cygwin-3.1.0 and mintty from desktop shortcut

[Brian Inglis]

On 2020-06-07 03:23, Takashi Yano via Cygwin wrote:
> On Sun, 7 Jun 2020 16:42:52 +0900
> Takashi Yano via Cygwin <cygwin@cygwin.com> wrote:
>> On Sun, 7 Jun 2020 00:15:59 -0600
>> Brian Inglis wrote:
>>> On 2020-06-06 19:35, Takashi Yano via Cygwin wrote:
>>>> On Sat, 06 Jun 2020 13:20:16 +0200
>>>> ASSI wrote:
>>>>> Takashi Yano via Cygwin writes:
>>>>>>> 1. Rename /usr/share/locale to something else, like local.bak.
>>>>>>> 2. Start mintty in the usual way.
>>>>>>> 3. Rename the directory from step 1 back to /usr/share/local.
>>>>>>> 4. Work just like the problem never existed either in the shell running
>>>>>>> inside the mintty or even start a new mintty.
>>>>>>
>>>>>> I guess renaming /usr/share/locale/locale.alias is enough.
>>>>>
>>>>> I've had some time to look into this problem again after having updated
>>>>> Cygwin to the latest and greatest.  Indeed, when
>>>>>
>>>>> /usr/share/locale/locale.alias
>>>>>
>>>>> gets renamed, the problem also goes away.  This is great because I don't
>>>>> really need the locale aliases for anything.  Btw, my laptop got
>>>>> upgraded to Win10 1909 (Enterprise) in the meantime, so the issue isn't
>>>>> specific to 1803 as was supected earlier.
>>>>>
>>>>> I then tried to figure out what exactly causes the problem and it turns
>>>>> out that it's the _presence_ of this file with the additional condition
>>>>> that it must not be owned by the user starting the mintty/shell.  Since
>>>>> I install Cygwin on my work laptop with a different (admin) account and
>>>>> not my (non-admin) user account, that explains why I am seeing the
>>>>> problem there and not on other machines.  Before you are going to
>>>>> suggest that it's the admin vs. non-admin rights: no, if I create a
>>>>> locale.alias with my user account (either as an empty file or a copy of
>>>>> the backup file), then the admin account is unable to start a shell in
>>>>> mintty successfully.  I have no idea why the ownership of a file that
>>>>> onnly should get read (and is readable by everyone) would have the
>>>>> effect I'm seeing, but maybe that gives the clue on where to look for a
>>>>> fix.
>>>>
>>>> Thanks for the additional information. I tested the following steps
>>>> to confirm if the problem can be reproduced.
>>>>
>>>> 1. Enable Administrator account.
>>>> 2. Remove all groups from account yano other than Users.
>>>> 3. Install cygwin for all with gettext package as Administrator.
>>>> 4. Run mintty from desktop shortcut as Administrator.
>>>> 5. Run mintty from desktop shortcut as yano.
>>>>
>>>> Both 4 and 5 successfully open mintty window with shell.
>>>>
>>>> I wonder what is the difference between my environment and yours.
>>>
>>> Locale setting?
>>>
>>> fhandler_tty.cc(fhandler_pty_slave::setup_locale)@2854 calls
>>> get_langinfo@2768 calls@2781
>>> nlsfuncs.cc(__set_locale_from_locale_alias)@1462
>>> which opens /usr/share/locale/locale.alias@1472.
>>>
>>> One problem I see with that is that __set_locale_from_locale_alias is meant to
>>> be called when loadlocale fails with an unrecognized locale, but in
>>> get_langinfo@2778 if the locale is not found, it is defaulted to C before
>>> __set_locale_from_locale_alias is called, defeating the purpose:
>>>
>>>   const char *locale = __loadlocale (&loc, LC_CTYPE, new_locale);
>>>   if (!locale)
>>>     locale = "C";
>>>
>>>   char tmp_locale[ENCODING_LEN + 1];
>>>   char *ret = __set_locale_from_locale_alias (locale, tmp_locale);
>>>   if (ret)
>>>     locale = tmp_locale;
>>
>> Hmm..., you are right. Furthermore, __set_locale_from_locale_alias()
>> here is completely unnecessary since it is already processed in
>> __loadlocale().
> 
> No. I was wrong. If locale alias is used, __loadlocale() returns
> aliased locale. Calling __set_locale_from_locale_alias() is
> necessary to resolve alias. For example, if locale is set to
> "japanese", which is defined in /usr/share/locale/locale.alias,
> __loadlocale() returns "japanese", while
> __set_locale_from_locale_alias() returns "ja_JP.eucJP".
> 
> __loadlocale() returns NULL when the alias resolution also fails.
> So the current code is as designed.

But if __loadlocale() returns a non-NULL string, then the locale and/or alias
has been resolved and loaded, so it is unnecessary to further call
__set_locale_from_locale_alias().
If __loadlocale() returns a NULL string, then you need to set it to the global
default locale "C.ASCII".

-- 
Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada

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