My first PR: improved keyboard support

guacamolie · March 6, 2024, 8:16pm

Hello, I recently created my first PR on flipperzero-firmware:

github.com/flipperdevices/flipperzero-firmware

bad_usb: add new keyboard layout file format

flipperdevices:dev ← vanguacamolie:bad-usb-keyboard-layout

opened 01:07PM - 04 Mar 24 UTC

vanguacamolie

+542 -45

# What's new The existing `.kl` file format is quite limited. It only support…s ASCII characters, and it assumes all characters can be pressed using a single key on the user's keyboard. The latter assumption is false even when just considering ASCII characters. For example, the US-International keyboard layout, which is the de facto standard keyboard layout in the Netherlands, uses dead keys for the following characters: ` ~ ^ ' ". To type any of these characters, one needs to press the same key as in the ANSI QWERTY layout, but followed by a space. This is not possible to describe in the current keyboard layout, thus making Dutch computers immune to Bad USB. The new file format makes this possible, by mapping characters to a sequence of keys, rather than just a single key. It also expands the format to support any Unicode codepoint, thus unlocking Bad USB to a much wider audience. Characters composed of multiple codepoints are not supported though, thus while this does make it possible to support é when encoded as U+00E9 LATIN SMALL LETTER E WITH ACUTE, it does not support é when encoded as U+0065 LATIN SMALL LETTER E + U+0301 COMBINING ACUTE ACCENT. The new file format is implemented in a fully backwards compatible way, allowing users to keep using existing .kl files they may have added. The documentation of the new file format can be found in `documentation/file_formats/BadUsbKeyboardFormat.md`. This commit also adds the keyboard layout `en-US-intl.kl`, which implements the US-International keyboard layout. # Verification One may use the following Bad USB script to verify that every key in `en-US-intl.kl` types correctly. One needs to configure their keyboard layout to US-International for this. On Linux, this is called English (US, intl., with dead keys). ``` STRING cat > /dev/null <<"EOF" ENTER STRING ~ !¹ @ # $£ % ^ & * ( ) _ +÷ ENTER STRING ` 1¡ 2² 3³ 4¤ 5€ 6¼ 7½ 8¾ 9‘ 0’ -¥ =× ENTER ENTER STRING QÄ WÅ EÉ R TÞ YÜ UÚ IÍ OÓ PÖ { } |¦ ENTER STRING qä wå eé r® tþ yü uú ií oó pö [« ]» \¬ ENTER ENTER STRING AÁ S§ DÐ F G H J K LØ :° " ENTER STRING aá sß dð f g h j k lø l¶ ' ENTER ENTER STRING ZÆ X C¢ V B NÑ M <Ç > ? ENTER STRING zæ x c© v b nñ mµ ,ç . /¿ ENTER STRING EOF ENTER ``` One should also verify that the default keyboard layout and the v1 keyboard layouts still work. One may also try to corrupt the v2 keyboard layout (easiest way is to remove a byte from the end), and verify that it falls back to the default keyboard layout. # Checklist (For Reviewer) - [ ] PR has description of feature/bug or link to Confluence/Jira task - [ ] Description contains actions to verify feature/bugfix - [ ] I've built this code, uploaded it to the device and verified feature/bugfix

This PR adds support for new keyboard layouts that couldn’t be supported before. Currently, Bad USB is unable to type the following characters on most Dutch keyboards: ` ~ ^ ' ". This is because US-International (the keyboard layout used in the Netherlands) requires a space to be pressed after typing any of these characters, otherwise it will attempt to merge the character with the next one.

Would anyone like to look at it? I’m curious what people think about it.

Before:

After:

jmr · March 7, 2024, 5:12am

Great work!

Zarcolio · March 7, 2024, 5:38am

Nice, but I use ALTSTRING instead of STRING for displaying lines with these characters. This is a lot easier and makes sure the script works without needing an additional action on the Flipper.

guacamolie · March 7, 2024, 8:22pm

Ah, interesting. It seems like ALTSTRING only works on Windows though. I use Linux, so I haven’t been able to try that.

This does make me wonder how much interest there would be in my PR. Since most people use Windows, and the current situation works acceptable enough for Windows, I could understand the maintainers not finding this worth the increased complexity. That said, I hope people still see the value in a proper cross-platform solution.

Hmm, does anyone know how long it usually takes for someone to look at the PR? Would love to get some feedback, but I don’t know if it’s considered acceptable to ping the maintainers for code reviews.

Zarcolio · March 7, 2024, 8:49pm

I didn’t that worked only with Windows, good to know!
Although less people use Linux, an addition to the firmware could aid in the rare case one finds a Linux station with a Dutch keyboard.

Don’t know anything about when PRs are being looked at…

guacamolie · March 7, 2024, 8:52pm

Or more commonly: macOS ;-).

guacamolie · March 7, 2024, 8:53pm

I just rewrote my PR description to be clearer. I think my initial one was way too dull

Zarcolio · March 7, 2024, 11:17pm

BTW, maybe the folks on Discord know anything about PRs being looked at?

guacamolie · March 8, 2024, 7:03am

Possibly. I’m in the server but I can’t send messages there due to not having a verified phone number. But I’m not sure how to contact anyone about not being able to send messages there, since I’m not able to send messages there…