node-folder-mirroring

A FUSE filesystem for local directory mirroring written in Node.js.

Usage:

$ sudo node node-folder-mirroring.js <source_dir> <target_dir> [-o <option> ...]

Mirroring the GPIO folder on a Raspberry PI 2

This tool has been tested on a Raspberry PI 2 Model B V1.1 with the aim of mirroring the GPIO folder. The tests have been performed with both the Raspbian Jessie Lite distribution and the Ubuntu 16.04 LTS distribution.

Note that the fuse-bindings library on which we base our implementation does not support the poll() POSIX call. Thus, at the moment, it is not possible to wait for some event on a file descriptor. This means that, for example, the watch() call of the onoff library does not currently work on the mirrored GPIO folder.

If you are interested in Raspberry Pi virtualization for Internet of Things and Fog/Edge scenarios, refer to https://github.com/flongo82/raspberry_virtualization for a more recent application of the code you can find here.

Raspbian Jessie Lite

Update and upgrade the system:

$ sudo apt update
$ sudo apt upgrade
$ sudo reboot

Install Node.js, FUSE, and other dependencies of node-folder-mirroring.js

$ curl -sL https://deb.nodesource.com/setup_7.x | sudo -E bash -
$ sudo apt install nodejs
$ sudo apt install fuse libfuse-dev
$ mkdir /home/pi/test_gpio_mirroring
$ cd /home/pi/test_gpio_mirroring
$ npm install fuse-bindings fs mknod path minimist
$ npm install https://github.com/PlayNetwork/node-statvfs/tarball/v3.0.0

Check GPIO

$ echo "4" > /sys/class/gpio/export
$ echo "out" > /sys/class/gpio/gpio4/direction
$ echo "1" > /sys/class/gpio/gpio4/value
$ cat /sys/class/gpio/gpio4/value
$ echo "4" > /sys/class/gpio/unexport

Mirror the GPIO folder

$ mkdir -p /home/pi/test_gpio_mirroring/sys/class/gpio
$ mkdir /home/pi/test_gpio_mirroring/sys/devices
$ wget https://raw.githubusercontent.com/flongo82/node-folder-mirroring/master/node-folder-mirroring.js
$ node node-folder-mirroring.js /sys/devices/ /home/pi/test_gpio_mirroring/sys/devices/ &> log_devices &
$ node node-folder-mirroring.js /sys/class/gpio/ /home/pi/test_gpio_mirroring/sys/class/gpio/ &> log_gpio &

Test the mirror folder

$ echo "4" > /home/pi/test_gpio_mirroring/sys/class/gpio/export
$ echo "out" > /home/pi/test_gpio_mirroring/sys/class/gpio/gpio4/direction
$ echo "1" > /home/pi/test_gpio_mirroring/sys/class/gpio/gpio4/value
$ cat /home/pi/test_gpio_mirroring/sys/class/gpio/gpio4/value
$ echo "4" > /home/pi/test_gpio_mirroring/sys/class/gpio/unexport

Ubuntu 16.04 LTS

Update and upgrade the system:

$ sudo apt update
$ sudo apt upgrade
$ sudo reboot

Install Node.js, FUSE, and other dependencies of node-folder-mirroring.js

$ sudo apt install fuse libfuse-dev pkg-config python2.7
$ curl -sL https://deb.nodesource.com/setup_7.x | sudo -E bash -
$ sudo apt install nodejs
$ mkdir /home/ubuntu/test_gpio_mirroring
$ cd /home/ubuntu/test_gpio_mirroring
$ npm config set python `which python2.7`
$ npm install fuse-bindings fs mknod path minimist
$ npm install https://github.com/PlayNetwork/node-statvfs/tarball/v3.0.0

Allow ubuntu user to access the GPIO folder

$ sudo addgroup gpio
$ sudo usermod -a -G gpio ubuntu
$ cat<<EOF | sudo tee /etc/udev/rules.d/99-gpio.rules
SUBSYSTEM=="input", GROUP="input", MODE="0660"
SUBSYSTEM=="i2c-dev", GROUP="i2c", MODE="0660"
SUBSYSTEM=="spidev", GROUP="spi", MODE="0660"
SUBSYSTEM=="bcm2835-gpiomem", GROUP="gpio", MODE="0660"

SUBSYSTEM=="gpio*", PROGRAM="/bin/sh -c '\\
        chown -R root:gpio /sys/class/gpio && chmod -R 770 /sys/class/gpio;\\
        chown -R root:gpio /sys/devices/virtual/gpio && chmod -R 770 /sys/devices/virtual/gpio;\\
        chown -R root:gpio /sys\$devpath && chmod -R 770 /sys\$devpath\\
'"

KERNEL=="ttyAMA[01]", PROGRAM="/bin/sh -c '\\
        ALIASES=/proc/device-tree/aliases; \\
        if cmp -s \$ALIASES/uart0 \$ALIASES/serial0; then \\
                echo 0;\\
        elif cmp -s \$ALIASES/uart0 \$ALIASES/serial1; then \\
                echo 1; \\
        else \\
                exit 1; \\
        fi\\
'", SYMLINK+="serial%c"

KERNEL=="ttyS0", PROGRAM="/bin/sh -c '\\
        ALIASES=/proc/device-tree/aliases; \\
        if cmp -s \$ALIASES/uart1 \$ALIASES/serial0; then \\
                echo 0; \\
        elif cmp -s \$ALIASES/uart1 \$ALIASES/serial1; then \\
                echo 1; \\
        else \\
                exit 1; \\
        fi \\
'", SYMLINK+="serial%c"
EOF
$ sudo reboot

Check GPIO

$ echo "4" > /sys/class/gpio/export
$ echo "out" > /sys/class/gpio/gpio4/direction
$ echo "1" > /sys/class/gpio/gpio4/value
$ cat /sys/class/gpio/gpio4/value
$ echo "4" > /sys/class/gpio/unexport

Mirror the GPIO folder

$ mkdir -p /home/ubuntu/test_gpio_mirroring/sys/class/gpio
$ mkdir /home/ubuntu/test_gpio_mirroring/sys/devices
$ wget https://raw.githubusercontent.com/flongo82/node-folder-mirroring/master/node-folder-mirroring.js
$ node node-folder-mirroring.js /sys/devices/ /home/ubuntu/test_gpio_mirroring/sys/devices/ &> log_devices &
$ node node-folder-mirroring.js /sys/class/gpio/ /home/ubuntu/test_gpio_mirroring/sys/class/gpio/ &> log_gpio &

Test the mirror folder

$ echo "4" > /home/ubuntu/test_gpio_mirroring/sys/class/gpio/export
$ echo "out" > /home/ubuntu/test_gpio_mirroring/sys/class/gpio/gpio4/direction
$ echo "1" > /home/ubuntu/test_gpio_mirroring/sys/class/gpio/gpio4/value
$ cat /home/ubuntu/test_gpio_mirroring/sys/class/gpio/gpio4/value
$ echo "4" > /home/ubuntu/test_gpio_mirroring/sys/class/gpio/unexport