make: Build out of tree component srcs under component build dir

Strips leading ../ when generating object file paths, keeps these in sync with the source files
otherwise.

This prevents object files landing in other directories, including outside the build directory, if
the component_srcdirs start with ../

components/libsodium/test/component.mk

@@ -3,6 +3,7 @@
 #
 
 LS_TESTDIR := ../libsodium/test/default
+LS_TEST_OBJDIR := libsodium/test/default
 
 ifdef TESTS_ALL
 $(info not linking libsodium tests, use 'TEST_COMPONENTS=libsodium' to test it)
@@ -27,10 +28,9 @@ COMPONENT_OBJS := test_sodium.o
 define sodium_testcase
 # This would generate 'warning "main" redefined' warnings at runtime, which are
 # silenced here. Only other solution involves patching libsodium's cmptest.h.
-$(LS_TESTDIR)/$(1).o: CFLAGS+=-Dxmain=$(1)_xmain -Dmain=$(1)_main
-$(LS_TESTDIR)/$(1).o: CPPFLAGS+=-Wp,-w
-ote:
-COMPONENT_OBJS += $(LS_TESTDIR)/$(1).o
+$(LS_TEST_OBJDIR)/$(1).o: CFLAGS+=-Dxmain=$(1)_xmain -Dmain=$(1)_main
+$(LS_TEST_OBJDIR)/$(1).o: CPPFLAGS+=-Wp,-w
+COMPONENT_OBJS += $(LS_TEST_OBJDIR)/$(1).o
 endef
 
 TEST_CASES := chacha20 aead_chacha20poly1305 box box2 ed25519_convert sign hash

make/common.mk

@@ -62,7 +62,7 @@ endef
 #
 # example $(call resolvepath,$(CONFIG_PATH),$(CONFIG_DIR))
 define resolvepath
-$(foreach dir,$(1),$(if $(filter /%,$(dir)),$(dir),$(subst //,/,$(2)/$(dir))))
+$(abspath $(foreach dir,$(1),$(if $(filter /%,$(dir)),$(dir),$(subst //,/,$(2)/$(dir)))))
 endef
 
 
@@ -86,3 +86,11 @@ endef
 define uniq
 $(if $1,$(firstword $1) $(call uniq,$(filter-out $(firstword $1),$1)))
 endef
+
+# macro to strip leading ../s from a path
+# Given $(1) which is a directory, remove any leading ../s from it
+# (recursively keeps removing ../ until not found)
+# if the path contains nothing but ../.., a single . is returned (cwd)
+define stripLeadingParentDirs
+$(foreach path,$(1),$(if $(subst ..,,$(path)),$(if $(filter ../%,$(path)),$(call stripLeadingParentDirs,$(patsubst ../%,%,$(path))),$(path)),.))
+endef

make/component_wrapper.mk

@@ -129,6 +129,11 @@ COMPONENT_OBJS := $(foreach obj,$(COMPONENT_OBJS),$(if $(filter $(realpath $(obj
 # Remove duplicates
 COMPONENT_OBJS := $(call uniq,$(COMPONENT_OBJS))
 
+# Remove any leading ../ from paths, so everything builds inside build dir
+COMPONENT_OBJS := $(call stripLeadingParentDirs,$(COMPONENT_OBJS))
+
+# COMPONENT_OBJDIRS is COMPONENT_SRCDIRS with the same transform applied
+COMPONENT_OBJDIRS := $(call stripLeadingParentDirs,$(COMPONENT_SRCDIRS))
 
