Index: tools/dest_build.py
===================================================================
--- tools/dest_build.py	(revision 491f773457ccde7aa37c290bb5e8e290cdec0297)
+++ tools/dest_build.py	(revision 491f773457ccde7aa37c290bb5e8e290cdec0297)
@@ -0,0 +1,107 @@
+#!/usr/bin/env python
+#
+# Copyright (c) 2012 Martin Decky
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+#
+# - Redistributions of source code must retain the above copyright
+#   notice, this list of conditions and the following disclaimer.
+# - Redistributions in binary form must reproduce the above copyright
+#   notice, this list of conditions and the following disclaimer in the
+#   documentation and/or other materials provided with the distribution.
+# - The name of the author may not be used to endorse or promote products
+#   derived from this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+# IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+# OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+# IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+# NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+# THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#
+
+"""
+HelenOS out-of-source-tree build utility
+"""
+
+import sys
+import os
+import stat
+import errno
+import subprocess
+
+exclude_names = set(['.svn', '.bzr'])
+
+def duplicate_tree(src_path, dest_path, current):
+	"Duplicate source directory tree in the destination path"
+	
+	for name in os.listdir(os.path.join(src_path, current)):
+		if name in exclude_names:
+			next
+		
+		following = os.path.join(current, name)
+		src = os.path.join(src_path, following)
+		dest = os.path.join(dest_path, following)
+		dest_parent = os.path.join(dest_path, current)
+		dest_stat = os.stat(src)
+		
+		# Create shadow directories
+		if stat.S_ISDIR(dest_stat.st_mode):
+			if not os.path.exists(dest):
+				os.mkdir(dest)
+			
+			if not os.path.isdir(dest):
+				raise IOError(errno.ENOTDIR, "Destination path exists, but is not a directory", dest)
+			
+			duplicate_tree(src_path, dest_path, following)
+		else:
+			# Compute the relative path from destination to source
+			relative = os.path.relpath(src, dest_parent)
+			
+			# Create symlink
+			if not os.path.exists(dest):
+				os.symlink(relative, dest)
+
+def usage(prname):
+	"Print usage syntax"
+	print(prname + " <SRC_PATH> <DEST_PATH> [MAKE ARGS...]")
+
+def main():
+	if len(sys.argv) < 3:
+		usage(sys.argv[0])
+		return 1
+	
+	# Source tree path
+	src_path = os.path.abspath(sys.argv[1])
+	if not os.path.isdir(src_path):
+		print("<SRC_PATH> must be a directory")
+		return 2
+	
+	# Destination tree path
+	dest_path = os.path.abspath(sys.argv[2])
+	if not os.path.exists(dest_path):
+		os.mkdir(dest_path)
+	
+	if not os.path.isdir(dest_path):
+		print("<DEST_PATH> must be a directory")
+		return 3
+	
+	# Duplicate source directory tree
+	duplicate_tree(src_path, dest_path, "")
+	
+	# Run the build from the destination tree
+	os.chdir(dest_path)
+	args = ["make"]
+	args.extend(sys.argv[3:])
+	
+	return subprocess.Popen(args).wait()
+
+if __name__ == '__main__':
+	sys.exit(main())