considering a different project directory struture

inspired by freebsd source tree

lib/Makefile

@@ -0,0 +1,30 @@
+# Copyright (c) 2023–2024 Emma Tebibyte <emma@tebibyte.media>
+# Copyright (c) 2023–2024 DTB <trinity@trinity.moe>
+# Copyright (c) 2023 Sasha Koshka <sashakoshka@tebibyte.media>
+# Copyright (c) 2024 Aaditya Aryal <aryalaadi123@gmail.com>
+# SPDX-License-Identifier: FSFAP
+#
+# Copying and distribution of this file, with or without modification, are
+# permitted in any medium without royalty provided the copyright notice and this
+# notice are preserved.  This file is offered as-is, without any warranty.
+
+include ../config.mk
+
+.PHONY: lib
+lib: ../$(BUILD)/o/libsysexits.rlib ../$(BUILD)/o/libgetopt.rlib \
+	../$(BUILD)/o/libstrerror.rlib
+
+../$(BUILD)/o/libgetopt.rlib: getopt-rs/lib.rs
+	$(RUSTC) $(RUSTFLAGS) --crate-type=lib --crate-name=getopt \
+		-o $@ getopt-rs/lib.rs
+
+../$(BUILD)/o/libstrerror.rlib: strerror.rs
+	$(RUSTC) $(RUSTFLAGS) --crate-type=lib -o $@ \
+		strerror.rs
+
+../$(BUILD)/o/libsysexits.rlib: $(SYSEXITS)sysexits.h
+	# bandage solution until bindgen(1) gets stdin support
+	printf '#define EXIT_FAILURE 1\n' | cat - $(SYSEXITS)sysexits.h \
+		> ../$(BUILD)/include/sysexits.h
+	bindgen --default-macro-constant-type signed --use-core --formatter=none \
+		../$(BUILD)/include/sysexits.h | $(RUSTC) $(RUSTFLAGS) --crate-type lib -o $@ -