ic-build 0.12.0

//! Selected native executables from Cargo's own package and artifact messages.

use super::{
    messages::{MessageDecoder, artifact_matches},
    observation::schema,
    selection::CargoSelection,
};
use ic_host_process::{
    child::OwnedChild,
    tool::{
        OutputLimit, OutputLimits, OutputStream, SuccessfulExit, communicate_child_with_observer,
    },
};
use std::{
    error::Error,
    ffi::OsString,
    io::{self, Write},
    path::PathBuf,
    process::{Command, Stdio},
};

#[cfg(test)]
mod tests;

/// Exact native target and caller-selected build arguments and decoding allowance.
pub struct NativeExecutableSpec<'a> {
    /// Unique package name in the selected Cargo metadata graph.
    pub package: &'a str,
    /// Cargo target name, without guessing an output filename.
    pub target_name: &'a str,
    /// `bin` or `example`, selecting Cargo's corresponding build target.
    pub target_kind: &'a str,
    /// Additional build arguments, such as profile and features. Package, target,
    /// manifest, target-directory and configuration overrides are refused; select
    /// shared configuration and paths in the command factory instead.
    /// Cargo's JSON message format is owned by this operation.
    pub build_args: &'a [OsString],
    /// Maximum metadata bytes or bytes in one Cargo JSON message, including LF.
    /// Total streamed diagnostic output and build duration have no default limit.
    pub max_message_bytes: usize,
}

/// Cargo-reported paths; mutable build-directory custody remains caller-owned.
#[derive(Debug)]
pub struct NativeExecutable {
    /// Absolute executable reported for the exact selected package and target.
    pub executable: PathBuf,
    /// Absolute target root reported by the same Cargo command's metadata.
    pub target_directory: PathBuf,
}

/// Build a selected native target and return Cargo's reported executable.
///
/// The factory supplies the same Cargo prefix, working directory, environment
/// and network/tool policy for metadata and build. Commands add `--locked`, exact
/// package/target selection and Cargo's JSON diagnostics format. Stdout is a
/// bounded-per-message protocol; rendered compiler diagnostics and piped stderr
/// stream to `diagnostics`. Other stderr configurations remain intact. Stdin is
/// null. This owns direct-child completion, not process-group or signal policy.
/// `admit` runs before each command factory, so caller interruption can refuse
/// another dispatch after metadata. In-flight commands still run to completion.
///
/// Callers exclude source/config/tool mutation and retain artifact custody. No
/// cache, installation, release admission, retry or elapsed-time default is added.
/// Interrupted or rejected capture uses Host's direct-child cleanup evidence.
///
/// # Errors
/// Refuses invalid selection before command effects, missing/ambiguous metadata
/// or artifacts, malformed/oversized messages, sink failures and command failures.
/// Original Host execution/status/cleanup causes remain downcastable.
pub fn build_native_executable(
    spec: &NativeExecutableSpec<'_>,
    mut cargo: impl FnMut() -> Command,
    mut diagnostics: impl Write,
    mut admit: impl FnMut() -> io::Result<()>,
) -> Result<NativeExecutable, Box<dyn Error + Send + Sync>> {
    let selector = match spec.target_kind {
        "bin" => "--bin",
        "example" => "--example",
        _ => return Err(protocol("native target kind must be bin or example").into()),
    };
    if spec.package.is_empty() || spec.target_name.is_empty() || spec.max_message_bytes == 0 {
        return Err(protocol("empty native target selection or message allowance").into());
    }
    let arguments = CargoSelection::parse(spec.build_args.to_vec());
    if !arguments.flags.is_empty() {
        return Err(protocol("native build arguments override the selected recipe").into());
    }
    arguments
        .profile
        .as_ref()
        .map_err(|message| protocol(message))?;
    admit()?;
    let mut command = cargo();
    command.args(["metadata", "--locked", "--no-deps", "--format-version", "1"]);
    command.args(&arguments.metadata_arguments);
    let mut bytes = Vec::new();
    execute(&mut command, |stream, chunk| match stream {
        OutputStream::Stdout => append(&mut bytes, chunk, spec.max_message_bytes),
        OutputStream::Stderr => diagnostics.write_all(chunk),
    })?;
    let (package_id, target_directory) = selection(serde_json::from_slice(&bytes)?, spec)?;
    admit()?;
    let mut command = cargo();
    command.args([
        "build",
        "--locked",
        "--message-format=json",
        "-p",
        spec.package,
        selector,
        spec.target_name,
    ]);
    command.args(spec.build_args);
    let mut decoder = MessageDecoder::new(spec.max_message_bytes, false);
    let mut executable = None;
    execute(&mut command, |stream, chunk| {
        if stream == OutputStream::Stderr {
            return diagnostics.write_all(chunk);
        }
        decoder.feed(chunk, |decoded| {
            selected_message(
                decoded,
                &package_id,
                spec,
                &mut executable,
                &mut diagnostics,
            )
        })
    })?;
    decoder.finish(|decoded| {
        selected_message(
            decoded,
            &package_id,
            spec,
            &mut executable,
            &mut diagnostics,
        )
    })?;
    Ok(NativeExecutable {
        executable: executable.ok_or_else(|| protocol("Cargo omitted the selected executable"))?,
        target_directory,
    })
}

