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Migrating from C to Rust - Part 1: Calling Rust Code from C

BY yeu2q
July 7, 2025
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Migrating from C to Rust: Introduction

Overview

  • Rust V1 was announced approximately 10 years ago and has grown in popularity.
  • Growing calls to transition from C and C++ to Rust, due to Rust’s memory safety feature.
  • This video is the start of a series on switching from using C as a main language to Rust.

Why Migrate to Rust?

  • Memory Safety: Unlike C, Rust provides memory safety without a garbage collector.
  • Avoiding Common Issues: Rust helps prevent pointer problems and buffer overflows common in C.
  • Security Improvements: Transitioning to Rust can make operating systems safer.

Transition Approach

  • Cannot cover everything in one video; requires a series of videos.
  • Moving to Rust involves learning the language well, despite tools and techniques for easing the transition.

Calling Rust from C

  • Focus on transitioning existing C code to Rust rather than vice versa.
  • Strategy involves translating C codebase function by function.

Example: Converting C to Rust

Initial C Code

A simple C program with:

  • v_random.c: Contains a random number generator.
  • main.c: Uses the library from v_random.c.

Transition to Rust:

  1. Convert v_random.c to Rust: Rewrite in Rust while keeping main.c unchanged.

  2. Rust Project Setup:

    • Create a Rust library using Cargo.
    • Edit Cargo.toml to build a static library.
  3. Rust Implementation Highlights:

    • Using unsafe blocks for global variables.
    • #[no_mangle] for avoiding name mangling.
    • extern "C" for foreign function interfaces.
  4. Compiling and Linking:

    • Compile Rust code with Cargo, generating a static library.
    • Use GCC to compile main.c, linking it with the Rust library.

Challenges:

  • Initial Rust implementation uses unsafe.
  • Transition to idiomatic Rust requires changes in C code, adding complexity.

Helpful Tools

  • cbindgen: Automatically generates C header files from Rust, aiding interoperability.

Conclusion

  • Part 2 of the series to be informed by user feedback.
  • Viewers encouraged to suggest topics for future videos or tutorials on Rust and C.

Community Engagement

  • Encouragement to provide feedback and suggestions via the comments section.
  • Mention of platforms for following updates: YouTube, X (formerly Twitter), Blue Sky, and Mastodon.