fixup bogus SetLastError()

[Andreas Mohr]

On Mon, Jun 04, 2001 at 11:11:23AM -0700, Alexandre Julliard wrote:
> Andreas Mohr <a.mohr at mailto.de> writes:
> 
> > objects/gdiobj.c really has no business dealing with SetLastError().
> > SetLastError() is a mechanism to communicate errors to external programs,
> > so it should definitely not be used for highly internal functions.
> 
> You didn't include the gdiobj.c patch, but I disagree with it
Hmm, strange. I did a diff with the files fetched from a pre-arranged
file list, and I'm damn sure that I had included that file there :-\

> anyway... There can be many good reasons for setting last error in
> internal functions; for instance setting it inside GDI_GetObjPtr
> avoids having to set it in every single caller. And in the very rare
> case where this is not what we want, the caller can always set it to
> another value.
Now that's where I disagree !
The caller can *not* always set it to another value.
If it does and the program intends to read the LastError of a *previously*
executed API that failed, then the LastError will be reset even though
it shouldn't have been !
(I know, programs that don't read the LastError immediately after function
return are braindead, but then we're writing for the Windows platform,
so we have lots of braindead programs anyway, right ? ;-)

In short: the SetLastError behaviour needs to match Windows behaviour very,
very closely.
And IMHO GDI_GetObjPtr() is such a widely used function that this will set
LastError 6 in every case of a NULL handle, so this will spoil a lot of
innocent error settings...
Of course one could argue that it should be the calling function that should
be fixed, then (to not pass a NULL handle to GDI_GetObjPtr).
This would be SelectObject() in this case, BTW.

What to do ?

-- 
Andreas Mohr                        Stauferstr. 6, D-71272 Renningen, Germany
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