filemap.hpp

/*
 * Copyright (c) 2003, 2021, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 *
 */

#ifndef SHARE_CDS_FILEMAP_HPP
#define SHARE_CDS_FILEMAP_HPP

#include "cds/metaspaceShared.hpp"
#include "include/cds.h"
#include "oops/array.hpp"
#include "oops/compressedOops.hpp"
#include "utilities/align.hpp"

// To understand the layout of the CDS archive file:
//
// java -Xlog:cds+map=info:file=cds.map:none:filesize=0
// java -Xlog:cds+map=debug:file=cds.map:none:filesize=0
// java -Xlog:cds+map=trace:file=cds.map:none:filesize=0

static const int JVM_IDENT_MAX = 256;

class CHeapBitMap;
class ClassFileStream;
class ClassLoaderData;
class ClassPathEntry;
class outputStream;

class SharedClassPathEntry {
  enum {
    modules_image_entry,
    jar_entry,
    signed_jar_entry,
    dir_entry,
    non_existent_entry,
    unknown_entry
  };

  void set_name(const char* name, TRAPS);

  u1     _type;
  bool   _is_module_path;
  bool   _from_class_path_attr;
  time_t _timestamp;          // jar timestamp,  0 if is directory, modules image or other
  int64_t      _filesize;     // jar/jimage file size, -1 if is directory, -2 if other
  Array<char>* _name;
  Array<u1>*   _manifest;

public:
  void init(bool is_modules_image, bool is_module_path, ClassPathEntry* cpe, TRAPS);
  void init_as_non_existent(const char* path, TRAPS);
  void metaspace_pointers_do(MetaspaceClosure* it);
  bool validate(bool is_class_path = true) const;

  // The _timestamp only gets set for jar files.
  bool has_timestamp() const {
    return _timestamp != 0;
  }
  bool is_dir()           const { return _type == dir_entry; }
  bool is_modules_image() const { return _type == modules_image_entry; }
  bool is_jar()           const { return _type == jar_entry; }
  bool is_signed()        const { return _type == signed_jar_entry; }
  void set_is_signed() {
    _type = signed_jar_entry;
  }
  bool from_class_path_attr() { return _from_class_path_attr; }
  time_t timestamp() const { return _timestamp; }
  const char* name() const;
  const char* manifest() const {
    return (_manifest == NULL) ? NULL : (const char*)_manifest->data();
  }
  int manifest_size() const {
    return (_manifest == NULL) ? 0 : _manifest->length();
  }
  void set_manifest(Array<u1>* manifest) {
    _manifest = manifest;
  }
  bool check_non_existent() const;
  void copy_from(SharedClassPathEntry* ent, ClassLoaderData* loader_data, TRAPS);
  bool in_named_module() {
    return is_modules_image() || // modules image doesn't contain unnamed modules
           _is_module_path;      // module path doesn't contain unnamed modules
  }
};

struct ArchiveHeapOopmapInfo {
  address _oopmap;               // bitmap for relocating embedded oops
  size_t  _offset;               // this oopmap is stored at this offset from the bottom of the BM region
  size_t  _oopmap_size_in_bits;
  size_t  _oopmap_size_in_bytes;
};

class SharedPathTable {
  Array<u8>* _table;
  int _size;
public:
  SharedPathTable() : _table(NULL), _size(0) {}
  SharedPathTable(Array<u8>* table, int size) : _table(table), _size(size) {}

  void dumptime_init(ClassLoaderData* loader_data, TRAPS);
  void metaspace_pointers_do(MetaspaceClosure* it);

  int size() {
    return _size;
  }
  SharedClassPathEntry* path_at(int index) {
    if (index < 0) {
      return NULL;
    }
    assert(index < _size, "sanity");
    char* p = (char*)_table->data();
    p += sizeof(SharedClassPathEntry) * index;
    return (SharedClassPathEntry*)p;
  }
  Array<u8>* table() {return _table;}
  void set_table(Array<u8>* table) {_table = table;}
};


class FileMapRegion: private CDSFileMapRegion {
  void assert_is_heap_region() const {
    assert(_is_heap_region, "must be heap region");
  }
  void assert_is_not_heap_region() const {
    assert(!_is_heap_region, "must not be heap region");
  }

public:
  static FileMapRegion* cast(CDSFileMapRegion* p) {
    return (FileMapRegion*)p;
  }

