Fix rpmsgfs/rpmsgfs_client.c:774:3: warning: 'strcpy' writing 1 or more bytes into a region of size 0 overflows the destination

[xiaoxiang781216]

Summary

Found by change #5476.

Impact

Minor, fix warning

Testing

Pass CI

[hartmannathan]

When DEBUGASSERT is a no-op, this check for buffer overflow will not exist.

I suggest:

if (len > space)
  {
    return -ENOMEM;
  }

provided space is number of bytes we can actually use. If require one more byte, use >= instead:

if (len >= space)
  {
    return -ENOMEM;
  }

[xiaoxiang781216]

There isn't rpmsg_free_tx_payload_buffer api yet:
OpenAMP/open-amp#361
That is why DEBUGASSERT is added here since we can't return the buffer to pool without sending.

[xiaoxiang781216]

Once OpenAMP/open-amp#361 get fixed, we can convert all DEBUGASSERT to if/else.