common.mk - mirrors/cros/chromiumos/platform/dm-verity - Git at Google

 # Copyright (C) 2010 The Chromium OS Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE.makefile file.
 #
 # This file provides a common architecture for building C/C++ source trees.
 # It uses recursive makefile inclusion to create a single make process which
 # can be built in the source tree or with the build products places elsewhere.
 #
 # To use:
 # 1. Place common.mk in your top source level
 # 2. In your top-level Makefile, place "include common.mk" at the top
 # 3. In all subdirectories, create a 'module.mk' file that starts with:
 #      include common.mk
 #    And then contains the remainder of your targets.
 # 4. All build targets should look like:
 #    $(BUILD)relative/path/target: ...
 #
 # See existing makefiles for rule examples.
 #
 # Exported macros:
 #   - cc_binary, cxx_binary provide standard compilation steps for binaries
 #   - cxx_library, cc_library provide standard compilation steps for sos
 #   All of the above optionally take an argument for extra flags.
 #   - update_archive creates/updates a given .a target
 #
 # Exported variables
 #  - RM_ON_CLEAN - append files to remove on calls to clean
 #  - RMDIR_ON_CLEAN - append dirs to remove on calls to clean
 #
 # Exported targets meant to have prerequisites added to:
 #  - all - Your $(OUT)target should be given
 #  - small_tests - requires something, even if it is just NONE
 #  - large_tests - requires something, even if it is just NONE
 #  - NONE - nop target for *_tests
 #  - FORCE - force the given target to run regardless of changes
 #
 # Possible command line variables:
 #   - COLOR=[0|1] to set ANSI color output (default: 1)
 #   - VERBOSE=[0|1] to hide/show commands (default: 0)
 #   - MODE=dbg to turn down optimizations (default: opt)
 #   - ARCH=[x86|arm|supported qemu name] (default: from portage or uname -m)
 #   - SPLITDEBUG=[0|1] splits debug info in target.debug (default: 1)
 #                      [SPLITDEBUG=0 MODE=opt will disable compiling with -g]
 #   - VALGRIND=[0|1] runs tests under valgrind (default: 0)
 #   - OUT=/path/to/builddir puts all output in given path
 #           (default: $PWD/build-$MODE. Use OUT=. for normal behavior)
 #   - VALGRIND_ARGS="" supplies extra memcheck arguments
 #
 # External CXXFLAGS and CFLAGS should be passed via the environment since this
 # file does not use 'override' to control them.

 # Behavior configuration variables
 SPLITDEBUG ?= 1
 VALGRIND ?= 0
 COLOR ?= 1
 VERBOSE ?= 0
 MODE ?= opt
 ARCH ?= $(shell uname -m)
 # TODO: profiling support not completed.
 PROFILING ?= 0

 # Put objects in a separate tree based on makefile locations
 # This means you can build a tree without touching it:
 #   make -C $SRCDIR  # will create ./build
 # Or
 #   make -C $SRCDIR OUT=$PWD
 # This variable is extended on subdir calls and doesn't need to be re-called.
 OUT ?= $(PWD)/build-$(MODE)/
 # Ensure a command-line supplied OUT has a slash
 override OUT := $(abspath $(OUT))/

 # Only call MODULE if we're in a submodule
 MODULES_LIST := $(filter-out Makefile %.d,$(MAKEFILE_LIST))
 ifeq ($(words $(filter-out Makefile common.mk %.d,$(MAKEFILE_LIST))),0)
 # Setup a top level SRC
 SRC ?= $(PWD)

 #
 # Helper macros
 #

 # Creates the actual archive with an index.
 # $(1) is the object suffix modified: pie or pic.
 define update_archive
   $(QUIET)mkdir -p $(dir $@)
   $(QUIET)# Create the archive in one step to avoid parallel use accessing it
   $(QUIET)# before all the symbols are present.
   @$(ECHO) "AR	$(subst $(PWD)/,,$(^:.o=.$(1).o)) -> $(subst $(PWD)/,,$@)"
   $(QUIET)$(AR) rcs $@ $(^:.o=.$(1).o)
 endef

 # Default compile from objects using pre-requisites but filters out
 # subdirs and .d files.
 define cc_binary
   $(call COMPILE_BINARY_implementation,CC,$(CFLAGS) $(1))
 endef

 define cxx_binary
   $(call COMPILE_BINARY_implementation,CXX,$(CXXFLAGS) $(1))
 endef

 # Default compile from objects using pre-requisites but filters out
 # subdirs and .d files.
 define cc_library
   $(call COMPILE_LIBRARY_implementation,CC,$(CFLAGS) $(1))
 endef
 define cxx_library
   $(call COMPILE_LIBRARY_implementation,CXX,$(CXXFLAGS) $(1))
 endef


 # Deletes files silently if they exist. Meant for use in any local
 # clean targets.
 define silent_rm
   $(QUIET)(test -n "$(wildcard $(1))" && \
     $(ECHO) -n '$(COLOR_RED)CLEANFILE$(COLOR_RESET) ' && \
     $(ECHO) '$(subst $(PWD)/,,$(wildcard $(1)))' && \
     $(RM) -f $(1) 2>/dev/null) || true
 endef
 define silent_rmdir
   $(QUIET)(test -n "$(wildcard $(1))" && \
     $(ECHO) -n '$(COLOR_RED)CLEANDIR$(COLOR_RESET) ' && \
     $(ECHO) '$(subst $(PWD)/,,$(wildcard $(1)))' && \
     $(RMDIR) $(1) 2>/dev/null) || true
 endef


