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mozilla / ffi-support

A crate to help expose Rust functions over the FFI.
Apache License 2.0
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readme

FFI Support

Docs

This crate implements a low-level support library to simplify implementing certain FFI patterns. It was originally created for patterns in the mozilla/application-services repository, but that repo is working on replacing all uses of this crate with the mozilla/uniffi-rs project.

In other words, we consider this crate soft-deprecated and replaced by UniFFI.

However, if this crate proves useful to others, it can assist with the following areas:

  1. Avoiding throwing panics over the FFI (which is undefined behavior)
  2. Translating rust errors (and panics) into errors that the caller on the other side of the FFI is able to handle.
  3. Converting strings to/from rust str.
  4. Passing non-string data (in a few ways, including exposing an opaque pointeer, marshalling data to JSON strings with serde, as well as arbitrary custom handling) back and forth between Rust and whatever the caller on the other side of the FFI is.

Additionally, it's documentation describes a number of the problems we've hit doing this to expose libraries to consumers on mobile platforms.

Usage

Add the following to your Cargo.toml

ffi-support = "0.4.4"

For further examples, the examples in the docs is the best starting point, followed by the usage code in the mozilla/application-services repo (for example here or here).

License

Dual licensed under the Apache License, Version 2.0 or http://www.apache.org/licenses/LICENSE-2.0 or the MIT license or http://opensource.org/licenses/MIT, at your option. All files in the project carrying such notice may not be copied, modified, or distributed except according to those terms.