WIP: Import GRUB static migration code

src/bootupd.rs

@@ -9,10 +9,13 @@ use crate::model::{ComponentStatus, ComponentUpdatable, ContentMetadata, SavedSt
 use crate::util;
 use anyhow::{anyhow, Context, Result};
 use clap::crate_version;
+use openat_ext::OpenatDirExt;
+use rustix::fs::link;
 use serde::{Deserialize, Serialize};
 use std::borrow::Cow;
 use std::collections::BTreeMap;
-use std::path::Path;
+use std::path::{Path, PathBuf};
+use std::thread::current;
 
 pub(crate) enum ConfigMode {
     None,
@@ -203,6 +206,10 @@ fn ensure_writable_boot() -> Result<()> {
     util::ensure_writable_mount("/boot")
 }
 
+fn ensure_writable_sysroot() -> Result<()> {
+    util::ensure_writable_mount("/sysroot")
+}
+
 /// daemon implementation of component update
 pub(crate) fn update(name: &str) -> Result<ComponentUpdateResult> {
     let mut state = SavedState::load_from_disk("/")?.unwrap_or_default();
@@ -489,6 +496,88 @@ pub(crate) fn client_run_validate() -> Result<()> {
     Ok(())
 }
 
+pub(crate) fn client_run_migrate() -> Result<()> {
+    // Used to condition execution of this unit at the systemd level
+    let stamp_file="/var/lib/.fedora_atomic_desktops_static_grub";
+
+    // Did we already complete the migration?
+    let ostree_cmd = std::process::Command::new("ostree")
+        .args(["config", "--repo=/sysroot/ostree/repo", "get", "sysroot.bootloader"]);
+    let bootloader = util::cmd_output(ostree_cmd).ok_or_else(|| anyhow!("Could not find read 'sysroot.bootloader' config from ostree repo. Not performing migration."));
+    if bootloader == "none" {
+        println!("ostree repo 'sysroot.bootloader' config option already set to 'none'.");
+        println!("Assuming that the migration is already complete.");
+        File::create(stamp_file)?;
+        return Ok(());
+    }
+
+    // Remount /boot read write just for this unit (we are called in a slave mount namespace by systemd)
+    ensure_writable_boot();
+
+    let grub_config_dir = PathBuf::from("/boot/grub2");
+    let dirfd = openat::Dir::open(grub_config_dir).ok_or_else(|| anyhow!("Could not open {}. Maybe /boot is not mounted? Not performing migration.", grub_config_dir));
+
+    // Migrate /boot/grub2/grub.cfg to a static GRUB config if it is a symlink
+    let grub_config_filename ="/boot/grub2/grub.cfg";
+    match dirfd.read_link("grub.cfg") {
+        Err(_) => {
+            println!("/boot/grub2/grub.cfg is not a symlink. Nothing to migrate.");
+        },
+        Ok(path) => {
+            println!("Migrating to a static GRUB config...");
+
+            // Backup the current GRUB config which is hopefully working right now
+            println!("Creating a backup of the current GRUB config in '/boot/grub2/grub.cfg.backup'...");
+
+            let current_config_path = grub_config_dir.clone();
+            current_config_path.push(path);
+            fs::copy(current_config_path, "/boot/grub2/grub.cfg.backup").ok_or_else(|| anyhow!("Could not copy the current GRUB config. Not performing migration."));
+
+            // Copy it again alongside the current symlink
+            fs::copy(current_config_path, "/boot/grub2/grub.cfg.current").ok_or_else(|| anyhow!("Could not copy the current GRUB config. Not performing migration."));
+
+            // Atomically exchange the configs
+            dirfd.local_exchange("grub.cfg.current", "/grub.cfg")?;
+
+            // Remove the now unsused symlink (optional cleanup, ignore any failures)
+            dirfd.remove_file("grub.cfg.current");
+
+            println!("GRUB config symlink successfully replaced with the current config.");
+        },
+    };
+
+    // # If /etc/default/grub exists then we have to force the regeneration of the
+    // # GRUB config to remove the ostree entries that duplicates the BLS ones
+    // if [[ -f "/etc/default/grub" ]]; then
+    //     echo "Marking bootloader as BLS capable..."
+    //     touch "/boot/grub2/.grub2-blscfg-supported"
+
+    //     echo "Regenerating a pure BLS GRUB config..."
+    //     grub2-mkconfig -o /boot/grub2/grub.cfg
+    // fi
+    if !destdir.exists(&first_dir_tmp)? {
+        copy_dir(destdir, first_dir.as_str(), &first_dir_tmp)?;
+        updates.insert(first_dir, first_dir_tmp);
+    }
+
+    // # Remount /sysroot read write just for this unit (we are called in a slave mount namespace by systemd)
+    ensure_writable_sysroot();
+
+    println!("Setting up 'sysroot.bootloader' to 'none' in ostree repo config...");
+    let status = std::process::Command::new("ostree")
+        .args(["config", "--repo=/sysroot/ostree/repo", "set", "sysroot.bootloader", "none"])
+        .status()?;
+    if !status.success() {
+        anyhow::bail!("Failed to set 'sysroot.bootloader' to 'none' in ostree repo config");
+    }
+
+    // Migration complete, let's write the stamp file
+    File::create(stamp_file)?;
+
+    println!("Static GRUB config migration completed successfully!");
+    Ok(())
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

src/cli/bootupctl.rs

@@ -58,6 +58,8 @@ pub enum CtlVerb {
     AdoptAndUpdate,
     #[clap(name = "validate", about = "Validate system state")]
     Validate,
+    #[clap(name = "migrate", about = "Migrate a system to static a GRUB config")]
+    Migrate,
 }
 
 #[derive(Debug, Parser)]
@@ -95,6 +97,7 @@ impl CtlCommand {
             CtlVerb::Backend(CtlBackend::Install(opts)) => {
                 super::bootupd::DCommand::run_install(opts)
             }
+            CtlVerb::Migrate => Self::run_migrate(),
         }
     }
 
@@ -132,6 +135,12 @@ impl CtlCommand {
         ensure_running_in_systemd()?;
         bootupd::client_run_validate()
     }
+
+    /// Runner for `migrate` verb.
+    fn run_migrate() -> Result<()> {
+        ensure_running_in_systemd()?;
+        bootupd::client_run_migrate()
+    }
 }
 
 /// Checks if the current process is (apparently at least)