refactor: split main.rs into registry, build, and qemu modules
main.rs keeps only the CLI definition and command dispatch: - registry.rs: image-name validation + XDG registry path handling (tests) - build.rs: podman mount/unmount, vmlinuz extraction, cpio/gzip initrd - qemu.rs: direct-kernel-boot VM launch No behavior change; cargo fmt/clippy/test pass, build/run paths verified against the mock-vm image.
This commit was merged in pull request #5.
This commit is contained in:
+115
@@ -0,0 +1,115 @@
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//! Build: mount a podman image, extract vmlinuz, and pack the rootfs as a
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//! gzipped cpio initrd in the registry.
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use anyhow::{Context, Result, bail};
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use flate2::write::GzEncoder;
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use std::fs::{self, File};
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use std::path::{Path, PathBuf};
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use std::process::{Command, Stdio};
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use crate::registry::registry_dir;
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pub(crate) fn build(image: &str) -> Result<()> {
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let mount_path = mount_image(image)?;
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println!("Mounted at: {}", mount_path.display());
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// Keep the build result so the image is unmounted even when the build fails.
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let result = build_artifacts(image, &mount_path);
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let unmounted = Command::new("podman")
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.args(["unshare", "--", "podman", "image", "unmount", image])
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.output()
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.is_ok_and(|out| out.status.success());
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if unmounted {
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println!("Unmounted image.");
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} else {
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eprintln!("warning: failed to unmount image '{}'", image);
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}
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result
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}
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fn mount_image(image: &str) -> Result<PathBuf> {
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let output = Command::new("podman")
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.args(["unshare", "--", "podman", "image", "mount", image])
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.output()
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.context("Failed to run podman image mount")?;
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let mount_path = String::from_utf8_lossy(&output.stdout).trim().to_string();
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if !output.status.success() || mount_path.is_empty() {
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bail!(
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"podman image mount failed: {}",
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String::from_utf8_lossy(&output.stderr).trim()
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);
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}
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Ok(PathBuf::from(mount_path))
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}
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fn build_artifacts(image: &str, mount_path: &Path) -> Result<()> {
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let mount_path = mount_path.to_str().context("mount path is not UTF-8")?;
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let vmlinuz_src = format!("{mount_path}/vmlinuz");
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// The rootless overlay mount only exists inside podman unshare's user
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// namespace, so every read of the rootfs must run there; pipes still
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// cross the namespace boundary.
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let has_kernel = Command::new("podman")
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.args(["unshare", "--", "test", "-f", &vmlinuz_src])
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.status()
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.context("Failed to check for /vmlinuz inside the image mount")?;
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if !has_kernel.success() {
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bail!("Image missing required /vmlinuz. Place kernel at /vmlinuz in Containerfile.");
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}
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let reg_dir = registry_dir(image)?;
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fs::create_dir_all(®_dir)?;
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println!("Registry: {}", reg_dir.display());
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let vmlinuz_dst = reg_dir.join("vmlinuz");
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let cp_status = Command::new("podman")
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.args([
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"unshare",
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"--",
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"cp",
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&vmlinuz_src,
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vmlinuz_dst.to_str().context("registry path is not UTF-8")?,
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])
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.status()
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.context("Failed to copy vmlinuz out of the image mount")?;
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if !cp_status.success() {
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bail!("Failed to copy vmlinuz to registry");
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}
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println!("Copied vmlinuz -> {}", vmlinuz_dst.display());
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// Pack the rootfs as a gzipped newc cpio archive; vmlinuz is excluded
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// because QEMU loads the kernel separately via -kernel. The cpio
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// pipeline runs inside the namespace, its stdout is compressed here.
