kernel_install: unwrap systemd if it's wrapped

jmarrero · jmarrero · commit af7e4c25f4c6 · 2025-01-28T20:27:50.000-05:00
when replacing the kernel packages using rpm-ostree but
with the layout in /usr/lib/kernel/install.conf set to ostree
we need to check for a wrapped systemd before calling dracut
to get the correct modules in the initramfs.

When rpm-ostree kernel-install is called from dnf or rpm we
don't wrap before running scripts so we were ok in that path.
diff --git a/rust/src/kernel_install.rs b/rust/src/kernel_install.rs
@@ -58,9 +58,11 @@ fn add(root: &Dir, argv: &[&str]) -> Result<()> {
         anyhow::bail!("No kernel version provided");
     };
     tracing::debug!("Installing kernel kver={kver}");
+    undo_systemctl_wrap()?;
     println!("Generating initramfs");
     crate::initramfs::run_dracut(root, &kver)?;
     println!("Running depmod");
+    redo_systemctl_wrap()?;
     Command::new("depmod")
         .args(["-a", kver])
         .run()
@@ -113,6 +115,30 @@ pub fn main(argv: &[&str]) -> Result<u8> {
     }
 }
 
+#[context("Unwrapping systemctl")]
+fn undo_systemctl_wrap() -> Result<()> {
+    let bin_path = &Dir::open_ambient_dir("usr/bin", cap_std::ambient_authority())?;
+    if !bin_path.exists("systemctl.rpmostreesave") {
+        // Not wrapped, just return.
+        return Ok(());
+    }
+    bin_path.rename("systemctl", &bin_path, "systemctl.backup")?;
+    bin_path.rename("systemctl.rpmostreesave", &bin_path, "systemctl")?;
+    Ok(())
+}
+
+#[context("Wrapping systemctl")]
+fn redo_systemctl_wrap() -> Result<()> {
+    let bin_path = &Dir::open_ambient_dir("usr/bin", cap_std::ambient_authority())?;
+    if !bin_path.exists("systemctl.backup") {
+        // We did not unwrap, just return.
+        return Ok(());
+    }
+    bin_path.rename("systemctl", &bin_path, "systemctl.rpmostreesave")?;
+    bin_path.rename("systemctl.backup", &bin_path, "systemctl")?;
+    Ok(())
+}
+
 #[cfg(test)]
 mod tests {
     use std::path::Path;