 #
 # Default variables for use in including makefiles
 #

 # All objects for .c files at the top level
 C_OBJECTS := $(patsubst %.c,$(OUT)%.o,$(wildcard *.c))

 # All objects for .cxx files at the top level
 CXX_OBJECTS := $(patsubst %.cc,$(OUT)%.o,$(wildcard *.cc))

 #
 # Default variable values
 #

 OBJCOPY ?= objcopy
 STRIP ?= strip
 RMDIR ?= rmdir
 # Only override CC and CXX if they are from make.
 ifeq ($(origin CC), default)
   CC = gcc
 endif
 ifeq ($(origin CXX), default)
   CXX = g++
 endif
 ifeq ($(origin RANLIB), default)
   RANLIB = ranlib
 endif
 RANLIB ?= ranlib
 ECHO = /bin/echo -e

 ifeq ($(PROFILING),1)
   $(warning PROFILING=1 disables relocatable executables.)
 endif

 # To update these from an including Makefile:
 #  CXXFLAGS += -mahflag  # Append to the list
 #  CXXFLAGS := -mahflag $(CXXFLAGS) # Prepend to the list
 #  CXXFLAGS := $(filter-out badflag,$(CXXFLAGS)) # Filter out a value
 # The same goes for CFLAGS.
 CXXFLAGS := $(CXXFLAGS) -Wall -Werror -fstack-protector-all  -DFORTIFY_SOURCE \
   -O2 -ggdb3 -DNDEBUG -Wa,--noexecstack
 CFLAGS := $(CFLAGS) -Wall -Werror -fstack-protector-all -DFORTIFY_SOURCE \
   -O2 -ggdb3 -DNDEBUG -Wa,--noexecstack

 ifeq ($(PROFILING),1)
   CFLAGS := -pg
   CXXFLAGS := -pg
 endif

 ifeq ($(MODE),dbg)
   CFLAGS := $(filter-out -O2 -DNDEBUG,$(CFLAGS)) -O1
   CXXFLAGS := $(filter-out -O2 -DNDEBUG,$(CXXFLAGS)) -O1
   # TODO: May need -nopie. need to check gdb
 else  # opt
   ifeq ($(SPLITDEBUG),0)
     # TODO: do we want -fomit-frame-pointer on x86?
     CFLAGS := $(filter-out -ggdb3,$(CFLAGS))
     CXXFLAGS := $(filter-out -ggdb3,$(CXXFLAGS))
   endif
 endif

 LDFLAGS := $(LDFLAGS) -Wl,-z,relro -Wl,-z,noexecstack

 # Fancy helpers for color if a prompt is defined
 ifeq ($(COLOR),1)
 COLOR_RESET = \x1b[0m
 COLOR_GREEN = \x1b[32;01m
 COLOR_RED = \x1b[31;01m
 COLOR_YELLOW = \x1b[33;01m
 endif

 # By default, silence build output.
 QUIET = @
 ifeq ($(VERBOSE),1)
   QUIET=
 endif

 #
 # Implementation macros for compile helpers above
 #

 # Useful for dealing with pie-broken toolchains.
 # Call make with PIE=0 to disable default PIE use.
 OBJ_PIE_FLAG = -fPIE
 COMPILE_PIE_FLAG = -pie
 ifeq ($(PIE),0)
   OBJ_PIE_FLAG =
   COMPILE_PIE_FLAG =
 endif

 # Default compile from objects using pre-requisites but filters out
 # all non-.o files.
 define COMPILE_BINARY_implementation
   @$(ECHO) "LD$(1)	$(subst $(PWD)/,,$@)"
   $(QUIET)$($(1)) $(COMPILE_PIE_FLAGS) -o $@ \
     $(filter %.o %.so %.a,$(^:.o=.pie.o)) $(LDFLAGS) $(2)
   $(call strip_library)
   @$(ECHO) "BIN	$(COLOR_GREEN)$(subst $(PWD)/,,$@)$(COLOR_RESET)"
   @$(ECHO) "	$(COLOR_YELLOW)-----$(COLOR_RESET)"
 endef

 # TODO: add version support extracted from PV environment variable
 #ifeq ($(PV),9999)
 #$(warning PV=$(PV). If shared object versions matter, please force PV=.)
 #endif
 # Then add -Wl,-soname,$@.$(PV) ?

