Does public_html/test exist?

No, it does not exist but it should not matter.

Duplicate of bug #52065

The issue is not open_basedir but that the functionality supporting is_dir() reports that the path does not exist, and the reason for that is assumed to be an open_basedir restriction. If public_html/test existed then you would not get this warning.

And how does it make not open_basedir problem? You are saying that I can't check if file/dir exists because it might not exist.

Then how about mkdir()? or file_exists() or is_file()? mkdir() cant create directory because it also does not exist? 

cat a.php
<?
ini_set("open_basedir","/home/naox/public_html/test");
mkdir("/home/naox/public_html/test");

php a.php

Warning: mkdir(): open_basedir restriction in effect. File(/home/naox/public_html/test) is not within the allowed path(s): (/home/naox/public_html/test) in /home/naox/public_html/naox.vipserv.org/a.php on line 3

> And how does it make not open_basedir problem? You are saying that I can't check
> if file/dir exists because it might not exist.

I'll try again.

open_basedir is not the problem. It works correctly. What does *not* work correctly is what PHP does when a file or directory does not exist.

if (path_exists_and_is_inside_open_basedir($path)) {
  // (A) good: exists
} else {
  if (open_basedir_is_enabled()) {
    // (B) bad: "open_basedir restriction in effect"
    // what if $path does not exist and is *inside* open_basedir!
  } else {
    // (C) good: does not exist
  }
}

It seems to me this issue is slightly different from bug #52065.
In this case, I'd say this is a documentation issue, namely that
it is not explicitly documented that the directories set in
open_basedir must exist.

> open_basedir is not the problem
> It works correctly

obviosuly

> What does *not* work correctly is what PHP does when a 
> file or directory does not exist

and why don't that get fixed given that this issue exists at least for 15 years now?

> open_basedir restriction in effect. File(/home/naox/public_html/test) 
> is not within the allowed path(s): (/home/naox/public_html/test/)

seriously:

A: /home/naox/public_html/test
B: /home/naox/public_html/test/

A is pretty clear within B and you could check that and shut up

Why would you want to specify a non existent directory as
open_basedir in the first place?

congratulations, with 7.4.21 is_file() starts with the same idiotic behavior

AUTOTEST ERROR-HANDLER: 'code: 2' 'msg: is_file(): open_basedir restriction in effect. File(/rte/../formate/formate.css) is not within the allowed path(s): (:/usr/share/php:/usr:/rpmbuild/PHP-PGO