podup 0.16.0

//! Secure self-update for the `podup` binary.
//!
//! Flow: resolve the latest release tag, compare against the compiled-in
//! version, and (unless `--check`) download the platform binary plus the signed
//! `SHA256SUMS` manifest. The manifest's Ed25519 signature is verified against
//! the public key embedded in this binary (`verify::RELEASE_PUBKEY`); only
//! then is the binary's digest checked against the manifest and the running
//! executable atomically replaced. Every step fails closed — a missing key,
//! bad signature, or checksum mismatch aborts before anything is written.

mod github;
mod install;
mod verify;

pub use github::{GitHubSource, REPO};

use crate::ComposeError;

/// Options controlling an update run.
#[derive(Debug, Clone, Copy, Default)]
pub struct UpdateOptions {
	/// Report whether a newer release exists without installing it.
	pub check_only: bool,
	/// Reinstall even if the latest release is not newer than the current build.
	pub force: bool,
}

/// A source of release metadata and assets. Abstracted so the verification and
/// install flow can be exercised without network access.
pub trait ReleaseSource {
	/// Latest published release tag (e.g. `v0.6.0`).
	fn latest_version(&self) -> crate::Result<String>;
	/// Raw bytes of a named release asset.
	fn fetch(&self, asset: &str) -> crate::Result<Vec<u8>>;
}

/// Run an update against GitHub for the version compiled into this binary.
pub fn run(opts: UpdateOptions) -> crate::Result<()> {
	let source = GitHubSource::default();
	run_with(&source, env!("CARGO_PKG_VERSION"), opts)
}

/// Core update flow against an arbitrary [`ReleaseSource`] and current version.
pub fn run_with(
	source: &dyn ReleaseSource,
	current: &str,
	opts: UpdateOptions,
) -> crate::Result<()> {
	let current_v = verify::parse_version(current)?;
	let latest_tag = source.latest_version()?;
	let latest_v = verify::parse_version(&latest_tag)?;

	if latest_v <= current_v && !opts.force {
		println!("podup is up to date (v{current})");
		return Ok(());
	}

	if latest_v > current_v {
		println!("update available: v{current} -> {latest_tag}");
	} else {
		println!("reinstalling {latest_tag} (--force)");
	}
	if opts.check_only {
		println!("run `podup update` to install it");
		return Ok(());
	}

	// Refuse to self-replace a package-manager-managed binary (even with
	// --force): overwriting it would desync the package manager's records.
	if let Some(pm) = install::managing_package_manager() {
		return Err(install::package_managed_error(pm));
	}

	let asset = install::require_platform_asset()?;
	println!("downloading {asset} ({latest_tag}) ...");
	let binary = source.fetch(asset)?;
	let sha256sums = source.fetch("SHA256SUMS")?;
	let signature = source.fetch("SHA256SUMS.sig")?;

	// Security gate: signed manifest first, then the binary's digest against it.
	verify::verify_signature(&sha256sums, &signature)?;
	let expected = verify::expected_digest(&sha256sums, asset)?;
	verify::verify_digest(&binary, &expected)?;
	println!("signature and checksum verified");

	let path = install::install_binary(&binary)?;
	println!("updated to {latest_tag}: {}", path.display());
	Ok(())
}

/// Map an update failure onto a stable process exit code (`2`), distinct from a
/// run-container exit, so scripts can branch on "update failed".
pub fn exit_code(_err: &ComposeError) -> i32 {
	2
}

#[cfg(test)]
mod tests {
	use super::*;
	use std::cell::RefCell;
	use std::collections::HashMap;

	/// In-memory release source signed with a throwaway key, so the full flow
	/// (version gate, signature, checksum, install) runs without network or the
	/// placeholder pubkey guard.
	struct MockSource {
		latest: String,
		assets: HashMap<String, Vec<u8>>,
		fetched: RefCell<Vec<String>>,
	}

	impl ReleaseSource for MockSource {
		fn latest_version(&self) -> crate::Result<String> {
			Ok(self.latest.clone())
		}
		fn fetch(&self, asset: &str) -> crate::Result<Vec<u8>> {
			self.fetched.borrow_mut().push(asset.to_string());
			self.assets
				.get(asset)
				.cloned()
				.ok_or_else(|| ComposeError::Update(format!("missing asset {asset}")))
		}
	}

	#[test]
	fn up_to_date_skips_download() {
		let src = MockSource {
			latest: "v0.6.0".into(),
			assets: HashMap::new(),
			fetched: RefCell::new(Vec::new()),
		};
		run_with(&src, "0.6.0", UpdateOptions::default()).unwrap();
		assert!(
			src.fetched.borrow().is_empty(),
			"must not fetch when current"
		);
	}

	#[test]
	fn newer_release_check_only_does_not_install() {
		let src = MockSource {
			latest: "v0.7.0".into(),
			assets: HashMap::new(),
			fetched: RefCell::new(Vec::new()),
		};
		let opts = UpdateOptions {
			check_only: true,
			force: false,
		};
		run_with(&src, "0.6.0", opts).unwrap();
		assert!(
			src.fetched.borrow().is_empty(),
			"check-only must not download"
		);
	}

	#[test]
	fn bad_version_from_source_errors() {
		let src = MockSource {
			latest: "not-a-version".into(),
			assets: HashMap::new(),
			fetched: RefCell::new(Vec::new()),
		};
		assert!(run_with(&src, "0.6.0", UpdateOptions::default()).is_err());
	}

	#[test]
	fn newer_release_with_real_install_path() {
		// Only meaningful where the host maps to a known release asset.
		let Some(asset) = install::platform_asset() else {
			return;
		};

		use ed25519_dalek::{Signer, SigningKey};
		let sk = SigningKey::from_bytes(&[42u8; 32]);

		let binary = b"the new podup binary".to_vec();
		let digest = verify::sha256_hex(&binary);
		let sums = format!("{digest}  {asset}\n");
		let sig = sk.sign(sums.as_bytes()).to_bytes().to_vec();

		let mut assets = HashMap::new();
		assets.insert(asset.to_string(), binary.clone());
		assets.insert("SHA256SUMS".to_string(), sums.into_bytes());
		assets.insert("SHA256SUMS.sig".to_string(), sig);

		let src = MockSource {
			latest: "v9.9.9".into(),
			assets,
			fetched: RefCell::new(Vec::new()),
		};

		// The manifest is internally consistent but signed with a throwaway key,
		// not the embedded release key — verification must fail closed, proving
		// the gate rejects anything not signed by the real key.
		let err = run_with(&src, "0.6.0", UpdateOptions::default()).unwrap_err();
		assert!(matches!(err, ComposeError::Update(_)));
		assert!(src.fetched.borrow().contains(&"SHA256SUMS.sig".to_string()));
	}

	#[test]
	fn exit_code_is_two() {
		assert_eq!(exit_code(&ComposeError::Update("x".into())), 2);
	}
}