core: stop wrapping kernel-install when layout=ostree is set

We also correctly parse the arguments passed on kernel-install.

docs/treefile.md

@@ -57,7 +57,8 @@ It supports the following parameters:
       upgrading from very old versions of libostree.
     * "modules": Kernel data goes just in `/usr/lib/modules`.  Use
       this for new systems, and systems that don't need to be upgraded
-      from very old libostree versions.
+      from very old libostree versions. This is the default for editions 2024
+      and above.
     * "kernel-install": The system is integrated with `/sbin/kernel-install`
       from systemd. You likely want to additionally pair this with configuring `layout=ostree`
       in `/usr/lib/kernel/install.conf`, and adding a wrapper script to

rust/src/core.rs

@@ -5,6 +5,7 @@
 
 use crate::cxxrsutil::*;
 use crate::ffiutil;
+use crate::kernel_install::is_ostree_layout;
 use anyhow::Context;
 use anyhow::{anyhow, Result};
 use camino::Utf8Path;
@@ -48,6 +49,8 @@ const USERMOD_WRAPPER: &[u8] = include_bytes!("../../src/libpriv/usermod-wrapper
 const KERNEL_INSTALL_PATH: &str = "usr/bin/kernel-install";
 const KERNEL_INSTALL_WRAPPER: &[u8] = include_bytes!("../../src/libpriv/kernel-install-wrapper.sh");
 
+// ## Check for layout and wrap if =ostree
+
 const RPMOSTREE_CORE_STAGED_RPMS_DIR: &str = "rpm-ostree/staged-rpms";
 
 pub(crate) const OSTREE_BOOTED: &str = "/run/ostree-booted";
@@ -166,9 +169,11 @@ impl FilesystemScriptPrep {
         (SYSTEMCTL_PATH, SYSTEMCTL_WRAPPER),
         (USERADD_PATH, USERADD_WRAPPER),
         (USERMOD_PATH, USERMOD_WRAPPER),
-        (KERNEL_INSTALL_PATH, KERNEL_INSTALL_WRAPPER),
     ];
 
+    const REPLACE_KERNEL_PATHS: &'static [(&'static str, &'static [u8])] =
+        &[(KERNEL_INSTALL_PATH, KERNEL_INSTALL_WRAPPER)];
+
     fn saved_name(name: &str) -> String {
         format!("{}.rpmostreesave", name)
     }
@@ -188,6 +193,16 @@ impl FilesystemScriptPrep {
                 rootfs.atomic_write_with_perms(path, contents, mode)?;
             }
         }
+        if std::path::Path::new(OSTREE_BOOTED).exists() && !is_ostree_layout()? {
+            for &(path, contents) in Self::REPLACE_KERNEL_PATHS {
+                let mode = Permissions::from_mode(0o755);
+                let saved = &Self::saved_name(path);
+                if rootfs.try_exists(path)? {
+                    rootfs.rename(path, &rootfs, saved)?;
+                    rootfs.atomic_write_with_perms(path, contents, mode)?;
+                }
+            }
+        }
         Ok(Box::new(Self {
             rootfs,
             enabled: true,
@@ -472,16 +487,22 @@ mod test {
         }
         // Replaced kernel-install.
         {
-            let original_kernel_install = "original kernel_install";
-            d.atomic_write_with_perms(super::KERNEL_INSTALL_PATH, original_kernel_install, mode)?;
-            let contents = d.read_to_string(super::KERNEL_INSTALL_PATH)?;
-            assert_eq!(contents, original_kernel_install);
-            let mut g = super::prepare_filesystem_script_prep(d.as_raw_fd())?;
-            let contents = d.read_to_string(super::KERNEL_INSTALL_PATH)?;
-            assert_eq!(contents.as_bytes(), super::KERNEL_INSTALL_WRAPPER);
-            g.undo()?;
-            let contents = d.read_to_string(super::KERNEL_INSTALL_PATH)?;
-            assert_eq!(contents, original_kernel_install);
+            if std::path::Path::new(OSTREE_BOOTED).exists() && !is_ostree_layout()? {
+                let original_kernel_install = "original kernel_install";
+                d.atomic_write_with_perms(
+                    super::KERNEL_INSTALL_PATH,
+                    original_kernel_install,
+                    mode,
+                )?;
+                let contents = d.read_to_string(super::KERNEL_INSTALL_PATH)?;
+                assert_eq!(contents, original_kernel_install);
+                let mut g = super::prepare_filesystem_script_prep(d.as_raw_fd())?;
+                let contents = d.read_to_string(super::KERNEL_INSTALL_PATH)?;
+                assert_eq!(contents.as_bytes(), super::KERNEL_INSTALL_WRAPPER);
+                g.undo()?;
+                let contents = d.read_to_string(super::KERNEL_INSTALL_PATH)?;
+                assert_eq!(contents, original_kernel_install);
+            }
         }
         Ok(())
     }

