bug#47790: 27.2; XDG_DATA_HOME evaluation in move-file-to-trash

bug#47790: 27.2; XDG_DATA_HOME evaluation in move-file-to-trash

[Thierry Volpiatto]

In `move-file-to-trash` there is this code:

    (or (getenv "XDG_DATA_HOME")
        "~/.local/share")

If XDG_DATA_HOME is not set getenv returns nil and that's fine, if
XDG_DATA_HOME is set to a file path this path is returned and it's fine
as well, however if user follow recommendations of
https://specifications.freedesktop.org/basedir-spec/latest/ar01s03.html
and set XDG_DATA_HOME to "$HOME/.local/share" then the above block will
return this value from getenv which is wrong, `substitute-in-file-name`
should be used here.

    (setenv "XDG_DATA_HOME" "$HOME/.local/share")
    (or (getenv "XDG_DATA_HOME")
         "~/.local/share")
    ==> "$HOME/.local/share"
    (substitute-in-file-name
     (or (getenv "XDG_DATA_HOME")
         "~/.local/share"))
    ==> /home/you/.local/share

Not far after in the code tou have this block that attempt to create the
trash directory:

    ;; Ensure that the trash directory exists; otherwise, create it.
    (with-file-modes #o700
      (unless (file-exists-p trash-files-dir)
        (make-directory trash-files-dir t))
      (unless (file-exists-p trash-info-dir)
        (make-directory trash-info-dir t)))

which expand to (make-directory "$HOME/.local/share" t)



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-- 
Thierry

bug#47790: 27.2; XDG_DATA_HOME evaluation in move-file-to-trash

[Eli Zaretskii]

> From: Thierry Volpiatto <thievol@posteo.net>
> Date: Thu, 15 Apr 2021 10:05:04 +0200
> 
> 
> In `move-file-to-trash` there is this code:
> 
>     (or (getenv "XDG_DATA_HOME")
>         "~/.local/share")
> 
> If XDG_DATA_HOME is not set getenv returns nil and that's fine, if
> XDG_DATA_HOME is set to a file path this path is returned and it's fine
> as well, however if user follow recommendations of
> https://specifications.freedesktop.org/basedir-spec/latest/ar01s03.html
> and set XDG_DATA_HOME to "$HOME/.local/share" then the above block will
> return this value from getenv which is wrong, `substitute-in-file-name`
> should be used here.
> 
>     (setenv "XDG_DATA_HOME" "$HOME/.local/share")

Is this a valid setting of an environment variable?  IOW, are values
of environment variables allowed to reference other environment
variables, and thus are applications required to recursively expand
the values of environment variables until no references are left?
And, as a corollary, does it mean that '$' in file names are not
supported by environment variables whose values are file names?

bug#47790: 27.2; XDG_DATA_HOME evaluation in move-file-to-trash

[Thierry Volpiatto]

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Eli Zaretskii <eliz@gnu.org> writes:

> Is this a valid setting of an environment variable?

Probably not in emacs with setenv, but in a .profile or .bash_profile,
maybe, at least according to
https://specifications.freedesktop.org/basedir-spec/latest/ar01s03.html
but is is up to you to decide if it is right or not to create a $HOME
directory which is a copy of the $HOME directory in the back of the user
each time he trashes a file with such setting (I added a warning in helm
documentation years ago about this).

-- 
Thierry

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bug#47790: 27.2; XDG_DATA_HOME evaluation in move-file-to-trash

[Basil L. Contovounesios]

Thierry Volpiatto <thievol@posteo.net> writes:

> Eli Zaretskii <eliz@gnu.org> writes:
>
>> Is this a valid setting of an environment variable?
>
> Probably not in emacs with setenv, but in a .profile or .bash_profile,
> maybe,

In shell RC files, double quotes would expand any contained variables.

> at least according to
> https://specifications.freedesktop.org/basedir-spec/latest/ar01s03.html

That spec doesn't say anything about variable expansion in different
contexts.  IME when someone says "set FOO to $HOME/.foo" without any
further qualification they are implicitly referring to the expansion of
$HOME.

