You must install development headers for fuse. On Fedora (or dnf based Linux OS):
dnf install fuse3-devel
On Ubuntu (or apt based Linux OS),
apt install libfuse3-dev
Make underlying filesystem directory:
mkdir ~/undofs/undofs-filedata
Compile the code using make and then execute ./undofs <mount-point>.
For example, to mount the filesystem at /mnt/undofs:
mkdir /mnt/undofs ; ./undofs -f /mnt/undofs
To print debug messages using printf use -f
You can now view the files and directories by:
ls /mnt/undofs