GNU bug report logs - #20923
mgetgroups.c vs getgrouplist warning on OS X

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Jim Meyering <jim <at> meyering.net>
To: bug-coreutils <at> gnu.org
Subject: mgetgroups.c vs getgrouplist warning on OS X
Date: Sun, 28 Jun 2015 16:41:42 -0700

I compiled the just-published snapshot on OS X configured with
--enable-gcc-warnings, and saw this:

lib/mgetgroups.c: In function 'mgetgroups':
lib/mgetgroups.c:90:45: error: pointer targets in passing argument 3
of 'getgrouplist' differ in signedness [-Werror=pointer-sign]
           ng = getgrouplist (username, gid, g, &max_n_groups);
                                             ^

Message #8 received at 20923 <at> debbugs.gnu.org (full text, mbox):

From: Paul Eggert <eggert <at> cs.ucla.edu>
To: Jim Meyering <jim <at> meyering.net>, 20923 <at> debbugs.gnu.org
Cc: Gnulib bugs <bug-gnulib <at> gnu.org>
Subject: Re: bug#20923: mgetgroups.c vs getgrouplist warning on OS X
Date: Sun, 28 Jun 2015 23:48:01 -0700

[Message part 1 (text/plain, inline)]

Jim Meyering wrote:
> I compiled the just-published snapshot on OS X configured with
> --enable-gcc-warnings, and saw this:
>
> lib/mgetgroups.c: In function 'mgetgroups':
> lib/mgetgroups.c:90:45: error: pointer targets in passing argument 3
> of 'getgrouplist' differ in signedness [-Werror=pointer-sign]
>             ng = getgrouplist (username, gid, g, &max_n_groups);

Does the attached gnulib patch fix things for you on OS X?

Its documentation lists OS X 10.11 (released this month), as I assume the 
incompatiblity is in the latest version of OS X and that Apple's never going to 
fix it....

[0001-mgetgroups-port-to-strict-OS-X.patch (text/x-diff, attachment)]

Message #11 received at 20923 <at> debbugs.gnu.org (full text, mbox):

From: Jim Meyering <jim <at> meyering.net>
To: Paul Eggert <eggert <at> cs.ucla.edu>
Cc: Gnulib bugs <bug-gnulib <at> gnu.org>, 20923 <at> debbugs.gnu.org
Subject: Re: bug#20923: mgetgroups.c vs getgrouplist warning on OS X
Date: Mon, 29 Jun 2015 10:48:42 -0700

On Sun, Jun 28, 2015 at 11:48 PM, Paul Eggert <eggert <at> cs.ucla.edu> wrote:
> Jim Meyering wrote:
>>
>> I compiled the just-published snapshot on OS X configured with
>> --enable-gcc-warnings, and saw this:
>>
>> lib/mgetgroups.c: In function 'mgetgroups':
>> lib/mgetgroups.c:90:45: error: pointer targets in passing argument 3
>> of 'getgrouplist' differ in signedness [-Werror=pointer-sign]
>>             ng = getgrouplist (username, gid, g, &max_n_groups);
>
>
> Does the attached gnulib patch fix things for you on OS X?
>
> Its documentation lists OS X 10.11 (released this month), as I assume the
> incompatiblity is in the latest version of OS X and that Apple's never going
> to fix it....

Hi Paul,
Thanks for writing that, but it did not help: the first variant compiled
just fine here (and probably everywhere),
so HAVE_GETGROUPLIST_WITH_INT was not defined.

The problem arises only when using --enable-gcc-warnings and the prototype-
required int* (type of argument 3) conflicts with the gid_t* argument.

Message #14 received at 20923 <at> debbugs.gnu.org (full text, mbox):

From: Paul Eggert <eggert <at> cs.ucla.edu>
To: Jim Meyering <jim <at> meyering.net>
Cc: Gnulib bugs <bug-gnulib <at> gnu.org>, 20923 <at> debbugs.gnu.org
Subject: Re: bug#20923: mgetgroups.c vs getgrouplist warning on OS X
Date: Mon, 29 Jun 2015 11:39:49 -0700

[Message part 1 (text/plain, inline)]

Jim Meyering wrote:
> the first variant compiled
> just fine here (and probably everywhere),
> so HAVE_GETGROUPLIST_WITH_INT was not defined.

Yes, well, it did work on GNU/Linux, which is what I tested it on.....

How about if we make the check pickier, so that it is likely to be triggered 
even without --enable-gcc-warnings, as in the attached?

[0001-mgetgroups-port-to-strict-OS-X.patch (text/x-diff, attachment)]

Message #17 received at 20923 <at> debbugs.gnu.org (full text, mbox):

From: Jim Meyering <jim <at> meyering.net>
To: Paul Eggert <eggert <at> cs.ucla.edu>
Cc: Gnulib bugs <bug-gnulib <at> gnu.org>, 20923 <20923 <at> debbugs.gnu.org>
Subject: Re: bug#20923: mgetgroups.c vs getgrouplist warning on OS X
Date: Mon, 29 Jun 2015 14:01:56 -0700

On Mon, Jun 29, 2015 at 11:39 AM, Paul Eggert <eggert <at> cs.ucla.edu> wrote:
> Jim Meyering wrote:
>>
>> the first variant compiled
>> just fine here (and probably everywhere),
>> so HAVE_GETGROUPLIST_WITH_INT was not defined.
>
>
> Yes, well, it did work on GNU/Linux, which is what I tested it on.....
>
> How about if we make the check pickier, so that it is likely to be triggered
> even without --enable-gcc-warnings, as in the attached?

Thanks for another patch! Unfortunately, that still evokes only a
warning at least
with gcc 6.0.0 20150426.

