winmm: mciSendString always returns a response string (albeit empty).

dlls/winmm/mci.c

@@ -1535,8 +1535,10 @@ DWORD WINAPI mciSendStringW(LPCWSTR lpstrCommand, LPWSTR lpstrRet,
 	dwRet = MCI_SendCommand(wmd ? wmd->wDeviceID : uDevID, wMsg, dwFlags, (DWORD_PTR)&data);
     }
     TRACE("=> 1/ %x (%s)\n", dwRet, debugstr_w(lpstrRet));
-    dwRet = MCI_HandleReturnValues(dwRet, wmd, retType, &data.generic, lpstrRet, uRetLen);
-    TRACE("=> 2/ %x (%s)\n", dwRet, debugstr_w(lpstrRet));
+    if (!LOWORD(dwRet)) {
+	dwRet = MCI_HandleReturnValues(dwRet, wmd, retType, &data.generic, lpstrRet, uRetLen);
+	TRACE("=> 2/ %x (%s)\n", dwRet, debugstr_w(lpstrRet));
+    }
 
 errCleanUp:
     if (auto_open) {
@@ -1569,9 +1571,9 @@ DWORD WINAPI mciSendStringA(LPCSTR lpstrCommand, LPSTR lpstrRet,
     MultiByteToWideChar( CP_ACP, 0, lpstrCommand, -1, lpwstrCommand, len );
     if (lpstrRet)
     {
+        if (uRetLen) *lpstrRet = '\0'; /* NT-w2k3 use memset(lpstrRet, 0, uRetLen); */
         lpwstrRet = HeapAlloc(GetProcessHeap(), 0, uRetLen * sizeof(WCHAR));
         if (!lpwstrRet) {
-            WARN("no memory\n");
             HeapFree( GetProcessHeap(), 0, lpwstrCommand );
             return MCIERR_OUT_OF_MEMORY;
         }

dlls/winmm/tests/mci.c

@@ -189,11 +189,15 @@ static void test_mciParser(HWND hwnd)
     err = mciSendString("open avivideo alias a", buf, sizeof(buf), hwnd);
     ok(!err,"open another: %s\n", dbg_mcierr(err));
 
+    buf[0]='z';
     err = mciSendString("", buf, sizeof(buf), NULL);
     todo_wine ok(err==MCIERR_MISSING_COMMAND_STRING,"empty string: %s\n", dbg_mcierr(err));
+    ok(!buf[0], "error buffer %s\n", buf);
 
+    buf[0]='d';
     err = mciSendString("open", buf, sizeof(buf), NULL);
     ok(err==MCIERR_MISSING_DEVICE_NAME,"open void: %s\n", dbg_mcierr(err));
+    ok(!buf[0], "open error buffer %s\n", buf);
 
     err = mciSendString("open notify", buf, sizeof(buf), NULL);
     todo_wine ok(err==MCIERR_INVALID_DEVICE_NAME,"open notify: %s\n", dbg_mcierr(err));
@@ -214,15 +218,19 @@ static void test_mciParser(HWND hwnd)
     err = mciSendString("status x length position", buf, sizeof(buf), NULL);
     todo_wine ok(err==MCIERR_FLAGS_NOT_COMPATIBLE,"status length+position: %s\n", dbg_mcierr(err));
 
+    buf[0]='I';
     err = mciSendString("set x time format milliseconds time format ms", buf, sizeof(buf), NULL);
     todo_wine ok(err==MCIERR_FLAGS_NOT_COMPATIBLE,"status length+position: %s\n", dbg_mcierr(err));
+    ok(!buf[0], "set error buffer %s\n", buf);
 
     /* device's response, not a parser test */
     err = mciSendString("status x", buf, sizeof(buf), NULL);
     todo_wine ok(err==MCIERR_MISSING_PARAMETER,"status waveaudio nokeyword: %s\n", dbg_mcierr(err));
 
+    buf[0]='G';
     err = mciSendString("status a", buf, sizeof(buf), NULL);
     todo_wine ok(err==MCIERR_UNSUPPORTED_FUNCTION,"status avivideo nokeyword: %s\n", dbg_mcierr(err));
+    ok(!buf[0], "status error buffer %s\n", buf);
 
     err = mciSendString("status x track", buf, sizeof(buf), NULL);
     todo_wine ok(err==MCIERR_BAD_INTEGER,"status waveaudio no track: %s\n", dbg_mcierr(err));
@@ -283,6 +291,7 @@ static void test_mciParser(HWND hwnd)
      * and return the one error code or MCIERR_MULTIPLE if they differ. */
     err = mciSendString("pause all", buf, sizeof(buf), NULL);
     todo_wine ok(err==MCIERR_MULTIPLE || broken(err==MCIERR_NONAPPLICABLE_FUNCTION),"pause all: %s\n", dbg_mcierr(err));
+    ok(!buf[0], "pause error buffer %s\n", buf);
 
     /* MCI_STATUS' dwReturn is a DWORD_PTR, others' a plain DWORD. */
     parm.status.dwItem = MCI_STATUS_TIME_FORMAT;
@@ -448,6 +457,7 @@ static void test_openCloseWAVE(HWND hwnd)
 
     err = mciSendString("sysinfo nodev installname", buf, sizeof(buf), hwnd);
     ok(err==MCIERR_INVALID_DEVICE_NAME,"sysinfo nodev installname: %s\n", dbg_mcierr(err));
+    ok(!buf[0], "sysinfo error buffer %s\n", buf);
 
     err = mciGetDeviceID("all");
     ok(MCI_ALL_DEVICE_ID==err || /* Win9x */(UINT16)MCI_ALL_DEVICE_ID==err,"mciGetDeviceID all returned %u, expected %d\n", err, MCI_ALL_DEVICE_ID);
@@ -584,6 +594,7 @@ static void test_recordWAVE(HWND hwnd)
     /* Info file fails until named in Open or Save. */
     err = mciSendString("info x file", buf, sizeof(buf), NULL);
     todo_wine ok(err==MCIERR_NONAPPLICABLE_FUNCTION,"mci info new file returned %s\n", dbg_mcierr(err));
+    ok(!buf[0], "info error buffer %s\n", buf);
 
     /* Check the default recording: 8-bits per sample, mono, 11kHz */
     err = mciSendString("status x samplespersec", buf, sizeof(buf), NULL);