 # Object files with embedded binaries to add to the component library
 # Correspond to the files named in COMPONENT_EMBED_FILES & COMPONENT_EMBED_TXTFILES
@@ -180,10 +185,10 @@ endef
 component_project_vars.mk::
 	$(details) "Building component project variables list $(abspath $@)"
 	@echo '# Automatically generated build file. Do not edit.' > $@
-	@echo 'COMPONENT_INCLUDES += $(call MakeVariablePath,$(addprefix $(COMPONENT_PATH)/,$(COMPONENT_ADD_INCLUDEDIRS)))' >> $@
+	@echo 'COMPONENT_INCLUDES += $(call MakeVariablePath,$(abspath $(addprefix $(COMPONENT_PATH)/,$(COMPONENT_ADD_INCLUDEDIRS))))' >> $@
 	@echo 'COMPONENT_LDFLAGS += $(call MakeVariablePath,-L$(COMPONENT_BUILD_DIR) $(COMPONENT_ADD_LDFLAGS))' >> $@
 	@echo 'COMPONENT_LINKER_DEPS += $(call MakeVariablePath,$(call resolvepath,$(COMPONENT_ADD_LINKER_DEPS),$(COMPONENT_PATH)))' >> $@
-	@echo 'COMPONENT_SUBMODULES += $(call MakeVariablePath,$(addprefix $(COMPONENT_PATH)/,$(COMPONENT_SUBMODULES)))' >> $@
+	@echo 'COMPONENT_SUBMODULES += $(call MakeVariablePath,$(abspath $(addprefix $(COMPONENT_PATH)/,$(COMPONENT_SUBMODULES))))' >> $@
 	@echo 'COMPONENT_LIBRARIES += $(COMPONENT_NAME)' >> $@
 	@echo 'component-$(COMPONENT_NAME)-build: $(addprefix component-,$(addsuffix -build,$(COMPONENT_DEPENDS)))' >> $@
 
@@ -236,41 +241,45 @@ endef
 # This pattern is generated for each COMPONENT_SRCDIR to compile the files in it.
 define GenerateCompileTargets
 # $(1) - directory containing source files, relative to $(COMPONENT_PATH) - one of $(COMPONENT_SRCDIRS)
+# $(2) - output build directory, which is $(1) with any leading ".."s converted to "."s to ensure output is always under build/
 #
-$(1)/%.o: $$(COMPONENT_PATH)/$(1)/%.c $(COMMON_MAKEFILES) $(COMPONENT_MAKEFILE) | $(COMPONENT_SRCDIRS)
+
+$(2)/%.o: $$(COMPONENT_PATH)/$(1)/%.c $(COMMON_MAKEFILES) $(COMPONENT_MAKEFILE) | $(COMPONENT_OBJDIRS)
 	$$(summary) CC $$(patsubst $$(PWD)/%,%,$$(CURDIR))/$$@
-	$$(CC) $$(CFLAGS) $$(CPPFLAGS) $$(addprefix -I ,$$(COMPONENT_INCLUDES)) $$(addprefix -I ,$$(COMPONENT_EXTRA_INCLUDES)) -I $(1) -c $$< -o $$@
+	$$(CC) $$(CFLAGS) $$(CPPFLAGS) $$(addprefix -I ,$$(COMPONENT_INCLUDES)) $$(addprefix -I ,$$(COMPONENT_EXTRA_INCLUDES)) -I $(1) -c $$(abspath $$<) -o $$@
 	$(call AppendSourceToDependencies,$$<,$$@)
 
-$(1)/%.o: $$(COMPONENT_PATH)/$(1)/%.cpp $(COMMON_MAKEFILES) $(COMPONENT_MAKEFILE) | $(COMPONENT_SRCDIRS)
+$(2)/%.o: $$(COMPONENT_PATH)/$(1)/%.cpp $(COMMON_MAKEFILES) $(COMPONENT_MAKEFILE) | $(COMPONENT_OBJDIRS)
 	$$(summary) CXX $$(patsubst $$(PWD)/%,%,$$(CURDIR))/$$@
-	$$(CXX) $$(CXXFLAGS) $$(CPPFLAGS) $$(addprefix -I ,$$(COMPONENT_INCLUDES)) $$(addprefix -I ,$$(COMPONENT_EXTRA_INCLUDES)) -I $(1) -c $$< -o $$@
+	$$(CXX) $$(CXXFLAGS) $$(CPPFLAGS) $$(addprefix -I ,$$(COMPONENT_INCLUDES)) $$(addprefix -I ,$$(COMPONENT_EXTRA_INCLUDES)) -I $(1) -c $$(abspath $$<) -o $$@
 	$(call AppendSourceToDependencies,$$<,$$@)
 