FWIW,

-- 
Basil

bug#47790: 27.2; XDG_DATA_HOME evaluation in move-file-to-trash

[Eli Zaretskii]

> From: "Basil L. Contovounesios" <contovob@tcd.ie>
> Cc: Eli Zaretskii <eliz@gnu.org>,  47790@debbugs.gnu.org
> Date: Thu, 15 Apr 2021 13:12:29 +0100
> 
> IME when someone says "set FOO to $HOME/.foo" without any further
> qualification they are implicitly referring to the expansion of
> $HOME.

That's what I knew, but Thierry seems to say otherwise.

bug#47790: 27.2; XDG_DATA_HOME evaluation in move-file-to-trash

[Thierry Volpiatto]

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Eli Zaretskii <eliz@gnu.org> writes:

>> From: "Basil L. Contovounesios" <contovob@tcd.ie>
>> Cc: Eli Zaretskii <eliz@gnu.org>,  47790@debbugs.gnu.org
>> Date: Thu, 15 Apr 2021 13:12:29 +0100
>> 
>> IME when someone says "set FOO to $HOME/.foo" without any further
>> qualification they are implicitly referring to the expansion of
>> $HOME.
>
> That's what I knew, but Thierry seems to say otherwise.

Well, it is common to set PATH like this:

PATH="$HOME/bin:$PATH"

you find this in ~/.profile or ~/.bashrc on many distros.
I didn't find documentaion about this though.
Anyway the problem is if one do this with XDG_DATA_HOME and trash files
from different directories, a copy of his home directory will be done in
each of those directories under literally "$HOME/user".
If you consider this is fine and normal you can close this bug report.

Thanks.

-- 
Thierry

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bug#47790: 27.2; XDG_DATA_HOME evaluation in move-file-to-trash

[Basil L. Contovounesios]

Thierry Volpiatto <thievol@posteo.net> writes:

> Eli Zaretskii <eliz@gnu.org> writes:
>
>>> From: "Basil L. Contovounesios" <contovob@tcd.ie>
>>> Cc: Eli Zaretskii <eliz@gnu.org>,  47790@debbugs.gnu.org
>>> Date: Thu, 15 Apr 2021 13:12:29 +0100
>>> 
>>> IME when someone says "set FOO to $HOME/.foo" without any further
>>> qualification they are implicitly referring to the expansion of
>>> $HOME.
>>
>> That's what I knew, but Thierry seems to say otherwise.
>
> Well, it is common to set PATH like this:
>
> PATH="$HOME/bin:$PATH"
>
> you find this in ~/.profile or ~/.bashrc on many distros.

Any variables enclosed in double quotes "..." are expanded when this
expression is evaluated by the shell.

You can confirm this by running 'echo "$PATH"'.

> I didn't find documentaion about this though.

See one of the following:
- 'man 1 dash', headings 'Double Quotes' and 'Parameter Expansion'.
- 'man 1 bash', headings 'QUOTING' and 'Parameter Expansion'.
- (info "(bash) Double Quotes")
  https://gnu.org/software/bash/manual/html_node/Double-Quotes.html

> Anyway the problem is if one do this with XDG_DATA_HOME and trash files
> from different directories, a copy of his home directory will be done in
> each of those directories under literally "$HOME/user".

But this only happens when you set XDG_DATA_HOME to a string that
includes shell variables, right?  If so...

> If you consider this is fine and normal you can close this bug report.

...then I don't think that was ever implied as being supported, and I
don't see the need to support it, but that's just one impression.

Thanks,

-- 
Basil

bug#47790: 27.2; XDG_DATA_HOME evaluation in move-file-to-trash

[Thierry Volpiatto]

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"Basil L. Contovounesios" <contovob@tcd.ie> writes:

> Thierry Volpiatto <thievol@posteo.net> writes:
>
>> Eli Zaretskii <eliz@gnu.org> writes:
>>
>>>> From: "Basil L. Contovounesios" <contovob@tcd.ie>
>>>> Cc: Eli Zaretskii <eliz@gnu.org>,  47790@debbugs.gnu.org
>>>> Date: Thu, 15 Apr 2021 13:12:29 +0100
>>>> 
>>>> IME when someone says "set FOO to $HOME/.foo" without any further
>>>> qualification they are implicitly referring to the expansion of
>>>> $HOME.
>>>
>>> That's what I knew, but Thierry seems to say otherwise.
>>
>> Well, it is common to set PATH like this:
>>
>> PATH="$HOME/bin:$PATH"
>>
>> you find this in ~/.profile or ~/.bashrc on many distros.
>
> Any variables enclosed in double quotes "..." are expanded when this
> expression is evaluated by the shell.
>
> You can confirm this by running 'echo "$PATH"'.