 # Default compile from objects using pre-requisites but filters out
 # all non-.o values. (Remember to add -L$(OUT) -llib)
 define COMPILE_LIBRARY_implementation
   @$(ECHO) "SHARED$(1)	$(subst $(PWD)/,,$@)"
   $(QUIET)$($(1)) -shared -Wl,-E -o $@ \
     $(filter %.o %.so %.a,$(^:.o=.pic.o)) $(2) $(LDFLAGS)
   $(call strip_library)
   @$(ECHO) "LIB	$(COLOR_GREEN)$(subst $(PWD)/,,$@)$(COLOR_RESET)"
   @$(ECHO) "	$(COLOR_YELLOW)-----$(COLOR_RESET)"
 endef

 define strip_library
   @$(ECHO) "STRIP	$(subst $(PWD)/,,$@)"
   $(if $(filter 1,$(SPLITDEBUG)), @$(ECHO) -n "DEBUG	"; \
     $(ECHO) "$(COLOR_YELLOW)$(subst $(PWD)/,,$@).debug$(COLOR_RESET)")
   $(if $(filter 1,$(SPLITDEBUG)), \
     $(QUIET)$(OBJCOPY) --only-keep-debug "$@" "$@.debug")
   $(if $(filter-out dbg,$(MODE)),$(QUIET)$(STRIP) --strip-unneeded "$@",)
 endef

 define strip_binary
   @$(ECHO) "STRIP	$(subst $(PWD)/,,$@)"
   $(if $(filter 1,$(SPLITDEBUG)), @$(ECHO) -n "DEBUG	"; \
     $(ECHO) "$(COLOR_YELLOW)$(subst $(PWD)/,,$@).debug$(COLOR_RESET)")
   $(if $(filter 1,$(SPLITDEBUG)), \
     $(QUIET)$(OBJCOPY) --only-keep-debug "$@" "$@.debug")
   $(if $(filter-out dbg,$(MODE)),$(QUIET)$(STRIP) --strip-unneeded "$@",)
 endef

 #
 # Pattern rules
 #

 %.o: %.pie.o %.pic.o
 	$(QUIET)touch $@

 $(OUT)%.pie.o: %.c
 	$(call OBJECT_PATTERN_implementation,CC,$(CFLAGS) $(OBJ_PIE_FLAG))

 $(OUT)%.pic.o: %.c
 	$(call OBJECT_PATTERN_implementation,CC,$(CFLAGS) -fPIC)

 $(OUT)%.pie.o: %.cc
 	$(call OBJECT_PATTERN_implementation,CXX,$(CXXFLAGS) $(OBJ_PIE_FLAG))

 $(OUT)%.pic.o: %.cc
 	$(call OBJECT_PATTERN_implementation,CXX,$(CXXFLAGS) -fPIC)


 define OBJECT_PATTERN_implementation
   @$(ECHO) "$(subst $(PWD)/,,$(1))	$(subst $(PWD)/,,$<)"
   $(QUIET)mkdir -p $(dir $@)
   $(QUIET)$($(1)) -c -MD -MF $(basename $@).d -o $@ $< $(2)
   $(QUIET)# Wrap all the deps in $(wildcard) so a missing header
   $(QUIET)# won't cause weirdness.  First we remove newlines and \,
   $(QUIET)# then wrap it.
   $(QUIET)sed -i -e :j -e '$$!N;s|\\\s*\n| |;tj' \
     -e 's|^\(.*\s*:\s*\)\(.*\)$$|\1 $$\(wildcard \2\)|' $(basename $@).d
 endef

 # NOTE: A specific rule for archive objects is avoided because parallel
 #       update of the archive causes build flakiness.
 # Instead, just make the objects the prerequisites and use update_archive
 # To use the foo.a(obj.o) functionality, targets would need to specify the
 # explicit object they expect on the prerequisite line.

 #
 # Architecture detection and QEMU wrapping
 #

 ARCH ?= $(shell uname -m)
 HOST_ARCH ?= $(shell uname -m)
 # emake will supply "x86" or "arm" for ARCH, but
 # if uname -m runs and you get x86_64, then this subst
 # will break.
 ifeq ($(subst x86,i386,$(ARCH)),i386)
   QEMU_ARCH := $(subst x86,i386,$(ARCH))  # x86 -> i386
 else
   QEMU_ARCH = $(ARCH)
 endif

 # If we're cross-compiling, try to use qemu for running the tests.
 QEMU_CMD ?=
 ifneq ($(QEMU_ARCH),$(HOST_ARCH))
   ifeq ($(SYSROOT),)
     $(info SYSROOT not defined. qemu-based testing disabled)
   else
     # A SYSROOT is assumed for QEmu use.
     USE_QEMU ?= 1
   endif
 endif

 #
 # Output full configuration at top level
 #

 # Don't show on clean
 ifneq ($(MAKECMDGOALS),clean)
   $(info build configuration:)
   $(info - OUT=$(OUT))
   $(info - MODE=$(MODE))
   $(info - SPLITDEBUG=$(SPLITDEBUG))
   $(info - VALGRIND=$(VALGRIND))
   $(info - COLOR=$(COLOR))
   $(info - ARCH=$(ARCH))
   $(info - QEMU_ARCH=$(QEMU_ARCH))
   $(info - SYSROOT=$(SYSROOT))
   $(info )
 endif

 #
 # Standard targets with detection for when they are improperly configured.
 #

 # all does not include tests by default
 all:
 	$(QUIET)(test -z "$^" && \
 	$(ECHO) "You must add your targets as 'all' prerequisites") || true
 	$(QUIET)test -n "$^"

