Add runc config/state/cli parser

src/runc/cli.rs

@@ -0,0 +1,69 @@
+use std::path::PathBuf;
+
+use clap::ValueEnum;
+use once_cell::sync::Lazy;
+
+#[derive(ValueEnum, Clone, Copy, PartialEq, Eq)]
+pub enum LogFormat {
+    Json,
+    Text,
+}
+
+/// runc command line.
+#[derive(clap::Parser)]
+pub struct Command {
+    #[command(flatten)]
+    pub global: GlobalOptions,
+
+    #[command(subcommand)]
+    pub command: Subcommand,
+}
+
+#[derive(clap::Args)]
+pub struct GlobalOptions {
+    #[arg(long)]
+    pub debug: bool,
+
+    #[arg(long)]
+    pub log: Option<PathBuf>,
+
+    #[arg(long, default_value = "text")]
+    pub log_format: LogFormat,
+
+    #[arg(long, default_value = "/run/runc")]
+    pub root: PathBuf,
+
+    #[arg(long)]
+    pub systemd_cgroup: bool,
+}
+
+#[derive(clap::Subcommand)]
+pub enum Subcommand {
+    // We only care about the `create` subcommand.
+    // We need to be able to parse the rest (hence `trailing_var_arg` and `external_subcommand`) without error, but
+    // we don't make use of these and forward to runc directly.
+    Create(CreateOptions),
+    Run {
+        #[arg(trailing_var_arg = true, allow_hyphen_values = true)]
+        args: Vec<String>,
+    },
+    #[command(external_subcommand)]
+    #[allow(unused)]
+    Other(Vec<String>),
+}
+
+static BUNDLE_DEFAULT: Lazy<PathBuf> = Lazy::new(|| std::env::current_dir().unwrap());
+
+#[derive(clap::Args)]
+pub struct CreateOptions {
+    #[arg(short, long, default_value = BUNDLE_DEFAULT.as_os_str())]
+    pub bundle: PathBuf,
+
+    #[arg(long)]
+    pub console_socket: Option<PathBuf>,
+
+    #[arg(long)]
+    pub pid_file: Option<PathBuf>,
+
+    pub container_id: String,
+}

src/runc/config.rs

@@ -0,0 +1,45 @@
+use std::collections::HashMap;
+use std::path::Path;
+
+use anyhow::{Context, Result};
+use serde::Deserialize;
+
+#[non_exhaustive]
+#[derive(Debug, Deserialize)]
+pub struct User {
+    pub uid: u32,
+    pub gid: u32,
+}
+
+#[non_exhaustive]
+#[derive(Debug, Deserialize)]
+pub struct Process {
+    pub user: User,
+}
+
+/// OCI config.
+///
+/// Only config that we need are implemented here.
+/// Ref: https://github.com/opencontainers/runtime-spec/blob/main/config.md
+#[non_exhaustive]
+#[derive(Debug, Deserialize)]
+pub struct Config {
+    pub process: Process,
+    #[serde(default)]
+    pub annotations: HashMap<String, String>,
+}
+
+impl Config {
+    pub fn from_str(s: &str) -> Result<Self> {
+        serde_json::from_str(s).context("Cannot parse config.json")
+    }
+
+    pub fn from_config(path: &Path) -> Result<Self> {
+        Self::from_str(&std::fs::read_to_string(path).context("Cannot read config.json")?)
+    }
+
+    pub fn from_bundle(bundle: &Path) -> Result<Self> {
+        let config = bundle.join("config.json");
+        Self::from_config(&config)
+    }
+}

src/runc/mod.rs

@@ -1 +1,4 @@
+pub mod cli;
+pub mod config;
 pub mod log;
+pub mod state;

src/runc/state.rs

@@ -0,0 +1,37 @@
+use std::path::{Path, PathBuf};
+
+use anyhow::{Context, Result};
+use serde::Deserialize;
+
+#[non_exhaustive]
+#[derive(Debug, Deserialize)]
+pub struct CgroupPaths {
+    #[serde(rename = "")]
+    pub unified: PathBuf,
+    pub devices: Option<PathBuf>,
+}
+
+/// runc `libcontainer` states.
+///
+/// Only states that we need are implemented here.
+/// Ref: https://github.com/opencontainers/runc/blob/6a2813f16ad4e3be44903f6fb499c02837530ad5/libcontainer/container_linux.go#L52
+#[non_exhaustive]
+#[derive(Debug, Deserialize)]
+pub struct State {
+    pub init_process_pid: u32,
+    pub cgroup_paths: CgroupPaths,
+}
+
+impl State {
+    pub fn from_str(s: &str) -> Result<Self> {
+        serde_json::from_str(s).context("Cannot parse state.json")
+    }
+
+    pub fn from_state(path: &Path) -> Result<Self> {
+        Self::from_str(&std::fs::read_to_string(path).context("Cannot read state.json")?)
+    }
+
+    pub fn from_root_and_id(root: &Path, id: &str) -> Result<Self> {
+        Self::from_state(&root.join(format!("{}/state.json", id)))
+    }
+}