build: Improve top-level Makefile

Define a set of functions that support the standard rules (build,
install, test, *etc*). Then simply add new components and tools to the
appropriate variable to support all the standard build semantics.

Fixes #331.

Signed-off-by: James O. D. Hunt <james.o.hunt@intel.com>

Makefile

@@ -3,21 +3,28 @@
 # SPDX-License-Identifier: Apache-2.0
 #
 
-default: runtime agent
+# List of available components
+COMPONENTS =
 
-runtime:
-	make -C src/runtime
+COMPONENTS += agent
+COMPONENTS += runtime
+COMPONENTS += trace-forwarder
 
-agent:
-	make -C src/agent
+# List of available tools
+TOOLS =
 
-test-runtime:
-	make -C src/runtime test
+TOOLS += agent-ctl
 
-test-agent:
-	make -C src/agent check
+STANDARD_TARGETS = build check clean install test
 
-test: test-runtime test-agent
+include utils.mk
+
+# Create the rules
+$(eval $(call create_all_rules,$(COMPONENTS),$(TOOLS),$(STANDARD_TARGETS)))
+
+# Non-standard rules
 
 generate-protocols:
 	make -C src/agent generate-protocols
+
+.PHONY: all default

utils.mk

@@ -0,0 +1,107 @@
+# Copyright (c) 2020 Intel Corporation
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+
+# Create a set of standard rules for a project such that:
+#
+# - The component depends on its Makefile.
+# - "build-$(component)" is an alias for "$(component)".
+#
+# Parameters:
+#
+# $1 - Directory component lives in.
+# $2 - Name of component.
+#
+# Note: The "clean" rule is the "odd one out" - it only depends on the
+# Makefile. This ensure that running clean won't first try to build the
+# project.
+
+define make_rules
+$(2) : $(1)/$(2)/Makefile
+	make -C $(1)/$(2)
+build-$(2) : $(2)
+
+check-$(2) : $(2)
+	make -C $(1)/$(2) check
+
+clean-$(2) : $(1)/$(2)/Makefile
+	make -C $(1)/$(2) clean
+
+install-$(2) : $(2)
+	make -C $(1)/$(2) install
+
+test-$(2) : $(2)
+	make -C $(1)/$(2) test
+
+.PHONY: \
+    $(2) \
+    build-$(2) \
+    clean-$(2) \
+    check-$(2) \
+    test-$(2) \
+    install-$(2)
+endef
+
+# Define a set of rules for a source component.
+#
+# Parameters:
+#
+# $1 - Name of component.
+
+define make_component_rules
+$(eval $(call make_rules,src,$(1)))
+endef
+
+# Define a set of rules for a tool.
+#
+# Parameters:
+#
+# $1 - name of tool
+
+define make_tool_rules
+$(eval $(call make_rules,tools,$(1)))
+endef
+
+# Create a "${target}-all" alias which will cause each component/tool
+# rule to be called.
+#
+# Parameters:
+#
+# $1 - List of targets to create rules for.
+
+define make_all_rules
+$(1)-all: $(foreach c,$(COMPONENTS) $(TOOLS),$(1)-$(c))
+
+.PHONY: $(1) $(1)-all
+endef
+
+# Create all rules for the caller.
+#
+# Entry point to this file.
+#
+# Parameters:
+#
+# $1 - List of components.
+# $2 - List of tools.
+# $3 - List of standard targets.
+define create_all_rules
+
+default: all
+
+all: $(1) $(2)
+
+# Create rules for all components.
+$(foreach c,$(1),$(eval $(call make_component_rules,$(c))))
+
+# Create rules for all tools.
+$(foreach c,$(2),$(eval $(call make_tool_rules,$(c))))
+
+# Create the "-all" rules.
+$(foreach a,$(3),$(eval $(call make_all_rules,$(a))))
+
+# Support "make ${target}"
+# (which is an alias for "make ${target}-all").
+$(3) : % : %-all
+
+endef