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let initrd_path = reg_dir.join("initrd");
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let script = r#"cd "$1" && find . -not -path ./vmlinuz | cpio -o -H newc"#;
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let mut cpio = Command::new("podman")
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.args(["unshare", "--", "sh", "-c", script, "sh", mount_path])
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.stdout(Stdio::piped())
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.spawn()
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.context("Failed to spawn the cpio pipeline")?;
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let initrd_file = File::create(&initrd_path).context("Failed to create initrd file")?;
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let mut encoder = GzEncoder::new(initrd_file, flate2::Compression::default());
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let cpio_stdout = cpio.stdout.take().context("cpio stdout was not piped")?;
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let copied = std::io::copy(&mut std::io::BufReader::new(cpio_stdout), &mut encoder);
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let stream_result = copied
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.and_then(move |_| encoder.finish().map(|_| ()))
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.context("Failed to write the gzipped initrd");
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let cpio_status = cpio
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.wait()
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.context("Failed to wait for the cpio pipeline")?;
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if let Err(e) = stream_result {
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let _ = fs::remove_file(&initrd_path);
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return Err(e);
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}
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if !cpio_status.success() {
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let _ = fs::remove_file(&initrd_path);
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bail!("find/cpio pipeline failed with status {cpio_status}");
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}
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println!("Created initrd -> {}", initrd_path.display());
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Ok(())
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}
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+7
-252
@@ -1,9 +1,9 @@
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use anyhow::{Context, Result, bail};
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mod build;
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mod qemu;
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mod registry;
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use anyhow::Result;
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use clap::{Parser, Subcommand};
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use flate2::write::GzEncoder;
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use std::fs::{self, File};
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use std::path::{Path, PathBuf};
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use std::process::{Command, Stdio};
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#[derive(Parser, Debug)]
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#[command(about = "Build bootable initrd VMs from container images")]
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@@ -33,256 +33,11 @@ fn main() -> Result<()> {
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let cli = Cli::parse();
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match cli.command {
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Commands::Build { image, _size: _ } => {
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build(&image)?;
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build::build(&image)?;
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}
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Commands::Run { name } => {
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run(&name)?;
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qemu::run(&name)?;
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}
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}
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Ok(())
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}
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/// Validate a user-supplied image name before it is used in a registry path.
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///
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/// The name becomes a directory under `$XDG_DATA_HOME/slim-rs/registry/`, so
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/// path separators and `.`/`..` would allow escaping that directory.
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/// Allow-list: ASCII alphanumerics plus `.`, `_`, `:`, `-` (covers image
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/// refs like `alpine:3.15`).
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fn validate_image_name(name: &str) -> Result<()> {
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let valid = !name.is_empty()
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&& name != "."
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&& name != ".."
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&& name
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.chars()
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.all(|c| c.is_ascii_alphanumeric() || matches!(c, '.' | '_' | ':' | '-'));
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if !valid {
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bail!(
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"invalid image name '{name}': must be non-empty and contain only \
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alphanumerics, '.', '_', ':' and '-' (no path separators or '..')"
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);
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}
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Ok(())
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}
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fn registry_dir(image: &str) -> Result<PathBuf> {
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validate_image_name(image)?;
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let base = xdg::BaseDirectories::with_prefix("slim-rs");
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let initrd_path = base
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.place_data_file(format!("registry/{image}/initrd"))
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.context("Failed to write to XDG_DATA_HOME")?;
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let reg_dir = initrd_path
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.parent()
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.expect("data file has a parent")
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.to_owned();
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// Defense in depth: the constructed path must stay inside the registry.
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let registry_root = base
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.place_data_file("registry/.root-check")
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.context("Failed to write to XDG_DATA_HOME")?
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.parent()
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.expect("data file has a parent")
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.to_owned();
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if !reg_dir.starts_with(®istry_root) {
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bail!(
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"invalid image name '{image}': registry path escapes {}",
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registry_root.display()
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);
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}
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Ok(reg_dir)
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}
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fn build(image: &str) -> Result<()> {
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let mount_path = mount_image(image)?;
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println!("Mounted at: {}", mount_path.display());
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// Keep the build result so the image is unmounted even when the build fails.
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let result = build_artifacts(image, &mount_path);
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let unmounted = Command::new("podman")
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.args(["unshare", "--", "podman", "image", "unmount", image])
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.output()
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.is_ok_and(|out| out.status.success());
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if unmounted {
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println!("Unmounted image.");
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} else {
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eprintln!("warning: failed to unmount image '{}'", image);
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}
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result
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}
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fn mount_image(image: &str) -> Result<PathBuf> {
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let output = Command::new("podman")
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.args(["unshare", "--", "podman", "image", "mount", image])
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.output()
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.context("Failed to run podman image mount")?;
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let mount_path = String::from_utf8_lossy(&output.stdout).trim().to_string();
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if !output.status.success() || mount_path.is_empty() {
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bail!(
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"podman image mount failed: {}",
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String::from_utf8_lossy(&output.stderr).trim()
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);
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}
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Ok(PathBuf::from(mount_path))
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}
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fn build_artifacts(image: &str, mount_path: &Path) -> Result<()> {
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let mount_path = mount_path.to_str().context("mount path is not UTF-8")?;
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let vmlinuz_src = format!("{mount_path}/vmlinuz");
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|
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// The rootless overlay mount only exists inside podman unshare's user
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// namespace, so every read of the rootfs must run there; pipes still
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// cross the namespace boundary.