rust/src/kernel_install.rs

@@ -11,6 +11,9 @@
 
 // SPDX-License-Identifier: Apache-2.0 OR MIT
 
+use std::fs::File;
+use std::io::{BufRead, BufReader};
+use std::path::Path;
 use std::process::Command;
 
 use anyhow::{Context, Result};
@@ -29,13 +32,36 @@ const SKIP: u8 = 77;
 const MODULES: &str = "usr/lib/modules";
 /// The default name for the initramfs.
 const INITRAMFS: &str = "initramfs.img";
+/// The path to the instal.conf that sets layout.
+const KERNEL_INSTALL_CONF: &str = "/usr/lib/kernel/install.conf";
+
+#[context("Verifying kernel-install layout file")]
+pub fn is_ostree_layout() -> Result<bool> {
+    let install_conf = Path::new(KERNEL_INSTALL_CONF);
+    if !install_conf.is_file() {
+        println!("can not read /usr/lib/kernel/install.conf");
+        return Ok(false);
+    }
+    let buff = BufReader::new(
+        File::open(install_conf).context("Failed to open /usr/lib/kernel/install.conf")?,
+    );
+    // Check for "layout=ostree" in the file
+    for line in buff.lines() {
+        let line = line.context("Failed to read line")?;
+        if line.trim() == "layout=ostree" {
+            return Ok(true);
+        }
+    }
+    Ok(false)
+}
 
 #[context("Adding kernel")]
 fn add(root: &Dir, argv: &[&str]) -> Result<()> {
     let mut argv_it = argv.iter().copied();
     let Some(kver) = argv_it.next() else {
         anyhow::bail!("No kernel version provided");
     };
+    tracing::debug!("Installing kernel kver={kver}");
     println!("Generating initramfs");
     crate::initramfs::run_dracut(root, &kver)?;
     println!("Running depmod");
@@ -51,6 +77,7 @@ fn add(root: &Dir, argv: &[&str]) -> Result<()> {
 
 #[context("Removing kernel")]
 fn remove(root: &Dir, kver: &str) -> Result<()> {
+    tracing::debug!("Removing kernel kver={kver}");
     let kdir = format!("{MODULES}/{kver}");
     let Some(kernel_dir) = root.open_dir_optional(&kdir)? else {
         return Ok(());
@@ -66,6 +93,7 @@ pub fn main(argv: &[&str]) -> Result<u8> {
     let Some(layout) = std::env::var_os(LAYOUT_VAR) else {
         return Ok(0);
     };
+    tracing::debug!("The LAYOUT_OSTREE is: {:?}", layout.to_str());
     if !matches!(layout.to_str(), Some(LAYOUT_OSTREE)) {
         return Ok(0);
     }
@@ -76,14 +104,15 @@ pub fn main(argv: &[&str]) -> Result<u8> {
         return Ok(0);
     }
     let root = &Dir::open_ambient_dir("/", cap_std::ambient_authority())?;
+    tracing::debug!("argv={argv:?}");
     match argv {
-        ["add", rest @ ..] => {
+        [_, _, "add", rest @ ..] => {
             add(root, rest)?;
             // In the case of adding a new kernel, we intercept everything else
             // today. In the future we can try to ensure we reuse what bits are there.
             Ok(SKIP)
         }
-        ["remove", kver] => {
+        [_, _, "remove", kver, ..] => {
             remove(root, kver)?;
             Ok(0)
         }