harn_hostlib/process/

handle.rs

//! Process abstraction trait used by `tools/proc` and
//! `tools/long_running`.
//!
//! Tier 1C of the de-flake epic (#1057). Production code spawns through
//! the [`ProcessSpawner`] trait — the default implementation in
//! `process::real` wraps `std::process::Child` and goes through
//! `harn_vm::process_sandbox`. Tests install a `MockSpawner` (see
//! `process::mock`) that returns deterministic [`MockProcess`] handles,
//! so process-tool tests no longer depend on real subprocess scheduling
//! or wall-clock timing.

use std::collections::BTreeMap;
use std::io::{self, Read, Write};
use std::path::PathBuf;
use std::sync::Arc;
use std::time::Duration;

/// Resolved exit information for a finished process. Mirrors the subset of
/// `std::process::ExitStatus` that the process-tool builtins surface.
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub struct ExitStatus {
    /// Exit code from `exit(2)` / `_exit(2)`. `None` means the process did not
    /// exit normally (it was terminated by a signal).
    pub code: Option<i32>,
    /// Unix signal that terminated the process, when applicable. `None` on
    /// non-Unix targets or when the process exited normally.
    pub signal: Option<i32>,
}

impl ExitStatus {
    /// Construct a normal exit with the given code.
    pub fn from_code(code: i32) -> Self {
        Self {
            code: Some(code),
            signal: None,
        }
    }

    /// Construct a signal-terminated exit.
    pub fn from_signal(signal: i32) -> Self {
        Self {
            code: None,
            signal: Some(signal),
        }
    }
}

/// How a spawn should treat the parent's environment. Mirrors the legacy
/// `EnvMode` from `tools/proc.rs`.
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum EnvMode {
    /// Inherit the parent's environment, then apply `env` overrides.
    InheritClean,
    /// Clear the environment, then apply `env`.
    Replace,
    /// Inherit the parent's environment and apply `env` (default behaviour).
    Patch,
}

/// Explicit secret-bearing environment variable names that the agent's
/// `run`/`command_run` tool must never leak into a child process (and thus
/// into the model context, since the child's stdout is returned to the
/// model as the tool result). These are matched case-insensitively in
/// addition to the suffix patterns in [`is_sensitive_env_name`].
const EXPLICIT_SENSITIVE_ENV_NAMES: &[&str] = &[
    "GITHUB_TOKEN",
    "GH_TOKEN",
    "HARN_CLOUD_API_KEY",
    "BURIN_ADMIN_TOKEN",
    "AWS_SECRET_ACCESS_KEY",
    "AWS_SESSION_TOKEN",
];

/// Provider-namespace prefixes whose entire family of variables is treated
/// as secret-bearing (e.g. `ANTHROPIC_API_KEY`, `OPENAI_ORG_ID`). Matched
/// case-insensitively against the start of the variable name.
const SENSITIVE_ENV_PREFIXES: &[&str] = &[
    "ANTHROPIC_",
    "OPENAI_",
    "OPENROUTER_",
    "FIREWORKS_",
    "TOGETHER_",
    "XAI_",
    "GROQ_",
];

/// Returns `true` when an environment variable name looks like it carries a
/// secret (provider API key, access token, OAuth client secret, etc.) and so
/// must be stripped from a child process spawned by the agent's `run` tool.
///
/// The check is deliberately conservative about credentials but permissive
/// about ordinary build/toolchain variables: `PATH`, `HOME`, `LANG`,
/// `CARGO_HOME`, language toolchain vars, etc. are *not* sensitive and stay
/// in the child environment so builds and tests still work.
///
/// Matching is case-insensitive and covers:
/// - suffix patterns `_API_KEY`, `_TOKEN`, `_SECRET`, `_KEY`;
/// - the provider prefixes in [`SENSITIVE_ENV_PREFIXES`];
/// - the explicit names in [`EXPLICIT_SENSITIVE_ENV_NAMES`].
pub fn is_sensitive_env_name(name: &str) -> bool {
    let upper = name.to_ascii_uppercase();
    if EXPLICIT_SENSITIVE_ENV_NAMES.contains(&upper.as_str()) {
        return true;
    }
    if SENSITIVE_ENV_PREFIXES
        .iter()
        .any(|prefix| upper.starts_with(prefix))
    {
        return true;
    }
    // Suffix patterns catch the long tail of provider/service credentials
    // (`*_API_KEY`, `*_TOKEN`, `*_SECRET`, `*_KEY`) without enumerating every
    // vendor. `_KEY` is last and broadest; it still excludes benign names
    // like `PATH`/`HOME`/`LANG` that don't end in these suffixes.
    upper.ends_with("_API_KEY")
        || upper.ends_with("_TOKEN")
        || upper.ends_with("_SECRET")
        || upper.ends_with("_KEY")
}