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let has_kernel = Command::new("podman")
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.args(["unshare", "--", "test", "-f", &vmlinuz_src])
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.status()
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.context("Failed to check for /vmlinuz inside the image mount")?;
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if !has_kernel.success() {
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bail!("Image missing required /vmlinuz. Place kernel at /vmlinuz in Containerfile.");
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}
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let reg_dir = registry_dir(image)?;
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fs::create_dir_all(®_dir)?;
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println!("Registry: {}", reg_dir.display());
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let vmlinuz_dst = reg_dir.join("vmlinuz");
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let cp_status = Command::new("podman")
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.args([
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"unshare",
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"--",
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"cp",
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&vmlinuz_src,
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vmlinuz_dst.to_str().context("registry path is not UTF-8")?,
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])
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.status()
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.context("Failed to copy vmlinuz out of the image mount")?;
|
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if !cp_status.success() {
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bail!("Failed to copy vmlinuz to registry");
|
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}
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println!("Copied vmlinuz -> {}", vmlinuz_dst.display());
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|
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// Pack the rootfs as a gzipped newc cpio archive; vmlinuz is excluded
|
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// because QEMU loads the kernel separately via -kernel. The cpio
|
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// pipeline runs inside the namespace, its stdout is compressed here.
|
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let initrd_path = reg_dir.join("initrd");
|
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let script = r#"cd "$1" && find . -not -path ./vmlinuz | cpio -o -H newc"#;
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let mut cpio = Command::new("podman")
|
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.args(["unshare", "--", "sh", "-c", script, "sh", mount_path])
|
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.stdout(Stdio::piped())
|
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.spawn()
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.context("Failed to spawn the cpio pipeline")?;
|
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|
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let initrd_file = File::create(&initrd_path).context("Failed to create initrd file")?;
|
||||
let mut encoder = GzEncoder::new(initrd_file, flate2::Compression::default());
|
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let cpio_stdout = cpio.stdout.take().context("cpio stdout was not piped")?;
|
||||
let copied = std::io::copy(&mut std::io::BufReader::new(cpio_stdout), &mut encoder);
|
||||
let stream_result = copied
|
||||
.and_then(move |_| encoder.finish().map(|_| ()))
|
||||
.context("Failed to write the gzipped initrd");
|
||||
let cpio_status = cpio
|
||||
.wait()
|
||||
.context("Failed to wait for the cpio pipeline")?;
|
||||
|
||||
if let Err(e) = stream_result {
|
||||
let _ = fs::remove_file(&initrd_path);
|
||||
return Err(e);
|
||||
}
|
||||
if !cpio_status.success() {
|
||||
let _ = fs::remove_file(&initrd_path);
|
||||
bail!("find/cpio pipeline failed with status {cpio_status}");
|
||||
}
|
||||
println!("Created initrd -> {}", initrd_path.display());
|
||||
|
||||
Ok(())
|
||||
}
|
||||
|
||||
fn run(name: &str) -> Result<()> {
|
||||
let reg_dir = registry_dir(name)?;
|
||||
let vmlinuz_path = reg_dir.join("vmlinuz");
|
||||
let initrd_path = reg_dir.join("initrd");
|
||||
if !vmlinuz_path.exists() || !initrd_path.exists() {
|
||||
bail!(
|
||||
"Registry missing vmlinuz/initrd for '{}'. Run `slim build` first.",
|
||||
name
|
||||
);
|
||||
}
|
||||
println!("Booting {} from registry: {}", name, reg_dir.display());
|
||||
println!(
|
||||
" qemu-system-x86_64 -m 256 -nographic -kernel {} -initrd {} -append 'console=ttyS0'",
|
||||
vmlinuz_path.display(),
|
||||
initrd_path.display()
|
||||
);
|
||||
|
||||
let cmdline = [
|
||||
"console=ttyS0,115200",
|
||||
"root=/dev/ram0",
|
||||
"rw",
|
||||
"earlyprintk=serial",
|
||||
"nokaslr",
|
||||
"raid=noautodetect",
|
||||
]
|
||||
.join(" ");
|
||||
|
||||
// Launch with a 5-second timeout for quick smoke verification
|
||||
let status = Command::new("qemu-system-x86_64")
|
||||
.args(["-m", "1024M"])
|
||||
.arg("-kernel")
|
||||
.arg(vmlinuz_path.as_os_str())
|
||||
.arg("-initrd")
|
||||
.arg(initrd_path.as_os_str())
|
||||
.args(["-append", &cmdline])
|
||||
.args(["-nographic"])
|
||||
.status()
|
||||
.context("Failed to launch qemu-system-x86_64")?;
|
||||
|
||||
match status.code() {
|
||||
Some(0) => println!("QEMU exited cleanly."),
|
||||
Some(126) | Some(127) => {
|
||||
bail!("Failed to start qemu-system-x86_64 (is it installed and in PATH?)")
