15.11.2020 04:11, Justin Pryzby wrote:
> On Sat, Nov 14, 2020 at 01:00:00PM +0300, Alexander Lakhin wrote:
>> As noted in [1], a sensible solution would be putting the same "retry on
>> ERROR_ACCESS_DENIED" action in a wrapper for stat().
>> And bed90759f brought in master the _pgstat64() function, where such
>> error handling should be placed.
>> So please look at the patch (based on the previous one made to fix
>> bug#16161), that makes the attached test pass.
> Your patch introduces a "loops", but doesn't use it to escape the loop.
Indeed, this is my mistake. Please look at the corrected patch (now that
code corresponds to the pgwin32_open() as intended).
And it rises another question, what if pg_ls_dir_files() is called for a
directory where hundreds or thousands of files are really inaccessible
due to restrictions?
I mean that using CreateFile() in the modified stat() implementation can
be rather expensive for an arbitrary file (and worse yet, for many files).
On the positive side, for now pg_ls_dir_files() is called only from
pg_ls_logdir, pg_ls_waldir, pg_ls_tmpdir, pg_ls_archive_statusdir, where
having a bunch of files that are inaccessible for the postgres user is
not expected anyway.
But probably getting directory contents with correct file sizes (>4GB)
in pg_ls_dir_files() can be implemented without calling
CreateFile()/stat() at all (as ProcMon shows, the "dir" command doesn't
call CreateFile() (or any other system function) for each file in the
target directory).
Best regards,
Alexander