init: Switch root upon reaching initfs.target

init.d/90_exit_initfs.switchroot

@@ -1,6 +0,0 @@
-[unit]
-requires_weak = ["50_rootfs.service"]
-
-[switchroot]
-prefix = "/usr"
-etcdir = "/etc"

init.d/90_initfs.target

@@ -0,0 +1,3 @@
+[unit]
+description = "initfs finalized"
+requires_weak = ["50_rootfs.service"]

init/src/main.rs

@@ -63,6 +63,12 @@ impl SwitchRoot {
         unit_store: &mut UnitStore,
         config: &mut InitConfig,
     ) {
+        eprintln!(
+            "init: switchroot to {} {}",
+            self.prefix.display(),
+            self.etcdir.display()
+        );
+
         config
             .envs
             .insert("PATH".to_owned(), self.prefix.join("bin").into_os_string());
@@ -84,12 +90,7 @@ impl SwitchRoot {
     }
 }
 
-fn run(
-    unit: &UnitId,
-    pending_units: &mut VecDeque<UnitId>,
-    unit_store: &mut UnitStore,
-    config: &mut InitConfig,
-) -> Result<()> {
+fn run(unit: &UnitId, unit_store: &mut UnitStore, config: &mut InitConfig) -> Result<()> {
     let unit = unit_store.unit_mut(unit);
 
     match &unit.kind {
@@ -118,14 +119,6 @@ fn run(
                 );
             }
         }
-        unit::UnitKind::SwitchRoot { switchroot } => {
-            eprintln!(
-                "init: switchroot to {} {}",
-                switchroot.prefix.display(),
-                switchroot.etcdir.display()
-            );
-            switchroot.clone().apply(pending_units, unit_store, config);
-        }
     }
 
     Ok(())
@@ -170,6 +163,7 @@ fn main() {
     }
 
     let runtime_target = UnitId("00_runtime.target".to_owned());
+    let initfs_target = UnitId("90_initfs.target".to_owned());
 
     'a: while let Some(unit) = pending_units.pop_front() {
         if let Some(condition_architecture) = &unit_store.unit(&unit).info.condition_architecture {
@@ -201,9 +195,17 @@ fn main() {
             }
         }
 
-        if let Err(err) = run(&unit, &mut pending_units, &mut unit_store, &mut init_config) {
+        if let Err(err) = run(&unit, &mut unit_store, &mut init_config) {
             eprintln!("init: failed to run {}: {}", unit.0, err);
         }
+
+        if unit == initfs_target {
+            SwitchRoot {
+                prefix: PathBuf::from("/usr"),
+                etcdir: PathBuf::from("/etc"),
+            }
+            .apply(&mut pending_units, &mut unit_store, &mut init_config);
+        }
     }
 
     libredox::call::setrens(0, 0).expect("init: failed to enter null namespace");

init/src/unit.rs

@@ -4,7 +4,6 @@ use std::{fs, io};
 
 use serde::Deserialize;
 
-use crate::SwitchRoot;
 use crate::script::{Command, Script};
 use crate::service::Service;
 
@@ -97,7 +96,6 @@ pub enum UnitKind {
     LegacyScript { script: Script },
     Service { service: Service },
     Target {},
-    SwitchRoot { switchroot: SwitchRoot },
 }
 
 #[derive(Deserialize)]
@@ -113,13 +111,6 @@ struct SerializedTarget {
     unit: UnitInfo,
 }
 
-#[derive(Deserialize)]
-#[serde(deny_unknown_fields)]
-struct SerializedSwitchRoot {
-    unit: UnitInfo,
-    switchroot: SwitchRoot,
-}
-
 impl Unit {
     pub fn from_file(config_path: &Path) -> io::Result<(Self, Vec<String>)> {
         let name = UnitId(
@@ -173,17 +164,6 @@ impl Unit {
                     .map_err(|err| io::Error::new(io::ErrorKind::InvalidData, err))?;
                 (target.unit, UnitKind::Target {}, vec![])
             }
-            Some("switchroot") => {
-                let switchroot: SerializedSwitchRoot = toml::from_str(&config)
-                    .map_err(|err| io::Error::new(io::ErrorKind::InvalidData, err))?;
-                (
-                    switchroot.unit,
-                    UnitKind::SwitchRoot {
-                        switchroot: switchroot.switchroot,
-                    },
-                    vec![],
-                )
-            }
             Some(_) => return Err(io::Error::other("invalid file extension")),
         };