 # Builds and runs tests for the target arch
 tests: small_tests large_tests

 small_tests: qemu FORCE
 	$(call TEST_implementation)

 large_tests: qemu FORCE
 	$(call TEST_implementation)

 qemu_clean: FORCE
 ifeq ($(USE_QEMU),1)
 	$(call silent_rm,$(PWD)/qemu-$(QEMU_ARCH))
 endif

 qemu: FORCE
 ifeq ($(USE_QEMU),1)
 	$(QUIET)$(ECHO) "QEMU	Preparing qemu-$(QEMU_ARCH)"
 	$(QUIET)cp -f /usr/bin/qemu-$(QEMU_ARCH) $(PWD)/qemu-$(QEMU_ARCH)
 	$(QUIET)chmod a+rx $(PWD)/qemu-$(QEMU_ARCH)
 endif

 # TODO(wad) separate chroot from qemu to make it possible to cross-compile
 #           and test outside of the chroot.
 ifeq ($(USE_QEMU),1)
   export QEMU_CMD = sudo chroot $(SYSROOT) \
     $(subst $(SYSROOT),,$(PWD))/qemu-$(QEMU_ARCH) \
     -drop-ld-preload \
     -E LD_LIBRARY_PATH="$(SYSROOT_LDPATH)" \
     -E HOME="$(HOME)" --
 endif

 VALGRIND_CMD =
 ifeq ($(VALGRIND),1)
   VALGRIND_CMD = /usr/bin/valgrind --tool=memcheck $(VALGRIND_ARGS) --
 endif

 define TEST_implementation
   $(QUIET)(test -z "$(filter FORCE qemu,$^)" && \
   $(ECHO) "No '$@' prerequisites defined!") || true
   $(QUIET)test -n "$^"
   $(QUIET)# TODO(wad) take root away after the chroot.
   $(QUIET)test "$(filter NONE,$^)" = "NONE" || \
     ((test "1" = "$(VALGRIND)" && test -n "$(USE_QEMU)" && \
       sudo mkdir -p $(SYSROOT)/proc && \
        sudo mount --bind /proc $(SYSROOT)/proc); \
     (status=0 && for tgt in $(subst $(SYSROOT),,$(filter-out FORCE qemu,$^)); \
     do \
       $(ECHO) "TEST	$$tgt"; \
       $(QEMU_CMD) $(VALGRIND_CMD) $$tgt $(GTEST_ARGS); \
       status=$$((status + $$?)); \
     done; (test "1" = "$(VALGRIND)" && test -n "$(USE_QEMU)" && \
            sudo umount $(SYSROOT)/proc); exit $$status))
 endef


 # Add the defaults from this dir to rm_clean
 define default_rm_clean
   $(OUT)$(1)*.d $(OUT)$(1)*.o $(OUT)$(1)*.debug
 endef

 # Start with the defaults
 RM_ON_CLEAN = $(call default_rm_clean)
 RMDIR_ON_CLEAN = $(OUT)

 # Recursive list reversal so that we get RMDIR_ON_CLEAN in reverse order.
 define reverse
 $(if $(1),$(call reverse,$(wordlist 2,$(words $(1)),$(1)))) $(firstword $(1))
 endef

 rm_clean: FORCE
 	$(call silent_rm,$(RM_ON_CLEAN))

 rmdir_clean: FORCE rm_clean
 	$(call silent_rmdir,$(call reverse,$(RMDIR_ON_CLEAN)))

 clean: qemu_clean rmdir_clean

 FORCE: ;
 # Empty rule for use when no special targets are needed, like large_tests
 NONE:

 .PHONY: clean NONE qemu_clean valgrind rm_clean rmdir_clean
 .DEFAULT_GOAL  :=  all
 # Don't let make blow away "intermediates"
 .PRECIOUS: $(OUT)%.pic.o $(OUT)%.pie.o

 # Start accruing build info
 OUT_DIRS = $(OUT)
 SRC_DIRS = .

 include $(wildcard $(OUT)*.d)
 SUBMODULE_DIRS = $(wildcard */module.mk)
 include $(SUBMODULE_DIRS)

 else  ## In duplicate inclusions of common.mk

 # Get the current inclusion directory without a trailing slash
 MODULE := $(patsubst %/,%, \
            $(dir $(lastword $(filter-out %common.mk,$(MAKEFILE_LIST)))))
 MODULE_NAME := $(subst /,_,$(MODULE))

 # Depth first
 $(eval OUT_DIRS += $(OUT)/$(MODULE))
 $(eval SRC_DIRS += $(MODULE))

 # Add the defaults from this dir to rm_clean
 $(eval RM_ON_CLEAN += $(call default_rm_clean,$(MODULE)/))
 $(eval RMDIR_ON_CLEAN += $(wildcard $(OUT)$(MODULE)/))

 $(info + submodule: $(MODULE_NAME))
 # We must eval otherwise they may be dropped.
 $(eval $(MODULE_NAME)_C_OBJECTS ?= \
   $(patsubst %.c,$(OUT)%.o,$(wildcard $(MODULE)/*.c)))
 $(eval $(MODULE_NAME)_CXX_OBJECTS ?= \
   $(patsubst %.cc,$(OUT)%.o,$(wildcard $(MODULE)/*.cc)))

