[LTP] [PATCH] syscalls/msgrcv07: Add functional test for MSG_COPY flag

[Yang Xu]

Hi Cyril

> Hi!
>> +static void test_msg_copy(void)
>> +{
>> +	struct msqid_ds buf = {0};
>> +
>> +	if (!msg_copy_sup)
>> +		tst_res(TCONF, "kernel doesn't support MSG_COPY flag, skip it");
>> +	prepare_queue();
>> +
>> +	/*
>> +	 * If MSG_COPY flag was specified, then mtype is interpreted as number
>> +	 * of the message to copy.
>> +	 */
>> +	SAFE_MSGRCV(queue_id, &rcv_buf, MSGSIZE, 0, MSG_COPY | IPC_NOWAIT);
>> +	if (strcmp(rcv_buf.mtext, MSG1) == 0 && rcv_buf.type == MSGTYPE1)
>> +		tst_res(TPASS, "msgrcv(MSG_COPY) got MSGTYPE1 msg data"
>> +			" correctly");
>> +	else
>> +		tst_res(TFAIL, "msgrcv(MSG_COPY) got MSGTYPE1 msg data"
>> +			" incorrectly");
>> +
>> +	SAFE_MSGRCV(queue_id, &rcv_buf, MSGSIZE, 1, MSG_COPY | IPC_NOWAIT);
>> +	if (strcmp(rcv_buf.mtext, MSG2) == 0 && rcv_buf.type == MSGTYPE2)
>> +		tst_res(TPASS, "msgrcv(MSG_COPY) got MSGTYPE2 msg data"
>> +			" correctly");
>> +	else
>> +		tst_res(TFAIL, "msgrcv(MSG_COPY) got MSGTYPE2 msg data"
>> +			" incorrectly");
>> +
>> +	SAFE_MSGCTL(queue_id, IPC_STAT, &buf);
>> +	if (buf.msg_qnum == 2)
>> +		tst_res(TPASS, "msgrcv(MSG_COPY) succeeded, msg queue "
>> +			"still has 2 msg");
>> +	else
>> +		tst_res(TFAIL, "msgrcv(MSG_COPY) msg queue expected 2 msg num,"
>> +			" but only got %d", (int)buf.msg_qnum);
>> +	SAFE_MSGCTL(queue_id, IPC_RMID, NULL);
>> +}
>>   
>>   static void setup(void)
>>   {
>>   	msgkey = GETIPCKEY();
>> +	prepare_queue();
>> +	TEST(msgrcv(queue_id, &rcv_buf, MSGSIZE, MSGTYPE1, MSG_COPY));
>> +	if (TST_RET != -1)
>> +		tst_res(TINFO, "msgrcv succeeded unexpectedly, kernel doesn't"
>> +			" support MSG_COPY flag");
>> +
>> +	if (TST_ERR == EINVAL) {
>> +		tst_res(TINFO, "msgrcv failed as expected when not using"
>> +			" MSG_COPY and IPC_NOWAIT concurrently");
>> +		msg_copy_sup = 1;
>> +	} else if (TST_ERR == ENOSYS) {
>> +		tst_res(TINFO, "kernel doesn't enable CONFIG_CHECKPOINT_RESTORE");
>> +	} else {
>> +		tst_res(TINFO | TTERRNO, "msgrcv failed when not using MSG_COPY"
>> +			"and IPC_NOWAIT concurrently, expected EINVAL but got");
>> +	}
> 
> Why can't we just check for ENOSYS in the test_msg_copy() instead?
In here, ENOSYS is differnt from other syscalls. only specifying 
MSG_COPY flag and CONFIG_CHECKPOINT_RESTORE was not enabled, returns 
ENOSYS. See[1]

So I use MSG_COPY without IPC_NOWAIT to check whether kernel supports 
MSG_COPY flag(It will trigger EINVAL error as man-page said).

If I misunderstand you, please let me know.

[1]https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=4a674f34ba04a0

>