Remove converting PKCS#8 passphrase to CString

use foreign_types::{ForeignType, ForeignTypeRef};

use libc::{c_int, c_long};

use openssl_macros::corresponds;

use std::convert::TryFrom;

use std::convert::{TryFrom, TryInto};

use std::ffi::CString;

use std::fmt;

use std::mem;

    /// Serializes a private key into a DER-formatted PKCS#8, using the supplied password to

    /// encrypt the key.

    ///

    /// # Panics

    ///

    /// Panics if `passphrase` contains an embedded null.

    #[corresponds(i2d_PKCS8PrivateKey_bio)]

    pub fn private_key_to_pkcs8_passphrase(

        &self,

    ) -> Result<Vec<u8>, ErrorStack> {

        unsafe {

            let bio = MemBio::new()?;

            let len = passphrase.len();

            let passphrase = CString::new(passphrase).unwrap();

            cvt(ffi::i2d_PKCS8PrivateKey_bio(

                bio.as_ptr(),

                self.as_ptr(),

                cipher.as_ptr(),

                passphrase.as_ptr() as *const _ as *mut _,

                len as ::libc::c_int,

                passphrase.len().try_into().unwrap(),

                None,

                ptr::null_mut(),

            ))?;