You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: shared.rs
    path of file: ./repos/stratisd/src/engine/strat_engine/backstore/crypt
    
    the code of the file until where you have to start completion: // This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.

use std::{
    fmt::{self, Formatter},
    fs::OpenOptions,
    io::Write,
    mem::forget,
    path::{Path, PathBuf},
    slice::from_raw_parts_mut,
};

use data_encoding::BASE64URL_NOPAD;
use either::Either;
use serde::{
    de::{Error, MapAccess, Visitor},
    ser::SerializeMap,
    Deserialize, Deserializer, Serialize, Serializer,
};
use serde_json::{from_value, to_value, Map, Value};
use sha2::{Digest, Sha256};
use tempfile::TempDir;

use devicemapper::{Bytes, DevId, DmName, DmNameBuf, DmOptions};
use libcryptsetup_rs::{
    c_uint,
    consts::{
        flags::{CryptActivate, CryptVolumeKey, CryptWipe},
        vals::{
            CryptDebugLevel, CryptLogLevel, CryptStatusInfo, CryptWipePattern, EncryptionFormat,
        },
    },
    register, set_debug_level, set_log_callback, CryptDevice, CryptInit, TokenInput,
};

use crate::{
    engine::{
        strat_engine::{
            backstore::{
                crypt::{
                    consts::{
                        CLEVIS_LUKS_TOKEN_ID, CLEVIS_TANG_TRUST_URL, CLEVIS_TOKEN_NAME,
    
    
fn sss_dispatch(json: &Value) -> StratisResult<Value> {
    let object = json
        .get("clevis")
        .and_then(|map| map.get("sss"))
        .and_then(|val| val.as_object())
        .ok_or_else(|| {
            StratisError::Msg("Expected an object for value of clevis.sss".to_string())
        })?;

    let threshold = object
        .get("t")
        .and_then(|val| val.as_u64())
        .ok_or_else(|| {
            StratisError::Msg("Expected an int for value of clevis.sss.t".to_string())
        })?;
    let jwes = object
        .get("jwe")
        .and_then(|val| val.as_array())
        .ok_or_else(|| {
            StratisError::Msg("Expected an array for value of clevis.sss.jwe".to_string())
        })?;

    let mut sss_map = Map::new();
    sss_map.insert("t".to_string(), Value::from(threshold));

    let mut pin_map = Map::new();
    for jwe in jwes {
        if let Value::String(ref s) = jwe {
            // NOTE: Workaround for the on-disk format for Shamir secret sharing
            // as written by clevis. The base64 encoded string delimits the end
            // of the JSON blob with a period.
            let json_s = Some(s.split_once('.').map_or(&**s, |x| x.0)).ok_or_else(|| {
                StratisError::Msg(format!(
                    "Splitting string {s} on character '.' did not result in \
                        at least one string segment."
                ))
            })?;

            let json_bytes = BASE64URL_NOPAD.decode(json_s.as_bytes())?;
            let value: Value = serde_json::from_slice(&json_bytes)?;
            let (pin, value) = pin_dispatch(&value)?;
            match pin_map.get_mut(&pin) {
                Some(Value::Array(ref mut vec)) => vec.push(value),
                None => {
                    pin_map.insert(pin, Value::from(vec![value]));
                }
                _ => {
                    return Err(StratisError::Msg(format!(
                        "There appears to be a data type that is not an array in \
                            the data structure being used to construct the sss JSON config
                            under pin name {pin}"
                    )))
                }
            };
        } else {
            return Err(StratisError::Msg(
                "Expected a string for each value in the array at clevis.sss.jwe".to_string(),
            ));
        }
    }
    sss_map.insert("pins".to_string(), Value::from(pin_map));

    Ok(Value::from(sss_map))
}