[TxMt] Atomic Saving / Saving Question

[Sune Foldager]

On 8. feb 2005, at 18:43, Chris Thomas wrote:

>> Huh? If I have file A hard linked with B and I "atomically" replace A 
>> (i.e. write A.new, move A.new to A) then I will break the link 
>> between A and B. That's the issue here, and that's certainly what 
>> happens in the scenario I just described :-). No HFS+ errors here.
>
> Right, but I'm talking specifically about the exchangedata system call 
> (or FSExchangeObjects). exchangedata is a Darwin VFS operation. It 
> calls into the file system implementation to perform the atomic 
> exchange. For HFS+, it explicitly preserves the file ID. I had assumed 
> it would preserve hardlinks as well, but it turns out that it just 
> errors out if one of the files is hardlinked (or has ever been 
> hardlinked).

I see... interesting. Of course somewhat unfortunate that it fails with 
multilinked files.... then, preserving the id/inode will only help with 
alises (if the file was moved since the alias was created).

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