Paul Gofman : winegstreamer: Try to handle broken IStream_Stat implementation in WM reader OpenStream().

[Alexandre Julliard]

Module: wine
Branch: master
Commit: 6ad606483959dbacf3179b277983b5b0404423fe
URL:    https://gitlab.winehq.org/wine/wine/-/commit/6ad606483959dbacf3179b277983b5b...

Author: Paul Gofman 
Date:   Wed Apr  3 15:02:49 2024 -0600

winegstreamer: Try to handle broken IStream_Stat implementation in WM reader OpenStream().

---

dlls/winegstreamer/wm_reader.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/dlls/winegstreamer/wm_reader.c b/dlls/winegstreamer/wm_reader.c
index 18910f87d40..c96d053ccae 100644
--- a/dlls/winegstreamer/wm_reader.c
+++ b/dlls/winegstreamer/wm_reader.c
@@ -2224,18 +2224,36 @@ static HRESULT WINAPI reader_Open(IWMSyncReader2 *iface, const WCHAR *filename)

static HRESULT WINAPI reader_OpenStream(IWMSyncReader2 *iface, IStream *stream)
 {
+    static const ULONG64 canary_size = 0xdeadbeeffeedcafe;
     struct wm_reader *reader = impl_from_IWMSyncReader2(iface);
     STATSTG stat;
     HRESULT hr;

TRACE("reader %p, stream %p.\n", reader, stream);

+    stat.cbSize.QuadPart = canary_size;
     if (FAILED(hr = IStream_Stat(stream, &stat, STATFLAG_NONAME)))
     {
         ERR("Failed to stat stream, hr %#lx.\n", hr);
         return hr;
     }

+    if (stat.cbSize.QuadPart == canary_size)
+    {
+        /* Call of Juarez: Gunslinger implements IStream_Stat as an empty function returning S_OK, leaving
+         * the output stat unchanged. Windows doesn't call IStream_Seek(_SEEK_END) and probably validates
+         * the size against WMV file headers so the bigger cbSize doesn't change anything.
+         * Such streams work as soon as the uninitialized cbSize is big enough which is usually the case
+         * (if that is not the case Windows will favour shorter cbSize). */
+        static const LARGE_INTEGER zero = { 0 };
+        ULARGE_INTEGER pos = { .QuadPart = canary_size };
+
+        if (SUCCEEDED(hr = IStream_Seek(stream, zero, STREAM_SEEK_END, &pos)))
+            IStream_Seek(stream, zero, STREAM_SEEK_SET, NULL);
+        stat.cbSize.QuadPart = pos.QuadPart == canary_size ? 0 : pos.QuadPart;
+        ERR("IStream_Stat did not fill the stream size, size from _Seek %I64u.\n", stat.cbSize.QuadPart);
+    }
+
     EnterCriticalSection(&reader->cs);

if (reader->wg_parser)