build: establish src/core layout for support modules (#617)

## What

- move `keywords.c`/`.h` and `locks.c`/`.h` into `src/core/`
- enable Automake `subdir-objects` for collision-safe nested object
placement
- update the Autotools binary, linked-test, standalone unit-test, and
fuzz paths
- make both cppcheck entry points share one complete nested-source
discovery path
- ignore nested Automake and Docker build artifacts
- retain existing header include names and the Autotools build

The four production source/header files are 100% renames with no content
changes. The remaining changes are build and verification plumbing
required by the new paths.

## Why

Spine production sources currently live in the repository root. This
starts the domain layout in a small, reviewable batch instead of
repeating #523, where the source move was coupled to an 11k-line
CMake/platform rewrite. `keywords` and `locks` were selected because
active PRs #597 and #614 do not modify their implementation files; only
shared build manifests overlap #597.

`subdir-objects` is enabled in this first production move so future
modules with the same basename cannot write the same top-level object
under parallel builds.

Closes #616.

## Verification

- `./bootstrap` with no subdirectory-source warnings
- `./configure --with-mysql=$(brew --prefix mariadb-connector-c)
--with-snmp=$(brew --prefix net-snmp) CPPFLAGS=-I$(brew --prefix
openssl@3)/include LDFLAGS=-L$(brew --prefix openssl@3)/lib`
- warning-enabled `make -j$(sysctl -n hw.ncpu)`; project sources
compile, with Homebrew Net-SNMP header warnings only
- `make check` (cmocka unavailable to Autoconf locally; 0 local tests)
- `make distcheck`; archive verified to contain all four `src/core`
files
- cppcheck source discovery verified under macOS Bash 3 and includes all
four relocated files
- standalone `tests/unit/Makefile` compiles through header resolution
with `-I../../src/core` (the local macOS link retains unrelated existing
client-library/toolchain issues)
- GitHub checks pass, including fuzz, sanitizers, coverage, `distcheck`,
gcc/clang, SNMPv3, and Rocky Linux

The local macOS fuzz build reaches both relocated files, then fails
identically on untouched `util.c` (`INT_MAX`) and Net-SNMP API
declarations on both this branch and `develop`. Linux fuzz CI is the
authoritative fuzz-build result.

---------

Signed-off-by: Thomas Vincent <thomasvincent@gmail.com>
Co-authored-by: TheWitness <thewitness@cacti.net>

.dockerignore

@@ -23,16 +23,16 @@ configure
 configure~
 libtool
 stamp-h1
-.deps/
-.dirstamp
-.libs/
-*.o
-*.lo
-*.la
-*.gcda
-*.gcno
-*.log
-*.tar.gz
+**/.deps/
+**/.dirstamp
+**/.libs/
+**/*.o
+**/*.lo
+**/*.la
+**/*.gcda
+**/*.gcno
+**/*.log
+**/*.tar.gz
 
 # the built binary itself
 /spine

.gitignore

@@ -20,6 +20,7 @@
 # +-------------------------------------------------------------------------+
 
 .deps
+.dirstamp
 Makefile
 Makefile.in
 configure

Makefile.am

@@ -22,7 +22,8 @@
 AUTOMAKE_OPTIONS = foreign
 ACLOCAL_AMFLAGS = -I m4
 
-spine_SOURCES = sql.c spine.c util.c snmp.c locks.c poller.c nft_popen.c php.c ping.c keywords.c error.c
+spine_SOURCES = sql.c spine.c util.c snmp.c src/core/locks.c poller.c \
+	nft_popen.c php.c ping.c src/core/keywords.c error.c
 
 configdir = $(sysconfdir)
 config_DATA = spine.conf.dist
@@ -48,8 +49,9 @@ man_MANS = spine.1
 
 # Headers are not referenced by any _SOURCES, so automake will not distribute
 # them unless they are listed. Without this the release tarball builds nothing.
-noinst_HEADERS = common.h error.h keywords.h locks.h nft_popen.h php.h \
-	ping.h poller.h snmp.h spine.h spine_sem.h sql.h uthash.h util.h
+noinst_HEADERS = common.h error.h src/core/keywords.h src/core/locks.h \
+	nft_popen.h php.h ping.h poller.h snmp.h spine.h spine_sem.h sql.h \
+	uthash.h util.h
 
 EXTRA_DIST = spine.1 spine.conf.dist
 
@@ -66,12 +68,9 @@ verify: docker-dev
 	docker run --rm spine-dev
 
 cppcheck: docker-dev
-	docker run --rm spine-dev bash -c \
-		"cppcheck --enable=all --std=c11 --error-exitcode=1 \
-		--suppress=missingIncludeSystem --suppress=unusedFunction \
-		--suppress=checkersReport --suppress=toomanyconfigs $(spine_SOURCES)"
+	docker run --rm -e VERIFY_CPPCHECK_ONLY=1 spine-dev
 
