huntedbytheirsandSisyphus
060fc03ab7
Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent) Co-authored-by: Sisyphus <[email protected]>
80 lines
3.4 KiB
Markdown
80 lines
3.4 KiB
Markdown
# vlibc
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A modern replacement for glibc: a performant, standard-conforming C library
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with modern extensions and high glibc compatibility.
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vlibc is written in C (C23, with C2y/C29 opt-in), built with Autotools and a
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single compiler (GCC, no fallback). Full static linking is a first-class,
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required capability.
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## Capabilities
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- **Five compatibility profiles**, from the lightest to the most compatible:
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1. `--enable-onlyposix` — pure POSIX, nothing more.
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2. `--enable-muslmimic` — musl-like, light and musl-compatible.
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3. `--enable-muslext` — musl-extended.
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4. `--enable-spoof` — a glibc replica, for drop-in compatibility with
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scripts and programs that rely on long-standing glibc behavior.
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5. *(default)* — **vlibc**: glibc-extended, without the spoofing layer, but
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with extended standard features and high glibc compatibility.
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- **Profiles 1-3 are functional.** `--enable-onlyposix`, `--enable-muslmimic`,
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and `--enable-muslext` build with real build-time profile gating: a generated
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`include/vlibc/features.h` exposes `VLIBC_LEVEL`, the public `<stddef.h>` and
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`<string.h>` headers are gated by it, and an initial string slice (`memcpy`,
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`memmove`, `memset`, `strlen`, `strcmp`, `strlcpy`, `strlcat`,
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`strcasestr`) is compiled per level. Profiles 4 and 5 (`spoof`, `vlibc`)
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remain configure-level declarations in this increment.
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- **Two install methods** (`--with-install=`):
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- `alongside` (default) — install next to the system libc, under a
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vlibc-specific tree; the system libc is left untouched.
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- `overwrite` — replace the system libc in place.
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- **`vlibc-gcc` and `vlibc-clang`** compiler drivers, so consuming projects
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build against vlibc with either compiler.
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- **Full static linking** is required for every profile except `spoof`.
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- **Compiler intent** is declared on the public API (e.g.
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`__attribute__((const))`) so the compiler can fold and eliminate calls,
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keeping statically linked binaries small.
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## Build
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```sh
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./autogen.sh # regenerate build system + configure
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make # build
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make debug # build with -O0 -g3 into bin/debug/
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make release # build with -O3 into bin/release/
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make bench # build and run benchmarks
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make clean # remove build artifacts
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make compile-commands # regenerate compile_commands.json (needs bear)
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```
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Common configure options:
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```sh
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./autogen.sh --enable-spoof # glibc replica profile
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./autogen.sh --with-install=overwrite # replace system libc
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./autogen.sh --with-libc=glibc # benchmark against glibc
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./autogen.sh --enable-c29 # experimental C2y (C29)
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```
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User-provided `CFLAGS` and `LDFLAGS` are honored.
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## Layout
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```
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include/ public headers (mandatory)
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src/ implementation sources
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benchmarks/ benchmark harnesses (vs. glibc/musl)
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docs/ behavior and glibc-difference documentation
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thirdparty/ vendored third-party libraries
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tools/ vlibc-gcc / vlibc-clang driver templates
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bin/{release,debug}/ build outputs
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```
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## Documentation
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- `docs/overview.md` — what vlibc is and how it behaves.
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- `docs/compatibility.md` — the five profiles and glibc differences.
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- `docs/install.md` — the two install methods.
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- `CONTRIBUTING.md` — how to contribute.
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- `STYLEGUIDE.md` — how code should look.
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