 # Continue recursive inclusion of module.mk files
 SUBMODULE_DIRS = $(wildcard $(MODULE)/*/module.mk)

 include $(wildcard $(OUT)$(MODULE)/*.d)
 include $(SUBMODULE_DIRS)
 endif
	# Copyright (C) 2010 The Chromium OS Authors. All rights reserved.
	# Use of this source code is governed by a BSD-style license that can be
	# found in the LICENSE.makefile file.
	#
	# This file provides a common architecture for building C/C++ source trees.
	# It uses recursive makefile inclusion to create a single make process which
	# can be built in the source tree or with the build products places elsewhere.
	#
	# To use:
	# 1. Place common.mk in your top source level
	# 2. In your top-level Makefile, place "include common.mk" at the top
	# 3. In all subdirectories, create a 'module.mk' file that starts with:
	# include common.mk
	# And then contains the remainder of your targets.
	# 4. All build targets should look like:
	# $(BUILD)relative/path/target: ...
	#
	# See existing makefiles for rule examples.
	#
	# Exported macros:
	# - cc_binary, cxx_binary provide standard compilation steps for binaries
	# - cxx_library, cc_library provide standard compilation steps for sos
	# All of the above optionally take an argument for extra flags.
	# - update_archive creates/updates a given .a target
	#
	# Exported variables
	# - RM_ON_CLEAN - append files to remove on calls to clean
	# - RMDIR_ON_CLEAN - append dirs to remove on calls to clean
	#
	# Exported targets meant to have prerequisites added to:
	# - all - Your $(OUT)target should be given
	# - small_tests - requires something, even if it is just NONE
	# - large_tests - requires something, even if it is just NONE
	# - NONE - nop target for *_tests
	# - FORCE - force the given target to run regardless of changes
	#
	# Possible command line variables:
	# - COLOR=[0\|1] to set ANSI color output (default: 1)
	# - VERBOSE=[0\|1] to hide/show commands (default: 0)
	# - MODE=dbg to turn down optimizations (default: opt)
	# - ARCH=[x86\|arm\|supported qemu name] (default: from portage or uname -m)
	# - SPLITDEBUG=[0\|1] splits debug info in target.debug (default: 1)
	# [SPLITDEBUG=0 MODE=opt will disable compiling with -g]
	# - VALGRIND=[0\|1] runs tests under valgrind (default: 0)
	# - OUT=/path/to/builddir puts all output in given path
	# (default: $PWD/build-$MODE. Use OUT=. for normal behavior)
	# - VALGRIND_ARGS="" supplies extra memcheck arguments
	#
	# External CXXFLAGS and CFLAGS should be passed via the environment since this
	# file does not use 'override' to control them.

	# Behavior configuration variables
	SPLITDEBUG ?= 1
	VALGRIND ?= 0
	COLOR ?= 1
	VERBOSE ?= 0
	MODE ?= opt
	ARCH ?= $(shell uname -m)
	# TODO: profiling support not completed.
	PROFILING ?= 0

	# Put objects in a separate tree based on makefile locations
	# This means you can build a tree without touching it:
	# make -C $SRCDIR # will create ./build
	# Or
	# make -C $SRCDIR OUT=$PWD
	# This variable is extended on subdir calls and doesn't need to be re-called.
	OUT ?= $(PWD)/build-$(MODE)/
	# Ensure a command-line supplied OUT has a slash
	override OUT := $(abspath $(OUT))/

	# Only call MODULE if we're in a submodule
	MODULES_LIST := $(filter-out Makefile %.d,$(MAKEFILE_LIST))
	ifeq ($(words $(filter-out Makefile common.mk %.d,$(MAKEFILE_LIST))),0)
	# Setup a top level SRC
	SRC ?= $(PWD)

	#
	# Helper macros
	#

	# Creates the actual archive with an index.
	# $(1) is the object suffix modified: pie or pic.
	define update_archive
	$(QUIET)mkdir -p $(dir $@)
	$(QUIET)# Create the archive in one step to avoid parallel use accessing it
	$(QUIET)# before all the symbols are present.
	@$(ECHO) "AR $(subst $(PWD)/,,$(^:.o=.$(1).o)) -> $(subst $(PWD)/,,$@)"
	$(QUIET)$(AR) rcs $@ $(^:.o=.$(1).o)
	endef

	# Default compile from objects using pre-requisites but filters out
	# subdirs and .d files.
	define cc_binary
	$(call COMPILE_BINARY_implementation,CC,$(CFLAGS) $(1))
	endef

	define cxx_binary
	$(call COMPILE_BINARY_implementation,CXX,$(CXXFLAGS) $(1))
	endef

	# Default compile from objects using pre-requisites but filters out
	# subdirs and .d files.
	define cc_library
	$(call COMPILE_LIBRARY_implementation,CC,$(CFLAGS) $(1))
	endef
	define cxx_library
	$(call COMPILE_LIBRARY_implementation,CXX,$(CXXFLAGS) $(1))
	endef


	# Deletes files silently if they exist. Meant for use in any local
	# clean targets.
	define silent_rm
	$(QUIET)(test -n "$(wildcard $(1))" && \
	$(ECHO) -n '$(COLOR_RED)CLEANFILE$(COLOR_RESET) ' && \
	$(ECHO) '$(subst $(PWD)/,,$(wildcard $(1)))' && \
	$(RM) -f $(1) 2>/dev/null) \|\| true
	endef
	define silent_rmdir
	$(QUIET)(test -n "$(wildcard $(1))" && \
	$(ECHO) -n '$(COLOR_RED)CLEANDIR$(COLOR_RESET) ' && \
	$(ECHO) '$(subst $(PWD)/,,$(wildcard $(1)))' && \
	$(RMDIR) $(1) 2>/dev/null) \|\| true
	endef



