Add scaffold subcommand

Signed-off-by: Ludvig Liljenberg <4257730+ludfjig@users.noreply.github.com>

Author: ludfjig

.github/workflows/ci.yml

@@ -41,6 +41,9 @@ jobs:
     - name: Run example
       shell: bash
       run: just run-guest
+    - name: Test scaffold
+      shell: bash
+      run: just test-scaffold
 
   spelling:
     name: Spell check with typos

justfile

@@ -7,11 +7,15 @@ fmt:
     cargo +nightly fmt --all -- --check
     cargo +nightly fmt --all --manifest-path ./examples/host/Cargo.toml -- --check
     cargo +nightly fmt --all --manifest-path ./examples/guest/Cargo.toml -- --check
+    # These are standalone template files not part of any crate, so cargo fmt wont find them.
+    rustfmt +nightly --check ./src/scaffold/guest/_main.rs ./src/scaffold/host/_main.rs
 
 fmt-apply:
     cargo +nightly fmt --all
     cargo +nightly fmt --all --manifest-path ./examples/host/Cargo.toml
     cargo +nightly fmt --all --manifest-path ./examples/guest/Cargo.toml
+    # These are standalone template files not part of any crate, so cargo fmt wont find them.
+    rustfmt +nightly ./src/scaffold/guest/_main.rs ./src/scaffold/host/_main.rs
 
 clippy:
     cargo clippy --all -- -D warnings
@@ -22,4 +26,7 @@ build-guest:
     cargo hyperlight build --manifest-path ./examples/guest/Cargo.toml
 
 run-guest: build-guest
-    cargo run --manifest-path ./examples/host/Cargo.toml -- ./target/x86_64-hyperlight-none/debug/guest
+    cargo run --manifest-path ./examples/host/Cargo.toml -- ./target/x86_64-hyperlight-none/debug/guest
+
+test-scaffold:
+    cargo test --test scaffold

src/main.rs

@@ -3,6 +3,7 @@ use std::env;
 use cargo_hyperlight::cargo;
 
 mod perf;
+mod scaffold;
 
 const VERSION: &str = env!("CARGO_PKG_VERSION");
 const GIT_HASH: &str = env!("GIT_HASH");
@@ -26,6 +27,12 @@ fn main() {
                 std::process::exit(1);
             }
         }
+        Some(a) if a == "scaffold" => {
+            if let Err(e) = scaffold::run(args) {
+                eprintln!("{e:?}");
+                std::process::exit(1);
+            }
+        }
         _ => {
             cargo()
                 .expect("Failed to create cargo command")

src/scaffold/_gitignore

@@ -0,0 +1 @@
+target

src/scaffold/guest/_Cargo.toml

@@ -0,0 +1,9 @@
+[package]
+name = "{name}"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+hyperlight-guest = "{version}"
+hyperlight-guest-bin = "{version}"
+hyperlight-common = { version = "{version}", default-features = false }

src/scaffold/guest/_main.rs

@@ -0,0 +1,58 @@
+#![no_std]
+#![no_main]
+extern crate alloc;
+extern crate hyperlight_guest_bin;
+
+use alloc::string::String;
+use alloc::vec::Vec;
+use core::sync::atomic::{AtomicI32, Ordering};
+
+use hyperlight_common::flatbuffer_wrappers::function_call::FunctionCall;
+use hyperlight_common::flatbuffer_wrappers::guest_error::ErrorCode;
+use hyperlight_guest::bail;
+use hyperlight_guest::error::Result;
+use hyperlight_guest_bin::{guest_function, host_function};
+
+static COUNTER: AtomicI32 = AtomicI32::new(0);
+
+// Declare a host function that the guest can call. The string is the
+// registration name (must match what the host passes to register()).
+// If omitted, the Rust function name is used.
+// The host must register this before the sandbox is initialized.
+#[host_function("GetWeekday")]
+fn get_weekday() -> Result<String>;
+
+// Register a guest function that can be called by the host.
+#[guest_function("SayHello")]
+fn say_hello(name: String) -> Result<String> {
+    let weekday = get_weekday()?;
+    Ok(alloc::format!("Hello, {name}! Today is {weekday}."))
+}
+
+// Guest functions can take multiple arguments of different types.
+#[guest_function("Add")]
+fn add(a: i32, b: i32) -> Result<i32> {
+    Ok(a + b)
+}
+
+// Increments a counter and returns the new value. State persists across
+// calls until the host restores a snapshot, which resets all VM memory
+// back to the state it was in when the snapshot was taken.
+#[guest_function("Increment")]
+fn increment() -> Result<i32> {
+    COUNTER.fetch_add(1, Ordering::Relaxed);
+    Ok(COUNTER.load(Ordering::Relaxed))
+}
+
+// Called once when the guest binary is loaded, during evolve().
+// Use this for initialization.
+#[unsafe(no_mangle)]
+pub extern "C" fn hyperlight_main() {}
+
+// Called when the host calls a guest function not handled by #[guest_function].
+// You usually don't need to modify this.
+#[unsafe(no_mangle)]
+pub fn guest_dispatch_function(function_call: FunctionCall) -> Result<Vec<u8>> {
+    let function_name = function_call.function_name;
+    bail!(ErrorCode::GuestFunctionNotFound => "{function_name}");
+}

