🚀 go-pugleaf

In article <9207221341.AA22022@sunmanager.lrz-muenchen.de>, 
a2824ak@sunmanager.lrz-muenchen.de (Thomas Kaiser) writes:
|> Dear Sirs:
|> 
|> i discovered an bug, when gcc -g -O removed (optimized) a statement. It
|> removes count-- from the example.
|> 
|> With regards
|> 
|> Thomas Kaiser
|> Leibniz Supercomputing Centre
|> Muenchen
|> Germany
|> 
|> --
|> -------------------------------------------------------------------------
|> Thomas Kaiser         Internet:	kaiser@sunmanager.lrz-muenchen.de
|> LRZ-Muenchen          X400:	C=DE;A=DBP;P=LRZ-MUENCHEN;OU=LRZ;S=Kaiser
|> -------------------------------------------------------------------------
|> 
|> 
|> ------------------------------------------------------------------
|> int make_snmp_query(ip_address, variable, the_community, count)
|> 
|> char *ip_address;
|> char *variable;
|> char *the_community;
|> int  count;
|> 
|> {
|>   int i;
|> 
|>   alarm(10);
|>   if (setjmp(env)) {
|>     printf("xifload: receive timed out from %s\n", ip_address);
|>     close(s);
|>     for (i=0; i<num_malloc; i++)
|>       free(malloc_table[i]);
|>     num_malloc = 0;
|>     if (count <= 1)
|>       return -1;
|>     else {
|>       count--;        <------------------ will be removed
|>       alarm(10);
|>     }
|>   }
|>   make_the_query(ip_address, variable, the_community);
|>   alarm(0);
|>   for (i=0; i<num_malloc; i++)
|>     free(malloc_table[i]);
|>   num_malloc = 0;
|>   return 0;
|> }

While this is undoubtably frustrating I don't see how gcc can be
expected to understand your function without including setjmp as an
element of the language. As I see it gcc believes that count isn't used
after your decrement so why decrement it. I think that something like
this will work without problem:

{
   if (setjmp(env)) {
     printf("xifload: receive timed out from %s\n", ip_address);
     close(s);
   }
   while (num_malloc > 0)
     free(malloc_table[--num_malloc]);
   if (count-- > 0) {
     alarm(10);
     make_the_query(ip_address, variable, the_community);
     alarm(0);
   }
   while (num_malloc > 0)
     free(malloc_table[--num_malloc]);
   num_malloc = 0; /* shouldn't be required */

   return count > 0 ? 0 : -1;
}

-- 

Michael Salmon

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