1 files changed, 42 insertions, 0 deletions
diff --git a/src/buildtool/crypto/hash_impl_git.cpp b/src/buildtool/crypto/hash_impl_git.cpp
new file mode 100644
index 00000000..9cb2a761
--- /dev/null
+++ b/src/buildtool/crypto/hash_impl_git.cpp
@@ -0,0 +1,42 @@
+#include <array>
+#include <cstdint>
+
+#include "openssl/sha.h"
+#include "src/buildtool/crypto/hash_impl.hpp"
+
+/// \brief Hash implementation for Git blob ids.
+/// Does not support incremental hashing.
+class HashImplGit final : public IHashImpl {
+  public:
+    auto Update(std::string const& /*data*/) noexcept -> bool final {
+        return false;
+    }
+
+    auto Finalize() && noexcept -> std::optional<std::string> final {
+        return std::nullopt;
+    }
+
+    auto Compute(std::string const& data) && noexcept -> std::string final {
+        SHA_CTX ctx;
+        std::string const header{"blob " + std::to_string(data.size()) + '\0'};
+        if (SHA1_Init(&ctx) == 1 &&
+            SHA1_Update(&ctx, header.data(), header.size()) == 1 &&
+            SHA1_Update(&ctx, data.data(), data.size()) == 1) {
+            auto out = std::array<std::uint8_t, SHA_DIGEST_LENGTH>{};
+            if (SHA1_Final(out.data(), &ctx) == 1) {
+                return std::string{out.begin(), out.end()};
+            }
+        }
+        FatalError();
+        return {};
+    }
+
+    [[nodiscard]] auto DigestLength() const noexcept -> std::size_t final {
+        return SHA_DIGEST_LENGTH;
+    }
+};
+
+/// \brief Factory for Git implementation
+auto CreateHashImplGit() -> std::unique_ptr<IHashImpl> {
+    return std::make_unique<HashImplGit>();
+}