1. Update our open() wrapper to check for NT's STATUS_DELETE_PENDING
and translate it to Unix-like errors. This is done with
RtlGetLastNtStatus(), which is dynamically loaded from ntdll. A new
file win32ntdll.c centralizes lookup of NT functions, in case we decide
to add more in the future.
2. Remove non-working code that was trying to do something similar for
stat(), and just reuse the open() wrapper code. As a side effect,
stat() also gains resilience against "sharing violation" errors.
3. Since stat() is used very early in process startup, remove the
requirement that the Win32 signal event has been created before
pgwin32_open_handle() is reached. Instead, teach pg_usleep() to fall
back to a non-interruptible sleep if reached before the signal event is
available.
This could be back-patched, but for now it's in master only. The
problem has apparently been with us for a long time and generated only a
few complaints. Proposed patches trigger it more often, which led to
this investigation and fix.
Reviewed-by: Andres Freund <andres@anarazel.de>
Reviewed-by: Alexander Lakhin <exclusion@gmail.com>
Reviewed-by: Juan José Santamaría Flecha <juanjo.santamaria@gmail.com>
Discussion: https://postgr.es/m/CA%2BhUKGJz_pZTF9mckn6XgSv69%2BjGwdgLkxZ6b3NWGLBCVjqUZA%40mail.gmail.com
GetFinalPathNameByHandleA() cannot be used in compilation environments
where _WIN32_WINNT < 0x0600, meaning at least Windows XP used by some
buildfarm members under MinGW that Postgres still needs to support.
This was reported as a compilation warning by the buildfarm, but this is
actually worse than the report as the code would have not worked.
Instead, this switches to GetFileInformationByHandle() that is able to
fail for standard streams and succeed for redirected ones, which is what
we are looking for herein the code emulating fstat(). We also know that
it is able to work in all the environments still supported, thanks to
the existing logic of win32stat.c.
Issue introduced by 10260c7, so backpatch down to 14.
Reported-by: Justin Pryzby, via buildfarm member jacana
Author: Michael Paquier
Reviewed-by: Juan José Santamaría Flecha
Discussion: https://postgr.es/m/20211129050122.GK17618@telsasoft.com
Backpatch-through: 14
The emulation of fstat() in win32stat.c caused two issues with the
existing in-core callers, failing on EINVAL when using a stream as
argument:
- psql's \copy would crash when using a stream.
- pg_recvlogical would fail with -f -.
The tests in copyselect.sql from the main test suite covers the first
case, and there is a TAP test for the second case. However, in both
cases, as the standard streams are always redirected, automated tests
did not notice those issues, requiring a terminal on Windows to be
reproducible.
This issue has been introduced in bed9075, and the origin of the problem
is that GetFileInformationByHandle() does not work directly on streams,
so this commit adds an extra code path to emulate and return a set of
stats that match best with the reality. Note that redirected streams
rely on handles that can be queried with GetFileInformationByHandle(),
but we can rely on GetFinalPathNameByHandleA() to detect this case.
Author: Dmitry Koval, Juan José Santamaría Flecha
Discussion: https://postgr.es/m/17288-6b58a91025a8a8a3@postgresql.org
Backpatch-through: 14
This reverts commit 54fb8c7, as per the issues reported by fairywren
when it comes to MinGW because of the lack of microsoft_native_stat()
there. Using just stat() for MSVC is not sufficient to take care of the
concurrency problems with files pending on deletion. It may be possible
to paint some __MINGW64__ in the code to switch to a different
implementation of stat() in this build context, but I am not sure either
if relying on the implementation of stat() in MinGW to take care of the
problems we are trying to fix is enough or not. So this needs more
study.
Discussion: https://postgr.es/m/YOvOlfRrIO0yGtgw@paquier.xyz
Backpatch-through: 14
The code introduced by bed9075 to enhance the stat() implementation on
Windows for file sizes larger than 4GB fails to properly detect files
pending for deletion with its method based on NtQueryInformationFile()
or GetFileInformationByHandleEx(), as proved by Alexander Lakhin in a
custom TAP test of his own.
The method used in the implementation of open() to sleep and loop when
when failing on ERROR_ACCESS_DENIED (EACCES) is showing much more
stability, so switch to this method. This could still lead to issues if
the permission problem stays around for much longer than the timeout of
1 second used, but that should (hopefully) never happen in
performance-critical paths. Still, there could be a point in increasing
the timeouts for the sake of machines that handle heavy loads.
Note that WIN32's open() now uses microsoft_native_stat() as it should
be similar to stat() when working around issues with concurrent file
deletions.
I have spent some time testing this patch with pgbench in combination
of the SQL functions from genfile.c, as well as running the TAP test
provided on the thread with MSVC builds, and this looks much more
stable than the previous method.
Author: Alexander Lakhin
Reviewed-by: Tom Lane, Michael Paquier, Justin Pryzby
Discussion: https://postgr.es/m/c3427edf-d7c0-ff57-90f6-b5de3bb62709@gmail.com
Backpatch-through: 14
After de8feb1f3a, some warnings remained
that were only visible when using GCC on Windows. Fix those as well.
Note that the ecpg test source files don't use the full pg_config.h,
so we can't use pg_funcptr_t there but have to do it the long way.
Hack things so that our idea of "struct stat" is equivalent to Windows'
struct __stat64, allowing it to have a wide enough st_size field.
Instead of relying on native stat(), use GetFileInformationByHandle().
This avoids a number of issues with Microsoft's multiple and rather
slipshod emulations of stat(). We still need to jump through hoops
to deal with ERROR_DELETE_PENDING, though :-(
Pull the relevant support code out of dirmod.c and put it into
its own file, win32stat.c.
Still TODO: do we need to do something different with lstat(),
rather than treating it identically to stat()?
Juan José Santamaría Flecha, reviewed by Emil Iggland;
based on prior work by Michael Paquier, Sergey Zubkovsky, and others
Discussion: https://postgr.es/m/1803D792815FC24D871C00D17AE95905CF5099@g01jpexmbkw24
Discussion: https://postgr.es/m/15858-9572469fd3b73263@postgresql.org
Bruce Momjian
Thomas Munro
Michael Paquier
Peter Eisentraut
Tom Lane