omea-kernel-x86-64 0.1.4

//! Pre-built x86_64 runtime assets for omea's **KVM** backend,
//! packaged as a Rust crate so embedders never fetch binaries out of band.
//!
//! This is the current x86_64 implementation of the architecture-split asset
//! contract. You normally don't depend on it directly — depend on the
//! [`omea-kernel`] facade, which re-exports the right arch's crate by
//! `target_arch`. Cargo only downloads the sub-crate matching the build
//! target, so an x86_64 build pulls only this crate.
//!
//! Three assets are bundled:
//!
//! 1. **Linux kernel** ([`KERNEL_BYTES`]) — a minimal-config x86_64
//!    `bzImage` (Linux 6.12). Everything the microVM needs is built in
//!    (`MODULES=n`): virtio-MMIO (+`CMDLINE_DEVICES`), virtio-blk,
//!    virtio-vsock, squashfs, overlayfs, ext4, 8250 console. No module
//!    loading, no host-kernel coupling.
//! 2. **busybox** ([`BUSYBOX_BYTES`]) — a static x86_64 busybox. The KVM
//!    bake stages it into the agent initramfs as the PID-1 init's toolbox
//!    (mount, switch_root, overlay setup).
//! 3. **`omea-agent`** ([`OMEA_AGENT_BYTES`]) — the in-VM
//!    control agent (static x86_64-musl). Runs as PID 1 inside the
//!    container after `switch_root`, serving `exec`/control RPCs over vsock.
//!
//! The KVM backend builds the container rootfs (overlayfs + `switch_root`)
//! directly in the agent initramfs's generated init.
//!
//! [`omea-kernel`]: https://crates.io/crates/omea-kernel

/// Raw bytes of the x86_64 kernel — a minimal-config Linux `bzImage`.
///
/// The omea KVM backend loads this as the guest kernel. The bytes are
/// staged into `OUT_DIR` by `build.rs` (env override or bundled `kernel.xz`).
pub const KERNEL_BYTES: &[u8] = include_bytes!(concat!(env!("OUT_DIR"), "/kernel"));

/// Length of the kernel image in bytes — `KERNEL_BYTES.len()`, const-evaluable.
pub const KERNEL_LEN: usize = KERNEL_BYTES.len();

/// Raw bytes of the static x86_64 busybox staged into the agent initramfs.
/// The generated PID-1 init uses it for the overlayfs + `switch_root` dance
/// that builds the writable container rootfs from the read-only OCI squashfs.
pub const BUSYBOX_BYTES: &[u8] = include_bytes!(concat!(env!("OUT_DIR"), "/busybox"));

/// Length of the busybox binary in bytes.
pub const BUSYBOX_LEN: usize = BUSYBOX_BYTES.len();

/// Raw bytes of the in-VM `omea-agent` (static x86_64-musl ELF). Runs
/// as PID 1 inside the container post-`switch_root`, serving docker-style
/// `exec` and other control RPCs over vsock.
pub const OMEA_AGENT_BYTES: &[u8] = include_bytes!(concat!(env!("OUT_DIR"), "/omea-agent"));

/// Length of the omea-agent binary in bytes.
pub const OMEA_AGENT_LEN: usize = OMEA_AGENT_BYTES.len();

/// Write the bundled kernel image to `dest`. Overwrites any existing file;
/// the parent dir must exist (use [`extract_kernel_to_with_parents`] to mkdir).
pub fn extract_kernel_to(dest: &std::path::Path) -> std::io::Result<()> {
    std::fs::write(dest, KERNEL_BYTES)
}

/// Like [`extract_kernel_to`] but `mkdir -p`'s the parent dir first.
pub fn extract_kernel_to_with_parents(dest: &std::path::Path) -> std::io::Result<()> {
    if let Some(parent) = dest.parent() {
        std::fs::create_dir_all(parent)?;
    }
    extract_kernel_to(dest)
}

/// Write the bundled busybox to `dest`, executable (mode 0o755) on Unix.
pub fn extract_busybox_to(dest: &std::path::Path) -> std::io::Result<()> {
    std::fs::write(dest, BUSYBOX_BYTES)?;
    set_executable(dest)
}

/// Like [`extract_busybox_to`] but `mkdir -p`'s the parent dir first.
pub fn extract_busybox_to_with_parents(dest: &std::path::Path) -> std::io::Result<()> {
    if let Some(parent) = dest.parent() {
        std::fs::create_dir_all(parent)?;
    }
    extract_busybox_to(dest)
}

/// Write the bundled `omea-agent` to `dest`, executable on Unix.
pub fn extract_omea_agent_to(dest: &std::path::Path) -> std::io::Result<()> {
    std::fs::write(dest, OMEA_AGENT_BYTES)?;
    set_executable(dest)
}

/// Like [`extract_omea_agent_to`] but `mkdir -p`'s the parent first.
pub fn extract_omea_agent_to_with_parents(dest: &std::path::Path) -> std::io::Result<()> {
    if let Some(parent) = dest.parent() {
        std::fs::create_dir_all(parent)?;
    }
    extract_omea_agent_to(dest)
}

#[cfg(unix)]
fn set_executable(dest: &std::path::Path) -> std::io::Result<()> {
    use std::os::unix::fs::PermissionsExt;
    let mut perms = std::fs::metadata(dest)?.permissions();
    perms.set_mode(0o755);
    std::fs::set_permissions(dest, perms)
}

#[cfg(not(unix))]
fn set_executable(_dest: &std::path::Path) -> std::io::Result<()> {
    Ok(())
}