typing string via VNC is unreliable

[Zhaocong]

QEMU version is 3.0.0

# Description

The problem is that, when typing string through VNC, it can be unreliable -- sometimes some key strokes get skipped, sometimes get swapped, sometimes get repeated. There's no problem when typing through VNC on physical hardware.

# Steps to reproduce

1. Launch virtual machine by:

    qemu-kvm -display vnc=:1 -m 2048 opensuse-leap-15.qcow2

2. Connect to VNC by:

    vncviewer -Shared :5901

3. Simulate a series of key strokes by "vncdotool" [1]:

    vncdotool -s 127.0.0.1::5901 typefile strings_to_be_typed.txt

4. Usually after a few hundred keys are typed, something goes wrong.

I attached a screenshot that it mistypes " hello" to "h ello".

[1] https://github.com/sibson/vncdotool

[Gao (alapha23)]

In my case the problem is quite subtle.
Nearly every time we send the key strokes, the guest os keeps receiving space or tab or new line character. And ending part of the text is truncated, where the truncated part is fixed depending on the keystrokes we are sending.
Additionally, the keystrokes are mis-ordered at a higher frequency than 1 out of a few hundreds as you said.

In brief,
- Repeatedly receiving space, tab or new line character as ending
- Truncation regarding ending part of key strokes
- characters are mis-ordered, lost, repeated

A question is, how can you make character transaction faster with vncdotool? In my case, vncdotool is typing fairly slow.

I found this debian bug report quite useful, what do you think? https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=758881

Re-producing procedures
---

I re-produced the problem in a slightly different way since your method seems not working for me.

> qemu-img create tumbleweed.img 40G
> qemu-system-x86_64 -drive file=tumbleweed.img,if=virtio -boot d -cdrom openSUSE-Tumbleweed-DVD-x86_64-Snapshot20181119-Media.iso -m 2048 --enable-kvm -display vnc=:1
> qemu-system-x86_64 -drive file=tumbleweed.img,if=virtio -m 4G --enable-kvm -display vnc=:1

[Thomas Huth (th-huth)]

The QEMU project is currently considering to move its bug tracking to
another system. For this we need to know which bugs are still valid
and which could be closed already. Thus we are setting older bugs to
"Incomplete" now.

If you still think this bug report here is valid, then please switch
the state back to "New" within the next 60 days, otherwise this report
will be marked as "Expired". Or please mark it as "Fix Released" if
the problem has been solved with a newer version of QEMU already.

Thank you and sorry for the inconvenience.

[Launchpad Janitor (janitor)]

[Expired for QEMU because there has been no activity for 60 days.]