p-token: Add withdraw_excess_lamports instruction (#36)

* Update workspace

* Rename interface crate

* Fix spelling

* [wip]: Fix review comments

* A few more fixes

* Fix merge

* Update workspace

* Rename interface crate

* Fix spelling

* [wip]: Fix review comments

* Add withdraw_excess_lamports instruction

* Add test

* Add missing safety comments

* Add more tests

* Fix merge

* Use assert_matches

Author: febo

Cargo.lock

@@ -478,6 +478,18 @@ pub enum TokenInstruction {
     ///   - `&str` The `ui_amount` of tokens to reformat.
     UiAmountToAmount,
 
+    /// This instruction is to be used to rescue SOL sent to any `TokenProgram`
+    /// owned account by sending them to any other account, leaving behind only
+    /// lamports for rent exemption.
+    ///
+    /// Accounts expected by this instruction:
+    ///
+    ///   0. `[writable]` Source Account owned by the token program
+    ///   1. `[writable]` Destination account
+    ///   2. `[signer]` Authority
+    ///   3. `..+M` `[signer]` M signer accounts.
+    WithdrawExcessLamports = 38,
+
     /// Executes a batch of instructions. The instructions to be executed are specified
     /// in sequence on the instruction data. Each instruction provides:
     ///   - `u8`: number of accounts
@@ -506,7 +518,7 @@ impl TryFrom<u8> for TokenInstruction {
     fn try_from(value: u8) -> Result<Self, Self::Error> {
         match value {
             // SAFETY: `value` is guaranteed to be in the range of the enum variants.
-            0..=24 | 255 => Ok(unsafe { core::mem::transmute::<u8, TokenInstruction>(value) }),
+            0..=24 | 38 | 255 => Ok(unsafe { core::mem::transmute::<u8, TokenInstruction>(value) }),
             _ => Err(ProgramError::InvalidInstructionData),
         }
     }

interface/src/instruction.rs

@@ -21,7 +21,9 @@ spl-token-interface = { version = "^0", path = "../interface" }
 
 [dev-dependencies]
 assert_matches = "1.5.0"
+num-traits = "0.2"
 solana-program-test = "2.1"
 solana-sdk = "2.1"
 spl-token = { version="^4", features=["no-entrypoint"] }
+spl-token-2022 = { version="^7", features=["no-entrypoint"] }
 test-case = "3.3.1"

p-token/Cargo.toml

@@ -257,6 +257,13 @@ fn inner_process_remaining_instruction(
 
             process_ui_amount_to_amount(accounts, instruction_data)
         }
+        // 38 - WithdrawExcessLamports
+        38 => {
+            #[cfg(feature = "logging")]
+            pinocchio::msg!("Instruction: WithdrawExcessLamports");
+
+            process_withdraw_excess_lamports(accounts)
+        }
         _ => Err(ProgramError::InvalidInstructionData),
     }
 }