mausberry-switch-libgpiod

A GPIO monitoring daemon for Raspberry Pi devices that uses libgpiod to watch for signals from a Mausberry Circuits switch and safely power off the system.

This is a fork of t-richards/mausberry-switch that replaces the legacy sysfs GPIO interface with the modern libgpiod library.

• libgpiod instead of sysfs: Uses the modern Linux GPIO character device API via libgpiod instead of the deprecated /sys/class/gpio interface.
• No more glib dependency: The only runtime dependency is now libgpiod2.
• Proper signal handling: Uses sigaction() and sig_atomic_t for safe, portable signal handling.
• Configuration file support: Reads pin numbers, shutdown command, and delay from /etc/mausberry-switch.conf.
• Hardened systemd service: Runs with ProtectSystem=strict, NoNewPrivileges, and other security restrictions.

Build dependencies:

• libgpiod-dev (>= 1.0)
• build-essential
• dh-autoreconf

Runtime dependency:

• libgpiod2 (>= 1.0)

autoreconf -i -f
./configure
make
sudo make install

Download the latest release (v0.9.1) and install it directly on your Pi:

# Download
wget https://github.com/tomcek42/mausberry-switch-libgpiod/releases/download/v0.9.1/mausberry-switch_0.9.1_armhf.deb

# Install
sudo dpkg -i mausberry-switch_0.9.1_armhf.deb
sudo apt-get -f install

The mausberry-switch systemd service will be automatically enabled and started when you install the package.

# Stop the service temporarily
sudo systemctl stop mausberry-switch

# Disable the service from automatically starting at boot
sudo systemctl disable mausberry-switch

All options are in /etc/mausberry-switch.conf:

[Pins]
Out=23
In=24

[Config]
ShutdownCommand=systemctl poweroff
Delay=0

After changing the configuration, restart the service:

sudo systemctl restart mausberry-switch

The official Mausberry setup script polls GPIO state in a bash loop:

while [ 1 = 1 ]; do
    cat /sys/class/gpio/gpio$GPIOpin1/value
    sleep 1
done

This daemon instead uses libgpiod's event-based API to wait for GPIO edge events without burning CPU cycles. The process sleeps until the kernel signals a GPIO state change.

The Linux kernel's sysfs GPIO interface (/sys/class/gpio) has been deprecated since Linux 4.8. libgpiod is the recommended replacement, providing:

• A stable, well-defined API
• Proper resource management (no manual export/unexport)
• Edge event detection without poll(2) on file descriptors
• Better error handling and diagnostics

Available as open source under the terms of the MIT License.