|
||||
}
|
||||
Some(code) => bail!("QEMU exited with code {code}"),
|
||||
None => bail!("QEMU terminated by a signal"),
|
||||
}
|
||||
Ok(())
|
||||
}
|
||||
|
||||
#[cfg(test)]
|
||||
mod tests {
|
||||
use super::validate_image_name;
|
||||
|
||||
#[test]
|
||||
fn accepts_valid_image_names() {
|
||||
for name in [
|
||||
"alpine:3.15",
|
||||
"slim",
|
||||
"mock-vm",
|
||||
"my_vm",
|
||||
"a.b.c",
|
||||
"vm-1.2.3",
|
||||
] {
|
||||
validate_image_name(name).unwrap_or_else(|e| panic!("{name} rejected: {e}"));
|
||||
}
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn rejects_traversal_and_separators() {
|
||||
for name in [
|
||||
"",
|
||||
".",
|
||||
"..",
|
||||
"../evil",
|
||||
"../../tmp/evil",
|
||||
"a/b",
|
||||
"/abs",
|
||||
"a\\b",
|
||||
"foo bar",
|
||||
"vm;rm",
|
||||
"vm\n",
|
||||
] {
|
||||
assert!(
|
||||
validate_image_name(name).is_err(),
|
||||
"{name:?} should be rejected"
|
||||
);
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
+56
@@ -0,0 +1,56 @@
|
||||
//! QEMU: boot a registry entry with qemu-system-x86_64 using direct kernel
|
||||
//! boot (-kernel/-initrd).
|
||||
|
||||
use anyhow::{Context, Result, bail};
|
||||
use std::process::Command;
|
||||
|
||||
use crate::registry::registry_dir;
|
||||
|
||||
pub(crate) fn run(name: &str) -> Result<()> {
|
||||
let reg_dir = registry_dir(name)?;
|
||||
let vmlinuz_path = reg_dir.join("vmlinuz");
|
||||
let initrd_path = reg_dir.join("initrd");
|
||||
if !vmlinuz_path.exists() || !initrd_path.exists() {
|
||||
bail!(
|
||||
"Registry missing vmlinuz/initrd for '{}'. Run `slim build` first.",
|
||||
name
|
||||
);
|
||||
}
|
||||
println!("Booting {} from registry: {}", name, reg_dir.display());
|
||||
println!(
|
||||
" qemu-system-x86_64 -m 256 -nographic -kernel {} -initrd {} -append 'console=ttyS0'",
|
||||
vmlinuz_path.display(),
|
||||
initrd_path.display()
|
||||
);
|
||||
|
||||
let cmdline = [
|
||||
"console=ttyS0,115200",
|
||||
"root=/dev/ram0",
|
||||
"rw",
|
||||
"earlyprintk=serial",
|
||||
"nokaslr",
|
||||
"raid=noautodetect",
|
||||
]
|
||||
.join(" ");
|
||||
|
||||
let status = Command::new("qemu-system-x86_64")
|
||||
.args(["-m", "1024M"])
|
||||
.arg("-kernel")
|
||||
.arg(vmlinuz_path.as_os_str())
|
||||
.arg("-initrd")
|
||||
.arg(initrd_path.as_os_str())
|
||||
.args(["-append", &cmdline])
|
||||
.args(["-nographic"])
|
||||
.status()
|
||||
.context("Failed to launch qemu-system-x86_64")?;
|
||||
|
||||
match status.code() {
|
||||
Some(0) => println!("QEMU exited cleanly."),
|
||||
Some(126) | Some(127) => {
|
||||
bail!("Failed to start qemu-system-x86_64 (is it installed and in PATH?)")
