From 40e43a153f1a41754162f6945412b00d51c6835f Mon Sep 17 00:00:00 2001
From: Marcus Holland-Moritz <github@mhxnet.de>
Date: Fri, 23 Aug 2024 16:05:38 +0200
Subject: [PATCH] feat(internal): allow storing "." and ".." in
 dir_entry_view_impl

---
 .../dwarfs/reader/internal/metadata_types.h   | 50 ++++++++++++-------
 src/reader/internal/metadata_types.cpp        | 49 ++++++++++++------
 2 files changed, 66 insertions(+), 33 deletions(-)

diff --git a/include/dwarfs/reader/internal/metadata_types.h b/include/dwarfs/reader/internal/metadata_types.h
index 89d6499c..08f2d38e 100644
--- a/include/dwarfs/reader/internal/metadata_types.h
+++ b/include/dwarfs/reader/internal/metadata_types.h
@@ -34,6 +34,7 @@
 #include <dwarfs/file_stat.h>
 #include <dwarfs/file_type.h>
 
+#include <dwarfs/internal/packed_ptr.h>
 #include <dwarfs/internal/string_table.h>
 
 #include <dwarfs/gen-cpp2/metadata_layouts.h>
@@ -119,38 +120,49 @@ class dir_entry_view_impl {
   using DirEntryView =
       ::apache::thrift::frozen::View<thrift::metadata::dir_entry>;
 
+  enum class entry_name_type : uint8_t {
+    other,
+    self,
+    parent,
+  };
+
   dir_entry_view_impl(DirEntryView v, uint32_t self_index,
-                      uint32_t parent_index, global_metadata const& g)
+                      uint32_t parent_index, global_metadata const& g,
+                      entry_name_type name_type)
       : v_{v}
       , self_index_{self_index}
       , parent_index_{parent_index}
-      , g_{&g} {}
+      , g_{&g, name_type} {}
 
   dir_entry_view_impl(InodeView v, uint32_t self_index, uint32_t parent_index,
-                      global_metadata const& g)
+                      global_metadata const& g, entry_name_type name_type)
       : v_{v}
       , self_index_{self_index}
       , parent_index_{parent_index}
-      , g_{&g} {}
+      , g_{&g, name_type} {}
 
-  static std::shared_ptr<dir_entry_view_impl>
-  from_dir_entry_index_shared(uint32_t self_index, uint32_t parent_index,
-                              global_metadata const& g);
-  static std::shared_ptr<dir_entry_view_impl>
-  from_dir_entry_index_shared(uint32_t self_index, global_metadata const& g);
+  static std::shared_ptr<dir_entry_view_impl> from_dir_entry_index_shared(
+      uint32_t self_index, uint32_t parent_index, global_metadata const& g,
+      entry_name_type name_type = entry_name_type::other);
+  static std::shared_ptr<dir_entry_view_impl> from_dir_entry_index_shared(
+      uint32_t self_index, global_metadata const& g,
+      entry_name_type name_type = entry_name_type::other);
 
   static dir_entry_view_impl
   from_dir_entry_index(uint32_t self_index, uint32_t parent_index,
-                       global_metadata const& g);
+                       global_metadata const& g,
+                       entry_name_type name_type = entry_name_type::other);
   static dir_entry_view_impl
-  from_dir_entry_index(uint32_t self_index, global_metadata const& g);
+  from_dir_entry_index(uint32_t self_index, global_metadata const& g,
+                       entry_name_type name_type = entry_name_type::other);
 
   // TODO: this works, but it's strange; a limited version of
   // dir_entry_view_impl
   //       should work without a parent for these use cases
-  static std::string name(uint32_t index, global_metadata const& g);
+  static std::string
+  name(uint32_t index, global_metadata const& g); // TODO: remove?
   static std::shared_ptr<inode_view_impl>
-  inode_shared(uint32_t index, global_metadata const& g);
+  inode_shared(uint32_t index, global_metadata const& g); // TODO: remove?
 
   std::string name() const;
   std::shared_ptr<inode_view_impl> inode_shared() const;
@@ -175,16 +187,18 @@ class dir_entry_view_impl {
   auto make_inode() const;
 
   template <template <typename...> class Ctor>
-  static auto make_dir_entry_view(uint32_t self_index, uint32_t parent_index,
-                                  global_metadata const& g);
+  static auto
+  make_dir_entry_view(uint32_t self_index, uint32_t parent_index,
+                      global_metadata const& g, entry_name_type name_type);
 
   template <template <typename...> class Ctor>
-  static auto
-  make_dir_entry_view(uint32_t self_index, global_metadata const& g);
+  static auto make_dir_entry_view(uint32_t self_index, global_metadata const& g,
+                                  entry_name_type name_type);
 
   std::variant<DirEntryView, InodeView> v_;
   uint32_t self_index_, parent_index_;
-  global_metadata const* g_;
+  dwarfs::internal::packed_ptr<global_metadata const, 2, entry_name_type> const
+      g_;
 };
 
