Re: RFA: PACKET_OVERHEAD constant added to remote.c

[Kevin Buettner <kevinb at cygnus dot com>]

On Nov 16,  1:20pm, Andrew Cagney wrote:

> > As far as remote_write_bytes() or remote_read_bytes() are concerned,
> > they get their packet sizes by calling get_memory_write_packet_size()
> > or get_memory_read_packet_size() which in turn determine the size by
> > calling get_memory_packet_size().  It is the latter function which
> > was returning too large a value.  It is also in this function where
> > I chose to make an adjustment:
> 
> Yes.  I'm just trying to understand if this is a recently introduced bug
> (by me) or has always been in there. (In particular prior to the change
> to remote.c below). 

Unclear.  I was able to use an x86 linux gdbserver with gdb prior to
your change below (without seeing the buffer overflow problem).  I
don't whether it was your change which caused the breakage or something
else.

Let me know if you'd like me to pursue this; I could do an update
to Nov 3 and see if the problem still exists...
 
> For what it's worth, there is a nasty overflow bug to do with
> remote_read_bytes() - it stuffs up the buffer allocation. Ulgh. Better
> fix that one.

Yes.  I saw your comment in get_memory_read_packet_size().

> 	Andrew
> 
> 
> Thu Nov  4 11:59:24 1999  Andrew Cagney  <cagney@b1.cygnus.com>
> 
>         * remote.c (get_memory_packet_size, set_memory_packet_size,
>         build_memory_packet_size): New functions. Set / compute / update
>         the size of a memory read / write packet.
>         (set_memory_read_packet_size, set_memory_write_packet_size): New
>         functions.  Verify changes to the memory read / write packet
> size.
>         (prefered_memory_write_packet_size,
>         current_memory_write_packet_size,
> prefered_memory_read_packet_size,
>         current_memory_read_packet_size): New variables.
>         (get_memory_read_packet_size, get_memory_write_packet_size): New
>         functions. Determine the current memory read/write packet size. 
> A
>         function is needed as ``current_register_packet_size'', a
> variable
>         is used in the calculation.
>         (register_remote_packet_sizes, build_remote_packet_sizes):
>         Initialize packet sizes according the current architecture.
>         (remote_fetch_registers, remote_write_bytes, remote_read_bytes,
>         build_remote_gdbarch_data): Update.
>         (_initialize_remote): Add the commands ``set remote
>         memory-read-packet-size'' and ``set remote
>         memory-write-packet-size''.  Deprecate ``set remotepacketsize''.