From 2f851743e0cf21509e9bde08b22a9ffa5853eeaf Mon Sep 17 00:00:00 2001
From: Ivan Shapovalov <intelfx@intelfx.name>
Date: Tue, 3 Sep 2024 11:06:37 +0200
Subject: [PATCH] miniupnpd: Makefile: generate dep-files during compilation

Implement the "Auto-Dependency Generation"[1] writeup by Paul D. Smith
and generate dep-files at the compilation time instead of requiring a
separate preprocessor pass. This removes the `depend` target as it is
not needed anymore.

[1]: https://make.mad-scientist.net/papers/advanced-auto-dependency-generation/
---
 miniupnpd/Makefile.linux     | 35 ++++++++++++++++-------------------
 miniupnpd/Makefile.linux_nft | 34 ++++++++++++++++------------------
 2 files changed, 32 insertions(+), 37 deletions(-)

diff --git a/miniupnpd/Makefile.linux b/miniupnpd/Makefile.linux
index b35e25f..b291c48 100644
--- a/miniupnpd/Makefile.linux
+++ b/miniupnpd/Makefile.linux
@@ -49,7 +49,8 @@ PKG_CONFIG ?= pkg-config
 CP = cp
 DOXYGEN ?= doxygen
 
-DEPFLAGS = -MM -MG -MT $(patsubst %.d,%.o,$@) -MT $@
+DEPDIR := .depend
+DEPFLAGS = -MMD -MP -MF $(@:%.o=$(DEPDIR)/%.d) -MT $@
 # -M : with system headers, -MM : without
 
 INSTALLPREFIX ?= $(PREFIX)/usr
@@ -66,8 +67,6 @@ NETFILTEROBJS = iptcrdr.o iptpinhole.o nfct_get.o
 
 ALLOBJS = $(BASEOBJS) $(LNXOBJS) $(NETFILTEROBJS) $(OTHEROBJS)
 
-DEP = $(ALLOBJS:.o=.d)
-
 NETFILTER_SCRIPTS = $(addprefix $(SRCDIR)/netfilter/, \
 	iptables_init.sh iptables_removeall.sh \
 	ip6tables_init.sh ip6tables_removeall.sh \
@@ -118,14 +117,14 @@ EXECUTABLES = miniupnpd testupnpdescgen testgetifstats \
               testgetroute testasyncsendto testportinuse \
               testssdppktgen testminissdp
 
-.PHONY:	all clean install depend dox
+.PHONY:	all clean install dox
 
 all:	$(EXECUTABLES)
 
 clean:
 	$(RM) config.h
 	$(RM) $(ALLOBJS)
-	$(RM) $(DEP)
+	$(RM) -r $(DEPDIR)
 	$(RM) $(EXECUTABLES)
 	$(RM) testupnpdescgen.o testgetifstats.o
 	$(RM) testupnppermissions.o testgetifaddr.o
@@ -198,26 +197,24 @@ miniupnpdctl:	miniupnpdctl.o
 config.mk config.h:	$(SRCDIR)/configure $(SRCDIR)/VERSION
 	$(SHELL) $< $(CONFIG_OPTIONS)
 
-depend:	$(DEP)
-
-%.d:	$(SRCDIR)/%.c
-	$(CC) $(CPPFLAGS) $(DEPFLAGS) -o $@ $<
-
 dox:	$(SRCDIR)/miniupnpd.doxyconf
 	(cat $< ; echo "INPUT=$(SRCDIR)" ) | $(DOXYGEN) -
 
-%.o:	$(SRCDIR)/%.c
-	$(CC) -c $(CFLAGS) $(CPPFLAGS) $< -o $@
+%.o:	$(SRCDIR)/%.c $(DEPDIR)/%.d | $(DEPDIR)
+	$(CC) -c $(DEPFLAGS) $(CFLAGS) $(CPPFLAGS) $< -o $@
 
-%.o:	$(SRCDIR)/linux/%.c
-	$(CC) -c $(CFLAGS) $(CPPFLAGS) $< -o $@
+%.o:	$(SRCDIR)/linux/%.c $(DEPDIR)/%.d | $(DEPDIR)
+	$(CC) -c $(DEPFLAGS) $(CFLAGS) $(CPPFLAGS) $< -o $@
 
-%.o:	$(SRCDIR)/netfilter/%.c
-	$(CC) -c $(CFLAGS) $(CPPFLAGS) $< -o $@
+%.o:	$(SRCDIR)/netfilter/%.c $(DEPDIR)/%.d | $(DEPDIR)
+	$(CC) -c $(DEPFLAGS) $(CFLAGS) $(CPPFLAGS) $< -o $@
 
 print-%:
 	@echo "$* = $($*)"
 
