Implement close examples

programs/9-closing-accounts/insecure-still-still/Cargo.toml

@@ -0,0 +1,19 @@
+[package]
+name = "closing-accounts-insecure-still-still"
+version = "0.1.0"
+description = "Created with Anchor"
+edition = "2018"
+
+[lib]
+crate-type = ["cdylib", "lib"]
+name = "closing_accounts_insecure_still"
+
+[features]
+no-entrypoint = []
+no-idl = []
+no-log-ix-name = []
+cpi = ["no-entrypoint"]
+default = []
+
+[dependencies]
+anchor-lang = "0.20.1"

programs/9-closing-accounts/insecure-still-still/Xargo.toml

@@ -0,0 +1,2 @@
+[target.bpfel-unknown-unknown.dependencies.std]
+features = []

programs/9-closing-accounts/insecure-still-still/src/lib.rs

@@ -0,0 +1,45 @@
+use anchor_lang::prelude::*;
+use std::io::Write;
+use std::ops::DerefMut;
+
+declare_id!("Fg6PaFpoGXkYsidMpWTK6W2BeZ7FEfcYkg476zPFsLnS");
+
+#[program]
+pub mod closing_accounts_insecure_still_still {
+    use super::*;
+
+    pub fn close(ctx: Context<Close>) -> ProgramResult {
+        let account = ctx.accounts.account.to_account_info();
+
+        let dest_starting_lamports = ctx.accounts.destination.lamports();
+
+        **ctx.accounts.destination.lamports.borrow_mut() = dest_starting_lamports
+            .checked_add(account.lamports())
+            .unwrap();
+        **account.lamports.borrow_mut() = 0;
+
+        let mut data = account.try_borrow_mut_data()?;
+        for byte in data.deref_mut().iter_mut() {
+            *byte = 0;
+        }
+
+        let dst: &mut [u8] = &mut data;
+        let mut cursor = std::io::Cursor::new(dst);
+        cursor
+            .write_all(&anchor_lang::__private::CLOSED_ACCOUNT_DISCRIMINATOR)
+            .unwrap();
+
+        Ok(())
+    }
+}
+
+#[derive(Accounts)]
+pub struct Close<'info> {
+    account: Account<'info, Data>,
+    destination: AccountInfo<'info>,
+}
+
+#[account]
+pub struct Data {
+    data: u64,
+}

programs/9-closing-accounts/insecure-still/Cargo.toml

@@ -0,0 +1,19 @@
+[package]
+name = "closing-accounts-insecure-still"
+version = "0.1.0"
+description = "Created with Anchor"
+edition = "2018"
+
+[lib]
+crate-type = ["cdylib", "lib"]
+name = "closing_accounts_insecure_still"
+
+[features]
+no-entrypoint = []
+no-idl = []
+no-log-ix-name = []
+cpi = ["no-entrypoint"]
+default = []
+
+[dependencies]
+anchor-lang = "0.20.1"

programs/9-closing-accounts/insecure-still/Xargo.toml

@@ -0,0 +1,2 @@
+[target.bpfel-unknown-unknown.dependencies.std]
+features = []

programs/9-closing-accounts/insecure-still/src/lib.rs

@@ -0,0 +1,45 @@
+use anchor_lang::prelude::*;
+use std::ops::DerefMut;
+
+declare_id!("Fg6PaFpoGXkYsidMpWTK6W2BeZ7FEfcYkg476zPFsLnS");
+
+#[program]
+pub mod closing_accounts_insecure_still {
+    use super::*;
+
+    pub fn close(ctx: Context<Close>) -> ProgramResult {
+        let account = ctx.accounts.account.to_account_info();
+
+        let dest_starting_lamports = ctx.accounts.destination.lamports();
+
+        **ctx.accounts.destination.lamports.borrow_mut() = dest_starting_lamports
+            .checked_add(account.lamports())
+            .unwrap();
+        **account.lamports.borrow_mut() = 0;
+
+        let mut data = account.try_borrow_mut_data()?;
+        for byte in data.deref_mut().iter_mut() {
+            *byte = 0;
+        }
+
+        Ok(())
+    }
+}
+
+#[derive(Accounts)]
+pub struct Initialize<'info> {
+    #[account(zero)]
+    account: Account<'info, Data>,
+    authority: Signer<'info>,
+}
+
+#[derive(Accounts)]
+pub struct Close<'info> {
+    account: Account<'info, Data>,
+    destination: AccountInfo<'info>,
+}
+
+#[account]
+pub struct Data {
+    data: u64,
+}

