From 3085e7339210ce946481150f9dd55bb5b3c824a0 Mon Sep 17 00:00:00 2001
From: Zebediah Figura <z.figura12@gmail.com>
Date: Tue, 14 Feb 2017 09:41:53 -0600
Subject: [PATCH] storage.dll16: Simplify operations in IStream16::Seek.

Signed-off-by: Zebediah Figura <z.figura12@gmail.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>
---
 dlls/storage.dll16/storage.c | 59 +++++++++++++++---------------------
 1 file changed, 24 insertions(+), 35 deletions(-)

diff --git a/dlls/storage.dll16/storage.c b/dlls/storage.dll16/storage.c
index 74aa7f99911..2ce35713be3 100644
--- a/dlls/storage.dll16/storage.c
+++ b/dlls/storage.dll16/storage.c
@@ -1179,44 +1179,33 @@ ULONG CDECL IStream16_fnRelease(IStream16 *iface)
  *    Does not handle 64 bits
  */
 HRESULT CDECL IStream16_fnSeek(IStream16 *iface, LARGE_INTEGER offset, DWORD whence,
-	ULARGE_INTEGER *newpos)
+                               ULARGE_INTEGER *newpos)
 {
-	IStream16Impl *This = impl_from_IStream16(iface);
-	TRACE_(relay)("(%p)->([%d.%d],%d,%p)\n",This,offset.u.HighPart,offset.u.LowPart,whence,newpos);
+    IStream16Impl *This = impl_from_IStream16(iface);
+    TRACE_(relay)("(%p)->([%d.%d],%d,%p)\n",This,offset.u.HighPart,offset.u.LowPart,whence,newpos);
 
-	switch (whence) {
-	/* unix SEEK_xx should be the same as win95 ones */
-	case SEEK_SET:
-		/* offset must be ==0 (<0 is invalid, and >0 cannot be handled
-		 * right now.
-		 */
-		assert(offset.u.HighPart==0);
-		This->offset.u.HighPart = offset.u.HighPart;
-		This->offset.u.LowPart = offset.u.LowPart;
-		break;
-	case SEEK_CUR:
-		if (offset.u.HighPart < 0) {
-			/* FIXME: is this negation correct ? */
-			offset.u.HighPart = -offset.u.HighPart;
-			offset.u.LowPart = (0xffffffff ^ offset.u.LowPart)+1;
+    switch (whence) {
+    case STREAM_SEEK_SET:
+        This->offset.QuadPart = offset.QuadPart;
+        break;
+    case STREAM_SEEK_CUR:
+        if ((offset.QuadPart < 0 && -offset.QuadPart > This->offset.QuadPart) ||
+            (offset.QuadPart > 0 && -offset.QuadPart <= This->offset.QuadPart))
+            return STG_E_INVALIDFUNCTION;
+        This->offset.QuadPart += offset.QuadPart;
+        break;
+    case STREAM_SEEK_END:
+        if (-offset.QuadPart > This->stde.pps_size)
+            return STG_E_INVALIDFUNCTION;
 
-			assert(offset.u.HighPart==0);
-			assert(This->offset.u.LowPart >= offset.u.LowPart);
-			This->offset.u.LowPart -= offset.u.LowPart;
-		} else {
-			assert(offset.u.HighPart==0);
-			This->offset.u.LowPart+= offset.u.LowPart;
-		}
-		break;
-	case SEEK_END:
-		assert(offset.u.HighPart==0);
-		This->offset.u.LowPart = This->stde.pps_size-offset.u.LowPart;
-		break;
-	}
-	if (This->offset.u.LowPart>This->stde.pps_size)
-		This->offset.u.LowPart=This->stde.pps_size;
-	if (newpos) *newpos = This->offset;
-	return S_OK;
+        This->offset.QuadPart = This->stde.pps_size + offset.QuadPart;
+        break;
+    }
+
+    if (This->offset.QuadPart>This->stde.pps_size)
+        This->offset.QuadPart=This->stde.pps_size;
+    if (newpos) *newpos = This->offset;
+    return S_OK;
 }
 
 /******************************************************************************