cbmc
coreHTTP
| cbmc | coreHTTP | |
|---|---|---|
| 5 | 1 | |
| 765 | 67 | |
| 3.5% | - | |
| 9.9 | 6.2 | |
| 1 day ago | 3 days ago | |
| C++ | C | |
| GNU General Public License v3.0 or later | MIT License |
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cbmc
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Xr0 Makes C Safer than Rust
This appears to be more limited than what CBMC[1] (the C Bounded Model Checker) can do. CBMC can do function contracts. CBMC can prove memory safety and even the absence of memory leaks for non-trivial code bases that pass pointers all over the place that must eventually be freed. Applying all the annotations to make this happen though is like 10x the work of getting the program actually running in the first place. CBMC definitely makes C safer than even safe Rust for projects that can invest the time to use it. There is an experimental Rust front end to CBMC called Kani[2] that aims to verify unsafe Rust (thus making unsafe Rust become safe) but it is far from the speed and robustness of the C front end.
[1] https://github.com/diffblue/cbmc
[2] https://github.com/model-checking/kani
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The C Bounded Model Checker: Criminally Underused
https://github.com/diffblue/cbmc/issues/7732 I'll note that some form of undefined behavior checking / documentation is on the roadmap for the next major version
- CBMC: The C Bounded Model Checker
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Using the Kani Rust Verifier on Tokio Bytes
So it seems to use cmbc and a bunch of other tools from cprover under the hood (bundled in the github release and setup on first run...). I would really like to have this "how" more visible in the documentation, it's essential to hint at the limitations of such an automated prover, even if the underlying system is rather powerful.
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Hard Things in Computer Science
> The only reliable way to have bug-free code is to prove it. It requires solid mathematical foundations and a programming language that allows formal proofs.
I'm going to be the "actually" guy and say that, actually, you can formally verify some studff about programs written in traditional/mainstream languages, like C. Matter of fact, this is a pretty lively research area, with some tools like CBMC [0] and Infer [1] also getting significant adoption in the industry.
[0]: https://github.com/diffblue/cbmc
[1]: https://fbinfer.com/
coreHTTP
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The C Bounded Model Checker: Criminally Underused
One of the examples they gave was an HTTP client, which would be a surprisingly non-toy example, so I looked at what they actually did in the code (https://github.com/FreeRTOS/coreHTTP/tree/main/test/cbmc).
Not that I'm an expert in processing what exactly is being tested, but it basically looks only able to prove that an individual function doesn't overrun buffers. If you tell it to assume that overflows can't happen (!). So I'm not impressed.
What are some alternatives?
sudoku-cbmc - SAT-based sudoku solver
tis-interpreter - An interpreter for finding subtle bugs in programs written in standard C
infer - A static analyzer for Java, C, C++, and Objective-C
kani - Kani Rust Verifier
c-semantics - Semantics of C in K
dmd - dmd D Programming Language compiler