factorize mounting read-only filesystems (squashfs, erofs)

build-dhcp-initrd

@@ -16,8 +16,8 @@ mkdir -p tmp/dl $dist
 linux=tmp/dl/linux-$linux_v
 modules=tmp/dl/modules-$linux_v
 
-[ -e $linux ]   || curl -o $linux   https://dkl.novit.io/dist/kernels/6.18.34
+[ -e $linux ]   || curl -o $linux   https://dkl.novit.io/dist/kernels/6.18.35
-[ -e $modules ] || curl -o $modules https://dkl.novit.io/dist/layers/modules/6.18.34 # TODO .erofs
+[ -e $modules ] || curl -o $modules https://dkl.novit.io/dist/layers/modules/6.18.35.erofs
 
 rm -fr $dir
 mkdir $dir
@@ -36,7 +36,7 @@ mv $dir.cpio.zst $dist/initrd
 cp $linux $dist/vmlinuz
 
 ukify build --output $uki --os-release "Direktil DHCP" \
-    --linux $linux --initrd $dist/initrd --cmdline "console=tty0 console=ttyS0,115200"
+    --linux $linux --initrd $dist/initrd
 
 MB=$(( 2**20 ))
 sz=$(( ( $(stat -c %s $uki) + MB ) / MB + 2 ))

dhcp/config.yaml

@@ -21,7 +21,7 @@ networks:
     ip li set lo up
 - name: main
   interfaces:
-  - var: iface
+  - var: ifaces
     n: -1
     udev: !has ID_NET_NAME_MAC
   script: |

src/cmd/init.rs

@@ -4,7 +4,7 @@ use std::collections::BTreeSet as Set;
 use std::convert::Infallible;
 use std::os::unix::fs::symlink;
 use tokio::sync::Mutex;
-use tokio::{fs, process::Command};
+use tokio::{fs, io::AsyncReadExt, process::Command};
 
 use crate::{cmd::version::version_string, dklog, input, utils};
 use dkl::bootstrap::Config;
@@ -154,7 +154,8 @@ use std::path::Path;
 
 async fn mount_modules(modules: &str, kernel_version: &str) -> Result<()> {
     info!("mounting modules");
-    mount(Some(modules), "/modules", "squashfs", None).await;
+
+    mount_ro_fs(modules, "/modules").await?;
 
     fs::create_dir_all("/lib/modules").await?;
     let modules_path = &format!("/modules/lib/modules/{kernel_version}");
@@ -243,6 +244,35 @@ async fn mount<S: AsRef<Path>>(
     .await
 }
 
+async fn mount_ro_fs(src: impl AsRef<Path>, dst: impl AsRef<Path>) -> Result<()> {
+    let src = src.as_ref();
+    let dst = dst.as_ref();
+
+    // identify RO fs type
+    let mut buf = [0u8; 1028];
+
+    fs::File::open(src)
+        .await
+        .map_err(|e| format_err!("open {}: {e}", src.display()))?
+        .read_exact(&mut buf)
+        .await
+        .map_err(|e| format_err!("read {}: {e}", src.display()))?;
+
+    let fstype = if buf[1024..1028] == 0xE0F5E1E2u32.to_le_bytes() {
+        "erofs"
+    } else {
+        "squashfs"
+    };
+
+    if let Err(e) = fs::create_dir_all(dst).await {
+        error!("failed to create dir {dst}: {e}", dst = dst.display());
+    }
+
+    let mut cmd = Command::new("mount");
+    cmd.args(["-t", fstype]).arg(src).arg(dst);
+    try_exec_cmd(cmd).await
+}
+
 async fn start_daemon(prog: &str, args: &[&str]) {
     let (cmd_str, mut cmd) = cmd_str(prog, args);
     retry_or_ignore(async || {
@@ -253,7 +283,7 @@ async fn start_daemon(prog: &str, args: &[&str]) {
     .await;
 }
 
-async fn try_exec_cmd(mut cmd: tokio::process::Command) -> Result<()> {
+async fn try_exec_cmd(mut cmd: Command) -> Result<()> {
     info!(
         "# {} {}",
         cmd.as_std().get_program().to_string_lossy(),

src/cmd/init/bootstrap.rs

@@ -3,7 +3,7 @@ use log::{debug, info, warn};
 use std::path::{Path, PathBuf};
 use tokio::{
     fs,
-    io::{AsyncBufReadExt, AsyncReadExt, AsyncWrite, AsyncWriteExt, BufReader},
+    io::{AsyncBufReadExt, AsyncWrite, AsyncWriteExt, BufReader},
 };
 
 use dkl::{
@@ -13,7 +13,7 @@ use dkl::{
     bootstrap::Config,
 };
 
-use super::{exec, mount, retry, retry_or_ignore, try_exec, try_exec_cmd};
+use super::{exec, mount, mount_ro_fs, retry, retry_or_ignore, try_exec, try_exec_cmd};
 use crate::{fs::walk_dir, utils};
 
 pub async fn bootstrap(cfg: Config) {
@@ -340,25 +340,7 @@ impl LayerMounter<'_> {
             .await
         };
 
-        retry(async || {
+        retry(async || mount_ro_fs(&mount_src, &tgt_dir).await).await;
-            let mut buf = [0u8; 1028];
-            fs::File::open(&mount_src)
-                .await
-                .map_err(|e| format_err!("open {}: {e}", mount_src.display()))?
-                .read_exact(&mut buf)
-                .await
-                .map_err(|e| format_err!("read {}: {e}", mount_src.display()))?;
-
-            let fstype = if buf[1024..1028] == 0xE0F5E1E2u32.to_le_bytes() {
-                "erofs"
-            } else {
-                "squashfs"
-            };
-
-            mount(Some(&mount_src), &tgt_dir, fstype, None).await;
-            Ok(())
-        })
-        .await;
 
         if !self.lower_dir.is_empty() {
             self.lower_dir.push(':');