#if INTERFACE
/*
** Possible return values from the undo_maybe_save() routine.
*/
#define UNDO_NONE     (0) /* Placeholder only used to initialize vars. */
#define UNDO_SAVED_OK (1) /* The specified file was saved succesfully. */
#define UNDO_DISABLED (2) /* File not saved, subsystem is disabled. */
#define UNDO_INACTIVE (3) /* File not saved, subsystem is not active. */
#define UNDO_TOOBIG   (4) /* File not saved, it exceeded a size limit. */
#endif

/*
** Undo the change to the file zPathname.  zPathname is the pathname
** of the file relative to the root of the repository.  If redoFlag is
** true the redo a change.  If there is nothing to undo (or redo) then
** this routine is a noop.

/*
** Save the current content of the file zPathname so that it
** will be undoable.  The name is relative to the root of the
** tree.
*/
void undo_save(const char *zPathname){
  if( undoDisable ) return;
  if( undo_maybe_save(zPathname, -1)!=UNDO_SAVED_OK ){

    fossil_panic("failed to save undo information for path: %s",
                 zPathname);
  }
}

/*
** Possibly save the current content of the file zPathname so

**          value less than zero, call the undo_save()
**          function instead.
**
** The return value of this function will always be one of the
** following codes:
**
** UNDO_SAVED_OK: The specified file was saved succesfully.
**
** UNDO_DISABLED: The specified file was NOT saved, because the
**                "undo subsystem" is disabled.  This error may
**                indicate that a call to undo_disable() was
**                issued.
**
** UNDO_INACTIVE: The specified file was NOT saved, because the
**                "undo subsystem" is not active.  This error
**                may indicate that a call to undo_begin() is
**                missing.
**
**   UNDO_TOOBIG: The specified file was NOT saved, because it
**                exceeded the specified size limit.  It is
**                impossible for this value to be returned if
**                the specified size limit is less than zero
**                (i.e. unlimited).
*/
int undo_maybe_save(const char *zPathname, i64 limit){
  char *zFullname;
  i64 size;
  int result;

  if( undoDisable ) return UNDO_DISABLED;
  if( !undoActive ) return UNDO_INACTIVE;
  zFullname = mprintf("%s%s", g.zLocalRoot, zPathname);
  size = file_wd_size(zFullname);
  if( limit<0 || size<=limit ){
    int existsFlag = (size>=0);
    int isLink = file_wd_islink(zFullname);
    Stmt q;

*/
const char *undo_save_message(int rc){
  static char zRc[32];

  switch( rc ){
    case UNDO_NONE:     return "undo is disabled for this operation";
    case UNDO_SAVED_OK: return "the save operation was successful";
    case UNDO_DISABLED: return "the undo subsystem is disabled";
    case UNDO_INACTIVE: return "the undo subsystem is inactive";
    case UNDO_TOOBIG:   return "the file is too big";
    default: {
      sqlite3_snprintf(sizeof(zRc), zRc, "of error code %d", rc);
    }
  }
  return zRc;