Add autotools build system (static-only, C17)
configure.ac enforces C17 and Linux/x86_64, refuses in-tree configure; Makefile.am builds libc.a plus crt0.o; the driver Makefile dispatches out-of-tree builds into bin/release (-O2) and bin/debug (-O0 -g). Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent) Co-authored-by: Sisyphus <[email protected]>
This commit is contained in:
Sisyphus
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# Driver Makefile — nulsl-libc
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#
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# This is the HAND-WRITTEN top-level makefile (committed to git). It never
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# runs the autotools machinery in-tree; instead it drives two out-of-tree
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# builds, one per bin/ directory, exactly as the Null Linux guidelines want:
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#
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# make release -> ./configure CFLAGS='-O2' into bin/release/
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# make debug -> ./configure CFLAGS='-O0 -g' into bin/debug/
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#
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# Run `./autogen.sh` once after cloning (or just run `make release` — it
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# regenerates the configure script itself when needed).
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#
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# Never run `./configure` at the repository root: configure.ac refuses it.
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.PHONY: all release debug bench check clean distclean compile_commands
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all: release
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# --- bootstrapping ---------------------------------------------------------
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# Regenerates configure (and friends) when autogen.sh is newer.
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configure: autogen.sh
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./autogen.sh
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# --- builds ----------------------------------------------------------------
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# Release is ALWAYS -O2 (project guideline #4).
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bin/release/Makefile: configure
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@mkdir -p bin/release
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@cd bin/release && ../../configure CFLAGS='-O2'
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bin/debug/Makefile: configure
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@mkdir -p bin/debug
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@cd bin/debug && ../../configure CFLAGS='-O0 -g'
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release: bin/release/Makefile
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$(MAKE) -C bin/release
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debug: bin/debug/Makefile
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$(MAKE) -C bin/debug
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# --- developer conveniences -------------------------------------------------
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bench: release
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$(MAKE) -C bin/release bench
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check: release
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$(MAKE) -C bin/release check
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# LSP support: compile_commands.json for clangd (requires `bear`).
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compile_commands: release
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@command -v bear >/dev/null 2>&1 || { \
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echo "error: 'bear' is not installed (sudo pacman -S bear, apt install bear, ...)"; exit 1; }
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@cd bin/release && bear --output ../../compile_commands.json -- $(MAKE) clean all
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clean:
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@test ! -f bin/release/Makefile || $(MAKE) -C bin/release clean
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@test ! -f bin/debug/Makefile || $(MAKE) -C bin/debug clean
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distclean: clean
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rm -rf bin/release bin/debug
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+66
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# Makefile.am — nulsl-libc
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#
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# This is the AUTOTOOLS makefile. It is only ever instantiated by a configure
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# run inside bin/release/ or bin/debug/ (never at the repository root).
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#
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# Everything is a static library. No libtool, no shared objects, no dynamic
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# linker. See docs/architecture.md.
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#
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# Benchmarks and tests live in one Makefile on purpose: automake orders
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# targets by dependency, so libc.a (and crt0.o) are guaranteed to exist
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# before any -nostdlib binary links against them. With SUBDIRS, recursion
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# builds the subdirectories first and linking breaks.
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AUTOMAKE_OPTIONS = foreign
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AM_CPPFLAGS = -I$(top_srcdir)/include
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AM_CFLAGS = -std=c17 -ffreestanding -fno-builtin -fno-stack-protector \
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-Wall -Wextra -Wshadow -Wpointer-arith
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lib_LIBRARIES = libc.a
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libc_a_SOURCES = \
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src/errno.c \
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src/stdio.c \
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src/stdlib.c \
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src/string.c \
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src/syscall.c \
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src/unistd.c
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# The C runtime entry point is deliberately NOT a member of libc.a: nothing
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# references _start, so the linker would never extract it from an archive.
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# It is built as a standalone object and linked explicitly by everything
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# that wants a runnable binary.
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noinst_DATA = crt0.o
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crt0.o: $(top_srcdir)/src/crt/crt0.S
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$(CC) $(AM_CPPFLAGS) $(CFLAGS) -c -o $@ $<
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CLEANFILES = crt0.o
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EXTRA_DIST = autogen.sh
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# --- benchmarks ------------------------------------------------------------
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# Fully static, -nostdlib: the numbers reflect exactly what ships.
