ito_core/

process.rs

//! Process execution boundary for core-side command invocation.

use std::fs;
use std::io;
use std::path::PathBuf;
use std::process::{Command, Stdio};
use std::thread;
use std::time::{Duration, Instant};

/// Process invocation request.
#[derive(Debug, Clone, Default)]
pub struct ProcessRequest {
    /// Executable name or absolute path.
    pub program: String,
    /// Positional arguments.
    pub args: Vec<String>,
    /// Optional working directory.
    pub current_dir: Option<PathBuf>,
}

impl ProcessRequest {
    /// Create a new request for the given program.
    ///
    /// The program can be an executable name (resolved via PATH) or an absolute path.
    /// Use the builder methods to configure arguments and working directory.
    pub fn new(program: impl Into<String>) -> Self {
        Self {
            program: program.into(),
            args: Vec::new(),
            current_dir: None,
        }
    }

    /// Add a single argument to the process invocation.
    ///
    /// This is a builder method that returns `self` for chaining.
    /// Arguments are passed to the process in the order they are added.
    pub fn arg(mut self, arg: impl Into<String>) -> Self {
        self.args.push(arg.into());
        self
    }

    /// Add multiple arguments to the process invocation.
    ///
    /// This is a builder method that returns `self` for chaining.
    /// Arguments are appended in iteration order after any previously added arguments.
    pub fn args<I, S>(mut self, args: I) -> Self
    where
        I: IntoIterator<Item = S>,
        S: Into<String>,
    {
        for arg in args {
            self.args.push(arg.into());
        }
        self
    }

    /// Set the working directory for the process.
    ///
    /// If not set, the process inherits the current working directory.
    /// This is a builder method that returns `self` for chaining.
    pub fn current_dir(mut self, dir: impl Into<PathBuf>) -> Self {
        self.current_dir = Some(dir.into());
        self
    }
}

/// Structured process execution output.
#[derive(Debug, Clone)]
pub struct ProcessOutput {
    /// Exit status code, or -1 if unavailable.
    pub exit_code: i32,
    /// Whether the process exited successfully.
    pub success: bool,
    /// Captured stdout.
    pub stdout: String,
    /// Captured stderr.
    pub stderr: String,
    /// True if execution was forcibly terminated due to timeout.
    pub timed_out: bool,
}

/// Process execution failure modes.
#[derive(Debug, thiserror::Error)]
pub enum ProcessExecutionError {
    /// Spawn failed before a child process was created.
    #[error("failed to spawn '{program}': {source}")]
    Spawn {
        /// Program being executed.
        program: String,
        /// Underlying I/O error.
        source: io::Error,
    },
    /// Waiting for process completion failed.
    #[error("failed waiting for '{program}': {source}")]
    Wait {
        /// Program being executed.
        program: String,
        /// Underlying I/O error.
        source: io::Error,
    },
    /// Creating a temporary output file failed.
    #[error("failed to create temp output file '{path}': {source}")]
    CreateTemp {
        /// Temp path used for output capture.
        path: PathBuf,
        /// Underlying I/O error.
        source: io::Error,
    },
    /// Reading a temporary output file failed.
    #[error("failed to read temp output file '{path}': {source}")]
    ReadTemp {
        /// Temp path used for output capture.
        path: PathBuf,
        /// Underlying I/O error.
        source: io::Error,
    },
}

/// Abstraction for process execution.
pub trait ProcessRunner {
    /// Execute a process and wait for completion, capturing all output.
    ///
    /// This method blocks until the process exits or fails to start.
    /// Both stdout and stderr are captured and returned in the result.
    fn run(&self, request: &ProcessRequest) -> Result<ProcessOutput, ProcessExecutionError>;

    /// Execute a process with a timeout, capturing all output.
    ///
    /// If the process doesn't complete within the timeout, it will be killed
    /// and the result will have `timed_out` set to true. Output captured
    /// before the timeout is still returned.
    fn run_with_timeout(
        &self,
        request: &ProcessRequest,
        timeout: Duration,
    ) -> Result<ProcessOutput, ProcessExecutionError>;
}

