Ctrl+Alt+Shift+2 doesn't send NUL in VT input mode

Mike Griese (@zadjii-msft)

Okay so Ctrl+Alt+Space was fixed for conhost, but it looks like it's still broken in the Terminal 😢 Now it's just generating a ^@, a single NUL.

I think the Terminal is synthesizing the right sequence, but maybe conpty is generating the wrong input for it now, or maybe the input that's generated by conpty doesn't get re-translated back to ^[^@ correctly. I can try to keep investigating to figure out where the miscommunication is, if you need help.

Leonard Hecker (@lhecker):

Mike Griese (@zadjii-msft) Yeah I was just about to say that as well.

As I wrote above the most puzzling thing for me though is if you change this if condition (line 510) to a simple ch != 0 - which should be correct as well.
If you attach a debugger you'll see that TerminalInput definitely invokes _pfnWriteEvents with a \x1b\x00 sequence.
But then showkey shows a ^[^R sequence instead. How can this happen? > I don't understand how such a benign change to the if condition can cause this. 😞

Okay I maybe saw what happened here.

On a en-us keyboard, '@' is shift+2.
When conpty sees a \x1b\x0, it converts it to [Shift_down, Ctrl_down, Alt_down, 2_down, 2_up, Alt_up, Ctrl_up, Shift_up].
- I did not pay a ton of attention to the keys that got synthesized here. I need to re-investigate the [2_down, 2_up]
When we get back to TerminalInput::HandleKey, we end up skipping that branch, because the ch was 0n50, which is 0x32, which is '2'.

I'm not sure what's exactly the right behavior here. I'd think we probably should send a different key, but I'll need to investigate more. It's possible that the ch != 0 change would work just fine, but I want to make sure that the upstream input from conpty is actually correct.
I've got a braindead fix that would fix showkey -a, but that doesn't really resolve the issue here for Win32 applications unfortunately, so I'm gonna file a separate issue to track this investigation.

Originally posted by Mike Griese (@zadjii-msft) in #4192 (comment)

`master`, Conhost+conpty, `Ctrl+alt+space`, (i/o modes):`(0x 1f7, 0x f)` (Win32 input)

Down: 1 Repeat: 1 KeyCode: 0x10 ScanCode: 0x2a Char: \0 (0x0) KeyState: 0x10
Down: 1 Repeat: 1 KeyCode: 0x12 ScanCode: 0x38 Char: \0 (0x0) KeyState: 0x12
Down: 1 Repeat: 1 KeyCode: 0x11 ScanCode: 0x1d Char: \0 (0x0) KeyState: 0x1a
Down: 1 Repeat: 1 KeyCode: 0x32 ScanCode: 0x3 Char: \0 (0x0) KeyState: 0x1a
Down: 0 Repeat: 1 KeyCode: 0x32 ScanCode: 0x3 Char: \0 (0x0) KeyState: 0x1a
Down: 0 Repeat: 1 KeyCode: 0x11 ScanCode: 0x1d Char: \0 (0x0) KeyState: 0x12
Down: 0 Repeat: 1 KeyCode: 0x12 ScanCode: 0x38 Char: \0 (0x0) KeyState: 0x10
Down: 0 Repeat: 1 KeyCode: 0x10 ScanCode: 0x2a Char: \0 (0x0) KeyState: 0x0

The interesting input here is Down: 1 Repeat: 1 KeyCode: 0x32 ScanCode: 0x3 Char: \0 (0x0) KeyState: 0x1a

`master`, Conhost+conpty, `Ctrl+alt+space`, (i/o modes):`(0x 3f7, 0x f)` (VT input)

Down: 1 Repeat: 1 KeyCode: 0x10 ScanCode: 0x2a Char: \0 (0x0) KeyState: 0x10
Down: 1 Repeat: 1 KeyCode: 0x12 ScanCode: 0x38 Char: \0 (0x0) KeyState: 0x12
Down: 1 Repeat: 1 KeyCode: 0x11 ScanCode: 0x1d Char: \0 (0x0) KeyState: 0x1a
Down: 1 Repeat: 1 KeyCode: 0x32 ScanCode: 0x0 Char: \0 (0x0) KeyState: 0x1a
Down: 0 Repeat: 1 KeyCode: 0x32 ScanCode: 0x3 Char: \0 (0x0) KeyState: 0x1a
Down: 0 Repeat: 1 KeyCode: 0x11 ScanCode: 0x1d Char: \0 (0x0) KeyState: 0x12
Down: 0 Repeat: 1 KeyCode: 0x12 ScanCode: 0x38 Char: \0 (0x0) KeyState: 0x10
Down: 0 Repeat: 1 KeyCode: 0x10 ScanCode: 0x2a Char: \0 (0x0) KeyState: 0x0

