[PATCH 2/2] riched20: Emulate a Windows bug that ignores undo/redo failure.

[Jinoh Kang]

From: Jinoh Kang <jinoh.kang.kr at gmail.com>

Signed-off-by: Jinoh Kang <jinoh.kang.kr at gmail.com>
---
 dlls/riched20/editor.c       | 10 ++++++++--
 dlls/riched20/editstr.h      | 13 +++++++++++++
 dlls/riched20/tests/editor.c |  2 --
 dlls/riched20/undo.c         |  2 ++
 4 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/dlls/riched20/editor.c b/dlls/riched20/editor.c
index 3628e51ac9b..2eb8b7d2a11 100644
--- a/dlls/riched20/editor.c
+++ b/dlls/riched20/editor.c
@@ -2938,6 +2938,8 @@ ME_TextEditor *ME_MakeEditor(ITextHost *texthost, BOOL bEmulateVersion10)
 
   ed->bEmulateVersion10 = bEmulateVersion10;
   ed->in_place_active = FALSE;
+  ed->last_undo_status = FALSE;
+  ed->last_redo_status = FALSE;
   ed->total_rows = 0;
   ITextHost_TxGetPropertyBits( ed->texthost, TXTBIT_RICHTEXT | TXTBIT_MULTILINE | TXTBIT_READONLY |
                                TXTBIT_USEPASSWORD | TXTBIT_HIDESELECTION | TXTBIT_SAVESELECTION |
@@ -3313,9 +3315,13 @@ LRESULT editor_handle_message( ME_TextEditor *editor, UINT msg, WPARAM wParam,
     return !list_empty( &editor->redo_stack );
   case WM_UNDO: /* FIXME: actually not the same */
   case EM_UNDO:
-    return ME_Undo(editor);
+    if (editor->nUndoMode == umIgnore) return FALSE;
+    ME_Undo(editor);
+    return editor->last_undo_status;
   case EM_REDO:
-    return ME_Redo(editor);
+    if (editor->nUndoMode == umIgnore) return FALSE;
+    ME_Redo(editor);
+    return editor->last_redo_status;
   case EM_SETFONTSIZE:
   {
       CHARFORMAT2W cf;
diff --git a/dlls/riched20/editstr.h b/dlls/riched20/editstr.h
index 3b166234f23..2b6e00a861f 100644
--- a/dlls/riched20/editstr.h
+++ b/dlls/riched20/editstr.h
@@ -384,6 +384,19 @@ typedef struct tagME_TextEditor
   unsigned int bEmulateVersion10 : 1;
   unsigned int in_place_active : 1;
   unsigned int have_texthost2 : 1;
+  /* Windows Rich Edit has a bug where undos are counted regardless
+   * of whether they are actually peformed or not.  It appears that
+   * each editor instance has an "undo successful" state variable
+   * that is set by an internal undo routine.  However, failure to
+   * perform the operation (e.g. undo stack is empty) supposedly does
+   * not clear this state variable, which leads to reporting undo
+   * count that may be greater than the number of times it has
+   * actually happened.  We emulate this bug by ignoring ME_Undo's
+   * return value and using the state variable directly.
+   */
+  unsigned int last_undo_status : 1;
+  /* Ditto for redo. */
+  unsigned int last_redo_status : 1;
   ME_TextBuffer *pBuffer;
   ME_Cursor *pCursors;
   DWORD props;
diff --git a/dlls/riched20/tests/editor.c b/dlls/riched20/tests/editor.c
index 79ee7007873..fc9178136e6 100644
--- a/dlls/riched20/tests/editor.c
+++ b/dlls/riched20/tests/editor.c
@@ -7111,7 +7111,6 @@ static void test_undo_status_bug(void)
     lresult = SendMessageA(hwnd, EM_CANUNDO, 0, 0);
     ok(lresult == FALSE, "EM_CANUNDO returned %Id\n", lresult);
     lresult = SendMessageA(hwnd, EM_UNDO, 0, 0);
-    todo_wine
     ok(lresult == TRUE, "EM_UNDO returned %Id\n", lresult);
 
     lresult = SendMessageA(hwnd, EM_CANREDO, 0, 0);
@@ -7122,7 +7121,6 @@ static void test_undo_status_bug(void)
     lresult = SendMessageA(hwnd, EM_CANREDO, 0, 0);
     ok(lresult == FALSE, "EM_CANREDO returned %Id\n", lresult);
     lresult = SendMessageA(hwnd, EM_REDO, 0, 0);
-    todo_wine
     ok(lresult == TRUE, "EM_REDO returned %Id\n", lresult);
 
     DestroyWindow(hwnd);
diff --git a/dlls/riched20/undo.c b/dlls/riched20/undo.c
index d95ce121234..fdeb5e4d423 100644
--- a/dlls/riched20/undo.c
+++ b/dlls/riched20/undo.c
@@ -439,6 +439,7 @@ BOOL ME_Undo(ME_TextEditor *editor)
 
   table_move_from_row_start( editor );
   add_undo( editor, undo_end_transaction );
+  editor->last_undo_status = TRUE;
   editor->nUndoStackSize--;
   editor->nUndoMode = nMode;
   ME_UpdateRepaint(editor, FALSE);
@@ -475,6 +476,7 @@ BOOL ME_Redo(ME_TextEditor *editor)
   }
   table_move_from_row_start( editor );
   add_undo( editor, undo_end_transaction );
+  editor->last_redo_status = TRUE;
   editor->nUndoMode = nMode;
   ME_UpdateRepaint(editor, FALSE);
   return TRUE;
-- 
GitLab

https://gitlab.winehq.org/wine/wine/-/merge_requests/326