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noinst_PROGRAMS = benchmarks/bench_strlen benchmarks/bench_syscall
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benchmarks_bench_strlen_SOURCES = benchmarks/bench_strlen.c
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benchmarks_bench_strlen_LDADD = crt0.o libc.a -lgcc
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benchmarks_bench_strlen_LDFLAGS = -nostdlib -static -no-pie -Wno-unused-command-line-argument
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benchmarks_bench_syscall_SOURCES = benchmarks/bench_syscall.c
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benchmarks_bench_syscall_LDADD = crt0.o libc.a -lgcc
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benchmarks_bench_syscall_LDFLAGS = -nostdlib -static -no-pie -Wno-unused-command-line-argument
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.PHONY: bench
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bench: all
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./benchmarks/bench_strlen
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./benchmarks/bench_syscall
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# --- tests ------------------------------------------------------------------
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check_PROGRAMS = tests/smoke
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TESTS = tests/smoke
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tests_smoke_SOURCES = tests/smoke.c
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tests_smoke_LDADD = crt0.o libc.a -lgcc
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tests_smoke_LDFLAGS = -nostdlib -static -no-pie -Wno-unused-command-line-argument
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Executable
+19
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#!/bin/sh
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# autogen.sh — regenerate all autotools machinery.
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#
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# Usage: ./autogen.sh (then: make release / make debug / make bench)
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#
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# Never run ./configure at the repository root — use the driver Makefile
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# targets instead, which configure out-of-tree into bin/{release,debug}.
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set -e
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cd "$(dirname "$0")"
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autoreconf -i -f -v
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echo
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echo "autotools machinery regenerated."
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echo "next: make release (bin/release/, CFLAGS='-O2')"
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echo " make debug (bin/debug/, CFLAGS='-O0 -g')"
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echo " make bench (benchmarks against the release build)"
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echo " make check (smoke tests)"
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dnl configure.ac — nulsl-libc, a very lightweight C17 libc for Linux.
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dnl
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dnl Static-only on purpose: the dynamic linker is a memory tax we refuse to
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dnl pay (see docs/architecture.md). libc.a is a plain archive, so no libtool.
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dnl
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dnl IMPORTANT: never run ./configure at the repository root. The root holds a
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dnl hand-written driver Makefile that builds into bin/{release,debug}; the
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dnl guard below refuses to overwrite it.
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AC_PREREQ([2.71])
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AC_INIT([nulsl-libc], [0.1.0], [], [nulsl-libc],
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[https://git.spectoria.dev/The-Null-Linux-Project/nulsl-libc])
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AC_CONFIG_SRCDIR([include/stdio.h])
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AC_CONFIG_AUX_DIR([build-aux])
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AC_CANONICAL_HOST
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AM_INIT_AUTOMAKE([foreign subdir-objects])
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dnl C17, and only C17 (project guideline #1). Modern autoconf ships no
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dnl AC_PROG_CC_C17 macro, so prove it with a compile test instead.
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AC_PROG_CC
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saved_CFLAGS="$CFLAGS"
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CFLAGS="$CFLAGS -std=c17"
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AC_COMPILE_IFELSE([AC_LANG_PROGRAM([#if __STDC_VERSION__ < 201710L
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#error "not C17"
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#endif
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], [])],
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[],
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[AC_MSG_ERROR([nulsl-libc requires a C17 compiler (GCC >= 8 or Clang >= 6); -std=c17 was rejected])])
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CFLAGS="$saved_CFLAGS"
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dnl Target validation: Linux on x86_64, for now.
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AS_CASE([$host_os],
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[linux*], [],
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[AC_MSG_ERROR([nulsl-libc currently targets Linux only (configured for $host_os)])])
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AS_CASE([$host_cpu],
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[x86_64], [],
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[AC_MSG_ERROR([nulsl-libc currently targets x86_64 only (configured for $host_cpu); src/arch/ is where new ports go])])
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dnl Plain archives need ar/ranlib; no libtool, no shared objects.
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AC_CHECK_TOOL([AR], [ar])
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AC_PROG_RANLIB
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dnl Refuse in-tree configuration: it would clobber the committed driver
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dnl Makefile that dispatches into bin/{release,debug}.
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AS_IF([test "x$srcdir" = "x." && test -f Makefile],
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[AC_MSG_ERROR([in-tree builds are disabled — run 'make release' or 'make debug' from the repository root instead])])
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AC_CONFIG_FILES([Makefile])
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AC_OUTPUT
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