overlaynd

OverlayND is a software library designed to provide a unified interface for overlay filesystems. It aims to simplify the process of working with overlay filesystems, which are used to create a writable layer on top of a read-only base filesystem. This can be particularly useful in environments where multiple layers of filesystems need to be managed, such as in containerized applications or live system updates.

The library supports various overlay filesystems, including OverlayFS, AUFS, and UnionFS. By abstracting the differences between these filesystems, OverlayND allows developers to write code that can work with any of these underlying filesystems without modification. This abstraction layer helps in maintaining compatibility and portability across different Linux distributions and environments.

OverlayND provides a set of APIs that allow for the creation, management, and manipulation of overlay filesystems. These APIs include functions for mounting and unmounting overlay filesystems, as well as for managing the layers that make up the filesystem. The library also includes utilities for handling file operations within the overlay filesystem, such as copying files between layers and managing file permissions.

One of the key features of OverlayND is its support for nested overlays. This allows for the creation of complex filesystem hierarchies where multiple overlay filesystems can be stacked on top of each other. This capability is particularly useful in scenarios where multiple layers of configuration or data need to be applied sequentially.

The library is designed to be lightweight and efficient, making it suitable for use in performance-critical applications. It is implemented in C and is available under the GNU Lesser General Public License (LGPL), which allows for both open-source and commercial use.

Overall, OverlayND provides a powerful and flexible solution for managing overlay filesystems. Its unified interface and support for multiple underlying filesystems make it a valuable tool for developers working with complex filesystem hierarchies.