Makefile: Add a BUILDDIR variable for out-of-tree builds

bfs can now be built from a read-only source tree.

2 files changed, 61 insertions, 52 deletions

diff --git a/Makefile b/Makefile
index e2d258e..3440575 100644
--- a/Makefile
+++ b/Makefile
@@ -35,6 +35,14 @@ INSTALL ?= install
 MKDIR ?= mkdir -p
 RM ?= rm -f
 
+export BUILDDIR ?= .
+DESTDIR ?=
+PREFIX ?= /usr
+MANDIR ?= $(PREFIX)/share/man
+
+BIN := $(BUILDDIR)/bin
+OBJ := $(BUILDDIR)/obj
+
 DEFAULT_CFLAGS := \
     -g \
     -Wall \
@@ -48,10 +56,6 @@ CFLAGS ?= $(DEFAULT_CFLAGS)
 LDFLAGS ?=
 DEPFLAGS ?= -MD -MP -MF $(@:.o=.d)
 
-DESTDIR ?=
-PREFIX ?= /usr
-MANDIR ?= $(PREFIX)/share/man
-
 LOCAL_CPPFLAGS := \
     -D__EXTENSIONS__ \
     -D_ATFILE_SOURCE \
@@ -189,58 +193,58 @@ CHECKS := $(STRATEGY_CHECKS) check-trie check-xtimegm
 # Custom test flags for distcheck
 DISTCHECK_FLAGS := -s TEST_FLAGS="--sudo --verbose=skipped"
 
-bfs: bin/bfs
+bfs: $(BIN)/bfs
 .PHONY: bfs
 
-all: bin/bfs bin/tests/mksock bin/tests/trie bin/tests/xtimegm
+all: $(BIN)/bfs $(BIN)/tests/mksock $(BIN)/tests/trie $(BIN)/tests/xtimegm
 .PHONY: all
 
-bin/bfs: \
-    obj/src/bar.o \
-    obj/src/bftw.o \
-    obj/src/color.o \
-    obj/src/ctx.o \
-    obj/src/darray.o \
-    obj/src/diag.o \
-    obj/src/dir.o \
-    obj/src/dstring.o \
-    obj/src/eval.o \
-    obj/src/exec.o \
-    obj/src/fsade.o \
-    obj/src/main.o \
-    obj/src/mtab.o \
-    obj/src/opt.o \
-    obj/src/parse.o \
-    obj/src/printf.o \
-    obj/src/pwcache.o \
-    obj/src/stat.o \
-    obj/src/trie.o \
-    obj/src/typo.o \
-    obj/src/util.o \
-    obj/src/xregex.o \
-    obj/src/xspawn.o \
-    obj/src/xtime.o
-
-bin/tests/mksock: obj/tests/mksock.o
-bin/tests/trie: obj/src/trie.o obj/tests/trie.o
-bin/tests/xtimegm: obj/src/xtime.o obj/tests/xtimegm.o
-
-bin/%:
+$(BIN)/bfs: \
+    $(OBJ)/src/bar.o \
+    $(OBJ)/src/bftw.o \
+    $(OBJ)/src/color.o \
+    $(OBJ)/src/ctx.o \
+    $(OBJ)/src/darray.o \
+    $(OBJ)/src/diag.o \
+    $(OBJ)/src/dir.o \
+    $(OBJ)/src/dstring.o \
+    $(OBJ)/src/eval.o \
+    $(OBJ)/src/exec.o \
+    $(OBJ)/src/fsade.o \
+    $(OBJ)/src/main.o \
+    $(OBJ)/src/mtab.o \
+    $(OBJ)/src/opt.o \
+    $(OBJ)/src/parse.o \
+    $(OBJ)/src/printf.o \
+    $(OBJ)/src/pwcache.o \
+    $(OBJ)/src/stat.o \
+    $(OBJ)/src/trie.o \
+    $(OBJ)/src/typo.o \
+    $(OBJ)/src/util.o \
+    $(OBJ)/src/xregex.o \
+    $(OBJ)/src/xspawn.o \
+    $(OBJ)/src/xtime.o
+
+$(BIN)/tests/mksock: $(OBJ)/tests/mksock.o
+$(BIN)/tests/trie: $(OBJ)/src/trie.o $(OBJ)/tests/trie.o
+$(BIN)/tests/xtimegm: $(OBJ)/src/xtime.o $(OBJ)/tests/xtimegm.o
+
+$(BIN)/%:
 	@$(MKDIR) $(@D)
 	+$(CC) $(ALL_LDFLAGS) $^ $(ALL_LDLIBS) -o $@
 
