Continue working on getting horizon back in shape

anvil/shell.py

@@ -250,6 +250,10 @@ def shellquote(text):
     return text
 
 
+def fileperms(path):
+    return (os.stat(path).st_mode & 0777)
+
+
 def listdir(path):
     return os.listdir(path)
 
@@ -655,6 +659,23 @@ def move(src, dst):
     return dst
 
 
+def write_file_and_backup(path, contents, bk_ext='org'):
+    perms = None
+    backup_path = None
+    if isfile(path):
+        perms = fileperms(path)
+        backup_path = "%s.%s" % (path, bk_ext)
+        if not isfile(backup_path):
+            LOG.debug("Backing up %s => %s", path, backup_path)
+            move(path, backup_path)
+        else:
+            LOG.debug("Leaving original backup of %s at %s", path, backup_path)
+    write_file(path, contents)
+    if perms is not None:
+        chmod(path, perms)
+    return backup_path
+
+
 def chmod(fname, mode):
     LOG.debug("Applying chmod: %r to %o" % (fname, mode))
     if not is_dry_run():