+ wxFileOffset ret_off, diff;
+
+ wxFileOffset last_access = GetLastAccess();
+
+ if ( !m_flushable )
+ {
+ switch (mode)
+ {
+ case wxFromStart:
+ diff = pos;
+ break;
+
+ case wxFromCurrent:
+ diff = pos + GetIntPosition();
+ break;
+
+ case wxFromEnd:
+ diff = pos + last_access;
+ break;
+
+ default:
+ wxFAIL_MSG( _T("invalid seek mode") );
+
+ return wxInvalidOffset;
+ }
+ if (diff < 0 || diff > last_access)
+ return wxInvalidOffset;
+ size_t int_diff = wx_truncate_cast(size_t, diff);
+ wxCHECK_MSG( (wxFileOffset)int_diff == diff, wxInvalidOffset, wxT("huge file not supported") );
+ SetIntPosition(int_diff);
+ return diff;
+ }
+
+ switch ( mode )
+ {
+ case wxFromStart:
+ // We'll try to compute an internal position later ...
+ ret_off = m_stream->OnSysSeek(pos, wxFromStart);
+ ResetBuffer();
+ return ret_off;
+
+ case wxFromCurrent:
+ diff = pos + GetIntPosition();
+
+ if ( (diff > last_access) || (diff < 0) )
+ {
+ // We must take into account the fact that we have read
+ // something previously.
+ ret_off = m_stream->OnSysSeek(diff-last_access, wxFromCurrent);
+ ResetBuffer();
+ return ret_off;
+ }
+ else
+ {
+ size_t int_diff = wx_truncate_cast(size_t, diff);
+ wxCHECK_MSG( (wxFileOffset)int_diff == diff, wxInvalidOffset, wxT("huge file not supported") );
+ SetIntPosition(int_diff);
+ return pos;
+ }
+
+ case wxFromEnd:
+ // Hard to compute: always seek to the requested position.
+ ret_off = m_stream->OnSysSeek(pos, wxFromEnd);
+ ResetBuffer();
+ return ret_off;
+ }
+
+ return wxInvalidOffset;
+}
+
+wxFileOffset wxStreamBuffer::Tell() const
+{
+ wxFileOffset pos;
+
+ // ask the stream for position if we have a real one
+ if ( m_stream )
+ {
+ pos = m_stream->OnSysTell();
+ if ( pos == wxInvalidOffset )
+ return wxInvalidOffset;
+ }
+ else // no associated stream
+ {
+ pos = 0;
+ }
+
+ pos += GetIntPosition();
+
+ if ( m_mode == read && m_flushable )
+ pos -= GetLastAccess();
+
+ return pos;