-FTP: unusable resume buttons in download dialogs

[MarcinW]

Tested with TC 8.51 RC1 32-bit.

Let's assume that we are transferring file(s) from/to FTP server and at least one destination file with same name exists. In this case, we get a confirmation dialog.

1) When uploading one or more files to an FTP server:
- binary mode and automatic mode: there are "Resume" and "Resume all" buttons in the confirmation dialog,
- text mode: these buttons are invisible - this makes sense, because we can't resume transfers in text mode.

2) When downloading one file from an FTP server:
- binary mode and automatic mode: there is a "Resume aborted download" button in the confirmation dialog,
- text mode: this button is still present - but it always generates an error: "501 REST: Resuming transfers not allowed in ASCII mode".

3) When downloading more than one file from an FTP server:
- binary mode and automatic mode: there are "Resume" and "Resume all" buttons in the confirmation dialog,
- text mode: these buttons are still present - but they always generate an error: "501 REST: Resuming transfers not allowed in ASCII mode".

In these red cases, resume buttons always generate errors, so they should be invisible.


Regards

[ghisler(Author)]

This isn't a bug in TC, the error comes from the server! There are some servers which support resume of text files, and some servers which do not support it. The problem is that the server has to count the line breaks to continue at the right position.

[MarcinW]

There are some servers which support resume of text files, and some servers which do not support it.

So - assuming that there are servers that support resuming text files when uploading - resume buttons should be visible also in the green case.

[ghisler(Author)]

No, it's not the same: When downloading, TC requests an overlapping part of the existing file, and compares 512 overlapping bytes to make sure the file was resumed at the right position. This is unfortunately not possible when uploading, so TC cannot know whether the server handled the line breaks issue correctly or not. Therefore the option is only offered when downloading. This problem doesn't exist for binary files.

[MarcinW]

Thanks for the explanation!