programs/9-closing-accounts/insecure/src/lib.rs

@@ -5,10 +5,26 @@ declare_id!("Fg6PaFpoGXkYsidMpWTK6W2BeZ7FEfcYkg476zPFsLnS");
 #[program]
 pub mod closing_accounts_insecure {
     use super::*;
-    pub fn initialize(ctx: Context<Initialize>) -> ProgramResult {
+
+    pub fn close(ctx: Context<Close>) -> ProgramResult {
+        let dest_starting_lamports = ctx.accounts.destination.lamports();
+
+        **ctx.accounts.destination.lamports.borrow_mut() = dest_starting_lamports
+            .checked_add(ctx.accounts.account.to_account_info().lamports())
+            .unwrap();
+        **ctx.accounts.account.to_account_info().lamports.borrow_mut() = 0;
+
         Ok(())
     }
 }
 
 #[derive(Accounts)]
-pub struct Initialize {}
+pub struct Close<'info> {
+    account: Account<'info, Data>,
+    destination: AccountInfo<'info>,
+}
+
+#[account]
+pub struct Data {
+    data: u64,
+}

programs/9-closing-accounts/recommended/src/lib.rs

@@ -5,10 +5,20 @@ declare_id!("Fg6PaFpoGXkYsidMpWTK6W2BeZ7FEfcYkg476zPFsLnS");
 #[program]
 pub mod closing_accounts_recommended {
     use super::*;
-    pub fn initialize(ctx: Context<Initialize>) -> ProgramResult {
+
+    pub fn close(ctx: Context<Close>) -> ProgramResult {
         Ok(())
     }
 }
 
 #[derive(Accounts)]
-pub struct Initialize {}
+pub struct Close<'info> {
+    #[account(mut, close = destination)]
+    account: Account<'info, Data>,
+    destination: AccountInfo<'info>,
+}
+
+#[account]
+pub struct Data {
+    data: u64,
+}

programs/9-closing-accounts/secure/src/lib.rs

@@ -1,14 +1,71 @@
+use anchor_lang::__private::CLOSED_ACCOUNT_DISCRIMINATOR;
 use anchor_lang::prelude::*;
+use std::io::{Cursor, Write};
+use std::ops::DerefMut;
 
 declare_id!("Fg6PaFpoGXkYsidMpWTK6W2BeZ7FEfcYkg476zPFsLnS");
 
 #[program]
 pub mod closing_accounts_secure {
     use super::*;
-    pub fn initialize(ctx: Context<Initialize>) -> ProgramResult {
+
+    pub fn close(ctx: Context<Close>) -> ProgramResult {
+        let dest_starting_lamports = ctx.accounts.destination.lamports();
+
+        let account = ctx.accounts.account.to_account_info();
+        **ctx.accounts.destination.lamports.borrow_mut() = dest_starting_lamports
+            .checked_add(account.lamports())
+            .unwrap();
+        **account.lamports.borrow_mut() = 0;
+
+        let mut data = account.try_borrow_mut_data()?;
+        for byte in data.deref_mut().iter_mut() {
+            *byte = 0;
+        }
+
+        let dst: &mut [u8] = &mut data;
+        let mut cursor = Cursor::new(dst);
+        cursor.write_all(&CLOSED_ACCOUNT_DISCRIMINATOR).unwrap();
+
+        Ok(())
+    }
+
+    pub fn force_defund(ctx: Context<ForceDefund>) -> ProgramResult {
+        let account = &ctx.accounts.account;
+
+        let data = account.try_borrow_data()?;
+        assert!(data.len() > 8);
+
+        let mut discriminator = [0u8; 8];
+        discriminator.copy_from_slice(&data[0..8]);
+        if discriminator == CLOSED_ACCOUNT_DISCRIMINATOR {
+            return Err(ProgramError::InvalidAccountData);
+        }
+
+        let dest_starting_lamports = ctx.accounts.destination.lamports();
+
+        **ctx.accounts.destination.lamports.borrow_mut() = dest_starting_lamports
+            .checked_add(account.lamports())
+            .unwrap();
+        **account.lamports.borrow_mut() = 0;
+
         Ok(())
     }
 }
 
 #[derive(Accounts)]
-pub struct Initialize {}
+pub struct Close<'info> {
+    account: Account<'info, Data>,
+    destination: AccountInfo<'info>,
+}
+
+#[derive(Accounts)]
+pub struct ForceDefund<'info> {
+    account: AccountInfo<'info>,
+    destination: AccountInfo<'info>,
+}
+
+#[account]
+pub struct Data {
+    data: u64,
+}