RE: [RFA] gdbserver/win32-low.c: Check Read/WriteProcessMemory return value (followup to [RFA] windows-nat.c: Handle ERROR_PARTIAL_COPY in windows_xfer_memory function)

["Pierre Muller" <pierre.muller@ics-cnrs.unistra.fr>]

> >   What about this patch,
> > it still does not allow to really return the number of bytes read or
> > written,
> > but at least it checks correctly if the API calls succeeded.
> 
> No, as long as the read_memory/write_memory interfaces do not
> support partial transfers, we should only return true if the
> all of LEN was transferred.  Otherwise, things like:
> 
> static int
> gdb_read_memory (CORE_ADDR memaddr, unsigned char *myaddr, int len)
> {
> ...
>     {
>       res = read_inferior_memory (memaddr, myaddr, len);
>       done_accessing_memory ();
> 
>       return res == 0 ? len : -1;
>     }
> }
> 
> will behave incorrectly in the ERROR_PARTIAL_COPY scenario...

  This is still done in win32_{read/write}_inferior_memory which are the two
only callers of the static child_xfer_memory function in win32-low.c 
  Thus the aim was to narrow the behavior gap between
windows-nat.c windows_xfer_memory function 
and the win32-low.c child_xfer_memory function,
without (for now) changing anything to the beghavior of gdbserver,
as guaranteed by the 
static int
win32_write_inferior_memory (CORE_ADDR memaddr, const unsigned char *myaddr,
                             int len)
{
  return child_xfer_memory (memaddr, (char *) myaddr, len, 1, 0) != len;
}

code...

The only thing I changed is that child_xfer_memory returns the correct
amount of read/written memory or -1 if an error, other than
ERRO_PARTIAL_COPY, occurred.
Thus I think that your answer is missing the intermediate
win32_{read/write}_inferior_memory level.


Pierre Muller