Merge pull request #1392 from crab2313/EVP_digestname

use ffi;

use std::ffi::CString;

use std::fmt;

use std::io;

use std::io::prelude::*;

        }

    }

    /// Returns the `MessageDigest` corresponding to an algorithm name.

    ///

    /// This corresponds to [`EVP_get_digestbyname`].

    ///

    /// [`EVP_get_digestbyname`]: https://www.openssl.org/docs/man1.1.0/crypto/EVP_DigestInit.html

    pub fn from_name(name: &str) -> Option<MessageDigest> {

        ffi::init();

        let name = CString::new(name).ok()?;

        unsafe {

            let ptr = ffi::EVP_get_digestbyname(name.as_ptr());

            if ptr.is_null() {

                None

            } else {

                Some(MessageDigest(ptr))

            }

        }

    }

    pub fn null() -> MessageDigest {

        unsafe { MessageDigest(ffi::EVP_md_null()) }

    }

            MessageDigest::sha256().as_ptr()

        );

    }

    #[test]

    fn from_name() {

        assert_eq!(

            MessageDigest::from_name("SHA256").unwrap().as_ptr(),

            MessageDigest::sha256().as_ptr()

        )

    }

}