[LTP] [PATCH v1] Refactor wait4/wait402.c to the new API

[Petr Vorel]

Hi Ioannis,

> Not major changes in functionality. Man page says, *wait for process to change
> state, BSD style*. So i kept the `_USE_BSD` macro, even if test seems to work
> anyway without it.
This is certainly wrong. _USE_BSD are glibc specific constants, which we should
avoid to use. man wait4(2) states for wait4():

   Since glibc 2.19:
	   _DEFAULT_SOURCE

   glibc 2.19 and earlier:
	   _BSD_SOURCE

_DEFAULT_SOURCE IMHO means it works by default, thus we wouldn't need anything.

musl libc guards it with:
#if defined(_GNU_SOURCE) || defined(_BSD_SOURCE)

But at least on Alpine (the most used musl based linux distro) also compiles
without any definition => let's remove it.

> Signed-off-by: ybonatakis <ybonatakis@suse.com>
Could you please use your real name?
Signed-off-by: Ioannis Bonatakis <ybonatakis@suse.com>

https://www.kernel.org/doc/html/latest/process/submitting-patches.html#sign-your-work-the-developer-s-certificate-of-origin

> ---
>  testcases/kernel/syscalls/wait4/wait402.c | 97 ++++-------------------
>  1 file changed, 17 insertions(+), 80 deletions(-)

> diff --git a/testcases/kernel/syscalls/wait4/wait402.c b/testcases/kernel/syscalls/wait4/wait402.c
> index 39b170253..13b2af533 100644
> --- a/testcases/kernel/syscalls/wait4/wait402.c
> +++ b/testcases/kernel/syscalls/wait4/wait402.c
> @@ -1,101 +1,38 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
>  /*
>   *
>   *   Copyright (c) International Business Machines  Corp., 2001
>   *   Copyright (c) 2012 Cyril Hrubis <chrubis@suse.cz>

nit: there should be a single space after *. Also I'd
/*
 * Copyright (c) International Business Machines  Corp., 2001
 * Copyright (c) 2012 Cyril Hrubis <chrubis@suse.cz>
 * Copyright (c) Linux Test Project, 2001-2015
 * Copyright (c) 2023 Ioannis Bonatakis <ybonatakis@suse.com>
 */

> - *
> - *   This program is free software;  you can redistribute it and/or modify
> - *   it under the terms of the GNU General Public License as published by
> - *   the Free Software Foundation; either version 2 of the License, or
> - *   (at your option) any later version.
> - *
> - *   This program is distributed in the hope that it will be useful,
> - *   but WITHOUT ANY WARRANTY;  without even the implied warranty of
> - *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
> - *   the GNU General Public License for more details.
> - *
> - *   You should have received a copy of the GNU General Public License
> - *   along with this program;  if not, write to the Free Software
> - *   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
> + *   Copyright (c) 2023 Ioannis Bonatakis <ybonatakis@suse.com>
>   */

> +/*\
> + * [Description]
> + *
> + * Check for ECHILD errno when using an illegal pid value
nit: missing dot at the end. Also I reword it a bit:
 * Check for ECHILD errno when call wait4(2) with an invalid pid value.
> + */

> -#include <errno.h>
> +#include "tst_test.h"
>  #define _USE_BSD
Removed (see above).

> -#include <sys/types.h>
> -#include <sys/resource.h>
>  #include <sys/wait.h>
> -#include <stdlib.h>
> -#include <string.h>
...

> +static pid_t pid_max;

> -int main(int ac, char **av)
> +static void run(void)
>  {
> -	int lc;
> -	pid_t epid = get_pid_max() + 1;
NOTE: max PID + 1 is invalid.
> -
>  	int status = 1;
There is no need to initialize the variable, it will be set by wait4().

>  	struct rusage rusage;

> -	tst_parse_opts(ac, av, NULL, NULL);
> -
> -	setup();
> -
> -	for (lc = 0; TEST_LOOPING(lc); lc++) {
> -		tst_count = 0;
> -
> -		TEST(wait4(epid, &status, 0, &rusage));
> -
> -		if (TEST_RETURN == 0) {
> -			tst_brkm(TFAIL, cleanup,
> -				 "call failed to produce expected error - errno = %d - %s",
> -				 TEST_ERRNO, strerror(TEST_ERRNO));
> -		}
> -
> -		switch (TEST_ERRNO) {
> -		case ECHILD:
> -			tst_resm(TPASS,
> -				 "received expected failure - errno = %d - %s",
> -				 TEST_ERRNO, strerror(TEST_ERRNO));
> -			break;
> -		default:
> -			tst_brkm(TFAIL, cleanup,
> -				 "call failed to produce expected "
> -				 "error - errno = %d - %s", TEST_ERRNO,
> -				 strerror(TEST_ERRNO));
> -		}
> -	}

> +	TST_EXP_FAIL2(wait4(pid_max, &status, 0, &rusage), ECHILD,
> +		      "wait4 fails with ECHILD");
	TST_EXP_FAIL2(wait4(pid_max + 1, &status, 0, &rusage), ECHILD);
NOTE: use +1, otherwise it would not be test for invalid pid value.

Also no need for "fails with ECHILD".

>  }

>  static void setup(void)
>  {
> +	SAFE_FILE_SCANF("/proc/sys/kernel/pid_max", "%d\n", &pid_max);
>  }

> +static struct tst_test test = {
> +	.test_all = run,
> +	.setup = setup,
> +};

In the end I fixed the issues and merged with the diff below.
Thanks for your work.

Kind regards,
Petr

+++ testcases/kernel/syscalls/wait4/wait402.c
@@ -1,30 +1,28 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
- *
- *   Copyright (c) International Business Machines  Corp., 2001
- *   Copyright (c) 2012 Cyril Hrubis <chrubis@suse.cz>
- *   Copyright (c) 2023 Ioannis Bonatakis <ybonatakis@suse.com>
+ * Copyright (c) International Business Machines  Corp., 2001
+ * Copyright (c) 2012 Cyril Hrubis <chrubis@suse.cz>
+ * Copyright (c) Linux Test Project, 2001-2015
+ * Copyright (c) 2023 Ioannis Bonatakis <ybonatakis@suse.com>
  */
 
 /*\
  * [Description]
  *
- * Check for ECHILD errno when using an illegal pid value
+ * Check for ECHILD errno when call wait4(2) with an illegal pid value.
  */
 
 #include "tst_test.h"
-#define _USE_BSD
 #include <sys/wait.h>
 
 static pid_t pid_max;
 
 static void run(void)
 {
-	int status = 1;
+	int status;
 	struct rusage rusage;
 
-	TST_EXP_FAIL2(wait4(pid_max, &status, 0, &rusage), ECHILD,
-		      "wait4 fails with ECHILD");
+	TST_EXP_FAIL2(wait4(pid_max + 1, &status, 0, &rusage), ECHILD);
 }
 
 static void setup(void)