1 files changed, 93 insertions, 0 deletions
diff --git a/config/makefiles/autotargets.mk b/config/makefiles/autotargets.mk
new file mode 100644
index 0000000000..a3a073b359
--- /dev/null
+++ b/config/makefiles/autotargets.mk
@@ -0,0 +1,93 @@
+# -*- makefile -*-
+# vim:set ts=8 sw=8 sts=8 noet:
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this file,
+# You can obtain one at http://mozilla.org/MPL/2.0/.
+#
+
+ifndef INCLUDED_AUTOTARGETS_MK #{
+
+# Conditional does not wrap the entire file so multiple
+# includes will be able to accumulate dependencies.
+
+###########################################################################
+#      AUTO_DEPS - A list of deps/targets drived from other macros.
+###########################################################################
+
+MKDIR ?= mkdir -p
+TOUCH ?= touch
+
+# declare for local use, rules.mk may not have been loaded
+space = $(NULL) $(NULL)
+
+# Deps will be considered intermediate when used as a pre-requisite for
+# wildcard targets.  Inhibit their removal, mkdir -p is a standalone op.
+.PRECIOUS: %/.mkdir.done
+
+#########################
+##---]  FUNCTIONS  [---##
+#########################
+
+# Squeeze can be overzealous, restore root for abspath
+getPathPrefix =$(if $(filter /%,$(1)),/)
+
+# Squeeze '//' from the path, easily created by string functions
+_slashSqueeze =$(foreach val,$(getargv),$(call getPathPrefix,$(val))$(subst $(space),/,$(strip $(subst /,$(space),$(val)))))
+
+# Squeeze extraneous directory slashes from the path
+#  o protect embedded spaces within the path
+#  o replace //+ sequences with /
+slash_strip = \
+  $(strip \
+    $(subst <--[**]-->,$(space),\
+	$(call _slashSqueeze,\
+    $(subst $(space),<--[**]-->,$(1))\
+  )))
+
+# Extract directory path from a dependency file.
+mkdir_stem =$(foreach val,$(getargv),$(subst /.mkdir.done,$(NULL),$(val)))
+
+## Generate timestamp file for threadsafe directory creation
+mkdir_deps =$(foreach dir,$(getargv),$(call slash_strip,$(dir)/.mkdir.done))
+
+#######################
+##---]  TARGETS  [---##
+#######################
+
+%/.mkdir.done: # mkdir -p -p => mkdir -p
+	$(subst $(space)-p,$(null),$(MKDIR)) -p '$(dir $@)'
+# Make the timestamp old enough for not being a problem with symbolic links
+# targets depending on it. Use Jan 3, 1980 to accomodate any timezone where
+# 198001010000 would translate to something older than FAT epoch.
+	@$(TOUCH) -t 198001030000 '$@'
+
+# A handful of makefiles are attempting "mkdir dot".
+# tbpl/valgrind builds are using this target
+# https://bugzilla.mozilla.org/show_bug.cgi?id=837754
+.mkdir.done:
+	@echo 'WARNING: $(MKDIR) -dot- requested by $(MAKE) -C $(CURDIR) $(MAKECMDGOALS)'
+	@$(TOUCH) -t 198001030000 '$@'
+
+INCLUDED_AUTOTARGETS_MK = 1
+endif #}
+
+
+## Accumulate deps and cleanup
+ifneq (,$(GENERATED_DIRS))
+  GENERATED_DIRS := $(strip $(sort $(GENERATED_DIRS)))
+  tmpauto :=$(call mkdir_deps,GENERATED_DIRS)
+  GENERATED_DIRS_DEPS +=$(tmpauto)
+endif
+
+#################################################################
+# One ring/dep to rule them all:
+#   config/rules.mk::all target is available by default
+#   Add $(AUTO_DEPS) as an explicit target dependency when needed.
+#################################################################
+
+AUTO_DEPS +=$(GENERATED_DIRS_DEPS)
+AUTO_DEPS := $(strip $(sort $(AUTO_DEPS)))
+
+# Complain loudly if deps have not loaded so getargv != $(NULL)
+$(call requiredfunction,getargv)