[Openmcl-devel] Weblocks-Demo Permission Denied Win32

Gary Byers gb at clozure.com
Mon Jan 11 05:36:39 UTC 2010

On Sun, 10 Jan 2010, John Federico wrote:

> On Sun, Jan 10, 2010 at 8:15 PM, Gary Byers <gb at clozure.com> wrote:
>> (The function CCL:OPEN-FILE-STREAMS returns a list of ... open lisp
>> file streams; it'd be interesting to see whether or not there's a lisp
>> stream open on a (deleted) temp file when the error occurs.)
> I just tried it again and got a similar error.  There are three .tem
> files sitting in the folder which I can't access:
> 3472150697.tem
> 3472154034.tem
> 3472163064.tem
> ("/usr/local/asdf-install/site/weblocks-stable/pub/stylesheets/vzn/dataform-import'.0.css"/4244
> ("/usr/local/asdf-install/site/weblocks-stable/pub/stylesheets/vzn/datagrid-import'.0.css"/4164
> ("/usr/local/asdf-install/site/weblocks-stable/pub/stylesheets/vzn/dataform-import'.0.css"/4108
> ISO-8859-1) #x9EF3246>)
> ?
> The backtrace from weblocks has this in it:
> (44380620) : 7 (%CREATE-FILE
> #P"c:/usr/local/asdf-install/site/weblocks-stable/pub/stylesheets/vzn/3472163064.tem"
> (44380644) : 8 (GEN-FILE-NAME
> #P"c:/usr/local/asdf-install/site/weblocks-stable/pub/stylesheets/vzn/pagination'.0'.css.gz")
> 191
> (44380658) : 9 (MAKE-FILE-STREAM
> "/usr/local/asdf-install/site/weblocks-stable/pub/stylesheets/vzn/pagination'.0.css.gz"
> :PRIVATE T) 999
> So that must be what is happening.  There is already a temp file there
> that was marked for deletion, and then it tries to create another one
> with the same name, giving the error.  Since it has been marked for
> deletion, then I am assuming that is why I can't access the file
> through windows explorer.

The file(s) that're queued for deletion should be deleted as soon as
the last open handle to them is closed.  (OPEN-FILE-STREAMS) seems
to indicate that no lisp file stream references any of the temporary
files, so I wonder what else might have an open handle to any of
these files.

> Is it possible to override GEN-FILE-NAME in ccl-init.lisp, and add an
> extra condition to test for "Permission Denied"?

You could aproximate the truth by checking to see if you get a
permission error in %CREATE-FILE when :IF-EXISTS is NIL and PROBE-FILE
says that the file exists.  (You don't really know if the file was
created - perhaps by some other program running with different
permissions - at some instant right after the attempt to create it
failed, and you don't really know whether the permission error has to
do with this case - a partially-deleted file - or with directory
permissions, but you do know that the file exsited at about the time
that we tried to create it with :IF-EXISTS NIL and you know that it
wasn't successfully created by this call to %CREATE-FILE, so returning
NIL in that case isn't totally inappropriate.)

I'd still like to know what's holding on to an open handle to the temp
file; I don't think that the lisp ever opens streams to these files,
so it seems like something in the lisp runtime/the little bit of C
library that we use/Windows itself that's neglecting to close a
handle.  If user code deletes and tries to recreate a file while an
open file stream still references the file, we can say "that doesn't
work on Windows, so don't do that"; if this just happens sometimes as
part of the :IF-EXISTS :SUPERSEDE mechanism, we can't really say
"don't use :IF-EXISTS :SUPERSEDE" ...

> Thank you very much for all the help thus far.  -John
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