Yes readdir was an example and I am saying error reporting is not very good.
I am suggesting ( requesting a feature ) that all I/O functions should
return better information so we can detect outcomes of I/O - whichever
function is used, whatever file system, whatever circumstance.
----- Original Message -----
From: "Keisial" <keis...@gmail.com>
To: "Ian Tighe" <ian.ti...@latitude-51.co.uk>
Cc: <internals@lists.php.net>
Sent: Thursday, September 17, 2009 1:54 PM
Subject: Re: [PHP-DEV] Detecting share violations over cifs with PHP?
Feature request
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
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