init: Introduce dependency handling

init.d.aarch64-unknown-redox/40_drivers

@@ -1,3 +1,4 @@
+requires_weak 30_live
 notify hwd
 notify RSDP_ADDR=$ RSDP_SIZE=$ hwd
 pcid-spawner --initfs

init.d.aarch64-unknown-redox/40_drivers.raspi3bp

@@ -1,2 +1,3 @@
+requires_weak 30_live
 unset RSDP_ADDR RSDP_SIZE
 notify bcm2835-sdhcid

init.d/00_nulld.service

@@ -1,5 +1,7 @@
 {
-    "unit": {},
+    "unit": {
+        "default_dependencies": false
+    },
     "service": {
         "cmd": "nulld",
         "type": {

init.d/00_randd.service

@@ -1,5 +1,7 @@
 {
-    "unit": {},
+    "unit": {
+        "default_dependencies": false
+    },
     "service": {
         "cmd": "randd",
         "args": [

init.d/00_rtcd.service

@@ -1,6 +1,7 @@
 {
     "unit": {
-        "description": "Set time from realtime clock"
+        "description": "Set time from realtime clock",
+        "default_dependencies": false
     },
     "service": {
         "cmd": "rtcd",

init.d/00_runtime.target

@@ -0,0 +1,12 @@
+{
+    "unit": {
+        "description": "Various daemons that relibc needs to function.",
+        "default_dependencies": false,
+        "requires_weak": [
+            "00_nulld.service",
+            "00_randd.service",
+            "00_rtcd.service",
+            "00_zerod.service"
+        ]
+    }
+}

init.d/00_zerod.service

@@ -1,5 +1,7 @@
 {
-    "unit": {},
+    "unit": {
+        "default_dependencies": false
+    },
     "service": {
         "cmd": "zerod",
         "type": {

init.d/10_logging

@@ -1,3 +1,4 @@
+requires_weak 00_runtime.target
 scheme log logd
 stdio /scheme/log
 scheme logging ramfs logging

init.d/20_graphics

@@ -1,3 +1,4 @@
+requires_weak 10_logging
 scheme input inputd
 notify FRAMEBUFFER_ADDR=$ FRAMEBUFFER_VIRT=$ FRAMEBUFFER_WIDTH=$ FRAMEBUFFER_HEIGHT=$ FRAMEBUFFER_STRIDE=$ vesad
 scheme fbbootlog fbbootlogd

init.d/30_live

@@ -1,2 +1,3 @@
+requires_weak 20_graphics
 # Note: Needs to start before drivers to ensure it gets priority when redoxfs searches for disks
 notify lived

init.d/40_drivers

@@ -1,3 +1,4 @@
+requires_weak 30_live
 notify ps2d
 notify RSDP_ADDR=$ RSDP_SIZE=$ hwd
 pcid-spawner --initfs

init.d/50_rootfs

@@ -1 +1,2 @@
+requires_weak 40_drivers
 REDOXFS_PASSWORD_ADDR=$ REDOXFS_PASSWORD_SIZE=$ redoxfs --uuid $REDOXFS_UUID file $REDOXFS_BLOCK

init.d/90_exit_initfs.switchroot

@@ -1,5 +1,7 @@
 {
-    "unit": {},
+    "unit": {
+        "requires_weak": ["50_rootfs"]
+    },
     "switchroot": {
         "prefix": "/usr",
         "etcdir": "/etc"

init/src/main.rs

@@ -1,8 +1,8 @@
-use std::collections::BTreeMap;
+use std::collections::{BTreeMap, VecDeque};
+use std::env;
 use std::ffi::OsString;
 use std::io::Result;
 use std::path::{Path, PathBuf};
-use std::{env, mem};
 
 use libredox::flag::{O_RDONLY, O_WRONLY};
 use serde::Deserialize;
@@ -58,7 +58,7 @@ struct SwitchRoot {
 impl SwitchRoot {
     fn apply(
         self,
-        pending_units: &mut Vec<UnitId>,
+        pending_units: &mut VecDeque<UnitId>,
         unit_store: &mut UnitStore,
         config: &mut InitConfig,
     ) {
@@ -85,7 +85,7 @@ impl SwitchRoot {
 
 fn run(
     unit: &UnitId,
-    pending_units: &mut Vec<UnitId>,
+    pending_units: &mut VecDeque<UnitId>,
     unit_store: &mut UnitStore,
     config: &mut InitConfig,
 ) -> Result<()> {
@@ -104,12 +104,25 @@ fn run(
             if config.log_debug {
                 eprintln!(
                     "Starting {}",
-                    unit.info.description.as_ref().unwrap_or(&unit.id.0)
+                    unit.info.description.as_ref().unwrap_or(&unit.id.0),
                 );
             }
             service.spawn(&config.envs);
         }
+        unit::UnitKind::Target {} => {
+            if config.log_debug {
+                eprintln!(
+                    "Started target {}",
+                    unit.info.description.as_ref().unwrap_or(&unit.id.0),
+                );
+            }
+        }
         unit::UnitKind::SwitchRoot { switchroot } => {
+            eprintln!(
+                "init: switchroot to {} {}",
+                switchroot.prefix.display(),
+                switchroot.etcdir.display()
+            );
             switchroot.clone().apply(pending_units, unit_store, config);
         }
     }
@@ -119,6 +132,7 @@ fn run(
 
 fn run_command(cmd: Command, config: &mut InitConfig) {
     match cmd {
+        Command::RequiresWeak(_) => {} // handled by unit parsing code
         Command::Nothing => {}
         Command::Echo(text) => println!("{text}"),
         Command::Stdio(stdio) => {
@@ -144,7 +158,7 @@ fn run_command(cmd: Command, config: &mut InitConfig) {
 fn main() {
     let mut init_config = InitConfig::new();
     let mut unit_store = UnitStore::new();
-    let mut pending_units = vec![];
+    let mut pending_units = VecDeque::new();
 
