[Bug 4436] Storage32 regression problem: ECAD app 'Easy-PC' is unable to create new project/design

[Wine Bugs]

http://bugs.winehq.org/show_bug.cgi?id=4436





------- Additional Comments From J.A.Gow at furrybubble.co.uk  2006-08-02 13:49 -------
Since then I have been doing some more digging into the problem and have come up
with a test that triggers the bugs: i.e. passes on Windows and fails on Wine
(latest CVS). Looking at the failure mode I feel that it has the potential to
break a _lot_ of apps.

It is as I thought that there is some issue with the object destructor for the
storage object being called and not actually releasing the object. I have
attached the complete patch to the tests for storage32 to this message if anyone
could try it I would be grateful, but I will just describe some of the reasoning
behind it first.

It seems that the problem is not the grfMode with which the file is opened, but
a reference counting method used within storage32. A call to the destructor of
the storage object is not destroying the object - with it left open the error
appears when a subsequent call to open the storage object fails with access
issues because the previous one is left open. So, I introduced this test that
exactly mimics the behaviour of the app. To do this, I needed a storage object
that contained a stream, so I wrote code in the appropriate conformance test
module to create one:


    r = StgOpenStorage( filename, NULL, STGM_TRANSACTED | STGM_WRITE |
STGM_SHARE_DENY_WRITE, NULL, 0, &stg);
    ok(r==S_OK, "StgOpenStorage failed\n");
    if(stg)
    {
        static const WCHAR stmname[] =  { 'w','i','n','e','t','e','s','t',0};
        IStream *stm = NULL;

        r = IStorage_CreateStream( stg, stmname, STGM_WRITE | STGM_SHARE_EXCLUSIVE,
                                   0, 0, &stm );
        ok(r == S_OK, "CreateStream should succeed\n");

        if(stm) {
            r=IStorage_Commit(stg,STGC_DEFAULT);
            ok(r==S_OK, "StorageCommit failed\n");

        }

        // Windows reference counting seems different....

        r = IStorage_Release(stg);
        ok(r == 0, "wrong ref count"); printf("- ref count = %lx\n",r);

        if(r) {
            r = IStorage_Release(stg);
            ok(r == 0, "wrong ref count"); printf(" - ref count = %lx\n",r);
        }

    }

It was here where I got the surprise! I expected this code to work on both Wine
and Windows, so the next part of the patch could trigger the bug. However I
found that on Windows, the first call to IStorage_Release returns zero, and the
storage object is destroyed. Under Wine however, the first call to
IStorage_Release returns 1 but does not destroy the object - the second call to
IStorage_Release returns zero and destroys the object. It appears that Windows
takes no notice of reference counts when the IStorage destructor is called! I
only discovered this because in the original test code I had two calls to
IStorage_Release straight after each other without the if(r) test: and although
it worked on Wine it segfaulted on Windows due to the 'stg' object being
destroyed on the first call. This proved the difference in behaviour.

Now on to the second part of the test, that attempted to re-open the closed
storage object, then open the stream within it:



    /* Easy-PC test 2 - this looks for the OpenStream mode check. Fails under
Wine */

    r = StgOpenStorage( filename, NULL, 0x00010020, NULL, 0, &stg);
    ok(r==S_OK, "StgOpenStorage failed\n");
    if(stg)
    {
        static const WCHAR stmname[] =  { 'w','i','n','e','t','e','s','t',0};
        IStream *stm = NULL;

        r = IStorage_OpenStream( stg, stmname, 0,
STGM_SHARE_EXCLUSIVE|STGM_READWRITE, 0, &stm );
        ok(r == S_OK, "OpenStream should succeed - "); printf("rc from
OpenStream : %lx\n",r);

        r = IStorage_Release(stg);
        ok(r == 0, "wrong ref count\n");
    }

Again, this works on Windows, but the OpenStream call fails with an access
denied error on Wine. This is the exact mode of the bug in the app.

Could one of the ole32 developers please contact me: I am happy to work with
them to resolve this problem as I need this app to work under Wine, but not
being a Windows programmer I am not fully familiar with the storage API. In the
meantime I will continue my investigation and see if I can fix this directly,
but I am sure it will happen sooner if I could work directly with the ole32
developer. 

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