Fil-C 0.666.1

This is a spare-time personal project that I'm doing for fun. It's called Fil-C.

What is it? It's a totally memory-safe version of C and C++. All memory safety errors are caught as Fil-C panics. Fil-C achieves this using a combination of real-time garbage collection and monotonic capabilities (all pointers are 128 bits and have of those bits are under strict GC control). Every fundamental C operation (as seen in LLVM IR) is checked against the capability. Fil-C has no unsafe escape hatch of any kind.

What is it not? It's not production-tested. There are probably things I've missed. It's slow (I haven't done any optimizations yet). And, it has no ABI compatibility with classic C or C++.

Requirements

Fil-C only works on Apple Silicon Macs and FreeBSD 14 on X86_64, for now.

Getting Started

If you downloaded Fil-C binaries, run:

./setup.sh

If you downloaded Fil-C source, run:

./setup_gits.sh
./build_all.sh

Then you'll be able to use Fil-C from within this directory. There is no way to "install" it, because that would be a crazy thing to do for such an experimental piece of software!

Things That Work

Included in the binary distribution (or if you build from source using build_all.sh) is:

Memory-safe SSH client and server.
Memory-safe curl.
Memory-safe libz and openssl.
Memory-safe libc (based on musl) and libc++ (based on LLVM's libc++).
A version of clang that you can use to compile C or C++ programs.

Fil-C catches all of the stuff that makes memory safety in C hard, like:

Out-of-bounds on the heap or stack.
Use-after free (also heap or stack).
Type confusion between pointers and non-pointers.
Type errors arising from linking.
Type errors arising from misuse of va_lists.
Pointer races.
System calls. All buffers passed to system calls are checked for bounds and type.
Lots of other stuff.

Fil-C comes with a reasonably complete POSIX libc and even supports tricky features like threads, signal handling, and mmap/munmap.

Things That Don't Work

Fil-C is not a complete product. Lots of stuff isn't done!

Fil-C doesn't catch stack exhaustion (i.e. recursing until you run out of stack).
Fil-C doesn't do anything about UB not related to memory, yet. For example, dividing by zero may take the compiler down a weird path.
C++ exception handling. Also, RTTI probably doesn't work yet.
I haven't even done the most obvious performance optimizations. Fil-C is super slow right now!
Probably other stuff, too!

These are all things that can be fixed. They just haven't been, yet.

Learn More

The best write-up of Fil-C is the manifesto.

You can also e-mail me: pizlo@mac.com

And follow my rants on Twitter.

I don't have a bug database or anything like that, so bothering me on Twitter or over e-mail is your best bet, probably. And I might ignore you anyway.