Translating Large-Scale C Repositories to Idiomatic Rust

TL;DR

Rustine is an automated pipeline that effectively translates large C repositories into safe, idiomatic, and readable Rust code, achieving high functional equivalence and safety improvements over prior methods.

Contribution

The paper introduces Rustine, a fully automated, scalable C-to-Rust translation pipeline that produces safe, idiomatic code with high functional accuracy, surpassing existing techniques.

Findings

Rustine achieves 87% functional equivalence on diverse C programs.

Rustine produces safer and more idiomatic Rust code compared to prior methods.

Human developers need only 4.5 hours on average to complete translations when tests fail.

Abstract

Existing C to Rust translation techniques fail to balance quality and scalability: transpilation-based approaches scale to large projects but produce code with poor safety, idiomaticity, and readability. In contrast, LLM-based techniques are prohibitively expensive due to their reliance on frontier models (without which they cannot reliably generate compilable translations), thus limiting scalability. This paper proposes Rustine, a fully automated pipeline for effective and efficient repository-level C to idiomatic safe Rust translation. Evaluating on a diverse set of 23 C programs, ranging from 27 to 13,200 lines of code, Rustine can generate fully compilable Rust code for all and achieve 87% functional equivalence (passing 1,063,099 assertions out of 1,221,192 in test suites with average function and line coverage of 74.7% and 72.2%). Compared to six prior repository-level C to Rust translation techniques, the translations by Rustine are overall safer (fewer raw pointers, pointer arithmetic, and unsafe constructs), more idiomatic (fewer Rust linter violations), and more readable. When the translations cannot pass all tests to fulfill functional equivalence, human developers were able to complete the task in 4.5 hours, on average, using Rustine as debugging support.