I already know this.

>> I didn't find documentaion about this though.
>
> See one of the following:
> - 'man 1 dash', headings 'Double Quotes' and 'Parameter Expansion'.
> - 'man 1 bash', headings 'QUOTING' and 'Parameter Expansion'.
> - (info "(bash) Double Quotes")
>   https://gnu.org/software/bash/manual/html_node/Double-Quotes.html

I know this as well... but this is unrelated to the problem you have in
emacs.

>> Anyway the problem is if one do this with XDG_DATA_HOME and trash files
>> from different directories, a copy of his home directory will be done in
>> each of those directories under literally "$HOME/user".
>
> But this only happens when you set XDG_DATA_HOME to a string that
> includes shell variables, right?  If so...
>
>> If you consider this is fine and normal you can close this bug report.
>
> ...then I don't think that was ever implied as being supported, and I
> don't see the need to support it, but that's just one impression.

Fair enough, so you can close this.

Thanks.

-- 
Thierry

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bug#47790: 27.2; XDG_DATA_HOME evaluation in move-file-to-trash

[Basil L. Contovounesios]

tags 47790 notabug
close 47790
quit

Thierry Volpiatto <thievol@posteo.net> writes:

> "Basil L. Contovounesios" <contovob@tcd.ie> writes:
>
>> Thierry Volpiatto <thievol@posteo.net> writes:
>>
>>> Eli Zaretskii <eliz@gnu.org> writes:
>>>
>>>>> From: "Basil L. Contovounesios" <contovob@tcd.ie>
>>>>> Cc: Eli Zaretskii <eliz@gnu.org>,  47790@debbugs.gnu.org
>>>>> Date: Thu, 15 Apr 2021 13:12:29 +0100
>>>>> 
>>>>> IME when someone says "set FOO to $HOME/.foo" without any further
>>>>> qualification they are implicitly referring to the expansion of
>>>>> $HOME.
>>>>
>>>> That's what I knew, but Thierry seems to say otherwise.
>>>
>>> Well, it is common to set PATH like this:
>>>
>>> PATH="$HOME/bin:$PATH"
>>>
>>> you find this in ~/.profile or ~/.bashrc on many distros.
>>
>> Any variables enclosed in double quotes "..." are expanded when this
>> expression is evaluated by the shell.
>>
>> You can confirm this by running 'echo "$PATH"'.
>
> I already know this.
>
>>> I didn't find documentaion about this though.
>>
>> See one of the following:
>> - 'man 1 dash', headings 'Double Quotes' and 'Parameter Expansion'.
>> - 'man 1 bash', headings 'QUOTING' and 'Parameter Expansion'.
>> - (info "(bash) Double Quotes")
>>   https://gnu.org/software/bash/manual/html_node/Double-Quotes.html
>
> I know this as well... but this is unrelated to the problem you have in
> emacs.

I never said it was related, but you used these shell examples to argue
that Emacs should expand shell variables present in environment variable
strings.

I was pointing out that your examples imply the opposite: that the shell
expands the variables long before they enter the environment (equivalent
to the use of substitute-in-file-name in the OP).

So Emacs is not necessarily behaving any differently to other programs
that query their environment, based on these examples.

>>> Anyway the problem is if one do this with XDG_DATA_HOME and trash files
>>> from different directories, a copy of his home directory will be done in
>>> each of those directories under literally "$HOME/user".
>>
>> But this only happens when you set XDG_DATA_HOME to a string that
>> includes shell variables, right?  If so...
>>
>>> If you consider this is fine and normal you can close this bug report.
>>
>> ...then I don't think that was ever implied as being supported, and I
>> don't see the need to support it, but that's just one impression.
>
> Fair enough, so you can close this.

Thanks, done.  We can always reopen it if new information comes to
light.

-- 
Basil