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]>
2026-08-30 04:09:45 -04:00
parent 6768ec36e7
commit 228ed097f0
4 changed files with 196 additions and 0 deletions
@@ -0,0 +1,66 @@
+# Makefile.am — nulsl-libc
+#
+# This is the AUTOTOOLS makefile. It is only ever instantiated by a configure
+# run inside bin/release/ or bin/debug/ (never at the repository root).
+#
+# Everything is a static library. No libtool, no shared objects, no dynamic
+# linker. See docs/architecture.md.
+#
+# Benchmarks and tests live in one Makefile on purpose: automake orders
+# targets by dependency, so libc.a (and crt0.o) are guaranteed to exist
+# before any -nostdlib binary links against them. With SUBDIRS, recursion
+# builds the subdirectories first and linking breaks.
+
+AUTOMAKE_OPTIONS = foreign
+
+AM_CPPFLAGS = -I$(top_srcdir)/include
+AM_CFLAGS = -std=c17 -ffreestanding -fno-builtin -fno-stack-protector \
+            -Wall -Wextra -Wshadow -Wpointer-arith
+
+lib_LIBRARIES = libc.a
+
+libc_a_SOURCES = \
+    src/errno.c \
+    src/stdio.c \
+    src/stdlib.c \
+    src/string.c \
+    src/syscall.c \
+    src/unistd.c
+
+# The C runtime entry point is deliberately NOT a member of libc.a: nothing
+# references _start, so the linker would never extract it from an archive.
+# It is built as a standalone object and linked explicitly by everything
+# that wants a runnable binary.
+noinst_DATA = crt0.o
+crt0.o: $(top_srcdir)/src/crt/crt0.S
+	$(CC) $(AM_CPPFLAGS) $(CFLAGS) -c -o $@ $<
+CLEANFILES = crt0.o
+
+EXTRA_DIST = autogen.sh
+
+# --- benchmarks ------------------------------------------------------------
+# Fully static, -nostdlib: the numbers reflect exactly what ships.
+
+noinst_PROGRAMS = benchmarks/bench_strlen benchmarks/bench_syscall
+
+benchmarks_bench_strlen_SOURCES = benchmarks/bench_strlen.c
+benchmarks_bench_strlen_LDADD = crt0.o libc.a -lgcc
+benchmarks_bench_strlen_LDFLAGS = -nostdlib -static -no-pie -Wno-unused-command-line-argument
+
+benchmarks_bench_syscall_SOURCES = benchmarks/bench_syscall.c
+benchmarks_bench_syscall_LDADD = crt0.o libc.a -lgcc
+benchmarks_bench_syscall_LDFLAGS = -nostdlib -static -no-pie -Wno-unused-command-line-argument
+
+.PHONY: bench
+bench: all
+	./benchmarks/bench_strlen
+	./benchmarks/bench_syscall
+
+# --- tests ------------------------------------------------------------------
+
+check_PROGRAMS = tests/smoke
+TESTS = tests/smoke
+
+tests_smoke_SOURCES = tests/smoke.c
+tests_smoke_LDADD = crt0.o libc.a -lgcc
+tests_smoke_LDFLAGS = -nostdlib -static -no-pie -Wno-unused-command-line-argument