Struct LamportSnapshot 

pub struct LamportSnapshot { /* private fields */ }

Snapshot of lamport balances for two accounts before a CPI.

Captures the source and destination balances so that after the CPI completes, we can verify the expected transfer occurred.

Implementations

impl LamportSnapshot

pub fn capture(source: &AccountView, destination: &AccountView) -> Self

Capture the current lamport balances of source and destination.

pub fn verify_transfer( &self, source: &AccountView, destination: &AccountView, amount: u64, ) -> ProgramResult

Verify that exactly amount lamports moved from source to destination.

Checks:

1. Source decreased by exactly amount
2. Destination increased by exactly amount
3. No overflow/underflow occurred

pub fn verify_deduction( &self, source: &AccountView, amount: u64, ) -> ProgramResult

Verify that the source decreased by exactly amount (one-sided check).

Use this when the destination is a program-controlled escrow or fee account where you only care about the deduction.

pub fn verify_unchanged( &self, source: &AccountView, destination: &AccountView, ) -> ProgramResult

Verify that neither balance changed (no-op CPI or read-only call).

pub fn source_before(&self) -> u64

Get the pre-CPI source balance.

pub fn destination_before(&self) -> u64

Get the pre-CPI destination balance.

Trait Implementations

impl Clone for LamportSnapshot

fn clone(&self) -> LamportSnapshot

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for LamportSnapshot

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Copy for LamportSnapshot