Cry for HELP

Hi all,

Whats wrong with my code?

Since a couple of day's I try to pass a message along to another
server. This should be done as much uninterpreted as possible. (What
I'm really on is a layered filesystem, but this dosn't matter yet.)

But I'm jumping around between all sorts of unrecoverable kernel
faults.

I understand, that I can't pass a message completly uninterpreted
because of the M_READ bit. So I tried to pass a message as follows.
This has been applied to FS_STAT messages only (by now).

/* return 0 on success otherwise a error string */
static char*
passrmsg(struct msg*m, struct file*f)
{
  int n;
  struct msg om;

  om = *m; /* make a rough copy */
  om.m_op = m->m_op | M_READ; /* regenerate the M_READ */

  /* copy all the buffer, not sure wether it is needed or not */
  for(n=0; n<m->m_nseg; ++n) {
  void *b;

    /* bufmalloc is a garbage collecting malloc. After the reply to
       "m", all buffers are free'd. It has proven to be stable .
       For tests one may forget about the "m" parameter use malloc
       instead and generate some memory leaks of no interest */

    b = bufmalloc(m,m->m_seg[n].s_buflen);
    if( b == NULL ) return ENOMEM;
    bcopy(m->m_seg[n].s_buf,b,m->m_seg[n].s_buflen);
    om.m_seg[n].s_buf=b;
  }

  n = msg_send(f->port,&om); /* send it to the layer below */
  if( n < 0 ) {
    return strerror();
  } else {
    return 0;
  }
}

The fancy result of this is, that it works for the first time and
break the kernel on the second invocation.

To make things simple I started this server (which handles only M_DUP,
M_CONNECT, M_DISCONNECT in a stable way and FS_STAT mainly by the code
above).
Then I mounted it on /test.
Next I did: stat /test.
This gave me the expected result.
Next step again: stat /test.
Now I got a assertion failed line 170 file ../mach/trap.c.

This is the point where I can only raise my hands.

BTW: I ran into a couple of problems with syslog.
When I pass a FS_STAT message in the way above and I do a syslog just
after the msg_send the result of the msg_send gets overwriten.
  There is a second problem, when I do a syslog between the msg_reply
and msg_receive the next msg_send will hand. But this apears to be too
complex to be answered. First I must work out the error condition
exactly.

Thanks for any help.

/Joerg
Received on Tue Dec 20 05:21:08 1994