From: Tom Lane <tgl@sss.pgh.pa.us>
To: Anders Kaseorg <andersk@mit.edu>
cc: Daniel Gustafsson <daniel@yesql.se>,
        Kyotaro Horiguchi <horikyota.ntt@gmail.com>, alvherre@alvh.no-ip.org,
        pgsql-hackers@lists.postgresql.org
Subject: Re: [PATCH] Prefer getenv("HOME") to find the UNIX home directory
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Comments: In-reply-to Anders Kaseorg <andersk@mit.edu>
	message dated "Sun, 09 Jan 2022 12:50:54 -0800"
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Date: Sun, 09 Jan 2022 16:04:07 -0500
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Anders Kaseorg <andersk@mit.edu> writes:
> On 1/9/22 10:59, Tom Lane wrote:
>> Given the POSIX requirements, it's basically impossible to believe
>> that there are interesting cases where $HOME isn't set.  Thus, it
>> seems to me that keeping the getpwuid calls will just mean carrying
>> untestable dead code, so we should simplify matters by ripping
>> those out and *only* consulting $HOME.

> While POSIX requires that the login program put you in a conforming 
> environment, nothing stops the user from building a non-conforming 
> environment, such as with ‘env -i’.  One could argue that such a user 
> deserves whatever broken behavior they might get.  But to me it seems 
> prudent to continue working there if it worked before.

The only case that the v1 patch helps such a user for is if they
unset HOME or set it precisely to ''.  If they set it to anything
else, it's still broken from their perspective.  So I do not find
that that argument holds water.

Moreover, ISTM that the only plausible use-case for unsetting HOME
is to prevent programs from finding stuff in your home directory.
What would be the point otherwise?  So it's pretty hard to envision
a case where somebody is actually using, and happy with, the
behavior you argue we ought to keep.

>> The v1 patch also neglects the matter of documentation.

> The reason I didn’t change the documentation is that this is already 
> what “~” is supposed to mean according to POSIX and common 
> implementations.

The point here is precisely that we're changing what *we* think ~
means.  I don't think we can just leave the docs unchanged.

			regards, tom lane