[PATCH] Gracefully handle incompatible locale data

[Carlos O'Donell]

On 09/29/2015 04:08 AM, Ludovic Courtès wrote:
> "Carlos O'Donell" <carlos@redhat.com> skribis:
> 
>> On 09/26/2015 06:24 AM, Ludovic Courtès wrote:
>>> Furthermore, the function in question returns EINVAL in other similar
>>> cases–e.g., when libc 2.22 loads LC_COLLATE data from libc 2.21.
>>
>> If you change this particular case to EINVAL, what does the user see
>> as a result of this change?
> 
> The user-visible change is that, if incompatible or broken locale data
> is found, a call like:
> 
>   setlocale (LC_ALL, "");
> 
> returns EINVAL instead of aborting.

Perfect.
 
>> Do they get a non-zero exit code from `localedef --list-archive` along
>> with an error written out to stderr?
> 
> ‘localedef’ starts with:
> 
>   setlocale (LC_MESSAGES, "");
>   setlocale (LC_CTYPE, "");
> 
> so it will no longer abort when invalid locale data is found (although
> in the 2.21 → 2.22 transition, only the LC_COLLATE data format differs
> anyway.)

OK.

> Apart from that, ‘localedef --list-archive’ simply opens the locale
> archive (typically /usr/lib/locale/locale-archive, regardless of the
> ‘LOCPATH’ environment variable value), so its behavior is unchanged.
> 
> Am I overlooking something?

If the locale-archive is upgraded to the new format with LC_COLLATE changed
what happens when you run localedef --list-archive? Does it list zero locales
and exit with an exit code of zero?

I would hope that it prints something about the broken locale, because after
the removal of the assertion you won't know anything is wrong with the archive?

>> This is the kind of change I'm expecting. If we are removing an assertion,
>> we should be replacing it with something meaningful and verifying that
>> meaningful change.
> 
> Yes, agreed.
> 
> The function that is changed, ‘_nl_intern_locale_data’, has only two
> callers in libc, and both check whether it returns NULL.  So it seems to
> me that the code is not introducing anything new in the API contract.
> WDYT?

It isn't introducing anything new, but you are removing an assert and we need
to make sure that the intent of the design remains: Warn the user something
is wrong with the locale data.

I see two cases:

- What does setlocale() return?

  - Verified. You say it returns EINVAL for the affected locale and that's perfect.

- What does localedef --list-archive return?

  - The new LC_COLLATE format will make it's way into the binary locale archive
    and that means glibc can't read the locale-archive? Does it fail? exit code?

If we cover those two cases with some kind of error message then I think we're done.

Cheers,
Carlos.