Terminal: CNL and CPL should be constrained by margins

Created on 27 Sep 2019 · 3Comments · Source: microsoft/terminal

Environment

Windows build number: Version 10.0.18362.295
Also test with a recent commit 7faf3342e0187841d590fd018452c5c69fd52271

Steps to reproduce

In a conhost WSL shell, execute the following command:

echo -e "\e[6;19r\e[12H\e[99ECNL\e[12H\e[99FCPL\e[r"

This does the following:

sets the top and bottom DECSTBM margins to 6 and 19
moves to line 12 (i.e. inside the margins)
executes the CNL sequence with a count of 99, to move down 99 lines
writes out CNL
moves back to line 12
executes the CPL sequence with a count of 99, to move up 99 lines
writes out CPL

Expected behavior

I can't find spec text to back this up, but in both XTerm and the Gnome VTE terminal these commands are constrained by the DECSTBM margins, so CNL doesn't move below row 19 (the bottom margin), and CPL doesn't move above row 6 (the top margin).

This is what the output looks like in XTerm:

Actual behavior

The margins are ignored by the Windows console, so CNL moves all the way to the bottom of the viewport, and CPL moves all the way to the top of the viewport.

I can't say for certain that this is wrong, but I think we should probably be trying to match the XTerm and VTE behaviour unless there is convincing evidence that they've got it wrong.

Area-VT Help Wanted Issue-Bug Product-Conhost Resolution-Fix-Committed

Source