants() {
        let cases = [
            ProgramError::Custom(0),
            ProgramError::Custom(1),
            ProgramError::Custom(u32::MAX),
            ProgramError::InvalidArgument,
            ProgramError::MissingRequiredSignature,
            ProgramError::AccountBorrowFailed,
            ProgramError::ArithmeticOverflow,
            ProgramError::IncorrectAuthority,
        ];
        for e in cases {
            assert_eq!(err_to_u64(e.clone()), u64::from(e));
        }
    }
}