[DRAFT] Add digest context copy function

[mamckee]

This PR adds the provider context copy function for newer versions of OpenSSL. This function copies the state into an existing context object instead of creating a new context object like context duplication.

[Copilot]

Pull request overview

Adds support for OpenSSL’s newer digest “copy context into an existing ctx” provider callback (OSSL_FUNC_DIGEST_COPYCTX) to complement the existing “duplicate context” (DUPCTX) implementation.

Changes:

• Introduces p_scossl_digest_copy_ctx for copying digest state into an existing SCOSSL_DIGEST_CTX when OSSL_FUNC_DIGEST_COPYCTX is available.
• Updates digest dispatch table macro generation to conditionally include OSSL_FUNC_DIGEST_COPYCTX for newer OpenSSL versions.
• Refactors the shared digest macro to separate “common helper function implementations” from “dispatch table construction”.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
SymCryptProvider/src/digests/p_scossl_digest_common.h	Declares copyctx and conditionally adds it to the digest dispatch macro.
SymCryptProvider/src/digests/p_scossl_digest_common.c	Implements p_scossl_digest_copy_ctx using SymCrypt’s stateCopyFunc.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.