Message #20 received at 20923 <at> debbugs.gnu.org (full text, mbox):

From: Jim Meyering <jim <at> meyering.net>
To: Paul Eggert <eggert <at> cs.ucla.edu>
Cc: Gnulib bugs <bug-gnulib <at> gnu.org>, 20923 <20923 <at> debbugs.gnu.org>
Subject: Re: bug#20923: mgetgroups.c vs getgrouplist warning on OS X
Date: Mon, 29 Jun 2015 15:35:51 -0700

On Mon, Jun 29, 2015 at 2:01 PM, Jim Meyering <jim <at> meyering.net> wrote:
> On Mon, Jun 29, 2015 at 11:39 AM, Paul Eggert <eggert <at> cs.ucla.edu> wrote:
>> Jim Meyering wrote:
>>>
>>> the first variant compiled
>>> just fine here (and probably everywhere),
>>> so HAVE_GETGROUPLIST_WITH_INT was not defined.
>>
>>
>> Yes, well, it did work on GNU/Linux, which is what I tested it on.....
>>
>> How about if we make the check pickier, so that it is likely to be triggered
>> even without --enable-gcc-warnings, as in the attached?
>
> Thanks for another patch! Unfortunately, that still evokes only a
> warning at least
> with gcc 6.0.0 20150426.

Darn it. I see that I mistakenly pushed one of your patches
when I pushed the linkat.m4 fix, Paul. Sorry about that.
Happy to revert, if you'd like that. Let me know.

Message #23 received at 20923 <at> debbugs.gnu.org (full text, mbox):

From: Paul Eggert <eggert <at> cs.ucla.edu>
To: Jim Meyering <jim <at> meyering.net>
Cc: Gnulib bugs <bug-gnulib <at> gnu.org>, 20923 <20923 <at> debbugs.gnu.org>
Subject: Re: bug#20923: mgetgroups.c vs getgrouplist warning on OS X
Date: Mon, 29 Jun 2015 19:19:05 -0700

[Message part 1 (text/plain, inline)]

Jim Meyering wrote:
> Darn it. I see that I mistakenly pushed one of your patches
> when I pushed the linkat.m4 fix, Paul. Sorry about that.
> Happy to revert, if you'd like that. Let me know.

No problem.  I installed the attached further patch; does it fix things for you? 
 If we can't get this to work I can revert the whole thing.

[0001-mgetgroups-fix-port-to-strict-OS-X.patch (text/x-diff, attachment)]

Message #26 received at 20923 <at> debbugs.gnu.org (full text, mbox):

From: Jim Meyering <jim <at> meyering.net>
To: Paul Eggert <eggert <at> cs.ucla.edu>
Cc: Gnulib bugs <bug-gnulib <at> gnu.org>, 20923 <20923 <at> debbugs.gnu.org>
Subject: Re: bug#20923: mgetgroups.c vs getgrouplist warning on OS X
Date: Mon, 29 Jun 2015 20:03:23 -0700

[Message part 1 (text/plain, inline)]

On Mon, Jun 29, 2015 at 7:19 PM, Paul Eggert <eggert <at> cs.ucla.edu> wrote:
> Jim Meyering wrote:
>>
>> Darn it. I see that I mistakenly pushed one of your patches
>> when I pushed the linkat.m4 fix, Paul. Sorry about that.
>> Happy to revert, if you'd like that. Let me know.
>
> No problem.  I installed the attached further patch; does it fix things for
> you?  If we can't get this to work I can revert the whole thing.

Thanks.

I adjusted via the attached patch (the declaration
of getgrouplist is in <unistd.h>, and the "then"-block
should use gid_t), and tested: there was not even a
warning for the test program emitted by the "then"-block,
so same result as before:

  lib/mgetgroups.c: In function 'mgetgroups':
  lib/mgetgroups.c:70:32: error: pointer targets in passing argument 3
of 'getgrouplist' differ in signedness [-Werror=pointer-sign]
   #  define getgrouplist_gids(g) (g)
                                  ^

[mgetgroups.m4.patch (application/octet-stream, attachment)]

Message #29 received at 20923 <at> debbugs.gnu.org (full text, mbox):

From: Paul Eggert <eggert <at> cs.ucla.edu>
To: Jim Meyering <jim <at> meyering.net>
Cc: Gnulib bugs <bug-gnulib <at> gnu.org>, 20923 <20923 <at> debbugs.gnu.org>
Subject: Re: bug#20923: mgetgroups.c vs getgrouplist warning on OS X
Date: Tue, 30 Jun 2015 09:36:28 -0700

[Message part 1 (text/plain, inline)]

Jim Meyering wrote:

> same result as before:

OK, let's give up on this approach and try something more direct.  I installed 
the attached patch; does it work on OS X?

[0001-mgetgroups-port-to-strict-OS-X.patch (text/x-diff, attachment)]

Message #32 received at 20923 <at> debbugs.gnu.org (full text, mbox):

From: Jim Meyering <jim <at> meyering.net>
To: Paul Eggert <eggert <at> cs.ucla.edu>
Cc: Gnulib bugs <bug-gnulib <at> gnu.org>, 20923 <20923 <at> debbugs.gnu.org>
Subject: Re: bug#20923: mgetgroups.c vs getgrouplist warning on OS X
Date: Tue, 30 Jun 2015 11:03:19 -0700

On Tue, Jun 30, 2015 at 9:36 AM, Paul Eggert <eggert <at> cs.ucla.edu> wrote:
> Jim Meyering wrote:
>
>> same result as before:
>
> OK, let's give up on this approach and try something more direct.  I
> installed the attached patch; does it work on OS X?

Perfect.
I made latest coreutils use latest from gnulib, and now it all compiles
warning-free there with --enable-gcc-warnings and gcc-6.x

Thank you!

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