-ifneq ($(MAKECMDGOALS),clean)
--include $(DEP)
-endif
+
+DEPFILES := $(ALLOBJS:%.o=$(DEPDIR)/%.d)
+$(DEPDIR): ; @mkdir -p $@
+$(DEPFILES):
+
+-include $(wildcard $(DEPFILES))
diff --git a/miniupnpd/Makefile.linux_nft b/miniupnpd/Makefile.linux_nft
index 30b35e8..2043ede 100644
--- a/miniupnpd/Makefile.linux_nft
+++ b/miniupnpd/Makefile.linux_nft
@@ -44,7 +44,8 @@ PKG_CONFIG ?= pkg-config
 CP = cp
 DOXYGEN ?= doxygen
 
-DEPFLAGS = -MM -MG -MT $(patsubst %.d,%.o,$@) -MT $@
+DEPDIR := .depend
+DEPFLAGS = -MMD -MP -MF $(@:%.o=$(DEPDIR)/%.d) -MT $@
 # -M : with system headers, -MM : without
 
 INSTALLPREFIX ?= $(PREFIX)/usr
@@ -61,8 +62,6 @@ NETFILTEROBJS = nftnlrdr.o nftpinhole.o nfct_get.o nftnlrdr_misc.o
 
 ALLOBJS = $(BASEOBJS) $(LNXOBJS) $(NETFILTEROBJS) $(OTHEROBJS)
 
-DEP = $(ALLOBJS:.o=.d)
-
 NFT_SCRIPTS = $(addprefix $(SRCDIR)/netfilter_nft/scripts/, \
 	nft_init.sh nft_removeall.sh nft_flush.sh nft_delete_chain.sh)
 
@@ -109,13 +108,14 @@ EXECUTABLES = miniupnpd miniupnpdctl \
               testupnppermissions testgetifaddr \
               testgetroute testasyncsendto testportinuse
 
-.PHONY:	all clean install depend dox
+.PHONY:	all clean install dox
 
 all:	$(EXECUTABLES)
 
 clean:
 	$(RM) config.h
 	$(RM) $(ALLOBJS)
+	$(RM) -r $(DEPDIR)
 	$(RM) $(EXECUTABLES)
 	$(RM) testupnpdescgen.o testgetifstats.o
 	$(RM) testupnppermissions.o testgetifaddr.o
@@ -169,26 +169,24 @@ miniupnpdctl:	miniupnpdctl.o
 config.mk config.h:	$(SRCDIR)/configure $(SRCDIR)/VERSION
 	$(SHELL) $< $(CONFIG_OPTIONS)
 
-depend:	$(DEP)
-
-%.d:	$(SRCDIR)/%.c
-	$(CC) $(CPPFLAGS) $(DEPFLAGS) -o $@ $<
-
 dox:	$(SRCDIR)/miniupnpd.doxyconf
 	(cat $< ; echo "INPUT=$(SRCDIR)" ) | $(DOXYGEN) -
 
-%.o:	$(SRCDIR)/%.c
-	$(CC) -c $(CFLAGS) $(CPPFLAGS) $< -o $@
+%.o:	$(SRCDIR)/%.c $(DEPDIR)/%.d | $(DEPDIR)
+	$(CC) -c $(DEPFLAGS) $(CFLAGS) $(CPPFLAGS) $< -o $@
 
-%.o:	$(SRCDIR)/linux/%.c
-	$(CC) -c $(CFLAGS) $(CPPFLAGS) $< -o $@
+%.o:	$(SRCDIR)/linux/%.c $(DEPDIR)/%.d | $(DEPDIR)
+	$(CC) -c $(DEPFLAGS) $(CFLAGS) $(CPPFLAGS) $< -o $@
 
-%.o:	$(SRCDIR)/netfilter_nft/%.c
-	$(CC) -c $(CFLAGS) $(CPPFLAGS) $< -o $@
+%.o:	$(SRCDIR)/netfilter_nft/%.c $(DEPDIR)/%.d | $(DEPDIR)
+	$(CC) -c $(DEPFLAGS) $(CFLAGS) $(CPPFLAGS) $< -o $@
 
 print-%:
 	@echo "$* = $($*)"
 
-ifneq ($(MAKECMDGOALS),clean)
--include $(DEP)
-endif
+
+DEPFILES := $(ALLOBJS:%.o=$(DEPDIR)/%.d)
+$(DEPDIR): ; @mkdir -p $@
+$(DEPFILES):
+
+-include $(wildcard $(DEPFILES))