Function read_file_capped 

pub fn read_file_capped(
    path: &Path,
    max_bytes: usize,
) -> Result<(Vec<u8>, bool)>

Read at most max_bytes from path. Returns (bytes, truncated) where bytes.len() <= max_bytes and truncated is true when the file was longer than the cap.

Unlike std::fs::read, a multi-gigabyte file never pulls more than max_bytes (+1 probe byte) into memory.