build.py: Add support for cleaning directories before a task in the form: do_taskname[cleandirs] = 'dir'

git-svn-id: https://svn.o-hand.com/repos/poky/trunk@2693 311d38ba-8fff-0310-9ca6-ca027cbcb966

bitbake/ChangeLog

@@ -10,6 +10,8 @@ Changes in BitBake 1.8.x:
 	- Handle paths in svn fetcher module parameter
 	- Support the syntax "export VARIABLE"
 	- Add bzr fetcher
+	- Add support for cleaning directories before a task in the form:
+	  do_taskname[cleandirs] = "dir"
 
 Changes in Bitbake 1.8.8:
 	- Rewrite svn fetcher to make adding extra operations easier 

bitbake/lib/bb/build.py

@@ -74,10 +74,13 @@ def exec_func(func, d, dirs = None):
     if not body:
         return
 
+    cleandirs = (data.expand(data.getVarFlag(func, 'cleandirs', d), d) or "").split()
+    for cdir in cleandirs:
+        os.system("rm -rf %s" % cdir)
+
     if not dirs:
-        dirs = (data.getVarFlag(func, 'dirs', d) or "").split()
+        dirs = (data.expand(data.getVarFlag(func, 'dirs', d), d) or "").split()
     for adir in dirs:
-        adir = data.expand(adir, d)
         mkdirhier(adir)
 
     if len(dirs) > 0: