Certain FTP servers refuse the SIZE command in ASCII mode (proftpd)
or refuse the SIZE command in ASCII mode for large files.
This is a security feature, as the SIZE command requires reading
the whole file and counting line ends which can cause denial of
services. In binary mode, the file size on disc is reported, which
is a relatively quick operation.
Qt had two problems here:
1. when size command fails, the total size was reported as -1,
whereas the documentation of QFtp::dataTransferProgress states
it should be reported as 0 (so that QProgressDialog can display
a wait note rather than progress bar)
2. SIZE command was sent before setting the type of the transfer
to ASCII / Binary. This is a problem as the size reported by
the server is incorrect. Also it usually means sending ASCII
SIZE for Binary transfers, which results in the 550 error on
FTP servers with DOS protection.
Task-Number: QTTH-1428
Reviewed-By: Peter Hartmann
(cherry picked from commit 72bf6105214bfc26cff33632f7f4bdeed9cdf362)
Change-Id: Ie1f356c34d6a04362eaca64befb00788f85c0ccb
Reviewed-by: Peter Hartmann <peter.hartmann@nokia.com>
4aa4198240