Add META_MODE support.

Off by default, build behaves normally.
WITH_META_MODE we get auto objdir creation, the ability to
start build from anywhere in the tree.

Still need to add real targets under targets/ to build packages.

Differential Revision:       D2796
Reviewed by: brooks imp

1 files changed, 65 insertions, 0 deletions

diff --git a/share/mk/auto.obj.mk b/share/mk/auto.obj.mk
new file mode 100644
index 000000000000..0c13ae538248
--- /dev/null
+++ b/share/mk/auto.obj.mk
@@ -0,0 +1,65 @@
+# $FreeBSD$
+# $Id: auto.obj.mk,v 1.10 2015/04/16 16:59:00 sjg Exp $
+#
+#	@(#) Copyright (c) 2004, Simon J. Gerraty
+#
+#	This file is provided in the hope that it will
+#	be of use.  There is absolutely NO WARRANTY.
+#	Permission to copy, redistribute or otherwise
+#	use this file is hereby granted provided that 
+#	the above copyright notice and this notice are
+#	left intact. 
+#      
+#	Please send copies of changes and bug-fixes to:
+#	sjg@crufty.net
+#
+
+ECHO_TRACE ?= echo
+
+.ifndef Mkdirs
+# A race condition in some versions of mkdir, means that it can bail 
+# if another process made a dir that mkdir expected to.
+# We repeat the mkdir -p a number of times to try and work around this.
+# We stop looping as soon as the dir exists.
+# If we get to the end of the loop, a plain mkdir will issue an error.
+Mkdirs= Mkdirs() { \
+	for d in $$*; do \
+		for i in 1 2 3 4 5 6; do \
+			mkdir -p $$d; \
+			test -d $$d && return 0; \
+		done > /dev/null 2>&1; \
+		mkdir $$d || exit $$?; \
+	done; }
+.endif
+
+# if MKOBJDIRS is set to auto (and NOOBJ isn't defined) do some magic...
+# This will automatically create objdirs as needed.
+# Skip it if we are just doing 'clean'.
+.if ${MK_AUTO_OBJ:Uno} == "yes"
+MKOBJDIRS= auto
+.endif
+.if !defined(NOOBJ) && !defined(NO_OBJ) && ${MKOBJDIRS:Uno} == auto
+# Use __objdir here so it is easier to tweak without impacting
+# the logic.
+.if !empty(MAKEOBJDIRPREFIX) && exists(${MAKEOBJDIRPREFIX})
+__objdir?= ${MAKEOBJDIRPREFIX}${.CURDIR}
+.endif
+__objdir?= ${MAKEOBJDIR:Uobj}
+__objdir:= ${__objdir:tA}
+.if ${.OBJDIR} != ${__objdir}
+# We need to chdir, make the directory if needed
+.if !exists(${__objdir}/) && \
+	(${.TARGETS} == "" || ${.TARGETS:Nclean*:N*clean:Ndestroy*} != "")
+# This will actually make it... 
+__objdir_made != echo ${__objdir}/; umask ${OBJDIR_UMASK:U002}; \
+        ${ECHO_TRACE} "[Creating objdir ${__objdir}...]" >&2; \
+        ${Mkdirs}; Mkdirs ${__objdir}
+__objdir:= ${__objdir:tA}
+.endif
+# This causes make to use the specified directory as .OBJDIR
+.OBJDIR: ${__objdir}
+.if ${.OBJDIR} != ${__objdir} && ${__objdir_made:Uno:M${__objdir}/*} != ""
+.error could not use ${__objdir}: .OBJDIR=${.OBJDIR}
+.endif
+.endif
+.endif