GNU bug report logs - #23537
timeout test gets false-positive for duration of -1.189731495357231765e+4932

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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: timeout test gets false-positive for duration of
 -1.189731495357231765e+4932
Date: Sat, 14 May 2016 10:09:19 -0700

On systems with recent glibc, this abuse of timeout elicits the expected error:

  $ src/timeout -- -1.189731495357231765e+4932 sleep 0
  src/timeout: invalid time interval ‘-1.189731495357231765e+4932’
  Try 'src/timeout --help' for more information.

But with glibc-2.12's strtod, that input maps to a double-precision
value of 0 rather than to -inf, so timeout does this:

  $ src/timeout -- -1.189731495357231765e+4932 sleep 0; echo $?
  0

Similarly, the sleep.sh test fails because even without the leading "-",
that number ($LDBL_MAX) maps to 0:

  $ src/timeout 0.1 sleep 1.189731495357231765e+4932; echo $?
  0

which causes two tests to fail:

  tests/misc/timeout-parameters
  tests/misc/sleep

I see a couple of ways to avoid trouble.
Perhaps the most general is to make gnulib's strtod module detect and
compensate for these errors.
But that's CentOS6-era glibc, so maybe not worth it for such a corner case.

Message #8 received at 23537 <at> debbugs.gnu.org (full text, mbox):

From: Paul Eggert <eggert <at> cs.ucla.edu>
To: Jim Meyering <jim <at> meyering.net>, 23537 <at> debbugs.gnu.org
Subject: Re: bug#23537: timeout test gets false-positive for duration of
 -1.189731495357231765e+4932
Date: Sat, 14 May 2016 10:32:21 -0700

Jim Meyering wrote:
> But that's CentOS6-era glibc, so maybe not worth it for such a corner case.

Yes, I tend to agree, this is quite low priority.

Message #11 received at 23537 <at> debbugs.gnu.org (full text, mbox):

From: Pádraig Brady <P <at> draigBrady.com>
To: Jim Meyering <jim <at> meyering.net>, 23537 <at> debbugs.gnu.org
Subject: Re: bug#23537: timeout test gets false-positive for duration of
 -1.189731495357231765e+4932
Date: Sun, 15 May 2016 12:21:08 +0100

On 14/05/16 18:09, Jim Meyering wrote:
> On systems with recent glibc, this abuse of timeout elicits the expected error:
>
>    $ src/timeout -- -1.189731495357231765e+4932 sleep 0
>    src/timeout: invalid time interval ‘-1.189731495357231765e+4932’
>    Try 'src/timeout --help' for more information.
>
> But with glibc-2.12's strtod, that input maps to a double-precision
> value of 0 rather than to -inf, so timeout does this:
>
>    $ src/timeout -- -1.189731495357231765e+4932 sleep 0; echo $?
>    0
>
> Similarly, the sleep.sh test fails because even without the leading "-",
> that number ($LDBL_MAX) maps to 0:
>

So the buggy strtod() is treating the overflow as underflow :(

>    $ src/timeout 0.1 sleep 1.189731495357231765e+4932; echo $?
>    0
>
> which causes two tests to fail:
>
>    tests/misc/timeout-parameters
>    tests/misc/sleep
>
> I see a couple of ways to avoid trouble.
> Perhaps the most general is to make gnulib's strtod module detect and
> compensate for these errors.
> But that's CentOS6-era glibc, so maybe not worth it for such a corner case.

Has up to date centos6 the bug?
I didn't see it with glibc-2.12-1.166.el6_7.7.x86_64

cheers,
Pádraig.

Message #14 received at 23537 <at> debbugs.gnu.org (full text, mbox):

From: Jim Meyering <jim <at> meyering.net>
To: Pádraig Brady <P <at> draigbrady.com>
Cc: 23537 <at> debbugs.gnu.org
Subject: Re: bug#23537: timeout test gets false-positive for duration of
 -1.189731495357231765e+4932
Date: Sun, 15 May 2016 08:06:57 -0700

On Sun, May 15, 2016 at 4:21 AM, Pádraig Brady <P <at> draigbrady.com> wrote:
> Has up to date centos6 the bug?
> I didn't see it with glibc-2.12-1.166.el6_7.7.x86_64

Yes. I am surprised that you don't see it and I do:

  $ rpm -q glibc
  glibc-2.12-1.166.el6_7.7.x86_64
  $ src/timeout 0.1 sleep 1.189731495357231765e+4932; echo $?
  0

Message #19 received at 23537-done <at> debbugs.gnu.org (full text, mbox):

From: Jim Meyering <jim <at> meyering.net>
To: Pádraig Brady <P <at> draigbrady.com>
Cc: 23537-done <at> debbugs.gnu.org
Subject: Re: bug#23537: timeout test gets false-positive for duration of
 -1.189731495357231765e+4932
Date: Sun, 15 May 2016 08:51:58 -0700

tags 23537 notabug
stop

On Sun, May 15, 2016 at 8:06 AM, Jim Meyering <jim <at> meyering.net> wrote:
> On Sun, May 15, 2016 at 4:21 AM, Pádraig Brady <P <at> draigbrady.com> wrote:
>> Has up to date centos6 the bug?
>> I didn't see it with glibc-2.12-1.166.el6_7.7.x86_64
>
> Yes. I am surprised that you don't see it and I do:
>
>   $ rpm -q glibc
>   glibc-2.12-1.166.el6_7.7.x86_64
>   $ src/timeout 0.1 sleep 1.189731495357231765e+4932; echo $?
>   0

Pádraig guessed (correctly) that I'd updated coreutils' gnulib to
include a temporarily buggy xstrdod
(811b09243ca01827469827bf0973728a8619d249), but not yet past the fix
from a day or so later.
So this was all a false alert.

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