riched20: WM_GETTEXT should return 0 on overflow but fill buffer anyway.

dlls/riched20/editor.c

@@ -2002,13 +2002,34 @@ static LRESULT RichEditWndProc_common(HWND hWnd, UINT msg, WPARAM wParam,
   case WM_GETTEXT:
   {
     GETTEXTEX ex;
+    LRESULT rc;
+    LPSTR bufferA = NULL;
+    LPWSTR bufferW = NULL;
+
+    if (unicode)
+        bufferW = richedit_alloc((wParam + 2) * sizeof(WCHAR));
+    else bufferA = richedit_alloc(wParam + 2);
 
-    ex.cb = wParam;
+    ex.cb = wParam + (unicode ? 2*sizeof(WCHAR) : 2);
     ex.flags = GT_USECRLF;
     ex.codepage = unicode ? 1200 : CP_ACP;
     ex.lpDefaultChar = NULL;
     ex.lpUsedDefaultChar = NULL;
-    return RichEditWndProc_common(hWnd, EM_GETTEXTEX, (WPARAM)&ex, lParam, unicode);
+    rc = RichEditWndProc_common(hWnd, EM_GETTEXTEX, (WPARAM)&ex, unicode ? (LPARAM)bufferW : (LPARAM)bufferA, unicode);
+
+    if (unicode)
+    {
+        memcpy((LPWSTR)lParam, bufferW, wParam);
+        if (lstrlenW(bufferW) >= wParam / sizeof(WCHAR)) rc = 0;
+    }
+    else
+    {
+        memcpy((LPSTR)lParam, bufferA, wParam);
+        if (strlen(bufferA) >= wParam) rc = 0;
+    }
+    if (bufferA != NULL) richedit_free(bufferA);
+    if (bufferW != NULL) richedit_free(bufferW);
+    return rc;
   }
   case EM_GETTEXTEX:
   {

dlls/riched20/tests/editor.c

@@ -656,14 +656,48 @@ static void test_WM_GETTEXT(void)
 {
     HWND hwndRichEdit = new_richedit(NULL);
     static const char text[] = "Hello. My name is RichEdit!";
+    static const char text2[] = "Hello. My name is RichEdit!\r";
+    static const char text2_after[] = "Hello. My name is RichEdit!\r\n";
     char buffer[1024] = {0};
     int result;
 
+    /* Baseline test with normal-sized buffer */
     SendMessage(hwndRichEdit, WM_SETTEXT, 0, (LPARAM) text);
+    result = SendMessage(hwndRichEdit, WM_GETTEXT, 1024, (LPARAM) buffer);
+    ok(result == strlen(buffer),
+        "WM_GETTEXT returned %d, expected %d\n", result, strlen(buffer));
     SendMessage(hwndRichEdit, WM_GETTEXT, 1024, (LPARAM) buffer);
     result = strcmp(buffer,text);
     ok(result == 0, 
         "WM_GETTEXT: settext and gettext differ. strcmp: %d\n", result);
+
+    /* Test for behavior in overflow case */
+    memset(buffer, 0, 1024);
+    result = SendMessage(hwndRichEdit, WM_GETTEXT, strlen(text), (LPARAM)buffer);
+    ok(result == 0,
+        "WM_GETTEXT returned %d, expected 0\n", result);
+    result = strcmp(buffer,text);
+    ok(result == 0,
+        "WM_GETTEXT: settext and gettext differ. strcmp: %d\n", result);
+
+    /* Baseline test with normal-sized buffer and carriage return */
+    SendMessage(hwndRichEdit, WM_SETTEXT, 0, (LPARAM) text2);
+    result = SendMessage(hwndRichEdit, WM_GETTEXT, 1024, (LPARAM) buffer);
+    ok(result == strlen(buffer),
+        "WM_GETTEXT returned %d, expected %d\n", result, strlen(buffer));
+    result = strcmp(buffer,text2_after);
+    ok(result == 0,
+        "WM_GETTEXT: settext and gettext differ. strcmp: %d\n", result);
+
+    /* Test for behavior of CRLF conversion in case of overflow */
+    memset(buffer, 0, 1024);
+    result = SendMessage(hwndRichEdit, WM_GETTEXT, strlen(text2), (LPARAM)buffer);
+    ok(result == 0,
+        "WM_GETTEXT returned %d, expected 0\n", result);
+    result = strcmp(buffer,text2);
+    ok(result == 0,
+        "WM_GETTEXT: settext and gettext differ. strcmp: %d\n", result);
+
     DestroyWindow(hwndRichEdit);
 }