/// Parameters describing a single spawn. The spawner is responsible for any
/// sandbox setup (Linux seccomp/landlock, macOS sandbox-exec, etc.) and for
/// configuring the child's process group when requested.
#[derive(Clone, Debug)]
pub struct SpawnSpec {
    /// Builtin name surfaced in error messages (e.g. `"hostlib_tools_run_command"`).
    pub builtin: &'static str,
    /// Program to execute. Must be non-empty (validated by the spawner).
    pub program: String,
    /// Arguments to pass to the program.
    pub args: Vec<String>,
    /// Working directory for the child. `None` inherits the parent's cwd.
    pub cwd: Option<PathBuf>,
    /// Environment overrides to apply (interpretation depends on `env_mode`).
    pub env: BTreeMap<String, String>,
    /// Variable names to strip from the inherited environment before `env`
    /// overrides apply. A key present in both `env_remove` and `env` ends up
    /// set (explicit overrides win). No effect under `EnvMode::Replace`,
    /// which already starts from an empty environment.
    pub env_remove: Vec<String>,
    /// How to treat the parent's environment.
    pub env_mode: EnvMode,
    /// Whether stdin will be written to (`true`) or piped to /dev/null (`false`).
    pub use_stdin: bool,
    /// Set the child's process group to its own pid (`setpgid(0, 0)`). Used
    /// for long-running handles so the kill-by-pgid path works.
    pub configure_process_group: bool,
}

/// Handle to a running (or finished) process. Used by both the synchronous
/// `proc::run` path and the long-running waiter thread.
///
/// The trait is intentionally small: the legacy code already managed
/// stdout/stderr drain on dedicated threads, and stdin is written once after
/// spawn — wrapping those reads/writes via boxed trait objects keeps the
/// real and mock paths uniform without forcing async into the rest of the
/// hostlib.
pub trait ProcessHandle: Send {
    /// OS process id, when available.
    fn pid(&self) -> Option<u32>;

    /// OS process group id, when available. Falls back to [`Self::pid`] on
    /// platforms that don't expose process groups.
    fn process_group_id(&self) -> Option<u32>;

    /// Returns a killer that can terminate the process even after the
    /// stdout/stderr/wait halves have been moved into the waiter thread.
    fn killer(&self) -> Arc<dyn ProcessKiller>;

    /// Take ownership of the stdin pipe, if the spawn requested one.
    fn take_stdin(&mut self) -> Option<Box<dyn Write + Send>>;

    /// Take ownership of the stdout reader.
    fn take_stdout(&mut self) -> Option<Box<dyn Read + Send>>;

    /// Take ownership of the stderr reader.
    fn take_stderr(&mut self) -> Option<Box<dyn Read + Send>>;

    /// Wait for the process to exit, optionally with a timeout, while
    /// polling `interrupt`. On timeout the spawner kills the child process
    /// tree (SIGKILL, historical semantics) and reports
    /// [`WaitOutcome::TimedOut`]. When `interrupt` returns `true` (scope
    /// cancellation, `deadline` expiry — see `harn_vm::op_interrupt`) the
    /// spawner gracefully terminates the child's process tree (SIGTERM,
    /// then SIGKILL after `harn_vm::op_interrupt::SUBPROCESS_TERM_GRACE`)
    /// and reports [`WaitOutcome::Interrupted`].
    fn wait_with_timeout(
        &mut self,
        timeout: Option<Duration>,
        interrupt: &dyn Fn() -> bool,
    ) -> io::Result<WaitOutcome>;

    /// Block until the process exits, no timeout, no interrupt polling.
    /// Used by the background (`background: true`) waiter thread, whose
    /// children deliberately outlive scope cancellation and deadlines.
    fn wait(&mut self) -> io::Result<ExitStatus>;
}