`master`, Conhost, `Ctrl+alt+space`, (i/o modes):`(0x 1f7, 0x f)` (Win32 input)

Down: 1 Repeat: 1 KeyCode: 0x11 ScanCode: 0x1d Char: \0 (0x0) KeyState: 0x28
Down: 1 Repeat: 1 KeyCode: 0x12 ScanCode: 0x38 Char: \0 (0x0) KeyState: 0x2a
Down: 1 Repeat: 1 KeyCode: 0x20 ScanCode: 0x39 Char: \0 (0x0) KeyState: 0x2a
Down: 0 Repeat: 1 KeyCode: 0x20 ScanCode: 0x39 Char: \0 (0x0) KeyState: 0x2a
Down: 0 Repeat: 1 KeyCode: 0x11 ScanCode: 0x1d Char: \0 (0x0) KeyState: 0x22
Down: 0 Repeat: 1 KeyCode: 0x12 ScanCode: 0x38 Char: \0 (0x0) KeyState: 0x20

`master`, Conhost, `Ctrl+alt+space`, (i/o modes):`(0x 3f7, 0x f)` (VT input)

Down: 1 Repeat: 1 KeyCode: 0x11 ScanCode: 0x1d Char: \0 (0x0) KeyState: 0x28
Down: 1 Repeat: 1 KeyCode: 0x12 ScanCode: 0x38 Char: \0 (0x0) KeyState: 0x2a
Down: 1 Repeat: 1 KeyCode: 0x0 ScanCode: 0x0 Char: ^[ (0x1b) KeyState: 0x0
Down: 1 Repeat: 1 KeyCode: 0x0 ScanCode: 0x0 Char: \0 (0x0) KeyState: 0x0
Down: 0 Repeat: 1 KeyCode: 0x20 ScanCode: 0x39 Char: \0 (0x0) KeyState: 0x2a
Down: 0 Repeat: 1 KeyCode: 0x11 ScanCode: 0x1d Char: \0 (0x0) KeyState: 0x22
Down: 0 Repeat: 1 KeyCode: 0x12 ScanCode: 0x38 Char: \0 (0x0) KeyState: 0x20

`master`, Conhost, `Ctrl+alt+shift+2`, (i/o modes):`(0x 1f7, 0x f)` (Win32 input)

Down: 1 Repeat: 1 KeyCode: 0x10 ScanCode: 0x2a Char: \0 (0x0) KeyState: 0x30
Down: 1 Repeat: 1 KeyCode: 0x11 ScanCode: 0x1d Char: \0 (0x0) KeyState: 0x38
Down: 1 Repeat: 1 KeyCode: 0x12 ScanCode: 0x38 Char: \0 (0x0) KeyState: 0x3a
Down: 1 Repeat: 1 KeyCode: 0x32 ScanCode: 0x3 Char: \0 (0x0) KeyState: 0x3a
Down: 0 Repeat: 1 KeyCode: 0x32 ScanCode: 0x3 Char: \0 (0x0) KeyState: 0x3a
Down: 0 Repeat: 1 KeyCode: 0x10 ScanCode: 0x2a Char: \0 (0x0) KeyState: 0x20

NOTE: this keystroke is what conpty is attempting to replicate

Leonard Hecker (@lhecker)

Okay I see what the problem is - I think it is the think Leonard Hecker (@lhecker) called out in #4192. Even in straight-up conhost, Ctrl+alt+shift+2 does not generate \x1b\x0.

IMO, Leonard Hecker (@lhecker) if you want to do the fix proposed in #4192, the ch != 0 fix, then I say go for it, and add this to the growing list of bugs that PR fixes 😆

I'll submit the other thing I found during the course of this investigation, but that will effectively hide the showkey -a repro case in the Terminal.

Mike Griese (@zadjii-msft)

Mike Griese (@zadjii-msft) I believe we're misunderstanding each other.

If I press Ctrl+Alt+Space or Ctrl+Alt+Shift+2, showkey -a will show the following output:

`Ctrl+Alt` condition	`showkey -a` output
`ch >= 0x40 && ch < 0x7F`	`^@`
`ch != 0`	`^[^R`

But as far as I can see it should be ^[^@, right?
Or am I misunderstanding you and ^[^R is actually correct? (...because, as you mentioned above, there's another bug involved here, which distorts the showkey output?)

