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freetds - RE: [freetds] some small patches...

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  • From: "Lowden, James K" <LowdenJK AT bernstein.com>
  • To: "'FreeTDS Development Group'" <freetds AT lists.ibiblio.org>
  • Subject: RE: [freetds] some small patches...
  • Date: Tue, 15 Apr 2003 11:33:17 -0400

> From: Thompson, Bill D (London) [mailto:ThompBil AT exchange.uk.ml.com]
> Sent: April 15, 2003 10:55 AM
>
> No, free(NULL) does not cause me problems, I was just being careful.

That's good.

> > tds_free_context(TDSCONTEXT *context)
> > {
> > tds_free_locale(context->locale);
> > TDS_ZERO_FREE(context);
> > }
>
> Well no... if context is NULL, you'll segment on referencing
> context->locale, so you need at least to check whether
> context is NULL or not...

Oops!

> so I guess you could simplify to....
>
> void tds_free_context(TDSCONTEXT *context)
> {
> if (context) {
> tds_free_locale(context->locale);
> context->locale = NULL;
> TDS_ZERO_FREE(context);
> }
> }

That's effectively what's in CVS now.

> if (g_dblib_ctx.tds_ctx) {
> tds_free_context(g_dblib_ctx.tds_ctx);
> g_dblib_ctx.tds_ctx = NULL;
> }
>
> Although tds_free_context freed the storage pointed to by *context ,
> g_dblib_ctx.tds_ctx was still set, as the pointer had been
> passed by value, not reference...

Come to think of it,

> context->locale = NULL;
> TDS_ZERO_FREE(context);

is two degrees of silliness. Not only is there no effect of
"context->locale = NULL", there's no effect the implicit "context = NULL"
either. Whoever calls tds_free_context() won't see any changed value of
context, because, as you say, it's passed by value.

We probably should avoid TDS_ZERO_FREE() in situations like this because
it's deceptive, and just use free() instead.

Thanks for the patches, Bill. Are you going to switch over to the newly
disturbed HEAD soon? I know you're planning a lot of work on ct-lib, and I
wouldn't want us to get too far out of synch.

--jkl


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