Struct Layer 

pub struct Layer { /* private fields */ }

Represents an overlay layer with its metadata and content.

Implementations

impl Layer

pub fn open(storage: &Storage, id: &str) -> Result<Self>

Open a layer by ID using fd-relative operations.

Errors

Returns an error if the layer directory doesn’t exist or cannot be opened.

pub fn id(&self) -> &str

Get the layer ID.

pub fn link_id(&self) -> &str

Get the short link ID for this layer.

pub fn parent_links(&self) -> &[String]

Get the parent link IDs for this layer.

pub fn parents(&self, storage: &Storage) -> Result<Vec<String>>

Get parent layer IDs (resolved from link IDs).

This resolves the short link IDs from the lower file to full layer IDs by reading the symlinks in the overlay/l/ directory.

Errors

Returns an error if any link cannot be resolved.

pub fn layer_dir(&self) -> &Dir

Get a reference to the layer directory handle.

pub fn diff_dir(&self) -> &Dir

Get a reference to the diff directory handle.

pub fn layer_chain(self, storage: &Storage) -> Result<Vec<Layer>>

Get the complete chain of layers from this layer to the base.

Returns layers in order: [self, parent, grandparent, …, base]

Errors

Returns an error if the layer chain exceeds the maximum depth of 500 layers.

pub fn open_file(&self, path: impl AsRef<Path>) -> Result<File>

Open a file in the layer’s diff directory using fd-relative operations.

Errors

Returns an error if the file doesn’t exist or cannot be opened.

pub fn open_file_std(&self, path: impl AsRef<Path>) -> Result<File>

Open a file and return a standard library File.

Errors

Returns an error if the file doesn’t exist or cannot be opened.

pub fn metadata(&self, path: impl AsRef<Path>) -> Result<Metadata>

Get metadata for a file in the layer’s diff directory.

Errors

Returns an error if the file doesn’t exist.

pub fn read_dir(&self, path: impl AsRef<Path>) -> Result<ReadDir>

Read directory entries using Dir handle.

Errors

Returns an error if the directory doesn’t exist.

pub fn has_whiteout(&self, parent_path: &str, filename: &str) -> Result<bool>

Check if a whiteout file exists for the given filename.

Whiteout format: .wh.<filename>

Arguments

• parent_path - The directory path containing the file (empty string or “.” for root)
• filename - The name of the file to check for whiteout

Errors

Returns an error if the directory cannot be accessed.

pub fn is_opaque_dir(&self, path: &str) -> Result<bool>

Check if a directory is marked as opaque (hides lower layers).

Opaque marker: .wh..wh..opq

Errors

Returns an error if the directory cannot be accessed.

Trait Implementations

impl Debug for Layer

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.