 using chunk_view = ::apache::thrift::frozen::View<thrift::metadata::chunk>;
diff --git a/src/reader/internal/metadata_types.cpp b/src/reader/internal/metadata_types.cpp
index 397c1fa4..a411c7fe 100644
--- a/src/reader/internal/metadata_types.cpp
+++ b/src/reader/internal/metadata_types.cpp
@@ -809,6 +809,15 @@ auto inode_view_impl::getgid() const -> gid_type {
 // TODO: pretty certain some of this stuff can be simplified
 
 std::string dir_entry_view_impl::name() const {
+  switch (g_.get_data()) {
+  case entry_name_type::other:
+    break;
+  case entry_name_type::self:
+    return ".";
+  case entry_name_type::parent:
+    return "..";
+  }
+
   return v_ |
          match{
              [this](DirEntryView const& dev) {
@@ -859,7 +868,8 @@ bool dir_entry_view_impl::is_root() const {
 template <template <typename...> class Ctor>
 auto dir_entry_view_impl::make_dir_entry_view(uint32_t self_index,
                                               uint32_t parent_index,
-                                              global_metadata const& g) {
+                                              global_metadata const& g,
+                                              entry_name_type name_type) {
   auto& meta = g.meta();
 
   if (auto de = meta.dir_entries()) {
@@ -872,7 +882,8 @@ auto dir_entry_view_impl::make_dir_entry_view(uint32_t self_index,
 
     auto dev = (*de)[self_index];
 
-    return Ctor<dir_entry_view_impl>()(dev, self_index, parent_index, g);
+    return Ctor<dir_entry_view_impl>()(dev, self_index, parent_index, g,
+                                       name_type);
   }
 
   DWARFS_CHECK(self_index < meta.inodes().size(),
@@ -884,12 +895,14 @@ auto dir_entry_view_impl::make_dir_entry_view(uint32_t self_index,
 
   auto iv = meta.inodes()[self_index];
 
-  return Ctor<dir_entry_view_impl>()(iv, self_index, parent_index, g);
+  return Ctor<dir_entry_view_impl>()(iv, self_index, parent_index, g,
+                                     name_type);
 }
 
 template <template <typename...> class Ctor>
 auto dir_entry_view_impl::make_dir_entry_view(uint32_t self_index,
-                                              global_metadata const& g) {
+                                              global_metadata const& g,
+                                              entry_name_type name_type) {
   auto& meta = g.meta();
 
   if (auto de = meta.dir_entries()) {
@@ -900,8 +913,8 @@ auto dir_entry_view_impl::make_dir_entry_view(uint32_t self_index,
     DWARFS_CHECK(dev.inode_num() < meta.directories().size(),
                  fmt::format("inode_num out of range: {0} >= {1}",
                              dev.inode_num(), meta.directories().size()));
-    return Ctor<dir_entry_view_impl>()(dev, self_index,
-                                       g.parent_dir_entry(dev.inode_num()), g);
+    return Ctor<dir_entry_view_impl>()(
+        dev, self_index, g.parent_dir_entry(dev.inode_num()), g, name_type);
   }
 
   DWARFS_CHECK(self_index < meta.inodes().size(),
@@ -916,33 +929,39 @@ auto dir_entry_view_impl::make_dir_entry_view(uint32_t self_index,
       iv, self_index,
       meta.entry_table_v2_2()[meta.directories()[iv.inode_v2_2()]
                                   .parent_entry()],
-      g);
+      g, name_type);
 }
 
 std::shared_ptr<dir_entry_view_impl>
 dir_entry_view_impl::from_dir_entry_index_shared(uint32_t self_index,
                                                  uint32_t parent_index,
-                                                 global_metadata const& g) {
-  return make_dir_entry_view<shared_ptr_ctor>(self_index, parent_index, g);
+                                                 global_metadata const& g,
+                                                 entry_name_type name_type) {
+  return make_dir_entry_view<shared_ptr_ctor>(self_index, parent_index, g,
+                                              name_type);
 }
 
 std::shared_ptr<dir_entry_view_impl>
 dir_entry_view_impl::from_dir_entry_index_shared(uint32_t self_index,
-                                                 global_metadata const& g) {
-  return make_dir_entry_view<shared_ptr_ctor>(self_index, g);
+                                                 global_metadata const& g,
+                                                 entry_name_type name_type) {
+  return make_dir_entry_view<shared_ptr_ctor>(self_index, g, name_type);
 }
 
 dir_entry_view_impl
 dir_entry_view_impl::from_dir_entry_index(uint32_t self_index,
                                           uint32_t parent_index,
-                                          global_metadata const& g) {
-  return make_dir_entry_view<stack_ctor>(self_index, parent_index, g);
+                                          global_metadata const& g,
+                                          entry_name_type name_type) {
+  return make_dir_entry_view<stack_ctor>(self_index, parent_index, g,
+                                         name_type);
 }
 
 dir_entry_view_impl
 dir_entry_view_impl::from_dir_entry_index(uint32_t self_index,
-                                          global_metadata const& g) {
-  return make_dir_entry_view<stack_ctor>(self_index, g);
+                                          global_metadata const& g,
+                                          entry_name_type name_type) {
+  return make_dir_entry_view<stack_ctor>(self_index, g, name_type);
 }
 
 std::shared_ptr<dir_entry_view_impl> dir_entry_view_impl::parent() const {