Rework composefs_booted to use kernel cmdline

Signed-off-by: Colin Walters <walters@verbum.org>

Author: cgwalters

crates/lib/src/cli.rs

@@ -21,7 +21,7 @@ use ostree_ext::composefs::fsverity;
 use ostree_ext::composefs::fsverity::FsVerityHashValue;
 use ostree_ext::composefs::splitstream::SplitStreamWriter;
 use ostree_ext::container as ostree_container;
-use ostree_ext::container_utils::{composefs_booted, ostree_booted};
+use ostree_ext::container_utils::ostree_booted;
 use ostree_ext::keyfileext::KeyFileExt;
 use ostree_ext::ostree;
 use schemars::schema_for;
@@ -36,7 +36,7 @@ use crate::lints;
 use crate::progress_jsonl::{ProgressWriter, RawProgressFd};
 use crate::spec::Host;
 use crate::spec::ImageReference;
-use crate::status::composefs_deployment_status;
+use crate::status::{composefs_booted, composefs_deployment_status};
 use crate::utils::sigpolicy_from_opt;
 
 /// Shared progress options
@@ -1073,7 +1073,7 @@ async fn switch(opts: SwitchOpts) -> Result<()> {
 /// Implementation of the `bootc rollback` CLI command.
 #[context("Rollback")]
 async fn rollback(opts: RollbackOpts) -> Result<()> {
-    if composefs_booted()? {
+    if composefs_booted()?.is_some() {
         composefs_rollback().await?
     } else {
         let sysroot = &get_storage().await?;
@@ -1229,14 +1229,14 @@ async fn run_from_opt(opt: Opt) -> Result<()> {
     let root = &Dir::open_ambient_dir("/", cap_std::ambient_authority())?;
     match opt {
         Opt::Upgrade(opts) => {
-            if composefs_booted()? {
+            if composefs_booted()?.is_some() {
                 upgrade_composefs(opts).await
             } else {
                 upgrade(opts).await
             }
         }
         Opt::Switch(opts) => {
-            if composefs_booted()? {
+            if composefs_booted()?.is_some() {
                 switch_composefs(opts).await
             } else {
                 switch(opts).await

crates/lib/src/status.rs

@@ -4,6 +4,7 @@ use std::io::IsTerminal;
 use std::io::Read;
 use std::io::Write;
 use std::str::FromStr;
+use std::sync::OnceLock;
 
 use anyhow::{Context, Result};
 use bootc_utils::try_deserialize_timestamp;
@@ -14,7 +15,6 @@ use ostree::glib;
 use ostree_container::OstreeImageReference;
 use ostree_ext::container as ostree_container;
 use ostree_ext::container::deploy::ORIGIN_CONTAINER;
-use ostree_ext::container_utils::composefs_booted;
 use ostree_ext::container_utils::ostree_booted;
 use ostree_ext::containers_image_proxy;
 use ostree_ext::keyfileext::KeyFileExt;
@@ -56,6 +56,21 @@ impl From<ImageSignature> for ostree_container::SignatureSource {
     }
 }
 
+/// Detect if we have composefs=<digest> in /proc/cmdline
+pub(crate) fn composefs_booted() -> Result<Option<&'static str>> {
+    static CACHED_DIGEST_VALUE: OnceLock<Option<String>> = OnceLock::new();
+    if let Some(v) = CACHED_DIGEST_VALUE.get() {
+        return Ok(v.as_deref());
+    }
+    let cmdline = crate::kernel_cmdline::Cmdline::from_proc()?;
+    let Some(kv) = cmdline.find_str("composefs") else {
+        return Ok(None);
+    };
+    let Some(v) = kv.value else { return Ok(None) };
+    let r = CACHED_DIGEST_VALUE.get_or_init(|| Some(v.to_owned()));
+    Ok(r.as_deref())
+}
+
 /// Fixme lower serializability into ostree-ext
 fn transport_to_string(transport: ostree_container::Transport) -> String {
     match transport {
@@ -484,7 +499,7 @@ pub(crate) async fn status(opts: super::cli::StatusOpts) -> Result<()> {
         let booted_deployment = sysroot.booted_deployment();
         let (_deployments, host) = get_status(&sysroot, booted_deployment.as_ref())?;
         host
-    } else if composefs_booted()? {
+    } else if composefs_booted()?.is_some() {
         composefs_deployment_status().await?
     } else {
         Default::default()

crates/ostree-ext/src/container_utils.rs

@@ -77,12 +77,6 @@ pub fn ostree_booted() -> io::Result<bool> {
     Path::new(&format!("/{OSTREE_BOOTED}")).try_exists()
 }
 
-/// Returns true if the system appears to have been booted with composefs.
-pub fn composefs_booted() -> io::Result<bool> {
-    let cmdline = std::fs::read_to_string("/proc/cmdline")?;
-    Ok(cmdline.contains("composefs="))
-}
-
 /// Returns true if the target root appears to have been booted via ostree.
 pub fn is_ostree_booted_in(rootfs: &Dir) -> io::Result<bool> {
     rootfs.try_exists(OSTREE_BOOTED)