Overwriting source file leaves destination full of zeros

[Jon Mitchell]

Hi,

I'm a little confused over what I'm seeing when a source file is
overwritten whilst an rsync is in progress. Instead of the destination
file being truncated, or an error being raised and the destination file
removed, I get a file of the correct length, but mostly full of nulls
where previously there were none. An example is shown here:

> ls -l big_file

-rw-------  1 jonm users 168797799 Jan 30 09:06 big_file

> ls -l small_file

-rw-r--r--  1 jonm users 9212 Jan 30 09:09 small_file

> od -c -j 168797700 big_file # show the tail of the big file
1203723004   e   R   a   t   e   T   r   u   n   c  \0  \0  \0  \0  \0  \0
1203723024 001 017   s   o   u   n   d   .   c   o   n   n   e   c   t   e
1203723044   d 001 001 023   E   t   h   e   r   n   e   t   0   .   c   o
1203723064   n   n   e   c   t   e   d 001 001 020   i   d   e   1   :   0
1203723104   .   c   o   n   n   e   c   t   e   d 001 001 021   f   l   o
1203723124   p   p   y   0   .   c   o   n   n   e   c   t   e   d 001  \0
1203723144  \0  \0  \0
1203723147

> sha1sum big_file
e9c56b070a077d942ac4db0ef48744cd1e5290a2  big_file

> rsync big_file big_file2

 # Whilst this is running 

> cp small_file big_file


> ls -l *_file*
-rw-------  1 jonm users      9212 Jan 30 09:11 big_file
-rw-r--r--  1 jonm users      9212 Jan 30 09:09 small_file
-rw-------  1 jonm users 168797799 Jan 30 09:11 big_file2

# big_file2 file size is correct

> sha1sum big_file2
71c5981c0b22a22fc59859e6a86ea6e51edbb6fb  big_file2

# sha1 differs

> od -c -j 168797700 big_file2

1203723004  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0
*
1203723144  \0  \0  \0
1203723147

# Last bytes of the big_file are all \0


Is this behaviour what you would expect from rsync? This is rsync version 2.6.6.

Thanks,
 Jon




______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please visit http://www.messagelabs.com/email 
______________________________________________________________________