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Re: fix off-by-one in dup2

On Wed, Dec 04, 2013 at 01:04:08PM +0100, Corinna Vinschen wrote:
>On Dec  4 12:36, Corinna Vinschen wrote:
>> On Dec  4 10:32, Corinna Vinschen wrote:
>> > Hi guys,
>> > [...etc...]
>> > The problem is still present in the current sources.
>> > [...]
>Ouch, ouch, ouch!  I tested the wrong DLL.  Actually current CVS fixes
>this problem.  Duh.  Sorry for the confusion.
>One question, though.  Assuming start is == size, then the current code
>in CVS extends the fd table by only 1.  If that happens often, the
>current code would have to call ccalloc/memcpy/cfree a lot.  Wouldn't
>it in fact be better to extend always by at least NOFILE_INCR, and to
>extend by (1 + start - size) only if start is > size + NOFILE_INCR?
>Something like
>  size_t extendby = (start >= size + NOFILE_INCR) ? 1 + start - size : NOFILE_INCR;
>Sorry again.  Fortunately it's my WJM week...

I don't think it is a common occurrence for start >= size.  It is
usually done when something like bash dup2's stdin/stdout/stderr to a
high fd.  Howeer, I'll check in something which guarantees that there is
always a NOFILE_INCR entries free after start.


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