Function compare_digests 

fn compare_digests(
    mtree: &Mtree,
    input_dir: &InputDir,
    file_name: &str,
) -> Result<(PathBuf, Vec<u8>), Error>

Compares the hash digest of a file with the recorded data in an Mtree.

Takes an mtree against which a file_name in input_dir is checked. Returns the absolute path to the file and a byte buffer that represents the contents of the file.

Errors

Returns an error if

• the file path (input_dir + file_name) does not exist,
• the file can not be read,
• the hash digest of the file does not match that initially recorded in mtree,
• or the file can not be found in mtree.