8238000: Crash in ClassLoader::record_result while dynamic dumping netty

Make a copy of the _shared_path_table for use during dynamic CDS dump.

Reviewed-by: iklam, minqi

src/hotspot/share/memory/dynamicArchive.cpp

@@ -956,7 +956,7 @@ void DynamicArchiveBuilder::relocate_buffer_to_target() {
   RelocateBufferToTarget patcher(this, (address*)_alloc_bottom, _buffer_to_target_delta);
   ArchivePtrMarker::ptrmap()->iterate(&patcher);
 
-  Array<u8>* table = FileMapInfo::shared_path_table().table();
+  Array<u8>* table = FileMapInfo::saved_shared_path_table().table();
   SharedPathTable runtime_table(to_target(table), FileMapInfo::shared_path_table().size());
   _header->set_shared_path_table(runtime_table);
 

src/hotspot/share/memory/filemap.cpp

@@ -293,6 +293,23 @@ void SharedClassPathEntry::set_name(const char* name, TRAPS) {
   strcpy(_name->data(), name);
 }
 
+void SharedClassPathEntry::copy_from(SharedClassPathEntry* ent, ClassLoaderData* loader_data, TRAPS) {
+  _type = ent->_type;
+  _timestamp = ent->_timestamp;
+  _filesize = ent->_filesize;
+  _from_class_path_attr = ent->_from_class_path_attr;
+  set_name(ent->name(), THREAD);
+
+  if (ent->is_jar() && !ent->is_signed() && ent->manifest() != NULL) {
+    Array<u1>* buf = MetadataFactory::new_array<u1>(loader_data,
+                                                    ent->manifest_size(),
+                                                    THREAD);
+    char* p = (char*)(buf->data());
+    memcpy(p, ent->manifest(), ent->manifest_size());
+    set_manifest(buf);
+  }
+}
+
 const char* SharedClassPathEntry::name() const {
   if (UseSharedSpaces && is_modules_image()) {
     // In order to validate the runtime modules image file size against the archived
@@ -381,10 +398,26 @@ void SharedPathTable::dumptime_init(ClassLoaderData* loader_data, Thread* THREAD
   num_entries += FileMapInfo::num_non_existent_class_paths();
   size_t bytes = entry_size * num_entries;
 
-  _table = MetadataFactory::new_array<u8>(loader_data, (int)(bytes + 7 / 8), THREAD);
+  _table = MetadataFactory::new_array<u8>(loader_data, (int)bytes, THREAD);
   _size = num_entries;
 }
 
+// Make a copy of the _shared_path_table for use during dynamic CDS dump.
+// It is needed because some Java code continues to execute after dynamic dump has finished.
+// However, during dynamic dump, we have modified FileMapInfo::_shared_path_table so
+// FileMapInfo::shared_path(i) returns incorrect information in ClassLoader::record_result().
+void FileMapInfo::copy_shared_path_table(ClassLoaderData* loader_data, Thread* THREAD) {
+  size_t entry_size = sizeof(SharedClassPathEntry);
+  size_t bytes = entry_size * _shared_path_table.size();
+
+  _saved_shared_path_table = SharedPathTable(MetadataFactory::new_array<u8>(loader_data, (int)bytes, THREAD),
+                                             _shared_path_table.size());
+
+  for (int i = 0; i < _shared_path_table.size(); i++) {
+    _saved_shared_path_table.path_at(i)->copy_from(shared_path(i), loader_data, THREAD);
+  }
+}
+
 void FileMapInfo::allocate_shared_path_table() {
   Arguments::assert_is_dumping_archive();
 
@@ -409,6 +442,8 @@ void FileMapInfo::allocate_shared_path_table() {
   }
 
   assert(i == _shared_path_table.size(), "number of shared path entry mismatch");
+
+  copy_shared_path_table(loader_data, THREAD);
 }
 
 int FileMapInfo::add_shared_classpaths(int i, const char* which, ClassPathEntry *cpe, TRAPS) {
@@ -937,10 +972,6 @@ bool FileMapInfo::get_base_archive_name_from_header(const char* archive_name,
   return true;
 }
 
-void FileMapInfo::restore_shared_path_table() {
-  _shared_path_table = _current_info->header()->shared_path_table();
-}
-
 // Read the FileMapInfo information from the file.
 
 bool FileMapInfo::init_from_file(int fd) {
@@ -1926,14 +1957,19 @@ void FileMapInfo::assert_mark(bool check) {
   }
 }
 
-void FileMapInfo::metaspace_pointers_do(MetaspaceClosure* it) {
+void FileMapInfo::metaspace_pointers_do(MetaspaceClosure* it, bool use_copy) {
-  _shared_path_table.metaspace_pointers_do(it);
+  if (use_copy) {
+    _saved_shared_path_table.metaspace_pointers_do(it);
+  } else {
+    _shared_path_table.metaspace_pointers_do(it);
+  }
 }
 
 FileMapInfo* FileMapInfo::_current_info = NULL;
 FileMapInfo* FileMapInfo::_dynamic_archive_info = NULL;
 bool FileMapInfo::_heap_pointers_need_patching = false;
 SharedPathTable FileMapInfo::_shared_path_table;
+SharedPathTable FileMapInfo::_saved_shared_path_table;
 bool FileMapInfo::_validating_shared_path_table = false;
 bool FileMapInfo::_memory_mapping_failed = false;
 GrowableArray<const char*>* FileMapInfo::_non_existent_class_paths = NULL;

src/hotspot/share/memory/filemap.hpp

@@ -95,6 +95,7 @@ public:
     _manifest = manifest;
   }
   bool check_non_existent() const;
+  void copy_from(SharedClassPathEntry* ent, ClassLoaderData* loader_data, TRAPS);
 };
 
 struct ArchiveHeapOopmapInfo {
@@ -335,6 +336,7 @@ private:
 
   // TODO: Probably change the following to be non-static
   static SharedPathTable       _shared_path_table;
+  static SharedPathTable       _saved_shared_path_table;
   static bool                  _validating_shared_path_table;
 
   // FileMapHeader describes the shared space data in the file to be
@@ -356,9 +358,12 @@ public:
   static SharedPathTable shared_path_table() {
     return _shared_path_table;
   }
-  void restore_shared_path_table();
+  static SharedPathTable saved_shared_path_table() {
+    return _saved_shared_path_table;
+  }
+
   bool init_from_file(int fd);
-  static void metaspace_pointers_do(MetaspaceClosure* it);
+  static void metaspace_pointers_do(MetaspaceClosure* it, bool use_copy = true);
 
   void log_paths(const char* msg, int start_idx, int end_idx);
 
@@ -482,6 +487,7 @@ public:
   static void stop_sharing_and_unmap(const char* msg);
 
   static void allocate_shared_path_table();
+  static void copy_shared_path_table(ClassLoaderData* loader_data, Thread* THREAD);
   static int add_shared_classpaths(int i, const char* which, ClassPathEntry *cpe, TRAPS);
   static void check_nonempty_dir_in_shared_path_table();
   bool validate_shared_path_table();

src/hotspot/share/memory/metaspaceShared.cpp

@@ -1375,7 +1375,7 @@ public:
         it->push(_global_klass_objects->adr_at(i));
       }
     }
-    FileMapInfo::metaspace_pointers_do(it);
+    FileMapInfo::metaspace_pointers_do(it, false);
     SystemDictionaryShared::dumptime_classes_do(it);
     Universe::metaspace_pointers_do(it);
     SymbolTable::metaspace_pointers_do(it);