Prevent deletion of file when it is being copied

[Nicolas Michel]

I think the problem that Nimit explains is only related to Nautillus. Am I
right Nimit? Also you didn't said if the file you deleted was the source or
the destination one?

Regards,
Nicolas

2012/9/27 Emmet Hikory <persia at ubuntu.com>

> Nimit Shah wrote:
> > While copying a file from my computer to external disk, I by mistake
> > shift+deleted the file. But still the file transfer dialog showed that it
> > was continuing. At the end of the transfer it failed.
> >
> > Hence i request you to add a check for file transfer before deleting the
> > file.
>
>     As much as this would be a lovely feature, I don't believe that it is
> something that we could implement in Ubuntu.
>
>     When copying a file, there are usually two ways to go about it: either
> open the entire file, and write it to a new location, or open a series of
> sections of the file, and write them each to a new location.  There are a
> very large number of programs that provide both of these mechanisms in the
> archive.  In the majority of cases, the first potential solution is not
> used, because it limits file copies to files that fit entirely in memory
> (with everything else), and requires a longer-running algorithm, but
> when the second method is used, the file cannot be allowed to be deleted
> before the file transfer is confirmed as complete.
>
>     When deleting a file, the usual practice is to remove the reference
> from the directory definitions (unlinking), leaving the underlying
> filesystem
> to manage recovery of the newly available space.  Again, there are a vast
> number of packages in the archive providing programs that do this.
>
>     In order to implement the feature you describe, we would have to either
> provide some systems interface that traps all calls to unlink() and checks
> some external reference to determine if it is being copied or patch all
> software that could potentially delete files to check the reference, whilst
> simultaneously patching every package that provides a means to copy a file
> to populate this reference during the file copy, which would make all such
> operations considerably slower, with potentially massive impact on server
> capacities, interactive response times, and battery life.
>
>     Further, it is unlikely that the developers and maintainers of most of
> the software in our archive would be willing to accept such patches, given
> the potential complications and incompatibilities with other systems, such
> that the result of this vast undertaking would require considerable ongoing
> development effort to port these patches for each new upstream release.
>
>     Lastly, in the event that any of the programs providing file copy
> functionality were to crash, they may not properly clear the reference
> indicating files whose deletion need block on the transfer completion.
> As a result of such a crash (or any other bug when updating references),
> a user's system may end up having any number of files that cannot be
> deleted without manual intervention into the file transfer reference.
>
> --
> Emmet HIKORY
>
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-- 
Nicolas MICHEL
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