Crate interprocess

Interprocess communication toolkit for Rust programs that aims to expose as many platform-specific features as possible while maintaining a uniform interface for all platforms and encouraging portable, correct code.

Interprocess communication primitives

Interprocess provides both OS-specific IPC interfaces and cross-platform abstractions for them.

Cross-platform IPC APIs

• Local sockets – similar to TCP sockets, but use filesystem or namespaced paths instead of ports on localhost, depending on the OS, bypassing the network stack entirely; implemented using named pipes on Windows and Unix domain sockets on Unix

Platform-specific, but present on both Unix-like systems and Windows

• Unnamed pipes – anonymous file-like objects for communicating privately in one direction, most commonly used to communicate between a child process and its parent

Unix-only

• FIFO files – special type of file which is similar to unnamed pipes but exists on the filesystem, often referred to as “named pipes” but completely different from Windows named pipes
• Unix domain sockets – Interprocess no longer provides those, as they are present in the standard library; they are, however, exposed as local sockets

Windows-only

• Named pipes – resemble Unix domain sockets, use a separate namespace instead of on-drive paths

Asynchronous I/O

Currently, only Tokio for local sockets, Unix domain sockets and Windows named pipes is supported. Support for async-std is planned.

Platform support

Interprocess supports Windows and all generic Unix-like systems. Additionally, platform-specific extensions are supported on select systems. The policy with those extensions is to put them behind #[cfg] gates and only expose on the supporting platforms, producing compile errors instead of runtime errors on platforms that have no support for those features.

Four levels of support (not called tiers to prevent confusion with Rust target tiers, since those work completely differently) are provided by Interprocess. It would be a breaking change for a platform to be demoted, although promotions quite obviously can happen as minor or patch releases.

Explicit support

OSes at this level: Windows, Linux, macOS

• Interprocess is guaranteed to compile and succeed in running all tests – it would be a critical bug for it not to
• CI, currently provided by GitHub Actions, runs on all of those platforms and displays an ugly red badge if anything is wrong on any of those systems
• Certain #[cfg]-gated platform-specific features are supported with stable public APIs

Explicit support without CI

OSes at this level: FreeBSD

• Interprocess is expected to compile and succeed in running all tests – it would be a bug for it not to
• Manual testing on local VMs is usually done before every release; CI is not provided solely because GitHub Actions selfishly ignores the existence of those wonderful systems
• Certain #[cfg]-gated platform-specific features are supported with stable public APIs

Support by association

OSes at this level: Dragonfly BSD, OpenBSD, NetBSD, Redox, Android, Fuchsia, iOS, tvOS, watchOS

• Interprocess is expected to compile and succeed in running all tests – it would be a bug for it not to
• No manual testing is performed, and CI is unavailable because GitHub Actions does not provide it
• Certain #[cfg]-gated platform-specific features that originate from other platforms are supported with stable public APIs because they behave here identically to how they do on an OS with a higher support level

Assumed support

OSes at this level: POSIX-conformant #[cfg(unix)] systems not listed above for which the libc crate compiles

• Interprocess is expected to compile and succeed in running all tests – it would be a bug for it not to
• Because this level encompasses a practically infinite amount of systems, no manual testing or CI can exist

Feature gates

• tokio, off by default – enables support for Tokio-powered efficient asynchronous IPC.

License

This crate, along with all community contributions made to it, is dual-licensed under MIT and Apache 2.0.

Modules

• bound_util
  Trait bound utilities.
• error
  Generic error types used throughout the crate.
• local_socket
  Local sockets, an IPC primitive featuring a server and multiple clients connecting to that server using a filesystem path or an identifier inside a special namespace, each having a private connection to that server.
• os
  Platform-specific functionality for various interprocess communication primitives.
• unnamed_pipe
  Creation and usage of unnamed pipes.

Traits

• TryClone
  Fallible OS object cloning.