Unl0kr

Framebuffer-based disk unlocker for the initramfs based on LVGL.

[[TOC]]

About

Unl0kr is an osk-sdl clone written in LVGL and rendering directly to the Linux framebuffer. As a result, it doesn't depend on GPU hardware acceleration.

For some background on how unl0kr came to be, see postmarketOS/osk-sdl#121.

Status

We are en route to v1 which aims at providing a useable, visually pleasant application including osk-sdl's most essential features. For details about the current status, see the v1 milestone. You may also browse the full list of open issues to get an idea of what's planned beyond v1.

Here are a few highlights of what already works:

• Password-entry UI including on-screen keyboard on the framebuffer
• Input device discovery for keyboards, mice, trackpads and touch screens
• On-screen keyboard control via:
  • One or more mice / trackpads (including cursor)
  • One or more hardware keyboards (including support for different layouts using XKB)
  • Touchscreen (tested on PinePhone)
• Switching on-screen keyboard layout at runtime (currently supported layouts: de, es, fr, us)
• Toggling on-screen keyboard with slide in/out animation
• Switching between light and dark theme at runtime
• Disclosing and hiding entered password at runtime
• Shutting down the device via a soft button

For a growing collection of demo videos, see the wiki.

Upstreaming

Over the course of implementing unl0kr, suitable fixes and features have been upstreamed to the lvgl and lv_drivers repositories. The benefit of this goes both ways. Downstream we can rely on the features being maintained in the future and upstream they can make the features available to the larger audience of LVGL users.

Below is a summary of contributions upstreamed thus far.

lvgl

• fix(examples) don't compile assets unless needed (✅ merged)
• feat(btnmatrix): add option to show popovers on button press (⏳ in review)
• feat(msgbox): add function to get selected button index (✅ merged)
• feat(msgbox): omit title label unless needed (✅ merged)
• fix(btnmatrix): make ORed values work correctly with lv_btnmatrix_has_btn_ctrl (✅ merged)

lv_drivers

• Add support for pointer devices to libinput driver (✅ merged)
• Add support for keypads to libinput driver (✅ merged)
• Add full keyboard support to libinput/evdev driver (✅ merged)
• Automatic device discovery via libinput (✅ merged)
• Make it possible to use multiple devices with the libinput and XKB drivers (✅ merged)
• Use LV_LOG instead of printf in fbdev driver (✅ merged)

Usage

For an overview of available command line options, run unl0kr with the -h or --help argument.

$ unl0kr --help
Usage: unl0kr [OPTION]

Mandatory arguments to long options are mandatory for short options too.
  -g, --geometry=NxM  Force a display size of N horizontal times M vertical pixels
  -h, --help          Print this message and exit
  -v, --verbose       Enable more detailed logging output on STDERR
  -V, --version       Print the unl0kr version and exit

Development

Dependencies

• lvgl (git submodule / linked statically)
• lv_drivers (git submodule / linked statically)
• squeek2lvgl (git submodule / linked statically)
• libinput
• libxkbcommon
• evdev kernel module

Building & running

For development and testing you can run the app in a VT. Unless your user account has special privileges, sudo will be needed to access input device files.

$ meson _build
$ meson compile -C _build
$ sudo chvt 2
$ sudo ./_build/unl0kr

With meson <0.55 use ninja instead of meson compile.

Fonts

In order to work with LVGL, fonts need to be converted to bitmaps, stored as C arrays. Unl0kr currently uses a combination of the Montserrat font for text and the FontAwesome font for pictograms. For both fonts only limited character ranges are included to reduce the binary size. To (re)generate the C file containing the combined font, run the following command

$ npx lv_font_conv --bpp 4 --size 32 --no-compress -o montserrat_extended_32.c --format lvgl \
    --font Montserrat-Regular.ttf \
      --range '0x0020-0x007F' \
      --range '0x00A0-0x00FF' \
      --range '0x0100-0x017F' \
      --range '0x2000-0x206F' \
      --range '0x20A0-0x20CF' \
    --font FontAwesome5-Solid+Brands+Regular.woff \
      --range '0xF001,0xF008,0xF00B,0xF00C,0xF00D,0xF011,0xF013,0xF015,0xF019,0xF01C,0xF021,0xF026,0xF027,0xF028,0xF03E,0xF0E0,0xF304,0xF043,0xF048,0xF04B,0xF04C,0xF04D,0xF051,0xF052,0xF053,0xF054,0xF067,0xF068,0xF06E,0xF070,0xF071,0xF074,0xF077,0xF078,0xF079,0xF07B,0xF093,0xF095,0xF0C4,0xF0C5,0xF0C7,0xF0C9,0xF0E7,0xF0EA,0xF0F3,0xF11C,0xF124,0xF158,0xF1EB,0xF240,0xF241,0xF242,0xF243,0xF244,0xF287,0xF293,0xF2ED,0xF55A,0xF7C2,0xF8A2' \
      --range '0xF042' \
      --range '0xF35B'

Below is a short explanation of the different unicode ranges used above.

• Montserrat
  • Basic Latin (0x0020-0x007F)
  • Latin-1 supplement (0x00A0-0x00FF)
  • Latin extended A (0x0100-0x017F)
  • General punctuation (0x2000-0x206F)
  • Currency symbols (0x20A0-0x20CF)
• FontAwesome
  • Standard LV_SYMBOL_* glyphs (0xF001,0xF008,0xF00B,0xF00C,0xF00D,0xF011,0xF013,0xF015,0xF019,0xF01C,0xF021,0xF026,0xF027,0xF028,0xF03E,0xF0E0,0xF304,0xF043,0xF048,0xF04B,0xF04C,0xF04D,0xF051,0xF052,0xF053,0xF054,0xF067,0xF068,0xF06E,0xF070,0xF071,0xF074,0xF077,0xF078,0xF079,0xF07B,0xF093,0xF095,0xF0C4,0xF0C5,0xF0C7,0xF0C9,0xF0E7,0xF0EA,0xF0F3,0xF11C,0xF124,0xF158,0xF1EB,0xF240,0xF241,0xF242,0xF243,0xF244,0xF287,0xF293,0xF2ED,0xF55A,0xF7C2,0xF8A2)
  • adjust (0xF042)
  • arrow-alt-circle-up (0xF35B)

Keyboard layouts

Unl0kr uses squeekboard layouts converted to C via squeek2lvgl. To regenerate the layouts, run

$ ./regenerate-layouts.sh

from the root of the repository.

Screen recording

For demonstration purposes you can record the framebuffer device, e.g. with ffmpeg:

$ sudo ffmpeg -f fbdev -i /dev/fb0 -r 24 -c:v libx264 -b:v 500k demo.avi

Acknowledgements

The lv_port_linux_frame_buffer project served as a starting point for the codebase.

The mouse cursor image was taken from lv_sim_emscripten.

License

Unl0kr is licensed under the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

The Montserrat font is licensed under the Open Font License.

The FontAwesome font is licensed under the Open Font License version 1.1.