-AM_CPPFLAGS = -I$(top_srcdir) -I$(top_builddir)
+AM_CPPFLAGS = -I$(top_srcdir) -I$(top_srcdir)/src/core -I$(top_builddir)
 
 check_PROGRAMS =
 
@@ -98,7 +97,8 @@ tests_unit_test_safety_fixes_LDADD   = $(CMOCKA_LIBS)
 # Everything except spine.c is linked as built; tests/fuzz/stubs.c supplies the
 # globals that spine.c would define.
 tests_unit_test_linked_SOURCES = tests/unit/test_linked.c tests/fuzz/stubs.c \
-	sql.c util.c snmp.c locks.c poller.c nft_popen.c php.c ping.c keywords.c error.c
+	sql.c util.c snmp.c src/core/locks.c poller.c nft_popen.c php.c ping.c \
+	src/core/keywords.c error.c
 tests_unit_test_linked_LDADD   = $(CMOCKA_LIBS) $(LIBS)
 
 TESTS = $(check_PROGRAMS)

configure.ac

@@ -30,7 +30,7 @@ AC_CONFIG_SRCDIR(spine.c)
 AC_PREFIX_DEFAULT(/usr/local/spine)
 AC_LANG(C)
 
-AM_INIT_AUTOMAKE([foreign])
+AM_INIT_AUTOMAKE([foreign subdir-objects])
 AM_SILENT_RULES([yes])
 AC_CONFIG_HEADERS(config/config.h)
 

scripts/verify.sh

@@ -2,12 +2,31 @@
 set -euo pipefail
 
 echo "=== cppcheck ==="
+source_list=$(mktemp)
+trap 'rm -f "$source_list"' EXIT
+find . -maxdepth 1 -type f \( -name '*.c' -o -name '*.h' \) \
+  -print0 > "$source_list"
+find src -type f \( -name '*.c' -o -name '*.h' \) \
+  -print0 >> "$source_list"
+source_files=()
+while IFS= read -r -d '' source_file; do
+  source_files+=("$source_file")
+done < "$source_list"
+if (( ${#source_files[@]} == 0 )); then
+  echo "ERROR: no C sources or headers found" >&2
+  exit 1
+fi
 cppcheck --enable=all --std=c11 --error-exitcode=1 \
+  -I. -Isrc/core \
   --suppress=missingIncludeSystem \
   --suppress=unusedFunction \
   --suppress=checkersReport \
   --suppress=toomanyconfigs \
-  -- *.c *.h 2>&1 | tee /tmp/cppcheck.txt
+  -- "${source_files[@]}" 2>&1 | tee /tmp/cppcheck.txt
+
+if [[ "${VERIFY_CPPCHECK_ONLY:-0}" == "1" ]]; then
+  exit 0
+fi
 
 echo ""
 echo "=== scan-build ==="

tests/fuzz/Makefile

@@ -24,10 +24,11 @@ NETSNMP_CFLAGS := $(filter -I% -D%, $(shell net-snmp-config --base-cflags 2>/dev
 NETSNMP_LIBS   := $(filter -l% -L%, $(shell net-snmp-config --libs 2>/dev/null))
 
 SPINE_SRC := $(addprefix $(SPINE_ROOT)/, \
-	ping.c util.c sql.c snmp.c locks.c poller.c nft_popen.c php.c keywords.c error.c)
+	ping.c util.c sql.c snmp.c src/core/locks.c poller.c nft_popen.c php.c \
+	src/core/keywords.c error.c)
 
 FUZZ_CFLAGS := $(SANITIZERS) -g -O1 -DHAVE_CONFIG_H \
-	-I$(SPINE_ROOT) -I$(SPINE_ROOT)/config \
+	-I$(SPINE_ROOT) -I$(SPINE_ROOT)/src/core -I$(SPINE_ROOT)/config \
 	$(NETSNMP_CFLAGS) \
 	$(shell mysql_config --include 2>/dev/null)
 

tests/unit/Makefile

@@ -35,6 +35,7 @@ CFLAGS += \
 	-std=c99 \
 	-D_DEFAULT_SOURCE \
 	-I$(SPINE_ROOT) \
+	-I$(SPINE_ROOT)/src/core \
 	-I$(SPINE_ROOT)/config \
 	$(CMOCKA_CFLAGS) \
 	$(MYSQL_CFLAGS) \