Messages in this thread | | | Date | Sun, 21 Mar 2004 16:25:31 -0800 (PST) | From | Davide Libenzi <> | Subject | Re: [PATCH] cowlinks v2 |
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On 21 Mar 2004, Eric W. Biederman wrote:
> Jörn Engel <joern@wohnheim.fh-wedel.de> writes: > > > On Sun, 21 March 2004 09:59:39 -0800, Davide Libenzi wrote: > > > > > > When I did that, fumes of an in-kernel implementation invaded my head for > > > a little while. Then you start thinking that you have to teach apps of new > > > open(2) semantics, you have to bloat kernel code a little bit and you have > > > to deal with a new set of errors cases that open(2) is not expected to > > > deal with. A fully userspace implementation did fit my needs at that time, > > > even if the LD_PRELOAD trick might break if weak aliases setup for open > > > functions change inside glibc. > > > > 209 fairly simple lines definitely have more appear than a full > > in-kernel implementation with many new corner-cases, yes. But it > > looks as if you ignore the -ENOSPC case, so you cheated a little. ;) > > > > No matter how you try, there is no way around an additional return > > code for open(), so we have to break compatibility anyway. The good > > news is that a) people not using this feature won't notice and b) all > > programs I tried so far can deal with the problem. Vim even has a > > decent error message - as if my patch was anticipated already. > > Actually there is... You don't do the copy until an actual write occurs. > Some files are opened read/write when there is simply the chance they might > be written to so delaying the copy is generally a win.
What about open+mmap?
- Davide
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