[patch] Cross-dev error, /etc versioning

[Miroslav Prymek]

Hello to all, 

I'am succesfully using bzr to version /etc using small scripts to correctly
store and retrieve files modes/permitions/flags.

But there's one problem: when .bzr is on different FS then the versioned files,
you get "Cross-device link" error with some operations. (see
https://bugs.launchpad.net/bzr/+bug/286268 )

I have written a small patch for this problem (below). Please review if it is
correct (as to the raised exceptions, directories handling etc.) and feel free
to use it as you wish.

Please note that this patch breaks atomicity of the _FileMover.rename(...). I
can't examine if it is a problem for bzr or not.

Many thx for great piece of SW! 

Miroslav Prymek



P.S. If someone wants to know details about correct /etc versioning, with
permissions handling, feel free to ask (preferably using this list).

PATCH (see http://bugs.python.org/issue212317 ):

--- bzrlib/transform.py.orig	2008-12-05 18:54:06.000000000 +0100
+++ bzrlib/transform.py	2008-12-13 15:38:19.000000000 +0100
@@ -2631,9 +2631,15 @@
         self.pending_deletions = []
 
     def rename(self, from_, to):
-        """Rename a file from one path to another.  Functions like os.rename"""
+        """Rename a file from one path to another.  Functions like os.rename
except EXDEV correct handling."""
         try:
-            os.rename(from_, to)
+            try:
+                os.rename(from_, to)
+            except OSError, e:
+                if e.errno == errno.EXDEV:
+                  open(to,'w').write(open(from_,'r').read())
+                  os.unlink(from_)
+                else: raise
         except OSError, e:
             if e.errno in (errno.EEXIST, errno.ENOTEMPTY):
                 raise errors.FileExists(to, str(e))