	#
	# Default variables for use in including makefiles
	#

	# All objects for .c files at the top level
	C_OBJECTS := $(patsubst %.c,$(OUT)%.o,$(wildcard *.c))

	# All objects for .cxx files at the top level
	CXX_OBJECTS := $(patsubst %.cc,$(OUT)%.o,$(wildcard *.cc))

	#
	# Default variable values
	#

	OBJCOPY ?= objcopy
	STRIP ?= strip
	RMDIR ?= rmdir
	# Only override CC and CXX if they are from make.
	ifeq ($(origin CC), default)
	CC = gcc
	endif
	ifeq ($(origin CXX), default)
	CXX = g++
	endif
	ifeq ($(origin RANLIB), default)
	RANLIB = ranlib
	endif
	RANLIB ?= ranlib
	ECHO = /bin/echo -e

	ifeq ($(PROFILING),1)
	$(warning PROFILING=1 disables relocatable executables.)
	endif

	# To update these from an including Makefile:
	# CXXFLAGS += -mahflag # Append to the list
	# CXXFLAGS := -mahflag $(CXXFLAGS) # Prepend to the list
	# CXXFLAGS := $(filter-out badflag,$(CXXFLAGS)) # Filter out a value
	# The same goes for CFLAGS.
	CXXFLAGS := $(CXXFLAGS) -Wall -Werror -fstack-protector-all -DFORTIFY_SOURCE \
	-O2 -ggdb3 -DNDEBUG -Wa,--noexecstack
	CFLAGS := $(CFLAGS) -Wall -Werror -fstack-protector-all -DFORTIFY_SOURCE \
	-O2 -ggdb3 -DNDEBUG -Wa,--noexecstack

	ifeq ($(PROFILING),1)
	CFLAGS := -pg
	CXXFLAGS := -pg
	endif

	ifeq ($(MODE),dbg)
	CFLAGS := $(filter-out -O2 -DNDEBUG,$(CFLAGS)) -O1
	CXXFLAGS := $(filter-out -O2 -DNDEBUG,$(CXXFLAGS)) -O1
	# TODO: May need -nopie. need to check gdb
	else # opt
	ifeq ($(SPLITDEBUG),0)
	# TODO: do we want -fomit-frame-pointer on x86?
	CFLAGS := $(filter-out -ggdb3,$(CFLAGS))
	CXXFLAGS := $(filter-out -ggdb3,$(CXXFLAGS))
	endif
	endif

	LDFLAGS := $(LDFLAGS) -Wl,-z,relro -Wl,-z,noexecstack

	# Fancy helpers for color if a prompt is defined
	ifeq ($(COLOR),1)
	COLOR_RESET = \x1b[0m
	COLOR_GREEN = \x1b[32;01m
	COLOR_RED = \x1b[31;01m
	COLOR_YELLOW = \x1b[33;01m
	endif

	# By default, silence build output.
	QUIET = @
	ifeq ($(VERBOSE),1)
	QUIET=
	endif

	#
	# Implementation macros for compile helpers above
	#

	# Useful for dealing with pie-broken toolchains.
	# Call make with PIE=0 to disable default PIE use.
	OBJ_PIE_FLAG = -fPIE
	COMPILE_PIE_FLAG = -pie
	ifeq ($(PIE),0)
	OBJ_PIE_FLAG =
	COMPILE_PIE_FLAG =
	endif

	# Default compile from objects using pre-requisites but filters out
	# all non-.o files.
	define COMPILE_BINARY_implementation
	@$(ECHO) "LD$(1) $(subst $(PWD)/,,$@)"
	$(QUIET)$($(1)) $(COMPILE_PIE_FLAGS) -o $@ \
	$(filter %.o %.so %.a,$(^:.o=.pie.o)) $(LDFLAGS) $(2)
	$(call strip_library)
	@$(ECHO) "BIN $(COLOR_GREEN)$(subst $(PWD)/,,$@)$(COLOR_RESET)"
	@$(ECHO) " $(COLOR_YELLOW)-----$(COLOR_RESET)"
	endef

	# TODO: add version support extracted from PV environment variable
	#ifeq ($(PV),9999)
	#$(warning PV=$(PV). If shared object versions matter, please force PV=.)
	#endif
	# Then add -Wl,-soname,$@.$(PV) ?