/// How a [`ProcessHandle::wait_with_timeout`] ended.
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum WaitOutcome {
    /// The process exited on its own.
    Exited(ExitStatus),
    /// The timeout elapsed; the spawner killed the child process tree.
    TimedOut,
    /// The interrupt callback fired; the spawner gracefully terminated the
    /// child's process tree.
    Interrupted,
}

/// Kill side of a [`ProcessHandle`]. Cloneable via `Arc` so cancellation
/// works after the waiter thread has taken ownership of the handle itself.
pub trait ProcessKiller: Send + Sync {
    /// Send SIGKILL to the process tree/group when applicable.
    fn kill(&self);
}

/// Spawner abstraction: produces [`ProcessHandle`] instances.
pub trait ProcessSpawner: Send + Sync {
    /// Spawn the configured process.
    fn spawn(&self, spec: SpawnSpec) -> Result<Box<dyn ProcessHandle>, ProcessError>;
}

/// Errors raised by a spawner. These map onto `HostlibError::Backend` /
/// `HostlibError::InvalidParameter` at the call site so the script-side
/// surface stays unchanged.
#[derive(Clone, Debug, thiserror::Error)]
pub enum ProcessError {
    /// `argv` was empty or otherwise malformed.
    #[error("invalid argv: {0}")]
    InvalidArgv(String),
    /// Sandbox setup (e.g. landlock policy assembly) failed.
    #[error("sandbox setup failed: {0}")]
    SandboxSetup(String),
    /// Sandbox rejected the supplied cwd.
    #[error("sandbox cwd rejected: {0}")]
    SandboxCwd(String),
    /// Sandbox rejected the spawn at execve time.
    #[error("sandbox rejected spawn: {0}")]
    SandboxSpawn(String),
    /// Generic spawn failure (typically io::Error from `Command::spawn`).
    #[error("spawn failed: {0}")]
    Spawn(String),
    /// A never-approvable UNIVERSAL catastrophic command (machine/disk/data
    /// destruction) was rejected by the floor BEFORE spawning. Enforced
    /// unconditionally at [`spawn_process`] — no `command_policy` required —
    /// so it is universal across every hostlib process tool, embedders, and
    /// standalone Harn. See
    /// [`harn_vm::orchestration::universal_catastrophic_reason`].
    #[error("{0}")]
    CatastrophicFloor(String),
}

use std::cell::RefCell;

thread_local! {
    static THREAD_SPAWNER: RefCell<Option<Arc<dyn ProcessSpawner>>> = const { RefCell::new(None) };
}

/// Install a per-thread spawner used by `spawn_process` from this thread.
/// Returns a guard that restores the previous spawner on drop. Tests use
/// this to install a [`super::mock::MockSpawner`]; production never calls
/// it (the default real spawner runs whenever no per-thread spawner is
/// installed).
///
/// Thread-local rather than global so parallel test execution is safe.
/// Process-tool spawns happen on the test's thread; the long-running
/// waiter threads operate on the handle that was already returned, so
/// they don't perform spawner lookups themselves.
pub fn install_spawner(spawner: Arc<dyn ProcessSpawner>) -> SpawnerGuard {
    let prev = THREAD_SPAWNER.with(|slot| slot.replace(Some(spawner)));
    SpawnerGuard { prev: Some(prev) }
}

/// Guard returned by [`install_spawner`]. Restores the previous spawner on
/// drop so installs nest correctly across tests.
pub struct SpawnerGuard {
    // Outer Option distinguishes "guard already restored" (None) from
    // "guard owes a restore" (Some(_)); inner Option carries the previous
    // spawner slot value (which can itself be None when no spawner was set).
    #[allow(clippy::option_option)]
    prev: Option<Option<Arc<dyn ProcessSpawner>>>,
}

impl Drop for SpawnerGuard {
    fn drop(&mut self) {
        if let Some(prev) = self.prev.take() {
            THREAD_SPAWNER.with(|slot| {
                *slot.borrow_mut() = prev;
            });
        }
    }
}

