SPI_execute_with_args call

Hello, colleagues !

I have to write random number generator state into database table
Table structure is
table rand_state
{
id serial not null primary key,
state_rand bytea
};

In C-function I do
size_t nr_ins = strlen ("insert into rand_state (state_rand) values ($1);");
char * r_sql = (char *) palloc (nr_ins + 1);
strncpy (r_sql, "insert into rand_state (state_rand) values ($1);", nr_ins);

Oid * oids = (Oid *)palloc (sizeof (Oid));
Datum * val = PointerGetDatum (randBuf);
*oids = BYTEAOID;
const char * nulls = "NULL";
int rins = SPI_execute_with_args (r_sql, 1, oids, val, nulls, false, 1);

randBuf is a void * pointer that contains random number generator state,
when I try to execute SPI_execute_with_args (r_sql, 1, oids, val, nulls,
false, 1); I receive error
The connection to the server was lost. Attempting reset: Failed.
Could you give some work examples for SPI_execute_with_args because I
didn't find them in documentation.

Thanks a lot.

--
Best regards,
Sincerely yours,
Yuriy Rusinov.