package: enhance infrastructure to support source dir override

When a variable <pkg>_OVERRIDE_SRCDIR is defined, then Buildroot will
no longer try to download, extract and patch the package. It will
simply use the value of this variable as the source directory for the
package. The contents of the package sources will be rsynced to the
package build directory in $(O)/build/pkg-version/.

This can be used to tell Buildroot that the sources for a given
package are inside some directory that you control, and which can be
versioned in Git/SVN, or handled in whichever way you want.

Those <pkg>_OVERRIDE_SRCDIR variables will be defined by a local
makefile included by Buildroot, which will be handled in a later
commit.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

package/Makefile.package.in

@@ -251,6 +251,25 @@ $(BUILD_DIR)/%/.stamp_extracted:
 	$(foreach hook,$($(PKG)_POST_EXTRACT_HOOKS),$(call $(hook))$(sep))
 	$(Q)touch $@
 
+# Rsync the source directory if the <pkg>_OVERRIDE_SRCDIR feature is
+# used.
+$(BUILD_DIR)/%/.stamp_rsynced:
+	@$(call MESSAGE,"Syncing from source dir $(SRCDIR)")
+	@test -d $(SRCDIR) || (echo "ERROR: $(SRCDIR) does not exist" ; exit 1)
+	rsync -au $(SRCDIR)/ $(@D)
+	$(Q)touch $@
+
+# Handle the SOURCE_CHECK and SHOW_EXTERNAL_DEPS cases for rsynced
+# packages
+$(BUILD_DIR)/%/.stamp_rsync_sourced:
+ifeq ($(DL_MODE),SOURCE_CHECK)
+	test -d $(SRCDIR)
+else ifeq ($(DL_MODE),SHOW_EXTERNAL_DEPS)
+	echo "file://$(SRCDIR)"
+else
+	@true # Nothing to do to source a local package
+endif
+
 # Patch
 #
 # The RAWNAME variable is the lowercased package name, which allows to
@@ -384,6 +403,10 @@ $(2)_BASE_NAME	=  $(1)-$$($(2)_VERSION)
 $(2)_DL_DIR	=  $$(DL_DIR)/$$($(2)_BASE_NAME)
 $(2)_DIR	=  $$(BUILD_DIR)/$$($(2)_BASE_NAME)
 
+ifneq ($$($(2)_OVERRIDE_SRCDIR),)
+$(2)_VERSION = custom
+endif
+
 ifndef $(2)_SOURCE
  ifdef $(3)_SOURCE
   $(2)_SOURCE = $($(3)_SOURCE)
@@ -429,6 +452,8 @@ $(2)_TARGET_INSTALL_IMAGES =	$$($(2)_DIR)/.stamp_images_installed
 $(2)_TARGET_INSTALL_HOST =      $$($(2)_DIR)/.stamp_host_installed
 $(2)_TARGET_BUILD =		$$($(2)_DIR)/.stamp_built
 $(2)_TARGET_CONFIGURE =		$$($(2)_DIR)/.stamp_configured
+$(2)_TARGET_RSYNC =	        $$($(2)_DIR)/.stamp_rsynced
+$(2)_TARGET_RSYNC_SOURCE =      $$($(2)_DIR)/.stamp_rsync_sourced
 $(2)_TARGET_PATCH =		$$($(2)_DIR)/.stamp_patched
 $(2)_TARGET_EXTRACT =		$$($(2)_DIR)/.stamp_extracted
 $(2)_TARGET_SOURCE =		$$($(2)_DIR)/.stamp_downloaded
@@ -489,6 +514,13 @@ $(1)-install-host:      $(1)-build $$($(2)_TARGET_INSTALL_HOST)
 $(1)-build:		$(1)-configure \
 			$$($(2)_TARGET_BUILD)
 
+ifeq ($$($(2)_OVERRIDE_SRCDIR),)
+# In the normal case (no package override), the sequence of steps is
+#  source, by downloading
+#  depends
+#  extract
+#  patch
+#  configure
 $(1)-configure:		$(1)-patch $(1)-depends \
 			$$($(2)_TARGET_CONFIGURE)
 
@@ -499,11 +531,25 @@ $(1)-extract:		$(1)-source \
 
 $(1)-depends:		$$($(2)_DEPENDENCIES)
 
+$(1)-source:		$$($(2)_TARGET_SOURCE)
+else
+# In the package override case, the sequence of steps
+#  source, by rsyncing
+#  depends
+#  configure
+$(1)-configure:		$(1)-depends \
+			$$($(2)_TARGET_CONFIGURE)
+
+$(1)-depends:		$(1)-rsync $$($(2)_DEPENDENCIES)
+
+$(1)-rsync:		$$($(2)_TARGET_RSYNC)
+
+$(1)-source:		$$($(2)_TARGET_RSYNC_SOURCE)
+endif
+
 $(1)-show-depends:
 			@echo $$($(2)_DEPENDENCIES)
 
-$(1)-source:		$$($(2)_TARGET_SOURCE)
-
 $(1)-uninstall:		$(1)-configure $$($(2)_TARGET_UNINSTALL)
 
 $(1)-clean:		$(1)-uninstall \
@@ -519,6 +565,10 @@ $$($(2)_TARGET_INSTALL_IMAGES):		PKG=$(2)
 $$($(2)_TARGET_INSTALL_HOST):           PKG=$(2)
 $$($(2)_TARGET_BUILD):			PKG=$(2)
 $$($(2)_TARGET_CONFIGURE):		PKG=$(2)
+$$($(2)_TARGET_RSYNC):                  SRCDIR=$$($(2)_OVERRIDE_SRCDIR)
+$$($(2)_TARGET_RSYNC):                  PKG=$(2)
+$$($(2)_TARGET_RSYNC_SOURCE):		SRCDIR=$$($(2)_OVERRIDE_SRCDIR)
+$$($(2)_TARGET_RSYNC_SOURCE):		PKG=$(2)
 $$($(2)_TARGET_PATCH):			PKG=$(2)
 $$($(2)_TARGET_PATCH):			RAWNAME=$(patsubst host-%,%,$(1))
 $$($(2)_TARGET_EXTRACT):		PKG=$(2)