Add upgrade --apply

Closes: #165

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

Author: cgwalters

lib/src/cli.rs

@@ -33,9 +33,17 @@ pub(crate) struct UpgradeOpts {
     #[clap(long)]
     pub(crate) touch_if_changed: Option<Utf8PathBuf>,
 
-    /// Check if an update is available without applying it
-    #[clap(long)]
+    /// Check if an update is available without applying it.
+    #[clap(long, conflicts_with = "apply")]
     pub(crate) check: bool,
+
+    /// Restart or reboot into the new target image.
+    ///
+    /// Currently, this option always reboots.  In the future this command
+    /// will detect the case where no kernel changes are queued, and perform
+    /// a userspace-only restart.
+    #[clap(long, conflicts_with = "check")]
+    pub(crate) apply: bool,
 }
 
 /// Perform an switch operation
@@ -364,6 +372,11 @@ async fn upgrade(opts: UpgradeOpts) -> Result<()> {
         if let Some(path) = opts.touch_if_changed {
             std::fs::write(&path, "").with_context(|| format!("Writing {path}"))?;
         }
+        if opts.apply {
+            crate::reboot::reboot()?;
+        }
+    } else {
+        tracing::debug!("No changes");
     }
 
     Ok(())

lib/src/lib.rs

@@ -16,6 +16,7 @@
 pub mod cli;
 pub(crate) mod deploy;
 mod lsm;
+mod reboot;
 mod reexec;
 mod status;
 mod utils;

lib/src/reboot.rs

@@ -0,0 +1,23 @@
+//! Handling of system restarts/reboot
+
+use std::io::Write;
+use std::process::Command;
+
+use fn_error_context::context;
+
+/// Initiate a system reboot.
+/// This function will only return in case of error.
+#[context("Initiating reboot")]
+pub(crate) fn reboot() -> anyhow::Result<()> {
+    // Flush output streams
+    let _ = std::io::stdout().flush();
+    let _ = std::io::stderr().flush();
+    let st = Command::new("reboot").status()?;
+    if !st.success() {
+        anyhow::bail!("Failed to reboot: {st:?}");
+    }
+    tracing::debug!("Initiated reboot, sleeping forever...");
+    loop {
+        std::thread::park();
+    }
+}