init: Introduce a json format for services

While I would have like to use toml, something inside the toml crate
seems to be using randomness, which is not yet available when init
starts.

Cargo.lock

@@ -1108,6 +1108,8 @@ dependencies = [
  "config",
  "daemon",
  "libredox",
+ "serde",
+ "serde_json",
 ]
 
 [[package]]

init.d/00_nulld.service

@@ -0,0 +1,4 @@
+{
+    "cmd": "nulld",
+    "type": { "scheme": "null" }
+}

init.d/00_randd.service

@@ -0,0 +1,5 @@
+{
+    "cmd": "randd",
+    "args": ["rand"],
+    "type": { "scheme": "rand" }
+}

init.d/00_rtcd.service

@@ -0,0 +1,4 @@
+{
+    "cmd": "rtcd",
+    "type": "oneshot"
+}

init.d/00_runtime

@@ -1,5 +0,0 @@
-# Various daemons that relibc needs to function.
-rtcd
-scheme null nulld
-scheme zero zerod
-scheme rand randd

init.d/00_zerod.service

@@ -0,0 +1,4 @@
+{
+    "cmd": "zerod",
+    "type": { "scheme": "zero" }
+}

init/Cargo.toml

@@ -6,6 +6,8 @@ license = "MIT"
 
 [dependencies]
 libredox.workspace = true
+serde = { version = "1", features = ["derive"] }
+serde_json = "1"
 
 config = { path = "../config" }
 daemon = { path = "../daemon" }

init/src/main.rs

@@ -1,12 +1,13 @@
 use std::collections::BTreeMap;
-use std::env;
-use std::ffi::OsString;
+use std::ffi::{OsStr, OsString};
 use std::io::Result;
 use std::path::Path;
+use std::{env, fs};
 
 use libredox::flag::{O_RDONLY, O_WRONLY};
 
 use crate::script::Command;
+use crate::service::Service;
 
 mod script;
 mod service;
@@ -74,6 +75,12 @@ fn switch_root(prefix: &Path, etcdir: &Path, config: &mut InitConfig) {
 }
 
 fn run(file: &Path, config: &mut InitConfig) -> Result<()> {
+    if file.extension() == Some(OsStr::new("service")) {
+        let service: Service = serde_json::from_str(&fs::read_to_string(file).unwrap()).unwrap();
+        service.spawn(&config.envs);
+        return Ok(());
+    }
+
     let (script, errors) = script::Script::from_file(file)?;
 
     for error in errors {

init/src/service.rs

@@ -2,15 +2,21 @@ use std::collections::BTreeMap;
 use std::ffi::OsString;
 use std::process::Command;
 
-#[derive(Debug)]
+use serde::Deserialize;
+
+#[derive(Debug, Deserialize)]
 pub struct Service {
     pub cmd: String,
+    #[serde(default)]
     pub args: Vec<String>,
+    #[serde(default)]
     pub envs: BTreeMap<String, String>,
+    #[serde(rename = "type")]
     pub type_: ServiceType,
 }
 
-#[derive(Debug, Default)]
+#[derive(Debug, Default, Deserialize)]
+#[serde(rename_all = "snake_case")]
 pub enum ServiceType {
     #[default]
     Notify,