[LTP] [PATCH] syscalls/msgget04: Add test for /proc/sys/kernel/msg_next_id

[Yang Xu]

HI Cyril

> Hi!
>> diff --git a/testcases/kernel/syscalls/ipc/msgget/msgget04.c b/testcases/kernel/syscalls/ipc/msgget/msgget04.c
>> new file mode 100644
>> index 000000000..3791f331a
>> --- /dev/null
>> +++ b/testcases/kernel/syscalls/ipc/msgget/msgget04.c
>> @@ -0,0 +1,66 @@
>> +// SPDX-License-Identifier: GPL-2.0-or-later
>> +/*
>> + * Copyright (c) 2020 FUJITSU LIMITED. All rights reserved.
>> + * Author: Yang Xu <xuyang2018.jy@cn.jujitsu.com>
>> + *
>> + * It is a basic test about msg_next_id.
>> + * msg_next_id specifies desired id for next allocated IPC message. By default
>> + * they are equal to -1, which means generic allocation logic. Possible values
>> + * to set are in range {0..INT_MAX}.
>> + * Toggle with non-default value will be set back to -1 by kernel after
>> + * successful IPC object allocation.
>> + */
>> +
>> +#include <errno.h>
>> +#include <string.h>
>> +#include <sys/types.h>
>> +#include <sys/ipc.h>
>> +#include <sys/msg.h>
>> +#include "tst_test.h"
>> +#include "tst_safe_sysv_ipc.h"
>> +#include "libnewipc.h"
>> +
>> +#define NEXT_ID_PATH "/proc/sys/kernel/msg_next_id"
>> +static int queue_id = 1, pid;
>> +static key_t msgkey;
>> +
>> +static void verify_msgget(void)
>> +{
>> +	SAFE_FILE_PRINTF(NEXT_ID_PATH, "%d", pid);
>> +
>> +	TEST(msgget(msgkey, IPC_CREAT | MSG_RW));
>> +	if (TST_RET == -1) {
>> +		tst_res(TFAIL | TTERRNO, "msgget() failed");
>> +		return;
>> +	}
>> +
>> +	queue_id = TST_RET;
>> +	if (queue_id == pid)
>> +		tst_res(TPASS, "msg_next_id succeeded, queue id %d", pid);
>> +	else
>> +		tst_res(TFAIL, "msg_next_id failed, expected id %d, but got %d", pid, queue_id);
>> +
>> +	TST_ASSERT_INT(NEXT_ID_PATH, -1);
>> +	SAFE_MSGCTL(queue_id, IPC_RMID, NULL);
>> +	pid++;
>> +}
>> +
>> +static void setup(void)
>> +{
>> +	msgkey = GETIPCKEY();
>> +	pid = getpid();
>> +}
>> +
>> +static void cleanup(void)
>> +{
>> +	if (queue_id != -1)
>> +		SAFE_MSGCTL(queue_id, IPC_RMID, NULL);
>> +	SAFE_FILE_SCANF(NEXT_ID_PATH, "-1");
> 
> Shouldn't this be SAFE_FILE_PRINTF() ?
Yes, sorry for the obvious mistake.
But if it will report EINVAL error when the value of NEXT_ID_PATH has 
been -1. I think we may need a flag.
> 
> Otherwise it looks fine, also I can fix this one before pushing.
>
I will send v2.

> 
> 
> Also what happens when we write id of existing id to that file? I guess
> that we can write another test that tries that...
I will look kernel code firstly, then write a case about this.

Best Regards
Yang Xu
> 
>> +}
>> +
>> +static struct tst_test test = {
>> +	.setup = setup,
>> +	.cleanup = cleanup,
>> +	.test_all = verify_msgget,
>> +	.needs_root = 1,
>> +};
>> -- 
>> 2.23.0
>>
>>
>>
>>
>> -- 
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>