remove rsmount dependency

src/dynlay.rs

@@ -30,17 +30,14 @@ impl<'t> Dynlay<'t> {
         }
 
         let mount_path = PathBuf::from(lay_dir).join("mounts").join(layer);
-        let mount_path_str = mount_path.to_string_lossy().into_owned();
 
         (fs::create_dir_all(&mount_path).await)
             .map_err(|e| format_err!("mkdir -p {mount_path:?} failed: {e}"))?;
 
         let mount_path = &fs::canonicalize(mount_path).await?;
+        let mount_path_str = &mount_path.to_string_lossy().into_owned();
 
-        let mut mount_info = rsmount::tables::MountInfo::new()?;
-        mount_info.import_mountinfo()?;
-
-        if mount_info.find_target(mount_path).is_some() {
+        if is_mount_point(mount_path_str).await? {
             info!("clearing previous mount");
 
             let mut paths = spawn_walk_dir(mount_path.clone());
@@ -163,3 +160,29 @@ where
         Err(format_err!("{program} failed: {status}"))
     }
 }
+
+async fn is_mount_point(target: &str) -> Result<bool> {
+    for line in fs::read_to_string("/proc/self/mounts").await?.lines() {
+        let line = line.trim_ascii();
+        if line.is_empty() || line.starts_with("#") {
+            continue;
+        }
+
+        let split: Vec<_> = line.split_ascii_whitespace().collect();
+        if split.len() < 6 {
+            continue;
+        }
+
+        // let dev = split[0];
+        let mount_point = split[1];
+        // let fstype = split[2];
+        // let mntops = split[3];
+        // let fs_freq = split[4];
+        // let fsck_passno = split[5];
+
+        if mount_point == target {
+            return Ok(true);
+        }
+    }
+    Ok(false)
+}