Module introspect 

Instruction introspection – stack height and sibling instruction access.

These wrappers support security patterns based on transaction and call-stack introspection:

• CPI guard: Detect if the current instruction is running inside a CPI call (stack height > 1). Prevents unauthorized composition – e.g., a governance instruction that must be top-level only.

• Precompile inspection: Read a previous sibling’s program ID and data. Program-ID checks alone do not authorize an action. Validate signature count, offsets, referenced instruction bytes, and the expected key/message.

• Secp256k1 recovery: Same pattern for Ethereum-compatible signatures.

Hopper wraps these syscalls behind small typed helpers so programs do not need to repeat raw unsafe glue at every call site.

Structs

ProcessedInstruction

Metadata about a previously processed sibling instruction.

ProcessedInstructionAccount

Account metadata returned by the sibling-instruction syscall.

ProcessedInstructionView

A processed sibling copied into caller-owned scratch buffers.

Constants

ED25519_PROGRAM_ID

Well-known precompile address for Ed25519 signature verification.

SECP256K1_PROGRAM_ID

Well-known precompile address for Secp256k1 signature recovery.

SECP256R1_PROGRAM_ID

Well-known precompile address for Secp256r1 (P-256) signature verification (SIMD-0075). This is the precompile that backs passkey / WebAuthn signature checks on Solana.

Functions

get_processed_instruction

Convenience reader for up to 1,232 data bytes and 64 account metas.

get_processed_instruction_into

Read a processed sibling without heap allocation or fixed-size scratch space.

get_stack_height

Get the current instruction stack height.

is_cpi

Returns true if the current instruction is running inside a CPI.

is_top_level

Returns true if the current instruction is at the top level (not running inside a CPI).

require_cpi

Require that the current instruction IS inside a CPI.

require_ed25519_instruction

Check that a previous sibling instruction was to the Ed25519 precompile.

require_secp256k1_instruction

Check that a previous sibling instruction was to the Secp256k1 precompile. Checks only the program ID, not payload validity or application authorization.

require_secp256r1_instruction

Check that a previous sibling instruction was to the Secp256r1 (P-256) precompile, the verification path for passkeys / WebAuthn.

require_top_level

Require that the current instruction is NOT a CPI call.