From e431542a5705d3c8681b1f0b2456cbc7f74f5105 Mon Sep 17 00:00:00 2001
From: Marcus Holland-Moritz <github@mhxnet.de>
Date: Sat, 23 Nov 2024 18:33:19 +0100
Subject: [PATCH] chore: allow access to thawed/unpacked metadata for rewriting

---
 include/dwarfs/reader/filesystem_v2.h        | 11 +++++++++++
 include/dwarfs/reader/internal/metadata_v2.h | 11 +++++++++++
 src/reader/filesystem_v2.cpp                 | 19 +++++++++++++++++++
 src/reader/internal/metadata_v2.cpp          |  8 ++++++++
 4 files changed, 49 insertions(+)

diff --git a/include/dwarfs/reader/filesystem_v2.h b/include/dwarfs/reader/filesystem_v2.h
index 49ed66083..4a54bea9d 100644
--- a/include/dwarfs/reader/filesystem_v2.h
+++ b/include/dwarfs/reader/filesystem_v2.h
@@ -52,6 +52,10 @@ class mmif;
 class os_access;
 class performance_monitor;
 
+namespace thrift::metadata {
+class metadata;
+}
+
 namespace reader {
 
 struct cache_tidy_config;
@@ -347,6 +351,9 @@ class filesystem_v2 {
     return impl_->get_block_category(block_number);
   }
 
+  std::unique_ptr<thrift::metadata::metadata> thawed_metadata() const;
+  std::unique_ptr<thrift::metadata::metadata> unpacked_metadata() const;
+
   class impl {
    public:
     virtual ~impl() = default;
@@ -442,6 +449,10 @@ class filesystem_v2 {
     virtual std::shared_ptr<internal::filesystem_parser> get_parser() const = 0;
     virtual std::optional<std::string>
     get_block_category(size_t block_number) const = 0;
+    virtual std::unique_ptr<thrift::metadata::metadata>
+    thawed_metadata() const = 0;
+    virtual std::unique_ptr<thrift::metadata::metadata>
+    unpacked_metadata() const = 0;
   };
 
  private:
diff --git a/include/dwarfs/reader/internal/metadata_v2.h b/include/dwarfs/reader/internal/metadata_v2.h
index 027b69a2f..f4eac8a1d 100644
--- a/include/dwarfs/reader/internal/metadata_v2.h
+++ b/include/dwarfs/reader/internal/metadata_v2.h
@@ -173,6 +173,14 @@ class metadata_v2 {
     return impl_->get_all_gids();
   }
 
+  std::unique_ptr<thrift::metadata::metadata> thaw() const {
+    return impl_->thaw();
+  }
+
+  std::unique_ptr<thrift::metadata::metadata> unpack() const {
+    return impl_->unpack();
+  }
+
   class impl {
    public:
     virtual ~impl() = default;
@@ -244,6 +252,9 @@ class metadata_v2 {
     virtual std::vector<file_stat::uid_type> get_all_uids() const = 0;
 
     virtual std::vector<file_stat::gid_type> get_all_gids() const = 0;
+
+    virtual std::unique_ptr<thrift::metadata::metadata> thaw() const = 0;
+    virtual std::unique_ptr<thrift::metadata::metadata> unpack() const = 0;
   };
 
  private:
diff --git a/src/reader/filesystem_v2.cpp b/src/reader/filesystem_v2.cpp
index fe957b8ee..26e315046 100644
--- a/src/reader/filesystem_v2.cpp
+++ b/src/reader/filesystem_v2.cpp
@@ -316,6 +316,15 @@ class filesystem_ final : public filesystem_v2::impl {
     return meta_.get_block_category(block_no);
   }
 
+  std::unique_ptr<thrift::metadata::metadata> thawed_metadata() const override {
+    return meta_.thaw();
+  }
+
+  std::unique_ptr<thrift::metadata::metadata>
+  unpacked_metadata() const override {
+    return meta_.unpack();
+  }
+
  private:
   filesystem_info const* get_info(fsinfo_options const& opts) const;
   void check_section(fs_section const& section) const;
@@ -1131,4 +1140,14 @@ filesystem_v2::header(std::shared_ptr<mmif> mm, file_off_t image_offset) {
   return internal::filesystem_parser(mm, image_offset).header();
 }
 
+std::unique_ptr<thrift::metadata::metadata>
+filesystem_v2::thawed_metadata() const {
+  return impl_->thawed_metadata();
+}
+
+std::unique_ptr<thrift::metadata::metadata>
+filesystem_v2::unpacked_metadata() const {
+  return impl_->unpacked_metadata();
+}
+
 } // namespace dwarfs::reader
diff --git a/src/reader/internal/metadata_v2.cpp b/src/reader/internal/metadata_v2.cpp
index 0777844c9..fd0440470 100644
--- a/src/reader/internal/metadata_v2.cpp
+++ b/src/reader/internal/metadata_v2.cpp
@@ -555,6 +555,14 @@ class metadata_ final : public metadata_v2::impl {
   std::vector<file_stat::uid_type> get_all_uids() const override;
   std::vector<file_stat::gid_type> get_all_gids() const override;
 
+  std::unique_ptr<thrift::metadata::metadata> unpack() const override {
+    return std::make_unique<thrift::metadata::metadata>(unpack_metadata());
+  }
+
+  std::unique_ptr<thrift::metadata::metadata> thaw() const override {
+    return std::make_unique<thrift::metadata::metadata>(meta_.thaw());
+  }
+
  private:
   template <typename K>
   using set_type = folly::F14ValueSet<K>;