src/scaffold/host/_Cargo.toml

@@ -0,0 +1,7 @@
+[package]
+name = "{name}"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+hyperlight-host = "{version}"

src/scaffold/host/_main.rs

@@ -0,0 +1,76 @@
+use std::path::PathBuf;
+use std::time::{SystemTime, UNIX_EPOCH};
+
+use hyperlight_host::{GuestBinary, MultiUseSandbox, UninitializedSandbox};
+
+fn main() -> hyperlight_host::Result<()> {
+    // TODO: support aarch64-hyperlight-none when aarch64 guests are supported.
+    let base = PathBuf::from("../guest/target/x86_64-hyperlight-none");
+    let guest_path = ["debug", "release"]
+        .iter()
+        .map(|p| base.join(p).join("{guest_name}"))
+        .find(|p| p.exists())
+        .expect(
+            "guest binary not found - build it first with: cd ../guest && cargo hyperlight build",
+        );
+
+    // Create a sandbox from the guest binary. It starts uninitialized so you
+    // can register host functions before the guest begins executing.
+    let mut sandbox = UninitializedSandbox::new(
+        GuestBinary::FilePath(guest_path.display().to_string()),
+        None,
+    )?;
+
+    // Register a host function that the guest can call.
+    sandbox.register("GetWeekday", weekday)?;
+
+    // Evolve into a MultiUseSandbox, which lets you call guest functions
+    // multiple times.
+    let mut sandbox: MultiUseSandbox = sandbox.evolve()?;
+
+    // Call a guest function with a single argument.
+    let result: String = sandbox.call("SayHello", "World".to_string())?;
+    println!("{result}");
+
+    // Multiple arguments are passed as a tuple.
+    let sum: i32 = sandbox.call("Add", (2_i32, 3_i32))?;
+    println!("2 + 3 = {sum}");
+
+    // Guest state persists between calls. Take a snapshot so we can
+    // restore back to this point later.
+    let snapshot = sandbox.snapshot()?;
+
+    let count: i32 = sandbox.call("Increment", ())?;
+    println!("count = {count}"); // 1
+    let count: i32 = sandbox.call("Increment", ())?;
+    println!("count = {count}"); // 2
+    let count: i32 = sandbox.call("Increment", ())?;
+    println!("count = {count}"); // 3
+
+    // Restore resets all guest memory back to the snapshot.
+    sandbox.restore(snapshot)?;
+
+    let count: i32 = sandbox.call("Increment", ())?;
+    println!("count after restore = {count}"); // 1 again
+
+    Ok(())
+}
+
+// Returns the current day of the week as a String.
+fn weekday() -> hyperlight_host::Result<String> {
+    let days = [
+        "Monday",
+        "Tuesday",
+        "Wednesday",
+        "Thursday",
+        "Friday",
+        "Saturday",
+        "Sunday",
+    ];
+    let secs = SystemTime::now()
+        .duration_since(UNIX_EPOCH)
+        .expect("system clock before Unix epoch")
+        .as_secs();
+    // January 1, 1970 was a Thursday (day index 3 when Monday = 0).
+    Ok(days[((secs / (60 * 60 * 24) + 3) % 7) as usize].to_string())
+}