That said, would you'd like me to modify #4192 to use a ch != 0 condition?
I can't decide by myself if I should. 😄

Oh jeez, you should be seeing ^[^@. Now I'm not sure what the right fix is.

I figured it out. I didn't realize I had to manually attach myself to OpenConsole.exe for debugging. 🙈
You basically already said all the right things (especially steps 2 and 3 above), but I didn't understand you, because I've been lacking the knowledge how all the code works together.

Anyways... I fixed the problem. (lol)
Turns out if you use MapVirtualKeyW you're probably doing something wrong. I guess? 😄

I replaced this:

terminal/src/terminal/input/terminalInput.cpp

Line 488 in 713550d

    
           auto wchPressedChar = gsl::narrow_cast<wchar_t>(MapVirtualKeyW(keyEvent.GetVirtualKeyCode(), MAPVK_VK_TO_CHAR));

with a call to ToUnicodeEx, similar to Terminal::_CharacterFromKeyEvent.
This call allows us to reliably turn the input event Alt+Ctrl+Shift+2 into an Alt+Ctrl+@ event, which then gets translated to Alt+0x00 and sent away. 🙂

Would you like me to add it to #4192 or open a separate PR afterwards?
I believe it makes sense to fix it separately.

I didn't realize I had to manually attach myself to OpenConsole.exe for debugging.

Literally my least favorite thing about using VS. JUST ATTACH TO CHILD PROCESSES. Or at least give me an option to auto-attach, sheesh.

Turns out if you use MapVirtualKeyW you're probably doing something wrong

You're sure right about that 😄 Glad you got that figured out!

Would you like me to add it to #4192 or open a separate PR afterwards?

Let's open another PR, since this has gotten bigger than a oneline fix ☺️

This fixes C-M-space for WSL but not for Win32, but I'm not sure ther…

Milestoning this for 1.x and taking off Triage

Fixed #5205: Ctrl+Alt+2 doesn't send ^[^@ (#5272)

Merged PR 5676764: Migrate OSS up to 16d00a6

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Ctrl+Alt+Shift+2 doesn't send NUL in VT input mode #5205

`master`, Conhost+conpty, `Ctrl+alt+space`, (i/o modes):`(0x 1f7, 0x f)` (Win32 input)

`master`, Conhost+conpty, `Ctrl+alt+space`, (i/o modes):`(0x 3f7, 0x f)` (VT input)

`master`, Conhost, `Ctrl+alt+space`, (i/o modes):`(0x 1f7, 0x f)` (Win32 input)

`master`, Conhost, `Ctrl+alt+space`, (i/o modes):`(0x 3f7, 0x f)` (VT input)

`master`, Conhost, `Ctrl+alt+shift+2`, (i/o modes):`(0x 1f7, 0x f)` (Win32 input)

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Ctrl+Alt+Shift+2 doesn't send NUL in VT input mode #5205

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zadjii-msft commented on Apr 1, 2020

master, Conhost+conpty, Ctrl+alt+space, (i/o modes):(0x 1f7, 0x f) (Win32 input)

master, Conhost+conpty, Ctrl+alt+space, (i/o modes):(0x 3f7, 0x f) (VT input)

master, Conhost, Ctrl+alt+space, (i/o modes):(0x 1f7, 0x f) (Win32 input)

master, Conhost, Ctrl+alt+space, (i/o modes):(0x 3f7, 0x f) (VT input)

master, Conhost, Ctrl+alt+shift+2, (i/o modes):(0x 1f7, 0x f) (Win32 input)

zadjii-msft commented on Apr 1, 2020

lhecker commented on Apr 1, 2020

zadjii-msft commented on Apr 1, 2020

lhecker commented on Apr 1, 2020

zadjii-msft commented on Apr 1, 2020

5 remaining items

DHowett-MSFT commented on Apr 3, 2020

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`master`, Conhost+conpty, `Ctrl+alt+space`, (i/o modes):`(0x 1f7, 0x f)` (Win32 input)

`master`, Conhost+conpty, `Ctrl+alt+space`, (i/o modes):`(0x 3f7, 0x f)` (VT input)

`master`, Conhost, `Ctrl+alt+space`, (i/o modes):`(0x 1f7, 0x f)` (Win32 input)

`master`, Conhost, `Ctrl+alt+space`, (i/o modes):`(0x 3f7, 0x f)` (VT input)

`master`, Conhost, `Ctrl+alt+shift+2`, (i/o modes):`(0x 1f7, 0x f)` (Win32 input)