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Subject: Re: Hang in libssh2_sftp_readdir

Re: Hang in libssh2_sftp_readdir

From: Peter Stuge <peter_at_stuge.se>
Date: Wed, 29 Jul 2009 16:24:07 +0200

Daniel Stenberg wrote:
>> I think this assumption is the problem - recv() can return early just like
>> write().
>
> Yes it can return early, but why would it return early if there is
> more data available already?

Any reason - is how I have interpreted the man pages. Paging in the
kernel or whatever lowlevel. A bit of a pain, but I've haven't had
this problem yet, working from that interpretation.

> I am sure. If there's data available and you only recv() parts of
> it, select() and poll() will return immediately as ready to read.

Ok.

>> Also, are they really called in a loop?
>
> They should be.

Then I don't understand the problem either. I suspect this loop
construct is not all right.

>> I am not sure simply reverting the patch is correct either. :\
>
> The change was made to not forcibly always recv() until it returns
> EWOULDBLOCK, but instead treat a short read as end of loop as well.
> If that turns out to be a bad assumption on my behalf, then a
> reversion should be at least decent. Or what flaw in this logic do
> you spot?

There was a problem also before the patch, which we still want to
fix. I'll look at this.

//Peter
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Received on 2009-07-29

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