/// Default runner backed by `std::process::Command`.
#[derive(Debug, Default)]
pub struct SystemProcessRunner;

impl ProcessRunner for SystemProcessRunner {
    fn run(&self, request: &ProcessRequest) -> Result<ProcessOutput, ProcessExecutionError> {
        let mut command = build_command(request);
        let output = command
            .output()
            .map_err(|source| ProcessExecutionError::Spawn {
                program: request.program.clone(),
                source,
            })?;
        Ok(ProcessOutput {
            exit_code: output.status.code().unwrap_or(-1),
            success: output.status.success(),
            stdout: String::from_utf8_lossy(&output.stdout).to_string(),
            stderr: String::from_utf8_lossy(&output.stderr).to_string(),
            timed_out: false,
        })
    }

    fn run_with_timeout(
        &self,
        request: &ProcessRequest,
        timeout: Duration,
    ) -> Result<ProcessOutput, ProcessExecutionError> {
        let now_ms = chrono::Utc::now().timestamp_millis();
        let pid = std::process::id();
        let stdout_path = temp_output_path("stdout", pid, now_ms);
        let stderr_path = temp_output_path("stderr", pid, now_ms);

        let stdout_file =
            fs::File::create(&stdout_path).map_err(|source| ProcessExecutionError::CreateTemp {
                path: stdout_path.clone(),
                source,
            })?;
        let stderr_file =
            fs::File::create(&stderr_path).map_err(|source| ProcessExecutionError::CreateTemp {
                path: stderr_path.clone(),
                source,
            })?;

        let mut command = build_command(request);
        let mut child = command
            .stdin(Stdio::null())
            .stdout(Stdio::from(stdout_file))
            .stderr(Stdio::from(stderr_file))
            .spawn()
            .map_err(|source| ProcessExecutionError::Spawn {
                program: request.program.clone(),
                source,
            })?;

        let started = Instant::now();
        let mut timed_out = false;
        let mut exit_code = -1;
        let mut success = false;

        loop {
            if let Some(status) =
                child
                    .try_wait()
                    .map_err(|source| ProcessExecutionError::Wait {
                        program: request.program.clone(),
                        source,
                    })?
            {
                exit_code = status.code().unwrap_or(-1);
                success = status.success();
                break;
            }

            if started.elapsed() >= timeout {
                timed_out = true;
                let _ = child.kill();
                let _ = child.wait();
                break;
            }

            thread::sleep(Duration::from_millis(50));
        }

        let stdout =
            fs::read_to_string(&stdout_path).map_err(|source| ProcessExecutionError::ReadTemp {
                path: stdout_path.clone(),
                source,
            })?;
        let stderr =
            fs::read_to_string(&stderr_path).map_err(|source| ProcessExecutionError::ReadTemp {
                path: stderr_path.clone(),
                source,
            })?;
        let _ = fs::remove_file(&stdout_path);
        let _ = fs::remove_file(&stderr_path);

        Ok(ProcessOutput {
            exit_code,
            success: !timed_out && success,
            stdout,
            stderr,
            timed_out,
        })
    }
}

fn build_command(request: &ProcessRequest) -> Command {
    let mut command = Command::new(&request.program);
    command.args(&request.args);
    if let Some(dir) = &request.current_dir {
        command.current_dir(dir);
    }
    command
}

fn temp_output_path(stream: &str, pid: u32, now_ms: i64) -> PathBuf {
    let mut path = std::env::temp_dir();
    path.push(format!("ito-process-{stream}-{pid}-{now_ms}.log"));
    path
}

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

    #[test]
    fn captures_stdout_and_stderr() {
        let runner = SystemProcessRunner;
        let request = ProcessRequest::new("sh").args(["-lc", "echo out; echo err >&2"]);
        let output = runner.run(&request).unwrap();
        assert!(output.success);
        assert_eq!(output.exit_code, 0);
        assert!(output.stdout.contains("out"));
        assert!(output.stderr.contains("err"));
        assert!(!output.timed_out);
    }

    #[test]
    fn captures_non_zero_exit() {
        let runner = SystemProcessRunner;
        let request = ProcessRequest::new("sh").args(["-lc", "echo boom >&2; exit 7"]);
        let output = runner.run(&request).unwrap();
        assert!(!output.success);
        assert_eq!(output.exit_code, 7);
        assert!(output.stderr.contains("boom"));
    }

    #[test]
    fn missing_executable_is_spawn_failure() {
        let runner = SystemProcessRunner;
        let request = ProcessRequest::new("__ito_missing_executable__");
        let result = runner.run(&request);
        match result {
            Err(ProcessExecutionError::Spawn { .. }) => {}
            other => panic!("expected spawn error, got {other:?}"),
        }
    }
}