FreeTDS Development Group

["ZIGLIO, Frediano, VF-IT" <Frediano.Ziglio AT vodafone.com>]

> 
> ZIGLIO, Frediano, VF-IT wrote:
> > 08:47:27.523087 (dblib.c:513):dbgetnull(0x4103728, 1, -1, 
> 0xbe9a9894)
> > 08:47:27.538366 (dblib.c:542):varaddr(0xbe9a9894) varlen -1 < 0?
> > t0011: dblib.c:544: dbgetnull: Assertion `varlen > 0' failed.
> 
> Thanks for looking at this.  At least you were seeing the same thing I
> was, and didn't suspect corruption.  Now I think I know 
> what's going on.  
> 
> If varlen == -1 and pnullrep->len == 0, why does the function 
> not return
> FAIL?  
> 
> Answer: integral promotion.  
> 
> The code:
> 
>       if (varlen < pnullrep->len) {
>               tdsdump_log(...);
>               return FAIL;
>       } 
> 
> needs to be:
> 
>       if (varlen < (long)pnullrep->len) {
>               tdsdump_log(...);
>               return FAIL;
>       } 
> 
> because varlen is int and pnullrep->len is size_t (unsigned int).  The
> rule: for two same-size ints, one signed and the other not, treat the
> signed as unsigned.  
> 
> Anyone know if gcc can warn about that?  
> 
> t0011 now passes, but I'm pretty sure the code is wrong.  dbgetnull()
> takes a length and an address; it has no more information 
> than that about
> what the NULL should look like.  STRINGBIND means pad the value with
> blanks and terminate it with '\0'.  dbgetnull() can't 'pad' because it
> doesn't know the column width.  
> 
> copy_data_to_host_var must determine the column width and 
> pass it (not -1)
> to dbgetnull().  
> 


This morning I wrote this patch... still not that much...

freddy77

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