Date: Mon, 16 Mar 2020 16:20:21 +0100 (CET)
From: Fabien COELHO <coelho@cri.ensmp.fr>
To: Justin Pryzby <pryzby@telsasoft.com>
cc: Alvaro Herrera <alvherre@2ndquadrant.com>,
    David Steele <david@pgmasters.net>, pgsql-hackers@postgresql.org,
    "Bossart, Nathan" <bossartn@amazon.com>,
    Thomas Munro <thomas.munro@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>
Subject: Re: pg_ls_tmpdir to show directories and shared filesets (and
 pg_ls_*)
In-Reply-To: <20200315212729.GC26184@telsasoft.com>
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About v11, ISTM that the recursive function should check for symbolic 
links and possibly avoid them:

  sh> cd data/base
  sh> ln -s .. foo

  psql> SELECT * FROM pg_ls_dir_recurse('.');
  ERROR:  could not stat file "./base/foo/base/foo/base/foo/base/foo/base/foo/base/foo/base/foo/base/foo/base/foo/base/foo/base/foo/base/foo/base/foo/base/foo/base/foo/base/foo/base/foo/base/foo/base/foo/base/foo/base/foo/base/foo/base/foo/base/foo/base/foo/base/foo/base/foo/base/foo/base/foo/base/foo/base/foo/base/foo/base/foo/base/foo/base/foo/base/foo/base/foo/base/foo/base/foo/base/foo/base/foo": Too many levels of symbolic links
  CONTEXT:  SQL function "pg_ls_dir_recurse" statement 1

This probably means using lstat instead of (in supplement to?) stat, and 
probably tell if something is a link, and if so not recurse in them.

-- 
Fabien.