Re: [user/tests/sysparams.c] Added more SetLastError(0)'s

[Dmitry Timoshkov]

"Paul Vriens" <Paul.Vriens(a)xs4all.nl> wrote:
> as discussed a few times on wine-devel, there isa  need to clear the
> last error before calling a SPI_{GET|SET} routine.
>
> It appears that not every call resets the last error to 0 on succession
> and thus errors will propagate and leave us in the dark.

You have to set last error to some bogus value (usually 0xdeadbeef)
in order to test whether an API really has changed it.

-- 
Dmitry.

[user/tests/sysparams.c] Added more SetLastError(0)'s

[Paul Vriens]

On Thu, 2005-03-03 at 08:24, Dmitry Timoshkov wrote:
> "Paul Vriens" <Paul.Vriens(a)xs4all.nl> wrote:
> > as discussed a few times on wine-devel, there isa  need to clear the
> > last error before calling a SPI_{GET|SET} routine.
> >
> > It appears that not every call resets the last error to 0 on succession
> > and thus errors will propagate and leave us in the dark.
>
> You have to set last error to some bogus value (usually 0xdeadbeef)
> in order to test whether an API really has changed it.
> OK,

make sense, that crossed my mind before especially when I wrote "It
appears...".

So the approach should be something like:

SetLastError(0xdeadbeef)
rc=SystemParametersInfoA( SPI_GET*, 0, &old_*, 0 );

if (rc == 0 && (GetLastError()==ERROR_CALL_NOT_IMPLEMENTED || GetLastError()==ERROR_INVALID_SPI_VALUE))
{
  /* Call is not implemented apparently */
  trace("SPI_{GET,SET}* not supported on this platform\n");
  return;
}

if (rc != 0 && (GetLastError()==0xdeadbeef))
{
  /* API did not change the last error to 0 */
  what_do_we_do_here?
}

if (rc != 0 && (GetLastError()==0))
{
  /* API changed the last error to 0 */
  do_nothing!
}

should we have an 'ok' call for the fact whether the last error is set
or not? If yes then we first need a lot of tracing to show the results
on several platforms.

Cheers,

Paul.

[user/tests/sysparams.c] Added more SetLastError(0)'s

[Alexandre Julliard]

Paul Vriens <Paul.Vriens(a)xs4all.nl> writes:
> if (rc != 0 && (GetLastError()==0xdeadbeef))
> {
>   /* API did not change the last error to 0 */
>   what_do_we_do_here?
> }
>
> if (rc != 0 && (GetLastError()==0))
> {
>   /* API changed the last error to 0 */
>   do_nothing!
> }

You should not check last error on success, it's meaningless except in
a few very specific cases.

-- 
Alexandre Julliard
julliard(a)winehq.org