	# Default compile from objects using pre-requisites but filters out
	# all non-.o values. (Remember to add -L$(OUT) -llib)
	define COMPILE_LIBRARY_implementation
	@$(ECHO) "SHARED$(1) $(subst $(PWD)/,,$@)"
	$(QUIET)$($(1)) -shared -Wl,-E -o $@ \
	$(filter %.o %.so %.a,$(^:.o=.pic.o)) $(2) $(LDFLAGS)
	$(call strip_library)
	@$(ECHO) "LIB $(COLOR_GREEN)$(subst $(PWD)/,,$@)$(COLOR_RESET)"
	@$(ECHO) " $(COLOR_YELLOW)-----$(COLOR_RESET)"
	endef

	define strip_library
	@$(ECHO) "STRIP $(subst $(PWD)/,,$@)"
	$(if $(filter 1,$(SPLITDEBUG)), @$(ECHO) -n "DEBUG "; \
	$(ECHO) "$(COLOR_YELLOW)$(subst $(PWD)/,,$@).debug$(COLOR_RESET)")
	$(if $(filter 1,$(SPLITDEBUG)), \
	$(QUIET)$(OBJCOPY) --only-keep-debug "$@" "$@.debug")
	$(if $(filter-out dbg,$(MODE)),$(QUIET)$(STRIP) --strip-unneeded "$@",)
	endef

	define strip_binary
	@$(ECHO) "STRIP $(subst $(PWD)/,,$@)"
	$(if $(filter 1,$(SPLITDEBUG)), @$(ECHO) -n "DEBUG "; \
	$(ECHO) "$(COLOR_YELLOW)$(subst $(PWD)/,,$@).debug$(COLOR_RESET)")
	$(if $(filter 1,$(SPLITDEBUG)), \
	$(QUIET)$(OBJCOPY) --only-keep-debug "$@" "$@.debug")
	$(if $(filter-out dbg,$(MODE)),$(QUIET)$(STRIP) --strip-unneeded "$@",)
	endef

	#
	# Pattern rules
	#

	%.o: %.pie.o %.pic.o
	$(QUIET)touch $@

	$(OUT)%.pie.o: %.c
	$(call OBJECT_PATTERN_implementation,CC,$(CFLAGS) $(OBJ_PIE_FLAG))

	$(OUT)%.pic.o: %.c
	$(call OBJECT_PATTERN_implementation,CC,$(CFLAGS) -fPIC)

	$(OUT)%.pie.o: %.cc
	$(call OBJECT_PATTERN_implementation,CXX,$(CXXFLAGS) $(OBJ_PIE_FLAG))

	$(OUT)%.pic.o: %.cc
	$(call OBJECT_PATTERN_implementation,CXX,$(CXXFLAGS) -fPIC)


	define OBJECT_PATTERN_implementation
	@$(ECHO) "$(subst $(PWD)/,,$(1)) $(subst $(PWD)/,,$<)"
	$(QUIET)mkdir -p $(dir $@)
	$(QUIET)$($(1)) -c -MD -MF $(basename $@).d -o $@ $< $(2)
	$(QUIET)# Wrap all the deps in $(wildcard) so a missing header
	$(QUIET)# won't cause weirdness. First we remove newlines and \,
	$(QUIET)# then wrap it.
	$(QUIET)sed -i -e :j -e '$$!N;s\|\\\s*\n\| \|;tj' \
	-e 's\|^\(.\s:\s\)\(.\)$$\|\1 $$\(wildcard \2\)\|' $(basename $@).d
	endef

	# NOTE: A specific rule for archive objects is avoided because parallel
	# update of the archive causes build flakiness.
	# Instead, just make the objects the prerequisites and use update_archive
	# To use the foo.a(obj.o) functionality, targets would need to specify the
	# explicit object they expect on the prerequisite line.

	#
	# Architecture detection and QEMU wrapping
	#

	ARCH ?= $(shell uname -m)
	HOST_ARCH ?= $(shell uname -m)
	# emake will supply "x86" or "arm" for ARCH, but
	# if uname -m runs and you get x86_64, then this subst
	# will break.
	ifeq ($(subst x86,i386,$(ARCH)),i386)
	QEMU_ARCH := $(subst x86,i386,$(ARCH)) # x86 -> i386
	else
	QEMU_ARCH = $(ARCH)
	endif

	# If we're cross-compiling, try to use qemu for running the tests.
	QEMU_CMD ?=
	ifneq ($(QEMU_ARCH),$(HOST_ARCH))
	ifeq ($(SYSROOT),)
	$(info SYSROOT not defined. qemu-based testing disabled)
	else
	# A SYSROOT is assumed for QEmu use.
	USE_QEMU ?= 1
	endif
	endif

	#
	# Output full configuration at top level
	#

	# Don't show on clean
	ifneq ($(MAKECMDGOALS),clean)
	$(info build configuration:)
	$(info - OUT=$(OUT))
	$(info - MODE=$(MODE))
	$(info - SPLITDEBUG=$(SPLITDEBUG))
	$(info - VALGRIND=$(VALGRIND))
	$(info - COLOR=$(COLOR))
	$(info - ARCH=$(ARCH))
	$(info - QEMU_ARCH=$(QEMU_ARCH))
	$(info - SYSROOT=$(SYSROOT))
	$(info )
	endif

	#
	# Standard targets with detection for when they are improperly configured.
	#

	# all does not include tests by default
	all:
	$(QUIET)(test -z "$^" && \
	$(ECHO) "You must add your targets as 'all' prerequisites") \|\| true
	$(QUIET)test -n "$^"