src/scaffold/mod.rs

@@ -0,0 +1,98 @@
+use std::ffi::OsString;
+use std::fs;
+use std::path::{Path, PathBuf};
+
+use anyhow::{Context, Result, ensure};
+use clap::Parser;
+
+const HYPERLIGHT_VERSION: &str = "0.13";
+
+const GUEST_CARGO_TOML: &str = include_str!("guest/_Cargo.toml");
+const GUEST_MAIN_RS: &str = include_str!("guest/_main.rs");
+const HOST_CARGO_TOML: &str = include_str!("host/_Cargo.toml");
+const HOST_MAIN_RS: &str = include_str!("host/_main.rs");
+const GITIGNORE: &str = include_str!("_gitignore");
+
+/// Scaffold a new Hyperlight project.
+#[derive(Parser, Debug)]
+#[command(name = "scaffold")]
+struct ScaffoldCli {
+    /// Path to create the project at. The directory name is used as the crate
+    /// name (like `cargo new`).
+    path: PathBuf,
+
+    /// Generate only a guest project instead of both host and guest.
+    #[arg(long, default_value_t = false)]
+    guest_only: bool,
+}
+
+pub fn run(args: impl Iterator<Item = OsString>) -> Result<()> {
+    let cli = ScaffoldCli::parse_from(args);
+
+    let name = cli
+        .path
+        .file_name()
+        .context("Invalid project path")?
+        .to_str()
+        .context("Project name must be valid UTF-8")?;
+
+    ensure!(!name.is_empty(), "Project name must not be empty");
+    ensure!(
+        !cli.path.exists(),
+        "Directory '{}' already exists",
+        cli.path.display()
+    );
+
+    if cli.guest_only {
+        write_guest(&cli.path, name)?;
+    } else {
+        let guest_name = format!("{name}-guest");
+        write_guest(&cli.path.join("guest"), &guest_name)?;
+        write_host(&cli.path.join("host"), &format!("{name}-host"), &guest_name)?;
+    }
+    write_file(cli.path.join(".gitignore"), GITIGNORE)?;
+
+    let dir = cli.path.display();
+    println!("Created project at '{dir}'\n");
+    if cli.guest_only {
+        println!("Build:");
+        println!("  cd {dir} && cargo hyperlight build");
+    } else {
+        println!("Build and run:");
+        println!("  cd {dir}/guest && cargo hyperlight build");
+        println!("  cd {dir}/host && cargo run");
+    }
+
+    Ok(())
+}
+
+fn write_guest(dir: &Path, name: &str) -> Result<()> {
+    let cargo_toml = GUEST_CARGO_TOML
+        .replace("{name}", name)
+        .replace("{version}", HYPERLIGHT_VERSION);
+    write_file(dir.join("Cargo.toml"), &cargo_toml)?;
+    write_file(dir.join("src/main.rs"), GUEST_MAIN_RS)?;
+    Ok(())
+}
+
+fn write_host(dir: &Path, name: &str, guest_name: &str) -> Result<()> {
+    let cargo_toml = HOST_CARGO_TOML
+        .replace("{name}", name)
+        .replace("{version}", HYPERLIGHT_VERSION);
+    let main_rs = HOST_MAIN_RS
+        .replace("{name}", name)
+        .replace("{guest_name}", guest_name);
+    write_file(dir.join("Cargo.toml"), &cargo_toml)?;
+    write_file(dir.join("src/main.rs"), &main_rs)?;
+    Ok(())
+}
+
+fn write_file(path: impl AsRef<Path>, content: &str) -> Result<()> {
+    let path = path.as_ref();
+    if let Some(parent) = path.parent() {
+        fs::create_dir_all(parent)
+            .with_context(|| format!("Failed to create directory '{}'", parent.display()))?;
+    }
+    fs::write(path, content).with_context(|| format!("Failed to write '{}'", path.display()))?;
+    Ok(())
+}