Unpack fields for metadata export

include/dwarfs/metadata_types.h

@@ -57,6 +57,10 @@ class global_metadata {
 
   string_table const& names() const { return names_; }
 
+  std::vector<thrift::metadata::directory> const& directories() const {
+    return directories_storage_;
+  }
+
  private:
   Meta const* const meta_;
   std::vector<thrift::metadata::directory> const directories_storage_;

include/dwarfs/string_table.h

@@ -56,6 +56,10 @@ class string_table {
 
   std::string operator[](size_t index) const { return impl_->lookup(index); }
 
+  std::vector<std::string> unpack() const { return impl_->unpack(); }
+
+  bool is_packed() const { return impl_->is_packed(); }
+
   static thrift::metadata::string_table
   pack(std::vector<std::string> const& input,
        pack_options const& options = pack_options());
@@ -65,6 +69,8 @@ class string_table {
     virtual ~impl() = default;
 
     virtual std::string lookup(size_t index) const = 0;
+    virtual std::vector<std::string> unpack() const = 0;
+    virtual bool is_packed() const = 0;
   };
 
  private:

src/dwarfs/metadata_v2.cpp

@@ -371,6 +371,8 @@ class metadata_ final : public metadata_v2::impl {
   template <typename K>
   using set_type = folly::F14ValueSet<K>;
 
+  thrift::metadata::metadata unpack_metadata() const;
+
   inode_view make_inode_view(uint32_t inode) const {
     // TODO: move compatibility details to metadata_types
     uint32_t index =
@@ -899,15 +901,45 @@ folly::dynamic metadata_<LoggerPolicy>::as_dynamic() const {
   return obj;
 }
 
+template <typename LoggerPolicy>
+thrift::metadata::metadata metadata_<LoggerPolicy>::unpack_metadata() const {
+  auto meta = meta_.thaw();
+
+  if (auto opts = meta.options_ref()) {
+    if (opts->packed_chunk_table) {
+      meta.chunk_table = chunk_table_;
+    }
+    if (opts->packed_directories) {
+      meta.directories = global_.directories();
+    }
+    if (opts->packed_shared_files_table) {
+      meta.shared_files_table_ref() = shared_files_;
+    }
+    if (auto const& names = global_.names(); names.is_packed()) {
+      meta.names = names.unpack();
+      meta.compact_names_ref().reset();
+    }
+    if (symlinks_.is_packed()) {
+      meta.symlinks = symlinks_.unpack();
+      meta.compact_symlinks_ref().reset();
+    }
+    opts->packed_chunk_table = false;
+    opts->packed_directories = false;
+    opts->packed_shared_files_table = false;
+  }
+
+  return meta;
+}
+
 template <typename LoggerPolicy>
 std::string metadata_<LoggerPolicy>::serialize_as_json(bool simple) const {
   std::string json;
   if (simple) {
     apache::thrift::SimpleJSONSerializer serializer;
-    serializer.serialize(meta_.thaw(), &json);
+    serializer.serialize(unpack_metadata(), &json);
   } else {
     apache::thrift::JSONSerializer serializer;
-    serializer.serialize(meta_.thaw(), &json);
+    serializer.serialize(unpack_metadata(), &json);
   }
   return json;
 }

src/dwarfs/string_table.cpp

@@ -41,6 +41,12 @@ class legacy_string_table : public string_table::impl {
     return std::string(v_[index]);
   }
 
+  std::vector<std::string> unpack() const override {
+    throw std::runtime_error("cannot unpack legacy string table");
+  }
+
+  bool is_packed() const override { return false; }
+
  private:
   string_table::LegacyTableView v_;
 };
@@ -113,6 +119,20 @@ class packed_string_table : public string_table::impl {
     return std::string(beg, end);
   }
 
+  std::vector<std::string> unpack() const override {
+    std::vector<std::string> v;
+    auto size = PackedIndex ? index_.size() : v_.index().size();
+    if (size > 0) {
+      v.reserve(size - 1);
+      for (size_t i = 0; i < size - 1; ++i) {
+        v.emplace_back(lookup(i));
+      }
+    }
+    return v;
+  }
+
+  bool is_packed() const override { return true; }
+
  private:
   string_table::PackedTableView v_;
   char const* const buffer_;