Re: bk commit into 5.1 tree (kaa:1.2659) BUG#31236

[Sergei Golubchik]

Hi!

On Feb 15, Alexey Kopytov wrote:
> ChangeSet@stripped, 2008-02-15 19:50:19+03:00, kaa@kaamos.(none) +9 -0
>   Fix for bug #31236: Inconsistent division by zero behavior for 
>                       floating point numbers
>   
>   Some math functions did not check if the result is a valid number
>   (i.e. neither of +-inf or nan).
>   
>   Fixed by validating the result where necessary and returning NULL in
>   case of invalid result.
> 
> diff -Nrup a/sql/item_func.cc b/sql/item_func.cc
> --- a/sql/item_func.cc	2008-01-19 20:59:07 +03:00
> +++ b/sql/item_func.cc	2008-02-15 19:50:18 +03:00
> @@ -1710,9 +1710,9 @@ double Item_func_atan::val_real()
>      double val2= args[1]->val_real();
>      if ((null_value=args[1]->null_value))
>        return 0.0;
> -    return fix_result(atan2(value,val2));
> +    return atan2(value,val2);

atan2 is always defined ? even if val2==0 ?

>    }
> -  return fix_result(atan(value));
> +  return atan(value);
>  }
>  
>  double Item_func_cos::val_real()
> diff -Nrup a/sql/item_func.h b/sql/item_func.h
> --- a/sql/item_func.h	2007-12-13 14:57:03 +03:00
> +++ b/sql/item_func.h	2008-02-15 19:50:18 +03:00
> @@ -192,6 +192,14 @@ public:
>                       void * arg, traverse_order order);
>    bool is_expensive_processor(uchar *arg);
>    virtual bool is_expensive() { return 0; }
> +  inline double fix_result(double value)
> +  {
> +    /* The following should be safe, even if we compare doubles */

the command makes no sense

> +    if (isfinite(value))
> +      return value;
> +    null_value=1;
> +    return 0.0;
> +  }
>  };
>  
> diff -Nrup a/sql/matherr.c b/sql/matherr.c
> --- a/sql/matherr.c	2006-12-30 23:02:07 +03:00
> +++ /dev/null	Wed Dec 31 16:00:00 196900

Why did you delete it ?
(won't default matherr print an error to stderr ?)

Regards / Mit vielen Grüssen,
Sergei

-- 
   __  ___     ___ ____  __
  /  |/  /_ __/ __/ __ \/ /   Sergei Golubchik <serg@stripped>
 / /|_/ / // /\ \/ /_/ / /__  Principal Software Developer/Server Architect
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