Allow programs to realloc their accounts within limits (#19475)

programs/bpf/rust/realloc/src/instructions.rs

@@ -0,0 +1,71 @@
+//! @brief Example Rust-based BPF realloc test program
+
+use solana_program::{
+    instruction::{AccountMeta, Instruction},
+    pubkey::Pubkey,
+};
+
+pub const REALLOC: u8 = 1;
+pub const REALLOC_EXTEND: u8 = 2;
+pub const REALLOC_EXTEND_AND_FILL: u8 = 3;
+pub const REALLOC_AND_ASSIGN: u8 = 4;
+pub const REALLOC_AND_ASSIGN_TO_SELF_VIA_SYSTEM_PROGRAM: u8 = 5;
+pub const ASSIGN_TO_SELF_VIA_SYSTEM_PROGRAM_AND_REALLOC: u8 = 6;
+pub const DEALLOC_AND_ASSIGN_TO_CALLER: u8 = 7;
+pub const CHECK: u8 = 8;
+pub const ZERO_INIT: u8 = 9;
+
+pub fn realloc(program_id: &Pubkey, address: &Pubkey, size: usize, bump: &mut u8) -> Instruction {
+    let mut instruction_data = vec![REALLOC, *bump];
+    instruction_data.extend_from_slice(&size.to_le_bytes());
+
+    *bump += 1;
+
+    Instruction::new_with_bytes(
+        *program_id,
+        &instruction_data,
+        vec![AccountMeta::new(*address, false)],
+    )
+}
+
+pub fn realloc_extend(
+    program_id: &Pubkey,
+    address: &Pubkey,
+    size: usize,
+    bump: &mut u8,
+) -> Instruction {
+    let mut instruction_data = vec![REALLOC_EXTEND, *bump];
+    instruction_data.extend_from_slice(&size.to_le_bytes());
+
+    *bump += 1;
+
+    Instruction::new_with_bytes(
+        *program_id,
+        &instruction_data,
+        vec![AccountMeta::new(*address, false)],
+    )
+}
+
+pub fn realloc_extend_and_fill(
+    program_id: &Pubkey,
+    address: &Pubkey,
+    size: usize,
+    fill: u8,
+    bump: &mut u64,
+) -> Instruction {
+    let mut instruction_data = vec![
+        REALLOC_EXTEND_AND_FILL,
+        fill,
+        *bump as u8,
+        (*bump / 255) as u8,
+    ];
+    instruction_data.extend_from_slice(&size.to_le_bytes());
+
+    *bump += 1;
+
+    Instruction::new_with_bytes(
+        *program_id,
+        &instruction_data,
+        vec![AccountMeta::new(*address, false)],
+    )
+}