From a5be6de770c9152f3248ce0f01ac3645e30a19ed Mon Sep 17 00:00:00 2001
From: Maksim Denisov <denisov.maksim@huawei.com>
Date: Wed, 17 Jul 2024 16:26:25 +0200
Subject: Use compile-time polymorphism in Hasher

...since runtime polymorphism was there just to avoid including openssl as a public dependency. A combination of forward declarations, std::variant and std::unique_ptr is used instead.
---
 src/buildtool/crypto/hasher.hpp | 46 ++++++++++++++---------------------------
 1 file changed, 15 insertions(+), 31 deletions(-)

(limited to 'src/buildtool/crypto/hasher.hpp')

diff --git a/src/buildtool/crypto/hasher.hpp b/src/buildtool/crypto/hasher.hpp
index c37cd34e..4987f7bb 100644
--- a/src/buildtool/crypto/hasher.hpp
+++ b/src/buildtool/crypto/hasher.hpp
@@ -17,7 +17,6 @@
 
 #include <cstddef>
 #include <cstdint>
-#include <limits>
 #include <memory>
 #include <optional>
 #include <string>
@@ -31,6 +30,8 @@ class Hasher final {
     /// \brief Types of hash implementations supported by generator.
     enum class HashType : std::uint8_t { SHA1, SHA256, SHA512 };
 
+    struct ShaContext;
+
     /// \brief The universal hash digest.
     /// The type of hash and the digest length depends on the hash
     /// implementation used to generated this digest.
@@ -40,11 +41,11 @@ class Hasher final {
       public:
         /// \brief Get pointer to raw bytes of digest.
         /// Length can be obtained using \ref Length.
-        [[nodiscard]] auto Bytes() const& -> std::string const& {
+        [[nodiscard]] auto Bytes() const& noexcept -> std::string const& {
             return bytes_;
         }
 
-        [[nodiscard]] auto Bytes() && -> std::string {
+        [[nodiscard]] auto Bytes() && noexcept -> std::string {
             return std::move(bytes_);
         }
 
@@ -65,35 +66,18 @@ class Hasher final {
         explicit HashDigest(std::string bytes) : bytes_{std::move(bytes)} {}
     };
 
-    /// \brief Interface for hash implementations
-    class IHashImpl {
-      public:
-        static constexpr size_t kCharsPerNumber =
-            std::numeric_limits<std::uint8_t>::max() /
-            std::numeric_limits<signed char>::max();
-
-        IHashImpl() noexcept = default;
-        IHashImpl(IHashImpl const&) = delete;
-        IHashImpl(IHashImpl&&) = default;
-        auto operator=(IHashImpl const&) -> IHashImpl& = delete;
-        auto operator=(IHashImpl&&) -> IHashImpl& = default;
-        virtual ~IHashImpl() = default;
-
-        /// \brief Feed data to the incremental hashing.
-        [[nodiscard]] virtual auto Update(std::string const& data) noexcept
-            -> bool = 0;
-
-        /// \brief Finalize the hashing and return hash as string of raw bytes.
-        [[nodiscard]] virtual auto Finalize() && noexcept
-            -> std::optional<std::string> = 0;
-
-        /// \brief Obtain length of the resulting hash string.
-        [[nodiscard]] virtual auto GetHashLength() const noexcept -> size_t = 0;
-    };
-
+    /// \brief Create and initialize a hasher
+    /// \return An initialized hasher on success or std::nullopt on failure.
     [[nodiscard]] static auto Create(HashType type) noexcept
         -> std::optional<Hasher>;
 
+    Hasher(Hasher&& other) noexcept;
+    auto operator=(Hasher&& other) noexcept -> Hasher&;
+
+    Hasher(Hasher const& other) noexcept = delete;
+    auto operator=(Hasher const& other) noexcept -> Hasher& = delete;
+    ~Hasher() noexcept;
+
     /// \brief Feed data to the hasher.
     auto Update(std::string const& data) noexcept -> bool;
 
@@ -104,9 +88,9 @@ class Hasher final {
     [[nodiscard]] auto GetHashLength() const noexcept -> std::size_t;
 
   private:
-    std::unique_ptr<IHashImpl> impl_;
+    std::unique_ptr<ShaContext> sha_ctx_;
 
-    explicit Hasher(std::unique_ptr<IHashImpl> impl) noexcept;
+    explicit Hasher(std::unique_ptr<ShaContext> sha_ctx) noexcept;
 };
 
 #endif  // INCLUDED_SRC_BUILDTOOL_CRYPTO_HASHER_HPP
-- 
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