Re: I'm having a crashing problem with FreeTDS under OSX

Il giorno ven, 06/03/2009 alle 00.52 -0500, James K. Lowden ha scritto:
> Daniel Parnell wrote:
> > 	here is the first little bit of the stack trace for the first
> > 	crash  
> > I'm seeing.
> > 
> > Program received signal EXC_BAD_ACCESS, Could not access memory.
> > Reason: KERN_PROTECTION_FAILURE at address: 0x00000016
> > 0x0010f7fa in free ()
> > (gdb) bt
> > #0  0x0010f7fa in free ()
> > #1  0x02f55c38 in _SQLAllocEnv (phenv=0x812c70) at odbc.c:1353
> 
> Bug.  Eh.  The pointer being freed might not have been allocated, and
> isn't zeroed when initialized.  
> 
> 	free(ctx->locale->date_fmt);
> 
> Locale is allocated by tds_alloc_locale() and initialized by
> tds_parse_locale().  Something's a little wrong, because
> tds_parse_locale() should find a proper date format string in
> locales.conf.  In case it doesn't, though, *nothing* initializes the
> memory; it's just pointing to random space.  A little while later, the
> ODBC driver fastidiously frees the tiny string it thinks was allocated,
> and you send a message to the list.  
> 
> I would double-check what's going on with TDSDUMPCONFIG, which should show
> a locales.conf being read and the date_fmt being initialized. But this
> patch wouldn't do any harm:
> 
> RCS file: /cvsroot/freetds/freetds/src/tds/mem.c,v
> retrieving revision 1.175.2.2
> diff -u -r1.175.2.2 mem.c
> --- src/tds/mem.c       5 Nov 2008 14:56:12 -0000       1.175.2.2
> +++ src/tds/mem.c       6 Mar 2009 05:49:34 -0000
> @@ -656,7 +656,7 @@
>  {
>         TDSLOCALE *locale;
>  
> -       TEST_MALLOC(locale, TDSLOCALE);
> +       TEST_CALLOC(locale, TDSLOCALE, 1);
>         return locale;
>  
>        Cleanup:
> 
> HTH.  
> 

#undef TEST_MALLOC
#define TEST_MALLOC(dest,type) \
        {if (!(dest = (type*)calloc(1, sizeof(type)))) goto Cleanup;}


so calloc is called. However I don't understand 0x0000016... memory
corruption ?? Failure to free(NULL) ??

Also consider that in locale.c

  } else if (!strcmp(option, TDS_STR_DATEFMT)) {
    free(locale->date_fmt);
    locale->date_fmt = strdup(value);
  }

so for the same reason you would have a core if locales.conf is found.

But code is so short...

freddy77