-$(1)/%.o: $$(COMPONENT_PATH)/$(1)/%.cc $(COMMON_MAKEFILES) $(COMPONENT_MAKEFILE) | $(COMPONENT_SRCDIRS)
+$(2)/%.o: $$(COMPONENT_PATH)/$(1)/%.cc $(COMMON_MAKEFILES) $(COMPONENT_MAKEFILE) | $(COMPONENT_OBJDIRS)
 	$$(summary) CXX $$(patsubst $$(PWD)/%,%,$$(CURDIR))/$$@
-	$$(CXX) $$(CXXFLAGS) $$(CPPFLAGS) $$(addprefix -I ,$$(COMPONENT_INCLUDES)) $$(addprefix -I ,$$(COMPONENT_EXTRA_INCLUDES)) -I $(1) -c $$< -o $$@
+	$$(CXX) $$(CXXFLAGS) $$(CPPFLAGS) $$(addprefix -I ,$$(COMPONENT_INCLUDES)) $$(addprefix -I ,$$(COMPONENT_EXTRA_INCLUDES)) -I $(1) -c $$(abspath $$<) -o $$@
 	$(call AppendSourceToDependencies,$$<,$$@)
 
-$(1)/%.o: $$(COMPONENT_PATH)/$(1)/%.S $(COMMON_MAKEFILES) $(COMPONENT_MAKEFILE) | $(COMPONENT_SRCDIRS)
+$(2)/%.o: $$(COMPONENT_PATH)/$(1)/%.S $(COMMON_MAKEFILES) $(COMPONENT_MAKEFILE) | $(COMPONENT_OBJDIRS)
 	$$(summary) AS $$(patsubst $$(PWD)/%,%,$$(CURDIR))/$$@
-	$$(CC) $$(CPPFLAGS) $$(DEBUG_FLAGS) $$(addprefix -I ,$$(COMPONENT_INCLUDES)) $$(addprefix -I ,$$(COMPONENT_EXTRA_INCLUDES)) -I $(1) -c $$< -o $$@
+	$$(CC) $$(CPPFLAGS) $$(DEBUG_FLAGS) $$(addprefix -I ,$$(COMPONENT_INCLUDES)) $$(addprefix -I ,$$(COMPONENT_EXTRA_INCLUDES)) -I $(1) -c $$(abspath $$<) -o $$@
 	$(call AppendSourceToDependencies,$$<,$$@)
 
 # CWD is build dir, create the build subdirectory if it doesn't exist
 #
-# (NB: Each .o file depends on all relative component build dirs $(COMPONENT_SRCDIRS), rather than just $(1), to work
+# (NB: Each .o file depends on all relative component build dirs $(COMPONENT_OBJDIRS), including $(2), to work
 # around a behaviour make 3.81 where the first pattern (randomly) seems to be matched rather than the best fit. ie if
 # you have objects a/y.o and a/b/c.o then c.o can be matched with $(1)=a & %=b/c, meaning that subdir 'a/b' needs to be
-# created but wouldn't be created if $(1)=a. Make 4.x doesn't have this problem, it seems to preferentially
-# choose the better match ie $(1)=a/b and %=c )
+# created but wouldn't be created if $(2)=a. Make 4.x doesn't have this problem, it seems to preferentially
+# choose the better match ie $(2)=a/b and %=c )
+#
+# Note: This may cause some issues for out-of-tree source files and make 3.81 :/
 #
-$(1):
-	mkdir -p $(1)
+$(2):
+	mkdir -p $(2)
 endef
 
 # Generate all the compile target patterns
-$(foreach srcdir,$(COMPONENT_SRCDIRS), $(eval $(call GenerateCompileTargets,$(srcdir))))
+$(foreach srcdir,$(COMPONENT_SRCDIRS), $(eval $(call GenerateCompileTargets,$(srcdir),$(call stripLeadingParentDirs,$(srcdir)))))
 
 ## Support for embedding binary files into the ELF as symbols