Re: backup manifests - Mailing list pgsql-hackers

On Fri, Apr 3, 2020 at 3:53 PM Robert Haas <robertmhaas@gmail.com> wrote:
> 2. Also, a bunch of machines were super-unhappy with
> 003_corruption.pl, failing with this sort of thing:
>
> pg_basebackup: error: could not get COPY data stream: ERROR:  symbolic
> link target too long for tar format: file name "pg_tblspc/16387",
> target "/home/fabien/pg/build-farm-11/buildroot/HEAD/pgsql.build/src/bin/pg_validatebackup/tmp_check/tmp_test_7w0w"
>
> Apparently, this is a known problem and the solution is to use
> TestLib::tempdir_short instead of TestLib::tempdir, so I pushed a fix
> to make it do that.

By and large, the buildfarm is a lot happier now, but fairywren
(Windows / Msys Server 2019 / 2 gcc 7.3.0 x86_64) failed like this:

# Postmaster PID for node "master" is 198420
error running SQL: 'psql:<stdin>:3: ERROR:  directory
"/tmp/9peoZHrEia" does not exist'
while running 'psql -XAtq -d port=51493 host=127.0.0.1
dbname='postgres' -f - -v ON_ERROR_STOP=1' with sql 'CREATE TABLE x1
(a int);
INSERT INTO x1 VALUES (111);
CREATE TABLESPACE ts1 LOCATION '/tmp/9peoZHrEia';
CREATE TABLE x2 (a int) TABLESPACE ts1;
INSERT INTO x1 VALUES (222);
' at /home/pgrunner/bf/root/HEAD/pgsql.build/../pgsql/src/test/perl/PostgresNode.pm
line 1531.
### Stopping node "master" using mode immediate

I wondered why this should be failing on this machine when none of the
other places where tempdir_short is used are similarly failing. The
answer appears to be that most of the TAP tests that use tempdir_short
just do this:

my $tempdir_short = TestLib::tempdir_short;

...and then ignore that variable completely for the rest of the
script.  That's not ideal, and we should probably remove those calls
to avoid giving that it's actually used for something. The two TAP
tests that actually do something with it - apart from the one I just
added - are pg_basebackup's 010_pg_basebackup.pl and pg_ctl's
001_start_stop.pl. However, both of those are skipped on Windows.
Also, PostgresNode.pm itself uses it, but only when UNIX sockets are
used, so again not on Windows. So it sorta looks to me like we no
preexisting tests that meaningfully exercise TestLib::tempdir_short on
Windows.

Given that, I suppose I should consider myself lucky if this ends up
working on *any* of the Windows critters, but given the implementation
I'm kinda surprised we have a problem. That function is just:

sub tempdir_short
{

        return File::Temp::tempdir(CLEANUP => 1);
}

And File::Temp's documentation says that the temporary directory is
picked using File::Spec's tmpdir(), which says that it knows about
different operating systems and will DTRT on Unix, Mac, OS2, Win32,
and VMS. Yet on fairywren it is apparently DTWT. I'm not sure why.

Any ideas?

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company