refactor: factor out find_inode_rank_offset

include/dwarfs/internal/metadata_utils.h

@@ -23,6 +23,11 @@
 
 #include <cstdint>
 
+#include <thrift/lib/cpp2/frozen/FrozenUtil.h>
+
+#include <dwarfs/gen-cpp2/metadata_layouts.h>
+#include <dwarfs/gen-cpp2/metadata_types.h>
+
 namespace dwarfs::internal {
 
 // This represents the order in which inodes are stored in inodes
@@ -37,4 +42,11 @@ enum class inode_rank {
 
 inode_rank get_inode_rank(uint32_t mode);
 
+size_t find_inode_rank_offset(
+    ::apache::thrift::frozen::Layout<thrift::metadata::metadata>::View meta,
+    inode_rank rank);
+
+size_t
+find_inode_rank_offset(thrift::metadata::metadata const& meta, inode_rank rank);
+
 } // namespace dwarfs::internal

src/internal/metadata_utils.cpp

@@ -19,15 +19,37 @@
  * along with dwarfs.  If not, see <https://www.gnu.org/licenses/>.
  */
 
+#include <algorithm>
+
+#include <boost/range/irange.hpp>
+
 #include <fmt/format.h>
 
 #include <dwarfs/error.h>
 #include <dwarfs/file_type.h>
 
 #include <dwarfs/internal/metadata_utils.h>
 
+#include <dwarfs/gen-cpp2/metadata_types.h>
+
 namespace dwarfs::internal {
 
+namespace {
+
+size_t find_inode_rank_offset_impl(inode_rank rank, size_t size,
+                                   auto&& get_inode_mode) {
+  auto range = boost::irange<size_t>(0, size);
+
+  auto it = std::lower_bound(range.begin(), range.end(), rank,
+                             [&](auto inode, inode_rank r) {
+                               return get_inode_rank(get_inode_mode(inode)) < r;
+                             });
+
+  return *it;
+}
+
+} // namespace
+
 inode_rank get_inode_rank(uint32_t mode) {
   switch (posix_file_type::from_mode(mode)) {
   case posix_file_type::directory:
@@ -48,4 +70,41 @@ inode_rank get_inode_rank(uint32_t mode) {
   }
 }
 
+size_t find_inode_rank_offset(
+    ::apache::thrift::frozen::Layout<thrift::metadata::metadata>::View meta,
+    inode_rank rank) {
+  auto get_mode = [&](auto index) {
+    return meta.modes()[meta.inodes()[index].mode_index()];
+  };
+
+  if (meta.dir_entries()) {
+    return find_inode_rank_offset_impl(
+        rank, meta.inodes().size(),
+        [&](auto inode) { return get_mode(inode); });
+  }
+
+  return find_inode_rank_offset_impl(
+      rank, meta.entry_table_v2_2().size(),
+      [&](auto inode) { return get_mode(meta.entry_table_v2_2()[inode]); });
+}
+
+size_t find_inode_rank_offset(thrift::metadata::metadata const& meta,
+                              inode_rank rank) {
+  auto get_mode = [&](auto index) {
+    return meta.modes().value().at(
+        meta.inodes().value().at(index).mode_index().value());
+  };
+
+  if (meta.dir_entries().has_value()) {
+    return find_inode_rank_offset_impl(
+        rank, meta.inodes()->size(),
+        [&](auto inode) { return get_mode(inode); });
+  }
+
+  return find_inode_rank_offset_impl(
+      rank, meta.entry_table_v2_2()->size(), [&](auto inode) {
+        return get_mode(meta.entry_table_v2_2().value().at(inode));
+      });
+}
+
 } // namespace dwarfs::internal

src/reader/internal/metadata_v2.cpp

@@ -602,27 +602,7 @@ class metadata_ final : public metadata_v2::impl {
   }
 
   size_t find_inode_offset(inode_rank rank) const {
-    if (meta_.dir_entries()) {
-      auto range = boost::irange(size_t(0), meta_.inodes().size());
-
-      auto it = std::lower_bound(
-          range.begin(), range.end(), rank, [&](auto inode, inode_rank r) {
-            auto mode = meta_.modes()[meta_.inodes()[inode].mode_index()];
-            return get_inode_rank(mode) < r;
-          });
-
-      return *it;
-    } else {
-      auto range = boost::irange(size_t(0), meta_.entry_table_v2_2().size());
-
-      auto it = std::lower_bound(range.begin(), range.end(), rank,
-                                 [&](auto inode, inode_rank r) {
-                                   auto iv = make_inode_view_impl(inode);
-                                   return get_inode_rank(iv.mode()) < r;
-                                 });
-
-      return *it;
-    }
+    return find_inode_rank_offset(meta_, rank);
   }
 
   directory_view make_directory_view(inode_view_impl const& iv) const {