From: Tom Lane <tgl@sss.pgh.pa.us>
To: d.kovalenko@postgrespro.ru
cc: pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #18971: Server passes an invalid (indirect) path in PGDATA to
 the external program
In-reply-to: <18971-53687392b125e4bf@postgresql.org>
References: <18971-53687392b125e4bf@postgresql.org>
Comments: In-reply-to PG Bug reporting form <noreply@postgresql.org>
	message dated "Sat, 28 Jun 2025 07:17:54 -0000"
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Date: Sat, 28 Jun 2025 15:13:25 -0400
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PG Bug reporting form <noreply@postgresql.org> writes:
> 4) pg_probackup3 process has the following environment variables:
> PWD=3D"/home/dima/MY/Work/CurrentTasks/2025/PBCKP-2289/_Iter003/001--Van=
illa-master/Probackup3/work01/tests/tmp_dirs/ArchiveTest/test_archive_get_=
relative_path/restored/data"
> PGDATA=3D"../../../../../../../../../../../../home/dima/MY/Work/CurrentT=
asks/2025/PBCKP-2289/_Iter003/001--Vanilla-master/Probackup3/work01/tests/=
tmp_dirs/ArchiveTest/test_archive_get_relative_path/restored/data"
> ---------- PROBLEM
> PGDATA (4) is invalid for pg_probackup3.

I do not think this is a Postgres bug.  The PGDATA environment
variable is not canonical, it is just the default to be used if
you don't specify a -D switch on the postmaster/pg_ctl command line.
In fact, it might not be set at all.  (I see that pg_ctl does set
it, but pg_ctl is not the only way to start the postmaster.)
Therefore, relying on PGDATA in a restore_command script isn't safe.
You should be relying on the current working directory (PWD) instead.

			regards, tom lane