sys_datacopy keeps returning "bad address" error

Hello!

For the purposes of testing something I have, I've set kernel/table.c
to allow "init" children to call any system call they want to call in
order to do some hacking, and I have a test program that calls
sys_datacopy().

In my program, I setup two character pointers called "source" and
"sink", with "source" initialized with some data. However, whenever I
do "sys_datacopy(SELF, source, SELF, sink, strlen(source))", I get
error code -14 returned, which is an EFAULT and means "bad address".

Is there something special I have to do with those addresses in order
to get sys_datacopy() to work with them? I'd really like to know,
because when I implement a new OS server, I'm going to need to use
sys_datacopy() in order to transfer large amounts of data to clients at
a time.

Thank you so very much in advance, and happy holidays!

Actually, it's really weird. When I made a very small straightfoward
test, I could get sys_datacopy() to work just fine. However, when I
run my larger code that is actually a set of unit tests, it fails. I
guess I will just have to step through it slowly.

Speaking of stepping through code, I don't have gdb installed. The GCC
4.1.1 package did not include gdb. Is there some other debugger I can
use on programs compiled with GCC under Minix?

Also, I'm very sorry that I continue to respond to my own posts. It's
just that I get stuck for hours on something and finally come here
after lots of searching. Then I have a light bulb that just flashes
and I discover the answer in no time.

Thanks!

P.S.: Where is a debugger I can use with GCC compiled code on Minix?
GDB is not installed with the GCC 4.1.1 package.

Here is the test code that works, by the way:

======== BEGIN CODE PASTE =========

#include <minix/config.h>
#include <minix/const.h>
#include <minix/com.h>
#include <minix/type.h>
#include <minix/ipc.h>
#include <minix/syslib.h>

#include <iostream>

int main()
{
using namespace std;
//char *source = new char[50], *sink = new char[50];
char source[50], sink[50];
memcpy(source, "test", strlen("test")+1);
printf("%s\n", source);
int ret = sys_datacopy(SELF, (long)source, SELF, (long)sink,
strlen(source)+1);
if (ret < 0) {
perror(__func__);
return ret;
}
printf("%d %s %s\n", ret, source, sink);
delete [] source;
delete [] sink;
return 0;
}