Calling fseek() or ftello() on a handle to a non-seeking device such as
a pipe or a communications device is not supported. Unfortunately,
MSVC's flavor of these routines, _fseeki64() and _ftelli64(), do not
return an error when given a pipe as handle. Some of the logic of
pg_dump and restore relies on these routines to check if a handle is
seekable, causing failures when passing the contents of pg_dump to
pg_restore through a pipe, for example.
This commit introduces wrappers for fseeko() and ftello() on MSVC so as
any callers are able to properly detect the cases of non-seekable
handles. This relies mainly on GetFileType(), sharing a bit of code
with the MSVC port for fstat(). The code in charge of getting a file
type is refactored into a new file called win32common.c, shared by
win32stat.c and the new win32fseek.c. It includes the MSVC ports for
fseeko() and ftello().
Like 765f5df, this is backpatched down to 14, where the fstat()
implementation for MSVC is able to understand about files larger than
4GB in size. Using a TAP test for that is proving to be tricky as
IPC::Run handles the pipes by itself, still I have been able to check
the fix manually.
Reported-by: Daniel Watzinger
Author: Juan José Santamaría Flecha, Michael Paquier
Discussion: https://postgr.es/m/CAC+AXB26a4EmxM2suXxPpJaGrqAdxracd7hskLg-zxtPB50h7A@mail.gmail.com
Backpatch-through: 14
The current implementation of _pgfstat64() is ineffective in detecting a
terminal handle or an anonymous named pipe. This commit improves our
port of fstat() to detect more efficiently such cases by relying on
GetFileType(), and returning more correct data when the type found is
either a FILE_TYPE_PIPE (_S_IFIFO) or a FILE_TYPE_CHAR (_S_IFCHR).
This is part of a more global fix to address failures when feeding the
output generated by pg_dump to pg_restore through a pipe, for example,
but not all of it. We are also going to need to do something about
fseek() and ftello() which are not reliable on WIN32 for the same cases
where fstat() was incorrect. Fixing fstat() is independent of the rest,
though, which is why both fixes are handled separately, and this is the
first part of it.
Reported-by: Daniel Watzinger
Author: Daniel Watzinger, Juan José Santamaría Flecha
Discussion: https://postgr.es/m/b1448cd7-871e-20e3-8398-895e2d1d3bf9@gmail.com
Backpatch-through: 14
Commit c5cb8f3b supposed that we'd only ever have to follow one junction
point in stat(), because we don't construct longer chains of them ourselves.
When examining a parent directory supplied by the user, we should really be
able to cope with longer chains, just in case someone has their system
set up that way. Choose an arbitrary cap of 8, to match the minimum
acceptable value of SYMLOOP_MAX in POSIX.
Previously I'd avoided reporting ELOOP thinking Windows didn't have it,
but it turns out that it does, so we can use the proper error number.
Reviewed-by: Roman Zharkov <r.zharkov@postgrespro.ru>
Discussion: https://postgr.es/m/CA%2BhUKGJ7JDGWYFt9%3D-TyJiRRy5q9TtPfqeKkneWDr1XPU1%2Biqw%40mail.gmail.com
Discussion: https://postgr.es/m/CA%2BhUKG%2BajSQ_8eu2AogTncOnZ5me2D-Cn66iN_-wZnRjLN%2Bicg%40mail.gmail.com
When using junction points to emulate symlinks on Windows, one edge case
was not handled correctly by commit c5cb8f3b: if a junction point is
broken (pointing to a non-existent path), we'd report ENOENT. This
doesn't break any known use case, but was noticed while developing a
test suite for these functions and is fixed here for completeness.
Also add translation ERROR_CANT_RESOLVE_FILENAME -> ENOENT, as that is
one of the errors Windows can report for some kinds of broken paths.
Discussion: https://postgr.es/m/CA%2BhUKG%2BajSQ_8eu2AogTncOnZ5me2D-Cn66iN_-wZnRjLN%2Bicg%40mail.gmail.com
We'd like to use precompiled headers on windows to reduce compile times. Right
now we rely on defining UMDF_USING_NTSTATUS before including postgres.h in a few
select places - which doesn't work with precompiled headers. Instead define
it globally.
When UMDF_USING_NTSTATUS is defined we need to explicitly include ntstatus.h,
winternl.h to get a comparable set of symbols. Right now these includes would
be required in a number of non-platform-specific .c files - to avoid that,
include them in win32_port.h. Based on my measurements that doesn't increase
compile times measurably.
Reviewed-by: Thomas Munro <thomas.munro@gmail.com>
Discussion: https://postgr.es/m/20220927011951.j3h4o7n6bhf7dwau@awork3.anarazel.de
Junction points will be reported with S_ISLNK(x.st_mode), simulating
POSIX lstat(). stat() will follow pseudo-symlinks, like in POSIX (but
only one level before giving up, unlike in POSIX).
This completes a TODO left by commit bed90759fcb.
Tested-by: Andrew Dunstan <andrew@dunslane.net> (earlier version)
Discussion: https://postgr.es/m/CA%2BhUKGLfOOeyZpm5ByVcAt7x5Pn-%3DxGRNCvgiUPVVzjFLtnY0w%40mail.gmail.com
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 de8feb1f3a23465b5737e8a8c160e8ca62f61339, 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
