Validate bazel_re::Digests in BazelDigestFactory

3 files changed, 85 insertions, 12 deletions

diff --git a/src/buildtool/common/TARGETS b/src/buildtool/common/TARGETS
index e2db528c..88364386 100644
--- a/src/buildtool/common/TARGETS
+++ b/src/buildtool/common/TARGETS
@@ -43,12 +43,16 @@
   { "type": ["@", "rules", "CC", "library"]
   , "name": ["bazel_digest_factory"]
   , "hdrs": ["bazel_digest_factory.hpp"]
+  , "srcs": ["bazel_digest_factory.cpp"]
   , "deps":
     [ "bazel_types"
     , ["src/buildtool/crypto", "hash_function"]
+    , ["src/buildtool/crypto", "hash_info"]
     , ["src/buildtool/file_system", "object_type"]
     , ["src/utils/cpp", "gsl"]
+    , ["src/utils/cpp", "expected"]
     ]
+  , "private-deps": [["src/buildtool/crypto", "hasher"]]
   , "stage": ["src", "buildtool", "common"]
   }
 , "common":
diff --git a/src/buildtool/common/bazel_digest_factory.cpp b/src/buildtool/common/bazel_digest_factory.cpp
new file mode 100644
index 00000000..4ff885aa
--- /dev/null
+++ b/src/buildtool/common/bazel_digest_factory.cpp
@@ -0,0 +1,49 @@
+// Copyright 2024 Huawei Cloud Computing Technology Co., Ltd.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "src/buildtool/common/bazel_digest_factory.hpp"
+
+#include <utility>
+
+#include "src/buildtool/crypto/hasher.hpp"
+
+auto BazelDigestFactory::Create(HashInfo const& hash_info,
+                                std::int64_t size) noexcept
+    -> bazel_re::Digest {
+    auto hash = hash_info.HashType() == HashFunction::Type::GitSHA1
+                    ? Prefix(hash_info.Hash(), hash_info.IsTree())
+                    : hash_info.Hash();
+
+    bazel_re::Digest digest{};
+    digest.set_hash(std::move(hash));
+    digest.set_size_bytes(size);
+    return digest;
+}
+
+auto BazelDigestFactory::ToHashInfo(HashFunction::Type hash_type,
+                                    bazel_re::Digest const& digest) noexcept
+    -> expected<HashInfo, std::string> {
+    bool const is_prefixed = IsPrefixed(hash_type, digest.hash());
+
+    auto hash = is_prefixed ? Unprefix(digest.hash()) : digest.hash();
+    auto const is_tree = is_prefixed and digest.hash().starts_with(kTreeTag);
+    return HashInfo::Create(hash_type, std::move(hash), is_tree);
+}
+
+auto BazelDigestFactory::IsPrefixed(HashFunction::Type hash_type,
+                                    std::string const& hash) noexcept -> bool {
+    auto const tagged_length =
+        HashFunction{hash_type}.MakeHasher().GetHashLength() + kTagLength;
+    return hash.size() == tagged_length;
+}
diff --git a/src/buildtool/common/bazel_digest_factory.hpp b/src/buildtool/common/bazel_digest_factory.hpp
index e08eabb7..67ee35cb 100644
--- a/src/buildtool/common/bazel_digest_factory.hpp
+++ b/src/buildtool/common/bazel_digest_factory.hpp
@@ -22,13 +22,33 @@
 #include "gsl/gsl"
 #include "src/buildtool/common/bazel_types.hpp"
 #include "src/buildtool/crypto/hash_function.hpp"
+#include "src/buildtool/crypto/hash_info.hpp"
 #include "src/buildtool/file_system/object_type.hpp"
+#include "src/utils/cpp/expected.hpp"
 
 class BazelDigestFactory final {
     static constexpr auto kBlobTag = "62";
     static constexpr auto kTreeTag = "74";
+    static constexpr std::size_t kTagLength = 2;
 
   public:
+    /// \brief Create bazel_re::Digest from preliminarily validated data.
+    /// \param hash_data    Validated hash
+    /// \param size         Size of the content
+    [[nodiscard]] static auto Create(HashInfo const& hash_info,
+                                     std::int64_t size) noexcept
+        -> bazel_re::Digest;
+
+    /// \brief Validate bazel_re::Digest
+    /// \param hash_type    Type of the hash function that was used for creation
+    /// of the hash
+    /// \param digest       Digest to be validated
+    /// \return Validated hash on success or an error message on failure.
+    [[nodiscard]] static auto ToHashInfo(
+        HashFunction::Type hash_type,
+        bazel_re::Digest const& digest) noexcept
+        -> expected<HashInfo, std::string>;
+
     /// \brief Hash content using hash function and return a valid
     /// bazel_re::Digest
     /// \tparam kType       Type of the hashing algorithm to be used
@@ -39,18 +59,9 @@ class BazelDigestFactory final {
     [[nodiscard]] static auto HashDataAs(HashFunction hash_function,
                                          std::string const& content)
         -> bazel_re::Digest {
-        static constexpr bool kIsTree = IsTreeObject(kType);
-        auto const hash_digest = kIsTree ? hash_function.HashTreeData(content)
-                                         : hash_function.HashBlobData(content);
-
-        auto hash = hash_function.GetType() == HashFunction::Type::GitSHA1
-                        ? Prefix(hash_digest.HexString(), kIsTree)
-                        : hash_digest.HexString();
-
-        bazel_re::Digest digest{};
-        digest.set_hash(std::move(hash));
-        digest.set_size_bytes(gsl::narrow<std::int64_t>(content.size()));
-        return digest;
+        auto const hash_info =
+            HashInfo::HashData(hash_function, content, IsTreeObject(kType));
+        return Create(hash_info, gsl::narrow<std::int64_t>(content.size()));
     }
 
   private:
@@ -58,6 +69,15 @@ class BazelDigestFactory final {
                                      bool is_tree) noexcept -> std::string {
         return (is_tree ? kTreeTag : kBlobTag) + hash;
     }
+
+    [[nodiscard]] static auto Unprefix(std::string const& hash) noexcept
+        -> std::string {
+        return hash.substr(kTagLength);
+    }
+
+    [[nodiscard]] static auto IsPrefixed(HashFunction::Type hash_type,
+                                         std::string const& hash) noexcept
+        -> bool;
 };
 
 #endif  // INCLUDED_SRC_BUILDTOOL_COMMON_BAZEL_DIGEST_FACTORY_HPP