initoverlayfs: Add initial initoverlayfs support

Run initoverlayfs in case the binary exists.

Signed-off-by: Douglas Schilling Landgraf <[email protected]>
Co-authored-by: Colin Walters <[email protected]>

rust/src/cliwrap/kernel_install.rs

@@ -10,6 +10,9 @@ use cap_std_ext::cap_std;
 use fn_error_context::context;
 use std::os::fd::AsRawFd;
 use std::process::Command;
+use std::path::Path;
+
+const INITOVERLAY_INSTALL_CMD: &str = "/usr/bin/initoverlayfs-install";
 
 /// Primary entrypoint to running our wrapped `kernel-install` handling.
 #[context("rpm-ostree kernel-install wrapper")]
@@ -42,7 +45,12 @@ pub(crate) fn main(argv: &[&str]) -> Result<()> {
     }
     if let Some(k) = new_kernel {
         undo_systemctl_wrap()?;
-        run_dracut(&k)?;
+        let initoverlayfs_path = Path::new(INITOVERLAY_INSTALL_CMD);
+        if initoverlayfs_path.exists() {
+            run_initoverlayfs()?;
+        } else {
+            run_dracut(&k)?;
+        }
         redo_systemctl_wrap()?;
     }
     Ok(())
@@ -64,6 +72,15 @@ fn redo_systemctl_wrap() -> Result<()> {
     Ok(())
 }
 
+#[context("Running initoverlayfs")]
+fn run_initoverlayfs() -> Result<()> {
+    let st = Command::new(INITOVERLAY_INSTALL_CMD).status()?;
+    if !st.success() {
+        anyhow::bail!("Failed to invoke {INITOVERLAY_INSTALL_CMD}");
+    }
+    Ok(())
+}
+
 #[context("Running dracut")]
 fn run_dracut(kernel_dir: &str) -> Result<()> {
     let root_fs = Utf8Dir::open_ambient_dir("/", cap_std::ambient_authority())?;
@@ -108,5 +125,8 @@ fn run_dracut(kernel_dir: &str) -> Result<()> {
         &root_fs,
         (Utf8Path::new("lib/modules").join(kernel_dir)).join("initramfs.img"),
     )?;
+
+    run_initoverlayfs()?;
+
     Ok(())
 }