Re: [Duplicity-talk] Duplicity crashes on locked files (windows)

[Georg Lutz]

>
>>
>> It seems like you explained - one can open the file but not access it.
>> BTW
>> the crash can also be reproduced with opened Excel or OOWrite files.
>
> This patch seems to work for me with OOWrite files.  Care to give it a
> try with Outlook files?
>

Hi Ken,

just tried it with outlook. Unfourtunately the effect is the same:
Duplicity keeps crashing. But I must admit that I cannot reproduce it
anymore with OOWrite. I tried to track the problem a bit down and looked
through the processmon logs.

I am not very familiar with Windows locking semantics, but I think the
problem is the exclusive lock (also blocking other read requests):

18019   16:40:43,8549556        OUTLOOK.EXE     2536    LockFile        
D:\Documents and
Settings\GeLutz\Local Settings\Application
Data\Microsoft\Outlook\archiv.pst       SUCCESS Exclusive: True, Offset: 533,
Length: 3.176.520.908

Later on python tries to read a range within this locking range. It fails,
because it is exclusively locked:

70292   16:41:05,3581132        python.exe      3728    ReadFile        
D:\Documents and
Settings\GeLutz\Local Settings\Application
Data\Microsoft\Outlook\archiv.pst       FILE LOCK CONFLICT      Offset: 0, 
Length:
65.536

Perhaps the exceptions needs really to be caught when reading the file
with "read(length)". I think this is not only windows related. It could
happen under linux too when e.g. reading a large file and the NFS server
went down or some filesystem errors occurs.

In that cases I would expect that the backup application just skips the
file but does not crash. :-)


Regards
   Georg

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