Re: Remote symbol lookup.

[Michael Snyder <msnyder at cygnus dot com>]

"Korbel, Michal" wrote:
> 
> Hi Michael

Hi Michal -- by the way, I am Cc:ing the gdb-patches mailing list.

> I use remote symbol lookup feature in gdbserver with multithread support,
> but I was have problem with remote_check_symbols() function. In my opinion
> the msg buffer was not properly set. In source version of remote.c we have:
> 
>   while (strncmp (reply, "qSymbol:", 8) == 0)
>     {
>       tmp = &reply[8];
>       end = hex2bin (tmp, msg, strlen (tmp) / 2);
>       msg[end] = '\0';
>       sym = lookup_minimal_symbol (msg, NULL, NULL);
>       if (sym == NULL)
>         sprintf (msg, "qSymbol::%s", &reply[8]);
>       else
>         sprintf (msg, "qSymbol:%s:%s",
>                  paddr_nz (SYMBOL_VALUE_ADDRESS (sym)),
>                  &reply[8]);
>       putpkt (msg);
>       getpkt (reply, PBUFSIZ, 0);
>     }
> 
> and after my changes (in red) works better.
> 
>     while (strncmp (reply, "qSymbol:", 8) == 0)
>     {
>         tmp = &reply[8];
>         sym = lookup_minimal_symbol (tmp, NULL, NULL);

Michal, this change will work only under one assumption:
your remote target (gdbserver) is not hex-encoding the symbol
name.  If you check the protocol spec in gdb/doc/gdb.texinfo, 
you'll see that this is a bug: the symbol name is meant to be
hex-encoded.  That is why the code in remote.c isn't working
for you.

I have a working implementation of the target side code
for linux threads, and we are trying to get it released
onto the sourceware site.  I know this would spare you a
lot of work, so I will try as hard as I can to speed up
the process.

>         if (sym == NULL)
>             sprintf (msg, "qSymbol::%s", tmp);
>         else
>             sprintf (msg, "qSymbol:%s:%s",
>                      paddr_nz (SYMBOL_VALUE_ADDRESS (sym)),
>                      tmp);
>         putpkt (msg);
>         getpkt (reply, PBUFSIZ, 0);
>     }
> 
> but I suggest try the last version with use "end" to set valid end of
> string:
> 
>     while (strncmp (reply, "qSymbol:", 8) == 0)
>     {
>         tmp = &reply[8];
>  /* Fix me: We are sure ':' is real end of string ! */
> /* If we are not sure, we need add more check */
> /* We can use max_length of symbol name */
>         end = 0;
>         while (tmp[end] != ':')
>           end++;
>         tmp[end] = '\0';
>         sym = lookup_minimal_symbol (tmp, NULL, NULL);
>         if (sym == NULL)
>             sprintf (msg, "qSymbol::%s", tmp);
>         else
>             sprintf (msg, "qSymbol:%s:%s",
>                      paddr_nz (SYMBOL_VALUE_ADDRESS (sym)),
>                      tmp);
>         putpkt (msg);
>         getpkt (reply, PBUFSIZ, 0);
>     }
> 
> > --------------------------------------------------------------------------
> > ------------
> Michal Korbel - Software engineer
> Intel Technology Poland Sp. z o.o.; ul. Slowackiego 173; 80-298 Gdansk
> tel. +48 58 34-81-726; fax: +48 58 34-81-505; mobile:+48 603-203-142
> ----------------------------------------------------------------------------
> ----------