Write automount unit files for /boot partition

citadel-tool/src/boot/mod.rs

@@ -3,6 +3,8 @@ use std::process::exit;
 
 use libcitadel::{Result,ResourceImage,CommandLine,format_error,KeyRing,LogLevel,Logger};
 use libcitadel::RealmManager;
+use crate::boot::disks::DiskPartition;
+use std::path::Path;
 
 mod live;
 mod disks;
@@ -15,7 +17,6 @@ pub fn main(args: Vec<String>) {
         Logger::set_log_level(LogLevel::Info);
     }
 
-
     let result = match args.get(1) {
         Some(s) if s == "rootfs" => do_rootfs(),
         Some(s) if s == "setup" => do_setup(),
@@ -57,6 +58,10 @@ fn do_setup() -> Result<()> {
     if CommandLine::overlay() {
         mount_overlay()?;
     }
+
+    if !(CommandLine::live_mode() || CommandLine::install_mode()) {
+        write_boot_automount()?;
+    }
     Ok(())
 }
 
@@ -88,3 +93,82 @@ fn do_start_realms() -> Result<()> {
     let manager = RealmManager::load()?;
     manager.start_boot_realms()
 }
+
+// Try to determine which partition on the system is the /boot partition and
+// generate mount/automount units for it.
+fn write_boot_automount() -> Result<()> {
+    Logger::set_log_level(LogLevel::Info);
+    let loader_dev = read_loader_dev_efi_var()?;
+    let boot_partitions = DiskPartition::boot_partitions(true)?
+        .into_iter()
+        .filter(|part| matches_loader_dev(part, &loader_dev))
+        .collect::<Vec<_>>();
+
+    if boot_partitions.len() == 1 {
+        write_automount_units(&boot_partitions[0])?;
+    } else {
+        warn!("Not writing /boot automount units because cannot uniquely determine boot partition");
+    }
+    Ok(())
+}
+
+// if the 'loader device' EFI variable is set, then dev will contain the UUID
+// of the device to match. If it has not been set, then return true to match
+// every partition.
+fn matches_loader_dev(partition: &DiskPartition, dev: &Option<String>) -> bool {
+    if let Some(ref dev) = dev {
+        match partition.partition_uuid() {
+            Err(err) => {
+                warn!("error running lsblk {}", err);
+                return true
+            },
+            Ok(uuid) => return uuid == dev.as_str(),
+        }
+    }
+    true
+}
+
+const LOADER_EFI_VAR_PATH: &str =
+    "/sys/firmware/efi/efivars/LoaderDevicePartUUID-4a67b082-0a4c-41cf-b6c7-440b29bb8c4f";
+
+fn read_loader_dev_efi_var() -> Result<Option<String>> {
+    let efi_var = Path::new(LOADER_EFI_VAR_PATH);
+    if efi_var.exists() {
+        let s = fs::read(efi_var)?
+            .into_iter().skip(4)  // u32 'attribute'
+            .filter(|b| *b != 0)  // string is utf16 ascii
+            .map(|b| (b as char).to_ascii_lowercase())
+            .collect::<String>();
+        Ok(Some(s))
+    } else {
+        info!("efi path does not exist");
+        Ok(None)
+    }
+}
+
+pub fn write_automount_units(partition: &DiskPartition) -> Result<()> {
+    let dev = partition.path().display().to_string();
+    info!("Writing /boot automount units to /run/systemd/system for {}", dev);
+    let mount_unit = BOOT_MOUNT_UNIT.replace("$PARTITION", &dev);
+    fs::write("/run/systemd/system/boot.mount", mount_unit)?;
+    fs::write("/run/systemd/system/boot.automount", BOOT_AUTOMOUNT_UNIT)?;
+    info!("Starting /boot automount service");
+    cmd!("/usr/bin/systemctl", "start boot.automount")?;
+    Ok(())
+}
+
+const BOOT_AUTOMOUNT_UNIT: &str = "\
+[Unit]
+Description=Automount /boot partition
+[Automount]
+Where=/boot
+TimeoutIdleSec=300
+";
+
+const BOOT_MOUNT_UNIT: &str = "\
+[Unit]
+Description=Mount /boot partition
+[Mount]
+What=$PARTITION
+Where=/boot
+";