|
||||
}
|
||||
Some(code) => bail!("QEMU exited with code {code}"),
|
||||
None => bail!("QEMU terminated by a signal"),
|
||||
}
|
||||
Ok(())
|
||||
}
|
||||
@@ -0,0 +1,95 @@
|
||||
//! Registry: local storage of built VM artifacts under
|
||||
//! `$XDG_DATA_HOME/slim-rs/registry/<image>/`.
|
||||
|
||||
use anyhow::{Context, Result, bail};
|
||||
use std::path::PathBuf;
|
||||
|
||||
/// Validate a user-supplied image name before it is used in a registry path.
|
||||
///
|
||||
/// The name becomes a directory under `$XDG_DATA_HOME/slim-rs/registry/`, so
|
||||
/// path separators and `.`/`..` would allow escaping that directory.
|
||||
/// Allow-list: ASCII alphanumerics plus `.`, `_`, `:`, `-` (covers image
|
||||
/// refs like `alpine:3.15`).
|
||||
pub(crate) fn validate_image_name(name: &str) -> Result<()> {
|
||||
let valid = !name.is_empty()
|
||||
&& name != "."
|
||||
&& name != ".."
|
||||
&& name
|
||||
.chars()
|
||||
.all(|c| c.is_ascii_alphanumeric() || matches!(c, '.' | '_' | ':' | '-'));
|
||||
if !valid {
|
||||
bail!(
|
||||
"invalid image name '{name}': must be non-empty and contain only \
|
||||
alphanumerics, '.', '_', ':' and '-' (no path separators or '..')"
|
||||
);
|
||||
}
|
||||
Ok(())
|
||||
}
|
||||
|
||||
pub(crate) fn registry_dir(image: &str) -> Result<PathBuf> {
|
||||
validate_image_name(image)?;
|
||||
let base = xdg::BaseDirectories::with_prefix("slim-rs");
|
||||
let initrd_path = base
|
||||
.place_data_file(format!("registry/{image}/initrd"))
|
||||
.context("Failed to write to XDG_DATA_HOME")?;
|
||||
let reg_dir = initrd_path
|
||||
.parent()
|
||||
.expect("data file has a parent")
|
||||
.to_owned();
|
||||
|
||||
// Defense in depth: the constructed path must stay inside the registry.
|
||||
let registry_root = base
|
||||
.place_data_file("registry/.root-check")
|
||||
.context("Failed to write to XDG_DATA_HOME")?
|
||||
.parent()
|
||||
.expect("data file has a parent")
|
||||
.to_owned();
|
||||
if !reg_dir.starts_with(®istry_root) {
|
||||
bail!(
|
||||
"invalid image name '{image}': registry path escapes {}",
|
||||
registry_root.display()
|
||||
);
|
||||
}
|
||||
Ok(reg_dir)
|
||||
}
|
||||
|
||||
#[cfg(test)]
|
||||
mod tests {
|
||||
use super::validate_image_name;
|
||||
|
||||
#[test]
|
||||
fn accepts_valid_image_names() {
|
||||
for name in [
|
||||
"alpine:3.15",
|
||||
"slim",
|
||||
"mock-vm",
|
||||
"my_vm",
|
||||
"a.b.c",
|
||||
"vm-1.2.3",
|
||||
] {
|
||||
validate_image_name(name).unwrap_or_else(|e| panic!("{name} rejected: {e}"));
|
||||
}
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn rejects_traversal_and_separators() {
|
||||
for name in [
|
||||
"",
|
||||
".",
|
||||
"..",
|
||||
"../evil",
|
||||
"../../tmp/evil",
|
||||
"a/b",
|
||||
"/abs",
|
||||
"a\\b",
|
||||
"foo bar",
|
||||
"vm;rm",
|
||||
"vm\n",
|
||||
] {
|
||||
assert!(
|
||||
validate_image_name(name).is_err(),
|
||||
"{name:?} should be rejected"
|
||||
);
|
||||
}
|
||||
}
|
||||
}
|
||||
Reference in New Issue
Block a user