fn build_context()

in aws-lc-rs/src/aead/aead_ctx.rs [235:275]
36 lines of code
2 McCabe index (conditional complexity)

    fn build_context(
        aead_fn: unsafe extern "C" fn() -> *const aws_lc::evp_aead_st,
        key_bytes: &[u8],
        tag_len: usize,
        direction: Option<AeadDirection>,
    ) -> Result<LcPtr<EVP_AEAD_CTX>, Unspecified> {
        let aead = unsafe { aead_fn() };

        // We are performing the allocation ourselves as EVP_AEAD_CTX_new will call EVP_AEAD_CTX_init by default
        // and this avoid having to zero and reinitalize again if we need to set an explicit direction.
        let mut aead_ctx: LcPtr<EVP_AEAD_CTX> =
            LcPtr::new(unsafe { OPENSSL_malloc(size_of::<EVP_AEAD_CTX>()) }.cast())?;

        unsafe { EVP_AEAD_CTX_zero(*aead_ctx.as_mut()) };

        if 1 != match direction {
            Some(direction) => unsafe {
                EVP_AEAD_CTX_init_with_direction(
                    *aead_ctx.as_mut(),
                    aead,
                    key_bytes.as_ptr(),
                    key_bytes.len(),
                    tag_len,
                    direction.into(),
                )
            },
            None => unsafe {
                EVP_AEAD_CTX_init(
                    *aead_ctx.as_mut(),
                    aead,
                    key_bytes.as_ptr(),
                    key_bytes.len(),
                    tag_len,
                    null_mut(),
                )
            },
        } {
            return Err(Unspecified);
        }
        Ok(aead_ctx)
    }