Using Ubuntu 14.04 host and Windows 7 guest only max. 12582911 bytes can be transferred via shared clipboard

[muzso]

I'm using an Ubuntu 14.04 (fully updated) host and a Windows 7 guest (fully updated). The guest has the new (5.0.16) Guest Additions, which was installed using Windows Safe Mode (so I could install basic 3D acceleration as well).

If I open a random text file of 12582911 bytes (eg. in Notepad) in the guest OS, select it's entire contents and copy it to the (shared) clipboard, then I can paste this into gedit in the host OS.

If I add a single character to the end of the file (so it becomes 12582912 bytes long) and do the same, I cannot paste the clipboards contents into eg. gedit in the host OS.

And of course: anything below 12582911 bytes works too and anything above 12582912 bytes doesn't work. :-)

I tried various apps in the guest (Notepad, Wordpad, Notepad++, Total Commander) to open the text file and copy it's contents to the shared clipboard. And I tried various apps in the host OS too to paste the contents of the clipboard. All showed the same symptom.

I created the test text file in linux using this command (I used unix2dos to convert the text file to DOS/Windows line endings so eg. Notepad won't die on me):

dd if=/dev/urandom bs=12M count=1 | base64 - | unix2dos | dd bs=1 count=12582911 of=test.txt

It's contents can still be transferred from guest to host via shared clipboard, but if you add only a single extra character to it, the clipboard transfer fails.

Nothing appears in VB's log or in the host's logs (eg. syslog). Neither when the clipboard transfer works, nor when it doesn't.

In the VM I've "Shared Clipboard" set to "bidirectional".