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Date: Thu, 17 Sep 2009 14:54:13 +0200
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To: Ian Tighe <ian.tighe@latitude-51.co.uk>
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Subject: Re: [PHP-DEV] Detecting share violations over cifs with PHP? Feature
 request
From: keisial@gmail.com (Keisial)

Ian Tighe `wrote:
> Hi ,
> I am using readdir with a view to selecting files for opening and
> reading or just taking a stat of them. I am doing this recursively. I
> test the output from readdir to see if its a file or dir or link etc
> and this works well. This suddenly changes though and an item is
> returned by readdir (that is a filename) but its type cannot be
> determined - it is not of any type at all! So looking at a wireshark
> trace revealed there had been a sharing violation but I was blissfully
> unaware of this.
>
> I am seeking to have such an error condition made available so that
> ANY i/o op can be tested not just for true or false but to further
> establish the i/o outcome and hence track sharing violations amongst
> other errors. Apart from the type issue above, my substantive point
> about readdir was this: If I get a false reply I am not sure if I had
> a failed i/o operation or I had come to the end of a directory list.
> As far as I can see ( and I may be wrong of course ) there is for PHP
> no difference between the two but the impact is significantly
> different. It was more to demonstrate that error reporting is fairly
> clumsy in these circumstances.
The readdir() system call doesn't have a better error checking. It will
return a null pointer on error, just as on eof. The only way to check if
it had an error is by setting errno to 0 before the call and checking
its status after it. And the reported shouldn't happen anyway, since
they are application errors (passing a bad fd...) not reading problems.

Perhaps the sharing violation should be reported by stat() instead of
readdir()?

> It is certainly true all the files I have seen so far that cause this
> problem related to either iTunes or Microsoft - especially internet
> explorer 8 recovery files. It must be they are exclusively locked and
> any attempt by my software makes to read them brings about a violation
> which cannot be detected, cannot be recovered from and thus not
> handled by me.
>
> I cannot reliably repeat it as I can barely detect it other than my
> software will carry on looking for files and directories and not being
> able to recognise types and actions I wanted are not carried out.  I
> have a wireshark trace of the smb protocol exchanges if that helps but
> it basically says trans2 query path request, trans2 query path
> response , create_andx request (which is probably a stat), which is
> retried several times and finally a create andx response indicating a
> sharing violation. If I could get hold of that in PHP I could
> react.............
> Thanks
> Ian