Program mutable lamports (#4964)

programs/bpf/build.rs

@@ -73,6 +73,7 @@ fn main() {
             "dep_crate",
             "iter",
             "many_args",
+            "external_spend",
             "noop",
             "panic",
             "tick_height",

programs/bpf/rust/external_spend/.gitignore

@@ -0,0 +1,3 @@
+/target/
+
+Cargo.lock

programs/bpf/rust/external_spend/Cargo.toml

@@ -0,0 +1,22 @@
+
+# Note: This crate must be built using build.sh
+
+[package]
+name = "solana-bpf-rust-external-spend"
+version = "0.17.0"
+description = "Solana BPF external spend program written in Rust"
+authors = ["Solana Maintainers <maintainers@solana.com>"]
+repository = "https://github.com/solana-labs/solana"
+license = "Apache-2.0"
+homepage = "https://solana.com/"
+edition = "2018"
+
+[dependencies]
+solana-sdk-bpf-utils = { path = "../../../../sdk/bpf/rust/rust-utils", version = "0.17.0" }
+
+[workspace]
+members = []
+
+[lib]
+crate-type = ["cdylib"]
+name = "solana_bpf_rust_external_spend"

programs/bpf/rust/external_spend/Xargo.toml

@@ -0,0 +1,6 @@
+[dependencies.compiler_builtins]
+path = "../../../../sdk/bpf/dependencies/rust-bpf-sysroot/src/compiler-builtins"
+features = ["c", "mem"]
+
+[target.bpfel-unknown-unknown.dependencies]
+alloc = { path = "../../../../sdk/bpf/dependencies/rust-bpf-sysroot/src/liballoc" }

programs/bpf/rust/external_spend/src/lib.rs

@@ -0,0 +1,21 @@
+//! @brief Example Rust-based BPF program that moves a lamport from one account to another
+
+#![no_std]
+#![allow(unreachable_code)]
+#![allow(unused_attributes)]
+
+extern crate solana_sdk_bpf_utils;
+
+use solana_sdk_bpf_utils::entrypoint::*;
+use solana_sdk_bpf_utils::{entrypoint, info};
+
+entrypoint!(process_instruction);
+fn process_instruction(ka: &mut [SolKeyedAccount], _info: &SolClusterInfo, _data: &[u8]) -> bool {
+    // account 0 is the mint and not owned by this program, any debit of its lamports
+    // should result in a failed program execution.  Test to ensure that this debit
+    // is seen by the runtime and fails as expected
+    *ka[0].lamports -= 1;
+
+    info!("Success");
+    true
+}

programs/bpf/tests/programs.rs

@@ -94,6 +94,7 @@ mod bpf {
                 ("solana_bpf_rust_dep_crate", true),
                 ("solana_bpf_rust_iter", true),
                 // ("solana_bpf_rust_many_args", true),  // Issue #3099
+                ("solana_bpf_rust_external_spend", false),
                 ("solana_bpf_rust_noop", true),
                 ("solana_bpf_rust_panic", false),
             ];
@@ -110,6 +111,7 @@ mod bpf {
                     ..
                 } = create_genesis_block(50);
                 let bank = Bank::new(&genesis_block);
+
                 // register some ticks, used by solana_bpf_rust_tick_height
                 for i in 0..10 {
                     bank.register_tick(&hash::hash(format!("hashing {}", i).as_bytes()));

sdk/bpf/rust/rust-utils/src/entrypoint.rs

@@ -15,7 +15,7 @@ pub struct SolKeyedAccount<'a> {
     /// Public key of the account
     pub is_signer: bool,
     /// Number of lamports owned by this account
-    pub lamports: u64,
+    pub lamports: &'a mut u64,
     /// On-chain data within this account
     pub data: &'a mut [u8],
     /// Program that owns this account
@@ -79,7 +79,7 @@ pub unsafe fn deserialize<'a>(
         offset += size_of::<SolPubkey>();
 
         #[allow(clippy::cast_ptr_alignment)]
-        let lamports = *(input.add(offset) as *const u64);
+        let lamports = &mut *(input.add(offset) as *mut u64);
         offset += size_of::<u64>();
 
         #[allow(clippy::cast_ptr_alignment)]

sdk/bpf/rust/rust-utils/src/log.rs

@@ -82,7 +82,7 @@ pub fn sol_log_params(ka: &[SolKeyedAccount], data: &[u8]) {
         sol_log("- Key");
         sol_log_key(&k.key);
         sol_log("- Lamports");
-        sol_log_64(0, 0, 0, 0, k.lamports);
+        sol_log_64(0, 0, 0, 0, *k.lamports);
         sol_log("- AccountData");
         sol_log_slice(k.data);
         sol_log("- Owner");