Crate dlopen[−][src]

Library for opening and working with dynamic link libraries (also known as shared object).

Overview

This library is an effort to make use of dynamic link libraries in Rust simple. Previously existing solutions were either unsafe, provided huge overhead of required writing too much code to achieve simple things. I hope that this library will help you to quickly get what you need and avoid errors.

Features

Main features

  • Supports majority of platforms and is platform independent.
  • Is consistent with Rust error handling mechanism and makes making mistakes much more difficult.
  • Is very lightweight. It mostly uses zero cost wrappers to create safer abstractions over platform API.
  • Is thread safe.
  • Is object-oriented programming friendly.
  • Has a low-level API that provides full flexibility of using libraries.
  • Has two high-level APIs that protect against dangling symbols - each in its own way.
  • High level APIs support automatic loading of symbols into structures. You only need to define a structure that represents an API. The rest happens automatically and requires only minimal amount of code.
  • Automatic loading of symbols helps you to follow the DRY paradigm.

Compare with other libraries

Feature dlopen libloading sharedlib
Basic functionality Yes Yes Yes
Multiplatform Yes Yes Yes
Dangling symbol prevention Yes Yes Yes
Thread safety Yes Potential problem with SetErrorMode() on older Windows platforms No support for SetErrorMode (library may block the application on Windows)
Loading of symbols into structures Yes No No
Overhead Minimal Minimal Some overhead
Low-level, unsafe API Yes Yes Yes
Object-oriented friendly Yes No Yes

Safety

Please note that while Rust aims at being 100% safe language, it does not yet provide mechanisms that would allow me to create a 100% safe library, so I had to settle on 99%. Also the nature of dynamic link libraries requires casting obtained pointers into types that are defined on the application side. And this cannot be safe. Having said that I still think that this library provides the best approach and greatest safety possible in Rust.

Usage:

Cargo.toml:

[dependencies]
dlopen = "0.1"

Documentation

Cargo documentation

Examples

Changelog

License

This code is licensed under MIT license.

Acknowledgement

Special thanks to Simonas Kazlauskas whose libloading became code base for my project.

Comparison of APIs:

  • raw - a low-level API. It is mainly intended to give you full flexibility if you decide to create you own custom solution for handling dynamic link libraries. For typical operations you probably should use one of high-level APIs.

  • symbor - a high-level API. It prevents dangling symbols by creating zero cost structural wrappers around symbols obtained from the library. These wrappers use Rust borrowing mechanism to make sure that the library will never get released before obtained symbols.

  • wrapper - a high-level API. It prevents dangling symbols by creating zero cost functional wrappers around symbols obtained from the library. These wrappers prevent accidental copying of raw symbols from library API. Dangling symbols are prevented by keeping library and its API in one structure - this makes sure that symbols and library are released together.

Additionally both high-level APIs provide a way to automatically load symbols into a structure using Rust reflection mechanism. Decision witch API should be used is a matter of taste - please check documentation of both of them and use the one that you prefer. At the moment none seems to have any reasonable advantage over the other.

Modules

raw

Low-level API for opening and getting raw symbols from dynamic link libraries.
symbor

High-level and safe API for opening and getting symbols from dynamic libraries. It is based on symbol borrowing mechanism and supports automatic loading of symbols into structures.
utils

Utilities for working with dynamic link libraries.
wrapper

High-level and safe API for opening and getting symbols from dynamic link libraries. It is based on wrapping private symbols with public functions to prevent direct access and supports automatic loading of symbols into structures.

Enums

Error

This is a library-specific error that is returned by all calls to all APIs.