[LTP] [PATCH] sigrelse01: Check if signal 34 is available for musl compat

[Petr Vorel]

Hi Florian,

> Do not select signal 34 when the test is run using musl. Signal 34 is
> used internally by musl as SIGSYNCCALL. Consequently, musl's signal()
> will return with an error status and errno set to EINVAL when trying
> to setup a signal handler for signal 34, causing the sigrelse01 test
> to fail.

> Since musl provides no preprocessor macro, we check for the
> availability of signal 34 by attempting to setup a signal handler. If
> signal() returns SIG_ERR with errno set to EINVAL then we assume the
> signal is unavailable. Knowing signal 34 is available with glibc, we
> perform this check only if __GLIBC__ is not defined.

...
> +++ b/testcases/kernel/syscalls/sigrelse/sigrelse01.c

> +#define _GNU_SOURCE

Unfortunately +#define _GNU_SOURCE causes test to hang, at least on glibc.
And I see for musl it is necessary to get sighandler_t.
Until you fix glibc with _GNU_SOURCE NACK.

But on glibc it also brought a warning, which means _GNU_SOURCE really switches
something on:

sigrelse01.c: In function ‘child’:
sigrelse01.c:397:33: warning: ‘sighold’ is deprecated: Use the sigprocmask function instead [-Wdeprecated-declarations]
  397 |                                 if ((rv = sighold(sig)) != 0) {
      |                                 ^~
In file included from /usr/include/sys/wait.h:36,
                 from sigrelse01.c:104:
/usr/include/signal.h:355:12: note: declared here
  355 | extern int sighold (int __sig) __THROW
      |            ^~~~~~~
sigrelse01.c:472:25: warning: ‘sigrelse’ is deprecated: Use the sigprocmask function instead [-Wdeprecated-declarations]
  472 |                         if ((rv = sigrelse(sig)) != 0) {
      |                         ^~
/usr/include/signal.h:359:12: note: declared here
  359 | extern int sigrelse (int __sig) __THROW
      |            ^~~~~~~~
sigrelse01.c: In function ‘timeout’:
sigrelse01.c:675:25: warning: unused parameter ‘sig’ [-Wunused-parameter]
  675 | static void timeout(int sig)
      |                     ~~~~^~~

Also this is a very old test, which needs cleanup and rewrite to new LTP API
(e.g. remove old unixes, e.g. VAX and get test more reliable). I suppose
handling signals with LTP legacy API is broken.

> +
>  #include <sys/types.h>
>  #include <sys/wait.h>
>  #include <errno.h>
>  #include <fcntl.h>
>  #include <signal.h>
> +#include <stdbool.h>

nit: I would postpone this after conversion this to new LTP API.
Script already uses legacy definitions
#define TRUE 1
#define FALSE 0
and on a different place happily returns 0 or 1.
Mixing that with <stdbool.h> makes even more mess.

Kind regards,
Petr