winmm: Inherit the seek position when using standard file handle.

dlls/winmm/mmio.c

@@ -670,9 +670,9 @@ static HMMIO MMIO_Open(LPSTR szFileName, MMIOINFO* refmminfo, DWORD dwOpenFlags,
     refmminfo->wErrorRet = send_message(wm->ioProc, &wm->info, MMIOM_OPEN,
                                         (LPARAM)szFileName, 0, FALSE);
 
-    /* grab file size, when possible */
+    /* update offsets and grab file size, when possible */
     if (wm->info.fccIOProc != FOURCC_MEM && (send_message(wm->ioProc, &wm->info, MMIOM_SEEK, 0, SEEK_CUR, FALSE)) != -1) {
-       pos = wm->info.lDiskOffset;
+       pos = wm->info.lBufOffset = wm->info.lDiskOffset;
        send_message(wm->ioProc, &wm->info, MMIOM_SEEK, 0, SEEK_END, FALSE);
        wm->dwFileSize = wm->info.lDiskOffset;
        send_message(wm->ioProc, &wm->info, MMIOM_SEEK, pos, SEEK_SET, FALSE);

dlls/winmm/tests/mmio.c

@@ -704,6 +704,8 @@ static void test_mmioSeek(void)
     const LONG size = sizeof(RIFF_buf), offset = 16;
     char test_file[MAX_PATH];
     MMRESULT res;
+    HFILE hfile;
+    OFSTRUCT ofs;
 
     /* test memory file */
     memset(&mmio, 0, sizeof(mmio));
@@ -784,6 +786,24 @@ static void test_mmioSeek(void)
         mmioClose(hmmio, 0);
     }
 
+    /* test seek position inheritance from standard file handle */
+    hfile = OpenFile(test_file, &ofs, OF_READ);
+    ok(hfile != HFILE_ERROR, "Failed to open the file, err %d\n", GetLastError());
+    if (hfile != HFILE_ERROR) {
+        pos = _llseek(hfile, offset, SEEK_SET);
+        ok(pos != HFILE_ERROR, "Failed to seek, err %d\n", GetLastError());
+        memset(&mmio, 0, sizeof(mmio));
+        mmio.fccIOProc = FOURCC_DOS;
+        mmio.adwInfo[0] = (DWORD)hfile;
+        hmmio = mmioOpen(NULL, &mmio, MMIO_READ | MMIO_DENYWRITE | MMIO_ALLOCBUF);
+        ok(hmmio != NULL, "mmioOpen error %u\n", mmio.wErrorRet);
+        if (hmmio != NULL) {
+            pos = mmioSeek(hmmio, 0, SEEK_CUR);
+            ok(pos == offset, "expected %d, got %d\n", offset, pos);
+            mmioClose(hmmio, 0);
+        }
+    }
+
     DeleteFileA(test_file);
 }