	# Builds and runs tests for the target arch
	tests: small_tests large_tests

	small_tests: qemu FORCE
	$(call TEST_implementation)

	large_tests: qemu FORCE
	$(call TEST_implementation)

	qemu_clean: FORCE
	ifeq ($(USE_QEMU),1)
	$(call silent_rm,$(PWD)/qemu-$(QEMU_ARCH))
	endif

	qemu: FORCE
	ifeq ($(USE_QEMU),1)
	$(QUIET)$(ECHO) "QEMU Preparing qemu-$(QEMU_ARCH)"
	$(QUIET)cp -f /usr/bin/qemu-$(QEMU_ARCH) $(PWD)/qemu-$(QEMU_ARCH)
	$(QUIET)chmod a+rx $(PWD)/qemu-$(QEMU_ARCH)
	endif

	# TODO(wad) separate chroot from qemu to make it possible to cross-compile
	# and test outside of the chroot.
	ifeq ($(USE_QEMU),1)
	export QEMU_CMD = sudo chroot $(SYSROOT) \
	$(subst $(SYSROOT),,$(PWD))/qemu-$(QEMU_ARCH) \
	-drop-ld-preload \
	-E LD_LIBRARY_PATH="$(SYSROOT_LDPATH)" \
	-E HOME="$(HOME)" --
	endif

	VALGRIND_CMD =
	ifeq ($(VALGRIND),1)
	VALGRIND_CMD = /usr/bin/valgrind --tool=memcheck $(VALGRIND_ARGS) --
	endif

	define TEST_implementation
	$(QUIET)(test -z "$(filter FORCE qemu,$^)" && \
	$(ECHO) "No '$@' prerequisites defined!") \|\| true
	$(QUIET)test -n "$^"
	$(QUIET)# TODO(wad) take root away after the chroot.
	$(QUIET)test "$(filter NONE,$^)" = "NONE" \|\| \
	((test "1" = "$(VALGRIND)" && test -n "$(USE_QEMU)" && \
	sudo mkdir -p $(SYSROOT)/proc && \
	sudo mount --bind /proc $(SYSROOT)/proc); \
	(status=0 && for tgt in $(subst $(SYSROOT),,$(filter-out FORCE qemu,$^)); \
	do \
	$(ECHO) "TEST $$tgt"; \
	$(QEMU_CMD) $(VALGRIND_CMD) $$tgt $(GTEST_ARGS); \
	status=$$((status + $$?)); \
	done; (test "1" = "$(VALGRIND)" && test -n "$(USE_QEMU)" && \
	sudo umount $(SYSROOT)/proc); exit $$status))
	endef


	# Add the defaults from this dir to rm_clean
	define default_rm_clean
	$(OUT)$(1).d $(OUT)$(1).o $(OUT)$(1)*.debug
	endef

	# Start with the defaults
	RM_ON_CLEAN = $(call default_rm_clean)
	RMDIR_ON_CLEAN = $(OUT)

	# Recursive list reversal so that we get RMDIR_ON_CLEAN in reverse order.
	define reverse
	$(if $(1),$(call reverse,$(wordlist 2,$(words $(1)),$(1)))) $(firstword $(1))
	endef

	rm_clean: FORCE
	$(call silent_rm,$(RM_ON_CLEAN))

	rmdir_clean: FORCE rm_clean
	$(call silent_rmdir,$(call reverse,$(RMDIR_ON_CLEAN)))

	clean: qemu_clean rmdir_clean

	FORCE: ;
	# Empty rule for use when no special targets are needed, like large_tests
	NONE:

	.PHONY: clean NONE qemu_clean valgrind rm_clean rmdir_clean
	.DEFAULT_GOAL := all
	# Don't let make blow away "intermediates"
	.PRECIOUS: $(OUT)%.pic.o $(OUT)%.pie.o

	# Start accruing build info
	OUT_DIRS = $(OUT)
	SRC_DIRS = .

	include $(wildcard $(OUT)*.d)
	SUBMODULE_DIRS = $(wildcard */module.mk)
	include $(SUBMODULE_DIRS)

	else ## In duplicate inclusions of common.mk

	# Get the current inclusion directory without a trailing slash
	MODULE := $(patsubst %/,%, \
	$(dir $(lastword $(filter-out %common.mk,$(MAKEFILE_LIST)))))
	MODULE_NAME := $(subst /,_,$(MODULE))

	# Depth first
	$(eval OUT_DIRS += $(OUT)/$(MODULE))
	$(eval SRC_DIRS += $(MODULE))

	# Add the defaults from this dir to rm_clean
	$(eval RM_ON_CLEAN += $(call default_rm_clean,$(MODULE)/))
	$(eval RMDIR_ON_CLEAN += $(wildcard $(OUT)$(MODULE)/))

	$(info + submodule: $(MODULE_NAME))
	# We must eval otherwise they may be dropped.
	$(eval $(MODULE_NAME)_C_OBJECTS ?= \
	$(patsubst %.c,$(OUT)%.o,$(wildcard $(MODULE)/*.c)))
	$(eval $(MODULE_NAME)_CXX_OBJECTS ?= \
	$(patsubst %.cc,$(OUT)%.o,$(wildcard $(MODULE)/*.cc)))

	# Continue recursive inclusion of module.mk files
	SUBMODULE_DIRS = $(wildcard $(MODULE)/*/module.mk)

	include $(wildcard $(OUT)$(MODULE)/*.d)
	include $(SUBMODULE_DIRS)
	endif