fn selection(
    metadata: schema::Metadata,
    spec: &NativeExecutableSpec<'_>,
) -> io::Result<(String, PathBuf)> {
    let mut matching = metadata
        .packages
        .into_iter()
        .filter(|package| package.name.as_str() == spec.package);
    let package = matching
        .next()
        .ok_or_else(|| protocol("Cargo omitted selected package"))?;
    if matching.next().is_some() {
        return Err(protocol("Cargo package name is ambiguous"));
    }
    if package
        .targets
        .iter()
        .filter(|target| matches_target(target, spec))
        .count()
        != 1
    {
        return Err(protocol("Cargo target is missing or ambiguous"));
    }
    if package.id.repr.is_empty() {
        return Err(protocol("Cargo omitted package identity"));
    }
    if !metadata.target_directory.is_absolute() {
        return Err(protocol("Cargo omitted absolute target directory"));
    }
    Ok((
        package.id.repr,
        metadata.target_directory.into_std_path_buf(),
    ))
}

fn matches_target(target: &schema::Target, spec: &NativeExecutableSpec<'_>) -> bool {
    target.name == spec.target_name && target.kind.contains(&spec.target_kind.into())
}

fn selected_message(
    message: schema::Message,
    package_id: &str,
    spec: &NativeExecutableSpec<'_>,
    executable: &mut Option<PathBuf>,
    diagnostics: &mut impl Write,
) -> io::Result<()> {
    match message {
        schema::Message::CompilerMessage(message) => {
            if let Some(rendered) = message.message.rendered {
                diagnostics.write_all(rendered.as_bytes())?;
            }
        }
        schema::Message::CompilerArtifact(artifact)
            if artifact_matches(
                &artifact,
                package_id,
                spec.target_name,
                &spec.target_kind.into(),
            ) =>
        {
            let path = artifact
                .executable
                .filter(|path| path.is_absolute())
                .ok_or_else(|| protocol("Cargo omitted absolute executable path"))?
                .into_std_path_buf();
            if executable.replace(path).is_some() {
                return Err(protocol("Cargo reported multiple selected executables"));
            }
        }
        _ => {}
    }
    Ok(())
}

fn execute(
    command: &mut Command,
    output: impl FnMut(OutputStream, &[u8]) -> io::Result<()>,
) -> Result<(), Box<dyn Error + Send + Sync>> {
    command.stdin(Stdio::null()).stdout(Stdio::piped());
    let mut child = OwnedChild::spawn_direct(command)?;
    communicate_child_with_observer(
        &mut child,
        None,
        OutputLimits {
            stdout: OutputLimit::Truncate(0),
            stderr: OutputLimit::Truncate(0),
            timeout: None,
        },
        SuccessfulExit::Cleanup,
        || false,
        output,
    )?
    .require_success()?;
    Ok(())
}

fn append(buffer: &mut Vec<u8>, bytes: &[u8], maximum: usize) -> io::Result<()> {
    if bytes.len() > maximum.saturating_sub(buffer.len()) {
        return Err(protocol("Cargo JSON message exceeds caller allowance"));
    }
    buffer.try_reserve(bytes.len()).map_err(io::Error::other)?;
    buffer.extend_from_slice(bytes);
    Ok(())
}

fn protocol(message: &'static str) -> io::Error {
    io::Error::new(io::ErrorKind::InvalidData, message)
}