Zig LIBC

A rewrite of the LIBC library in Zig ! Currently in a very, very alpha state, doesn't do a lot of things.

It aims to ONLY depend on zig's std.

If the behavior is different from musl/glibc/... then it is a bug. It aims for seamless integration / replacement.

It also has a tracing feature to allow you to follow your libc calls.

Summary

• Progress
  • C 89/90
  • C95 - CANNOT FIND ISO
  • C99
  • C11
  • C23
  • C29 - CANNOT FIND ISO
• Usage / Build
  • Build
  • Tests
  • Configuration
    • Tracing
• Why ?
• Acknowledgements

Progress

Here is the current progress on the implementation of the different headers.

C 89/90

See headers iso.
assert.h
ctype.h
errno.h
float.h
limits.h
locale.h
math.h
setjmp.h
signal.h
stdarg.h
stddef.h
stdio.h
stdlib.h
string.h
time.h

C95 - CANNOT FIND ISO

Because I cannot find the C95 iso file for free online, I will not implement the following headers until it changes.
iso646.h
wchar.h
wctype.h

C99

See headers iso.
complex.h
fenv.h
inttypes.h
stdbool.h (deprecated C23, to be removed ?)
stdint.h
tgmath.h

C11

See headers iso.
stdalign.h (deprecated C23, to be removed ?)
stdatomic.h
stdnoreturn.h
threads.h
uchar.h

C23

See headers iso p.191.
stdbit.h
stdckdint.h

C29 - CANNOT FIND ISO

Same as for C95, cannot find a free iso online. Will not implement.
stdmchar.h

Usage / Build

Exemple usage can be found in the tests/ directory in the form of *.c files. Basically, use it like libc :D

Build

For building, use the following command :

zig build

It will produce the following structure in the zig-out directory :

.
├── include
│   ├── assert.h
│   ├── stddef.h
│   └── ...
└── lib
    └── libzig_libc.a

Tests

If you want to run and build the tests, do :

zig build test

which will generate :

.
├── bin
    └── hello_world
    └── ...

You can pass additional arguments to all the tests using :

zig build test -- arg1 arg2 ...

Configuration

Additional parameters can be given at build time to modify the behavior of the library.

Tracing

zig build -Dtrace

Will output tracing to stderr which will satisfy the format :

[TRACE] LIBC '<function>' : <message>

This will clutter quite a lot your terminal but hopefully will help you trace back the error.

Why ?

There a multiple reasons why I wanted to create this project :

• The zig ecosystem still has a strong dependency on libc, which needs to then be distributed on all machines
• Zig allows to generate information about the target machine ! It will allow to then have a cross-platform implementation of LIBC
• It is a great project to learn various things
• The current "ziglibc" project is dead (last commit >2y ago) and has many drawbacks and bad tooling
• I feel like I can improve on the current solutions, and I want to try make an impact / help the zig ecosystem !

All these mad reasons have lead me to the most reasonable choice : write the entire LIBC in zig.

Acknowledgements

A lot of inspiration and help was taken from the following projects :

• CPP Reference - Header page
• Jonathan Marler's ziglibc as well as his talk
• Musl's LIBC implementation
• and more...