/// Return the currently installed spawner for this thread, falling back
/// to the default real spawner.
pub fn current_spawner() -> Arc<dyn ProcessSpawner> {
    THREAD_SPAWNER
        .with(|slot| slot.borrow().clone())
        .unwrap_or_else(super::real::default_spawner)
}

/// Spawn a process via the currently installed spawner.
///
/// This is the single chokepoint every hostlib process tool funnels through
/// (`run_command`, `run_test`, `run_build_command`, `manage_packages`, and the
/// long-running background path). The UNIVERSAL catastrophic-command floor is
/// enforced HERE, UNCONDITIONALLY — no `command_policy` on the stack is
/// required — so a machine/disk/data-destroying command (`rm -rf /`, fork bomb,
/// `mkfs`, `dd of=<device>`, `chmod -R 000`, `truncate -s 0` of a source file,
/// redirect-over-source, project-root delete) and the textual git-destructive
/// family (`git reset --hard`, `git clean -fd`, force-push) is rejected before
/// the child is ever created, on standalone Harn and under every embedder
/// alike. Structured git builtins remain the reviewed path for legitimate
/// force-with-lease workflows. The spec's raw `program`/`args` are classified
/// BEFORE any sandbox wrapper is applied, so a `sandbox-exec`/`bwrap` prefix
/// can't bury the real command.
pub fn spawn_process(spec: SpawnSpec) -> Result<Box<dyn ProcessHandle>, ProcessError> {
    let workspace_roots: Vec<String> = spec
        .cwd
        .as_ref()
        .map(|cwd| vec![cwd.display().to_string()])
        .unwrap_or_default();
    if let Some(reason) = harn_vm::orchestration::universal_catastrophic_reason(
        &spec.program,
        &spec.args,
        &workspace_roots,
    ) {
        return Err(ProcessError::CatastrophicFloor(reason));
    }
    current_spawner().spawn(spec)
}

#[cfg(test)]
mod tests {
    use super::is_sensitive_env_name;

    #[test]
    fn denies_secret_bearing_names() {
        // Suffix patterns.
        assert!(is_sensitive_env_name("ANTHROPIC_API_KEY"));
        assert!(is_sensitive_env_name("OPENAI_API_KEY"));
        assert!(is_sensitive_env_name("SOME_VENDOR_TOKEN"));
        assert!(is_sensitive_env_name("MY_CLIENT_SECRET"));
        assert!(is_sensitive_env_name("RANDOM_KEY"));
        // Explicit names.
        assert!(is_sensitive_env_name("GITHUB_TOKEN"));
        assert!(is_sensitive_env_name("GH_TOKEN"));
        assert!(is_sensitive_env_name("HARN_CLOUD_API_KEY"));
        assert!(is_sensitive_env_name("BURIN_ADMIN_TOKEN"));
        assert!(is_sensitive_env_name("AWS_SECRET_ACCESS_KEY"));
        assert!(is_sensitive_env_name("AWS_SESSION_TOKEN"));
        // Provider prefixes (even without a key/token suffix).
        assert!(is_sensitive_env_name("OPENROUTER_BASE_URL"));
        assert!(is_sensitive_env_name("FIREWORKS_ACCOUNT"));
        assert!(is_sensitive_env_name("TOGETHER_ORG"));
        assert!(is_sensitive_env_name("XAI_REGION"));
        assert!(is_sensitive_env_name("GROQ_PROJECT"));
    }

    #[test]
    fn allows_benign_build_and_toolchain_names() {
        assert!(!is_sensitive_env_name("PATH"));
        assert!(!is_sensitive_env_name("HOME"));
        assert!(!is_sensitive_env_name("CARGO_HOME"));
        assert!(!is_sensitive_env_name("LANG"));
        assert!(!is_sensitive_env_name("LC_ALL"));
        assert!(!is_sensitive_env_name("TERM"));
        assert!(!is_sensitive_env_name("USER"));
        assert!(!is_sensitive_env_name("RUSTUP_HOME"));
        assert!(!is_sensitive_env_name("CARGO_TARGET_DIR"));
        assert!(!is_sensitive_env_name("SHELL"));
    }

    #[test]
    fn matches_case_insensitively() {
        assert!(is_sensitive_env_name("anthropic_api_key"));
        assert!(is_sensitive_env_name("github_token"));
        assert!(!is_sensitive_env_name("path"));
    }
}