     SwitchRoot {
         prefix: Path::new("/scheme/initfs").to_owned(),
@@ -152,12 +166,25 @@ fn main() {
     }
     .apply(&mut pending_units, &mut unit_store, &mut init_config);
 
-    while !pending_units.is_empty() {
-        for unit in mem::take(&mut pending_units) {
-            if let Err(err) = run(&unit, &mut pending_units, &mut unit_store, &mut init_config) {
-                eprintln!("init: failed to run {}: {}", unit.0, err);
+    let runtime_target = UnitId("00_runtime.target".to_owned());
+
+    'a: while let Some(unit) = pending_units.pop_front() {
+        if unit_store.unit(&unit).info.default_dependencies {
+            if pending_units.contains(&runtime_target) {
+                pending_units.push_back(unit);
+                continue 'a;
             }
         }
+        for dep in &unit_store.unit(&unit).info.requires_weak {
+            if pending_units.contains(dep) {
+                pending_units.push_back(unit);
+                continue 'a;
+            }
+        }
+
+        if let Err(err) = run(&unit, &mut pending_units, &mut unit_store, &mut init_config) {
+            eprintln!("init: failed to run {}: {}", unit.0, err);
+        }
     }
 
     libredox::call::setrens(0, 0).expect("init: failed to enter null namespace");

init/src/script.rs

@@ -1,8 +1,8 @@
 use std::collections::BTreeMap;
-use std::path::PathBuf;
 use std::{env, io, iter};
 
 use crate::service::{Service, ServiceType};
+use crate::unit::UnitId;
 
 fn subst_env<'a>(arg: &str) -> String {
     if arg.starts_with('$') {
@@ -39,6 +39,9 @@ impl Script {
 
 #[derive(Clone, Debug)]
 pub enum Command {
+    // Dependencies
+    RequiresWeak(Vec<UnitId>),
+
     // Service
     Service(Service),
 
@@ -57,6 +60,7 @@ impl Command {
         };
 
         match cmd.as_str() {
+            "requires_weak" => Ok(Command::RequiresWeak(args.map(UnitId).collect::<Vec<_>>())),
             "echo" => Ok(Command::Echo(args.collect::<Vec<_>>().join(" "))),
             "stdio" => {
                 let Some(stdio) = args.next() else {

init/src/unit.rs

@@ -5,7 +5,7 @@ use std::{fs, io};
 use serde::Deserialize;
 
 use crate::SwitchRoot;
-use crate::script::Script;
+use crate::script::{Command, Script};
 use crate::service::Service;
 
 pub struct UnitStore {
@@ -56,12 +56,17 @@ impl UnitStore {
         (loaded_units, errors)
     }
 
+    pub fn unit(&self, unit: &UnitId) -> &Unit {
+        self.units.get(unit).unwrap()
+    }
+
     pub fn unit_mut(&mut self, unit: &UnitId) -> &mut Unit {
         self.units.get_mut(unit).unwrap()
     }
 }
 
-#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord)]
+#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Deserialize)]
+#[serde(transparent)]
 pub struct UnitId(pub String);
 
 pub struct Unit {
@@ -74,15 +79,20 @@ pub struct Unit {
 #[derive(Deserialize)]
 pub struct UnitInfo {
     pub description: Option<String>,
+    #[serde(default = "true_bool")]
+    pub default_dependencies: bool,
     #[serde(default)]
-    pub requires: Vec<String>,
-    #[serde(default)]
-    pub requires_weak: Vec<String>,
+    pub requires_weak: Vec<UnitId>,
+}
+
+fn true_bool() -> bool {
+    true
 }
 
 pub enum UnitKind {
     LegacyScript { script: Script },
     Service { service: Service },
+    Target {},
     SwitchRoot { switchroot: SwitchRoot },
 }
 
@@ -92,6 +102,11 @@ struct SerializedService {
     service: Service,
 }
 
+#[derive(Deserialize)]
+struct SerializedTarget {
+    unit: UnitInfo,
+}
+
 #[derive(Deserialize)]
 struct SerializedSwitchRoot {
     unit: UnitInfo,
@@ -114,11 +129,20 @@ impl Unit {
         let (info, kind, errors) = match config_path.extension().map(|ext| ext.to_str().unwrap()) {
             None => {
                 let (script, warnings) = Script::from_str(&config)?;
+                let mut requires_weak = vec![];
+                for command in &script.0 {
+                    match command {
+                        Command::RequiresWeak(deps) => {
+                            requires_weak.extend(deps.into_iter().cloned())
+                        }
+                        _ => {}
+                    }
+                }
                 (
                     UnitInfo {
                         description: None,
-                        requires: vec![],
-                        requires_weak: vec![],
+                        default_dependencies: true,
+                        requires_weak,
                     },
                     UnitKind::LegacyScript { script },
                     warnings,
@@ -134,6 +158,10 @@ impl Unit {
                     vec![],
                 )
             }
+            Some("target") => {
+                let target: SerializedTarget = serde_json::from_str(&config)?;
+                (target.unit, UnitKind::Target {}, vec![])
+            }
             Some("switchroot") => {
                 let switchroot: SerializedSwitchRoot = serde_json::from_str(&config)?;
                 (