es2button

This projects provides means to make use of buttons on epson scanners.

Requirements

You need to install epsonscan2. If,like me, you want to use this on an arm64 and can't find a suitable package, please see my epsonscan2 builder.

Why

I could not seem to get scanbd and friends working on my Epson (DS-310) scanner. After looking through the driver code I figured I will never as the buttons are just not exposed.

How does this work?

It uses the official EPSON epsonscan2 libraries to connect to the scanner and listen for the buttons.

When it detects a button press, it will:

• Disconnect from the scanner (allowing other programs to access it)
• Call a program that is passed to es2button with a series of environment variables that describe the scanner's state and buttons (see example/example-epsonscan2.sh)
• When the program exists, reconnect to the scanner and repeat
• When the scanner disconnects, the program exists

Build

Requirements

You need Rust (tested on 1.77). In addition, you will need to install a couple of dependencies that we need during building: pkg-config, a C compiler (e.g., clang), libusb (library and headers), and make if you decide to build with make.

On a debian system you'll just need to install:

pkg-config
make
clang
libusb-1.0-0
libusb-1.0-0-dev

See also Dockerfile or run make enter-docker to get into a build environment that can build es2button.

Building

To build a debian package, simply run make. The final deb file is placed in target/debian/.

Alternatively, you can also build using cargo. See the Makefile how cargo should be invoked.

Installation

You can install the generated deb file using dpkg -i.

The following section explains how es2button is integrated into the system.

Integration through udev & systemd

See udev-es2button.rules and systemd.service for how to listen to usb events and call systemd to launch es2button.

• udev-es2button.rules will be installed to /lib/udev/rules.d/61-es2button.rules and act upon epsonscan2 scanner detections that epsonscan2 installs at /lib/udev/rules.d/60-epsonscan2.rules.
• udev will activate the systemd.service that is installed to /lib/systemd/system/es2button@.service when it detects a device supported by epsonscan2. It passes a device identifier as an instance variable to instantiate the service to systemd.
• By default, systemd's es2button instance will execute /etc/es2button/entrypoint on button press which, by default, symlinks to /etc/es2button/default. This, in turn, just logs information about the requested button action (see journalctl -f while pushing the button to see the output).
• One can remove the symlink and add another executable file there which will not be overriden by the package installer. I've added the following entrypoint for my personal paperless-ngx installation:

#!/bin/bash

# change working dir
pushd /opt/paperless/consume
# example-epsonscan2.sh will output to $(pwd)/img%d.pdf (must be writable for root:scanner)
/usr/share/es2button/example/example-epsonscan2.sh
popd

License

The project is licensed under the MIT License:

Copyright © 2023 Jan Rüth

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

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This project itself links to libusb which is licensed under the LGPL-2.1.

This project itself uses headers from epsonscan2 as it dynamically loads (dlopen) a one of its libraries during runtime. epsonscan2 itself is licensed under LGPL-2.1. The headers are bundled with this source and are located in es2command-sys/cinterface.