install: Centralize PID1 definition

Hooray for `const`.

Signed-off-by: Colin Walters <[email protected]>

lib/src/install.rs

@@ -40,7 +40,6 @@ use ostree_ext::ostree;
 use ostree_ext::prelude::Cast;
 use ostree_ext::sysroot::SysrootLock;
 use rustix::fs::{FileTypeExt, MetadataExt as _};
-use rustix::thread::Pid;
 use serde::{Deserialize, Serialize};
 
 use self::baseline::InstallBlockDeviceOpts;
@@ -1641,9 +1640,10 @@ pub(crate) async fn install_to_filesystem(
         && fsopts.root_path.as_str() == ALONGSIDE_ROOT_MOUNT
         && !fsopts.root_path.try_exists()?
     {
+        tracing::debug!("Mounting host / to {ALONGSIDE_ROOT_MOUNT}");
         std::fs::create_dir(ALONGSIDE_ROOT_MOUNT)?;
         crate::mount::bind_mount_from_pidns(
-            Pid::from_raw(1).unwrap(),
+            crate::mount::PID1,
             "/".into(),
             ALONGSIDE_ROOT_MOUNT.into(),
             true,

lib/src/mount.rs

@@ -23,6 +23,14 @@ use serde::Deserialize;
 
 use crate::task::Task;
 
+/// Well known identifier for pid 1
+pub(crate) const PID1: Pid = const {
+    match Pid::from_raw(1) {
+        Some(v) => v,
+        None => panic!("Expected to parse pid1"),
+    }
+};
+
 #[derive(Deserialize, Debug)]
 #[serde(rename_all = "kebab-case")]
 #[allow(dead_code)]
@@ -266,5 +274,5 @@ pub(crate) fn ensure_mirrored_host_mount(path: impl AsRef<Utf8Path>) -> Result<(
         return Ok(());
     }
     tracing::debug!("Propagating host mount: {path}");
-    bind_mount_from_pidns(Pid::from_raw(1).unwrap(), path, path, true)
+    bind_mount_from_pidns(PID1, path, path, true)
 }