reinstall: Add problematic mounted filesystem warning

This uses findmnt to locate filesystem mounts that are on the same
source as the root mount. If any are found, the user is warned these
filesystems will persist unmounted in the bootc system. The user must
hit <enter> to proceed.

Signed-off-by: ckyrouac <[email protected]>

Author: ckyrouac

Cargo.lock

@@ -16,6 +16,7 @@ platforms = ["*-unknown-linux-gnu"]
 
 [dependencies]
 anyhow = { workspace = true }
+bootc-mount = { path = "../mount" }
 bootc-utils = { path = "../utils" }
 clap = { workspace = true, features = ["derive"] }
 crossterm = "0.29.0"

system-reinstall-bootc/Cargo.toml

@@ -40,6 +40,8 @@ fn run() -> Result<()> {
 
     prompt::get_ssh_keys(ssh_key_file_path)?;
 
+    prompt::mount_warning()?;
+
     let mut reinstall_podman_command =
         podman::reinstall_command(&config.bootc_image, ssh_key_file_path);
 

system-reinstall-bootc/src/main.rs

@@ -1,6 +1,7 @@
 use crate::{prompt, users::get_all_users_keys};
 use anyhow::{ensure, Context, Result};
 
+use bootc_mount::Filesystem;
 use crossterm::event::{self, Event};
 use std::time::Duration;
 
@@ -92,6 +93,42 @@ pub(crate) fn ask_yes_no(prompt: &str, default: bool) -> Result<bool> {
         .context("prompting")
 }
 
+pub(crate) fn mount_warning() -> Result<()> {
+    let mounts = bootc_mount::run_findmnt(&[], None)?;
+
+    let problematic_filesystems: Vec<&Filesystem> = mounts
+        .filesystems
+        .iter()
+        .find(|mount| mount.target == "/")
+        .map(|root| {
+            root.children
+                .iter()
+                .flatten()
+                .filter(|child| child.source == root.source)
+                .collect()
+        })
+        .unwrap_or_default();
+
+    if !problematic_filesystems.is_empty() {
+        println!();
+        println!("Notice: the following filesystems are currently mounted on the root disk. After rebooting into the bootc system, these filesystems will not be mounted. They will be preserved so you will need to manually mount or remove them.");
+        println!();
+        for fs in problematic_filesystems {
+            println!("{:?}", fs); //TODO: format this
+        }
+        println!();
+        println!("Press <enter> to continue.");
+
+        loop {
+            if let Event::Key(_) = event::read().unwrap() {
+                break;
+            }
+        }
+    }
+
+    Ok(())
+}
+
 /// Gather authorized keys for all user's of the host system
 /// prompt the user to select which users's keys will be imported
 /// into the target system's root user's authorized_keys file