Count zeroes on a disk or a file.
cargo install count-zeroes
count-zeroes /dev/sdXN
This is useful if you want to check if an SSD has been trimmed or a disk has been wiped-clean. I found no obvious way to do that and it's useful when you try to recover a filesystem to avoid chasing ghosts. In my case, an attempt to recover a BTRFS partition showed me there was a superblock somewhere but it was just some random unrelated data.
This program can be used as a library, it has no dependency. It is optimized for speed.