[lxc-devel] [PATCH] lxc_init.c: error handing for sigaction and sigprocmask

[S.Çağlar Onur]

On Thu, Jan 16, 2014 at 3:16 PM, Stéphane Graber <stgraber at ubuntu.com> wrote:
> On Thu, Jan 16, 2014 at 03:05:46PM -0500, S.Çağlar Onur wrote:
>> Hey,
>>
>> On Thu, Jan 16, 2014 at 11:03 AM, Stéphane Graber <stgraber at ubuntu.com> wrote:
>> > On Thu, Jan 16, 2014 at 03:30:01PM +0800, Qiang Huang wrote:
>> >> Look through all LXC code and seems like only here are missed.
>> >>
>> >> Signed-off-by: Qiang Huang <h.huangqiang at huawei.com>
>> >
>> > Acked-by: Stéphane Graber <stgraber at ubuntu.com>
>>
>> Looks like lxc-execute stopped working after this patch
>>
>> [caglar at qp:~/go/src/github.com/caglar10ur/lxc(devel)] sudo lxc-execute
>> -n t -- ls
>> lxc-init: Invalid argument - failed to sigaction
>>
>> reverting the commit makes it functional again
>>
>> [caglar at qp:~/go/src/github.com/caglar10ur/lxc(devel)] sudo lxc-execute
>> -n t -- ls
>> LICENSE  Makefile  README.md  const.go  container.go  examples  lxc.c
>> lxc.go  lxc.h  lxc_test.go  type.go  util.go
>
> Interesting, can we try to figure out what sig handler is failing, I
> believe that'd be more interesting than doing a plain revert as the
> intent of the previous commit still seems good.

Just submitted a possible fix to this problem

>>
>> >> ---
>> >> Maybe this bug can be marked resolved:
>> >> https://github.com/lxc/lxc/issues/83
>> >> ---
>> >>  src/lxc/lxc_init.c | 46 +++++++++++++++++++++++++++++++---------------
>> >>  1 file changed, 31 insertions(+), 15 deletions(-)
>> >>
>> >> diff --git a/src/lxc/lxc_init.c b/src/lxc/lxc_init.c
>> >> index d88a935..a59dd9c 100644
>> >> --- a/src/lxc/lxc_init.c
>> >> +++ b/src/lxc/lxc_init.c
>> >> @@ -123,11 +123,14 @@ int main(int argc, char *argv[])
>> >>        * mask all the signals so we are safe to install a
>> >>        * signal handler and to fork
>> >>        */
>> >> -     sigfillset(&mask);
>> >> -     sigdelset(&mask, SIGILL);
>> >> -     sigdelset(&mask, SIGSEGV);
>> >> -     sigdelset(&mask, SIGBUS);
>> >> -     sigprocmask(SIG_SETMASK, &mask, &omask);
>> >> +     if (sigfillset(&mask) ||
>> >> +         sigdelset(&mask, SIGILL) ||
>> >> +         sigdelset(&mask, SIGSEGV) ||
>> >> +         sigdelset(&mask, SIGBUS) ||
>> >> +         sigprocmask(SIG_SETMASK, &mask, &omask)) {
>> >> +             SYSERROR("failed to set signal mask");
>> >> +             exit(EXIT_FAILURE);
>> >> +     }
>> >>
>> >>       for (i = 1; i < NSIG; i++) {
>> >>               struct sigaction act;
>> >> @@ -143,15 +146,22 @@ int main(int argc, char *argv[])
>> >>                   i == SIGKILL)
>> >>                       continue;
>> >>
>> >> -             sigfillset(&act.sa_mask);
>> >> -             sigdelset(&act.sa_mask, SIGILL);
>> >> -             sigdelset(&act.sa_mask, SIGSEGV);
>> >> -             sigdelset(&act.sa_mask, SIGBUS);
>> >> -             sigdelset(&act.sa_mask, SIGSTOP);
>> >> -             sigdelset(&act.sa_mask, SIGKILL);
>> >> +             if (sigfillset(&act.sa_mask) ||
>> >> +                 sigdelset(&act.sa_mask, SIGILL) ||
>> >> +                 sigdelset(&act.sa_mask, SIGSEGV) ||
>> >> +                 sigdelset(&act.sa_mask, SIGBUS) ||
>> >> +                 sigdelset(&act.sa_mask, SIGSTOP) ||
>> >> +                 sigdelset(&act.sa_mask, SIGKILL)) {
>> >> +                     ERROR("failed to set signal");
>> >> +                     exit(EXIT_FAILURE);
>> >> +             }
>> >> +
>> >>               act.sa_flags = 0;
>> >>               act.sa_handler = interrupt_handler;
>> >> -             sigaction(i, &act, NULL);
>> >> +             if (sigaction(i, &act, NULL)) {
>> >> +                     SYSERROR("failed to sigaction");
>> >> +                     exit(EXIT_FAILURE);
>> >> +             }
>> >>       }
>> >>
>> >>       lxc_setup_fs();
>> >> @@ -170,7 +180,10 @@ int main(int argc, char *argv[])
>> >>               for (i = 1; i < NSIG; i++)
>> >>                       signal(i, SIG_DFL);
>> >>
>> >> -             sigprocmask(SIG_SETMASK, &omask, NULL);
>> >> +             if (sigprocmask(SIG_SETMASK, &omask, NULL)) {
>> >> +                     SYSERROR("failed to set signal mask");
>> >> +                     exit(EXIT_FAILURE);
>> >> +             }
>> >>
>> >>               NOTICE("about to exec '%s'", aargv[0]);
>> >>
>> >> @@ -180,8 +193,11 @@ int main(int argc, char *argv[])
>> >>       }
>> >>
>> >>       /* let's process the signals now */
>> >> -     sigdelset(&omask, SIGALRM);
>> >> -     sigprocmask(SIG_SETMASK, &omask, NULL);
>> >> +     if (sigdelset(&omask, SIGALRM) ||
>> >> +         sigprocmask(SIG_SETMASK, &omask, NULL)) {
>> >> +             SYSERROR("failed to set signal mask");
>> >> +             exit(EXIT_FAILURE);
>> >> +     }
>> >>
>> >>       /* no need of other inherited fds but stderr */
>> >>       close(fileno(stdin));
>> >> --
>> >> 1.8.3
>> >>
>> >
>> > --
>> > Stéphane Graber
>> > Ubuntu developer
>> > http://www.ubuntu.com
>> >
>> > _______________________________________________
>> > lxc-devel mailing list
>> > lxc-devel at lists.linuxcontainers.org
>> > http://lists.linuxcontainers.org/listinfo/lxc-devel
>> >
>>
>>
>>
>> --
>> S.Çağlar Onur <caglar at 10ur.org>
>> _______________________________________________
>> lxc-devel mailing list
>> lxc-devel at lists.linuxcontainers.org
>> http://lists.linuxcontainers.org/listinfo/lxc-devel
>
> --
> Stéphane Graber
> Ubuntu developer
> http://www.ubuntu.com
>
> _______________________________________________
> lxc-devel mailing list
> lxc-devel at lists.linuxcontainers.org
> http://lists.linuxcontainers.org/listinfo/lxc-devel
>



-- 
S.Çağlar Onur <caglar at 10ur.org>