FreeTDS Development Group

["Lowden, James K" <LowdenJK AT bernstein.com>]

> From:  Paparo, Joshua
> Sent: Friday, December 03, 2004 8:32 AM
> 
> I forgot to mention I was indeed setting 'datalen' to zero for null
> params but the bit I'm thinking of in the docs is:
> 
> "A pointer to the RPC parameter itself. If datalen is 0, this pointer
> will be ignored and treated as NULL."
> 
> This made me think I could just pass a null pointer for 'value' as
long
> as 'datalen' was zero.

You are correct.  You can pass a data pointer as NULL (or anything
else), provided you pass datalen as 0.  

The RPC code should not, IMHO, assume datalen==0 just because the data
pointer is NULL.  A NULL data pointer with a non-zero datalen should be
considered an error.  

My reasoning: It's very possible for the application to attempt to pass
a buffer and mistakenly pass NULL instead, even when it "knows" the
right length.  This could happen if malloc/realloc fail (and fail to be
checked), for instance.  If dblib were to assume the NULL were valid, it
would silently transmit the application's failed logic as bad data to
the database.  

--jkl

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