-obj/%.o: %.c obj/FLAGS
+$(OBJ)/%.o: %.c $(OBJ)/FLAGS
 	@$(MKDIR) $(@D)
 	$(CC) $(ALL_CFLAGS) -c $< -o $@
 
 # Save the full set of flags to rebuild everything when they change
-obj/FLAGS.new:
+$(OBJ)/FLAGS.new:
 	@$(MKDIR) $(@D)
 	@echo $(CC) : $(ALL_CFLAGS) : $(ALL_LDFLAGS) : $(ALL_LDLIBS) >$@
-.PHONY: obj/FLAGS.new
+.PHONY: $(OBJ)/FLAGS.new
 
 # Only update obj/FLAGS if obj/FLAGS.new is different
-obj/FLAGS: obj/FLAGS.new
+$(OBJ)/FLAGS: $(OBJ)/FLAGS.new
 	@test -e $@ && cmp -s $@ $< && rm $< || mv $< $@
 
 # Make sure that "make release" builds everything, but "make release obj/src/main.o" doesn't
@@ -251,10 +255,10 @@ $(FLAG_GOALS): $(FLAG_PREREQS)
 check: $(CHECKS)
 .PHONY: check $(CHECKS)
 
-$(STRATEGY_CHECKS): check-%: bin/bfs bin/tests/mksock
-	./tests/tests.sh --bfs="./bin/bfs -S $*" $(TEST_FLAGS)
+$(STRATEGY_CHECKS): check-%: $(BIN)/bfs $(BIN)/tests/mksock
+	./tests/tests.sh --bfs="$(BIN)/bfs -S $*" $(TEST_FLAGS)
 
-check-trie check-xtimegm: check-%: bin/tests/%
+check-trie check-xtimegm: check-%: $(BIN)/tests/%
 	$<
 
 distcheck:
@@ -271,12 +275,12 @@ endif
 .PHONY: distcheck
 
 clean:
-	$(RM) -r bin obj
+	$(RM) -r $(BIN) $(OBJ)
 .PHONY: clean
 
 install:
 	$(MKDIR) $(DESTDIR)$(PREFIX)/bin
-	$(INSTALL) -m755 bin/bfs $(DESTDIR)$(PREFIX)/bin/bfs
+	$(INSTALL) -m755 $(BIN)/bfs $(DESTDIR)$(PREFIX)/bin/bfs
 	$(MKDIR) $(DESTDIR)$(MANDIR)/man1
 	$(INSTALL) -m644 docs/bfs.1 $(DESTDIR)$(MANDIR)/man1/bfs.1
 	$(MKDIR) $(DESTDIR)$(PREFIX)/share/bash-completion/completions
@@ -293,12 +297,12 @@ uninstall:
 .PHONY: uninstall
 
 check-install:
-	+$(MAKE) install DESTDIR=pkg
-	+$(MAKE) uninstall DESTDIR=pkg
-	./bin/bfs pkg -not -type d -print -exit 1
-	$(RM) -r pkg
+	+$(MAKE) install DESTDIR=$(BUILDDIR)/pkg
+	+$(MAKE) uninstall DESTDIR=$(BUILDDIR)/pkg
+	$(BIN)/bfs $(BUILDDIR)/pkg -not -type d -print -exit 1
+	$(RM) -r $(BUILDDIR)/pkg
 .PHONY: check-install
 
 .SUFFIXES:
 
--include $(wildcard obj/*/*.d)
+-include $(wildcard $(OBJ)/*/*.d)
diff --git a/tests/tests.sh b/tests/tests.sh
index 434e058..eaf5add 100755
--- a/tests/tests.sh
+++ b/tests/tests.sh
@@ -897,7 +897,12 @@ function _realpath() {
 }
 
 TESTS=$(_realpath "$(dirname -- "${BASH_SOURCE[0]}")")
-BIN=$(_realpath "$TESTS/../bin")
+
+if [ "$BUILDDIR" ]; then
+    BIN=$(_realpath "$BUILDDIR/bin")
+else
+    BIN=$(_realpath "$TESTS/../bin")
+fi
 
 # Try to resolve the path to $BFS before we cd, while also supporting
 # --bfs="./bin/bfs -S ids"