ziglibc

ziglibc is an experimental libc implementation in Zig covering the C standard library plus a growing POSIX surface.

Status

• Builds with Zig 0.15.2.
• zig build test passes on:
  • Linux native
  • macOS targets executed through darling
  • Windows GNU targets executed through wine
• zig build conformance passes on the same matrix.
• The in-tree parity runner compares ziglibc and the platform libc for the validated matrix on:
  • process execution (system, popen, pclose)
  • signal/sigaction basics
  • strtol/strtod no-digit behavior
  • setitimer, select, pselect, and utimes where the platform libc exposes them

Repository Setup

Conformance sources are tracked as git submodules. Initialize them before running the test or conformance steps:

git submodule update --init --recursive

The conformance-related submodules live under dep/:

• dep/libc-test
• dep/tiny-regex-c
• dep/open_posix_testsuite
• dep/glibc-testsuite

Building

Build the default install artifacts with:

zig build

Run the project test suite with:

zig build test

Run the conformance suite bundle with:

zig build conformance

Useful individual steps:

zig build libc-test
zig build glibc-check
zig build posix-test-suite
zig build austin-group-tests
zig build re-tests

Cross-Platform Validation

On a Linux host, the build uses external runners for foreign test execution:

• Darwin targets: darling
• Windows GNU targets: wine

Examples:

zig build test -Dtarget=x86_64-macos
zig build conformance -Dtarget=x86_64-macos

zig build test -Dtarget=x86_64-windows-gnu
zig build conformance -Dtarget=x86_64-windows-gnu

aarch64-macos is also kept compiling in CI:

zig build -Dtarget=aarch64-macos

Using ziglibc

After zig build, point zig cc at the generated headers and libraries:

zig cc \
    -nostdlib \
    -I PATH_TO_ZIGLIBC_SRC/inc/libc \
    -I PATH_TO_ZIGLIBC_SRC/inc/posix \
    -I PATH_TO_ZIGLIBC_SRC/inc/linux \
    -L PATH_TO_ZIGLIBC_INSTALL/lib \
    -lstart \
    -lc

Notes

• The validated Linux/macOS/Windows matrix is green for both test and conformance.
• Remaining ENOSYS paths are scoped to unsupported targets or unsupported OS-specific features outside that matrix.
• The build will fail fast if required submodules are missing rather than cloning repositories during zig build.