core/cliwrap: Fix is_ostree_layout() in unit tests

rust/src/cliwrap.rs

@@ -68,6 +68,8 @@ pub fn entrypoint(args: &[&str]) -> Result<()> {
         return cliutil::exec_real_binary(name, args);
     }
 
+    let root = Dir::open_ambient_dir("/", cap_std::ambient_authority())?;
+
     let host_type = crate::get_system_host_type()?;
     if matches!(
         host_type,
@@ -78,7 +80,9 @@ pub fn entrypoint(args: &[&str]) -> Result<()> {
             "yum" | "dnf" => Ok(self::yumdnf::main(host_type, args)?),
             "dracut" => Ok(self::dracut::main(args)?),
             "grubby" => Ok(self::grubby::main(args)?),
-            "kernel-install" if !is_ostree_layout()? => Ok(self::kernel_install_wrap::main(args)?),
+            "kernel-install" if !is_ostree_layout(&root)? => {
+                Ok(self::kernel_install_wrap::main(args)?)
+            }
             _ => Err(anyhow!("Unknown wrapped binary: {}", name)),
         }
     } else {
@@ -163,7 +167,9 @@ fn write_wrappers(rootfs_dfd: &Dir, allowlist: Option<&HashSet<&str>>) -> Result
         .map(|p| p.file_name().unwrap())
         .collect::<HashSet<_>>();
 
-    if !is_ostree_layout()? {
+    let ostree_layout = is_ostree_layout(rootfs_dfd)?;
+
+    if !ostree_layout {
         all_names.insert(Utf8Path::new(KERNEL_INSTALL).file_name().unwrap());
     }
 
@@ -178,7 +184,7 @@ fn write_wrappers(rootfs_dfd: &Dir, allowlist: Option<&HashSet<&str>>) -> Result
     let allowlist_contains =
         |v: &(&Utf8Path, bool)| allowlist.map_or(true, |l| l.contains(v.0.file_name().unwrap()));
 
-    let final_binaries: Vec<&str> = if !is_ostree_layout()? {
+    let final_binaries: Vec<&str> = if !is_ostree_layout(rootfs_dfd)? {
         let mut combined_bins = Vec::from(WRAPPED_BINARIES);
         combined_bins.extend_from_slice(&[KERNEL_INSTALL]);
         combined_bins

rust/src/core.rs

@@ -192,7 +192,7 @@ impl FilesystemScriptPrep {
                 rootfs.atomic_write_with_perms(path, contents, mode)?;
             }
         }
-        if !is_ostree_layout()? {
+        if !is_ostree_layout(&rootfs)? {
             for &(path, contents) in Self::REPLACE_KERNEL_PATHS {
                 let mode = Permissions::from_mode(0o755);
                 let saved = &Self::saved_name(path);
@@ -217,6 +217,7 @@ impl FilesystemScriptPrep {
         for &path in Self::OPTIONAL_PATHS
             .iter()
             .chain(Self::REPLACE_OPTIONAL_PATHS.iter().map(|x| &x.0))
+            .chain(Self::REPLACE_KERNEL_PATHS.iter().map(|x| &x.0))
         {
             let saved = &Self::saved_name(path);
             if self.rootfs.try_exists(saved)? {
@@ -486,7 +487,7 @@ mod test {
         }
         // Replaced kernel-install.
         {
-            if !is_ostree_layout()? {
+            if !is_ostree_layout(&d)? {
                 let original_kernel_install = "original kernel_install";
                 d.atomic_write_with_perms(
                     super::KERNEL_INSTALL_PATH,

rust/src/kernel_install.rs

@@ -11,9 +11,7 @@
 
 // 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};
@@ -35,21 +33,17 @@ 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";
+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() {
-        tracing::debug!("can not read /usr/lib/kernel/install.conf");
+pub fn is_ostree_layout(rootfs: &Dir) -> Result<bool> {
+    let Some(conf) = rootfs.open_optional(KERNEL_INSTALL_CONF)? else {
         return Ok(false);
-    }
-    let buff = BufReader::new(
-        File::open(install_conf).context("Failed to open /usr/lib/kernel/install.conf")?,
-    );
+    };
+    let buf = BufReader::new(conf);
     // Check for "layout=ostree" in the file
-    for line in buff.lines() {
-        let line = line.context("Failed to read line")?;
+    for line in buf.lines() {
+        let line = line?;
         if line.trim() == "layout=ostree" {
             return Ok(true);
         }
@@ -118,3 +112,42 @@ pub fn main(argv: &[&str]) -> Result<u8> {
         _ => Ok(0),
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use std::path::Path;
+
+    use cap_std_ext::cap_tempfile;
+
+    use super::*;
+
+    #[test]
+    fn test_ostree_layout_parse() -> Result<()> {
+        let td = &cap_tempfile::tempdir(cap_std::ambient_authority())?;
+        assert!(!is_ostree_layout(&td).unwrap());
+        td.create_dir_all(Path::new(KERNEL_INSTALL_CONF).parent().unwrap())?;
+        td.write(KERNEL_INSTALL_CONF, "")?;
+        assert!(!is_ostree_layout(&td).unwrap());
+        td.write(
+            KERNEL_INSTALL_CONF,
+            indoc::indoc! { r#"
+            # some comments
+
+            layout=bacon
+        "# },
+        )?;
+        assert!(!is_ostree_layout(&td).unwrap());
+        td.write(
+            KERNEL_INSTALL_CONF,
+            indoc::indoc! { r#"
+            # this is an ostree layout
+            layout=ostree
+            # another comment
+        "# },
+        )?;
+
+        assert!(is_ostree_layout(&td).unwrap());
+
+        Ok(())
+    }
+}