  // Accessors
  int crc()                         const { return _crc; }
  size_t file_offset()              const { return _file_offset; }
  size_t mapping_offset()           const { return _mapping_offset; }
  size_t mapping_end_offset()       const { return _mapping_offset + used_aligned(); }
  size_t used()                     const { return _used; }
  size_t used_aligned()             const; // aligned up to MetaspaceShared::core_region_alignment()
  char*  mapped_base()              const { assert_is_not_heap_region(); return _mapped_base; }
  char*  mapped_end()               const { return mapped_base()        + used_aligned(); }
  bool   read_only()                const { return _read_only != 0; }
  bool   allow_exec()               const { return _allow_exec != 0; }
  bool   mapped_from_file()         const { return _mapped_from_file != 0; }
  size_t oopmap_offset()            const { assert_is_heap_region();     return _oopmap_offset; }
  size_t oopmap_size_in_bits()      const { assert_is_heap_region();     return _oopmap_size_in_bits; }

  void set_file_offset(size_t s)     { _file_offset = s; }
  void set_read_only(bool v)         { _read_only = v; }
  void set_mapped_base(char* p)      { _mapped_base = p; }
  void set_mapped_from_file(bool v)  { _mapped_from_file = v; }
  void init(int region_index, size_t mapping_offset, size_t size, bool read_only,
            bool allow_exec, int crc);

  void init_oopmap(size_t oopmap_offset, size_t size_in_bits) {
    _oopmap_offset = oopmap_offset;
    _oopmap_size_in_bits = size_in_bits;
  }

  void print(outputStream* st, int region_index);
};

class FileMapHeader: private CDSFileMapHeaderBase {
  friend class CDSOffsets;
  friend class VMStructs;

  size_t _header_size;

  // The following fields record the states of the VM during dump time.
  // They are compared with the runtime states to see if the archive
  // can be used.
  size_t _core_region_alignment;    // how shared archive should be aligned
  int    _obj_alignment;            // value of ObjectAlignmentInBytes
  address _narrow_oop_base;         // compressed oop encoding base
  int    _narrow_oop_shift;         // compressed oop encoding shift
  bool   _compact_strings;          // value of CompactStrings
  uintx  _max_heap_size;            // java max heap size during dumping
  CompressedOops::Mode _narrow_oop_mode; // compressed oop encoding mode
  int     _narrow_klass_shift;      // save narrow klass base and shift
  bool    _compressed_oops;         // save the flag UseCompressedOops
  bool    _compressed_class_ptrs;   // save the flag UseCompressedClassPointers
  size_t  _cloned_vtables_offset;   // The address of the first cloned vtable
  size_t  _serialized_data_offset;  // Data accessed using {ReadClosure,WriteClosure}::serialize()
  address _heap_begin;              // heap begin at dump time.
  address _heap_end;                // heap end at dump time.
  bool _base_archive_is_default;    // indicates if the base archive is the system default one

  // The following fields are all sanity checks for whether this archive
  // will function correctly with this JVM and the bootclasspath it's
  // invoked with.
  char  _jvm_ident[JVM_IDENT_MAX];  // identifier string of the jvm that created this dump

  // size of the base archive name including NULL terminator
  size_t _base_archive_name_size;

  // The following is a table of all the boot/app/module path entries that were used
  // during dumping. At run time, we validate these entries according to their
  // SharedClassPathEntry::_type. See:
  //      check_nonempty_dir_in_shared_path_table()
  //      validate_shared_path_table()
  //      validate_non_existent_class_paths()
  size_t _shared_path_table_offset;
  int    _shared_path_table_size;

  jshort _app_class_paths_start_index;  // Index of first app classpath entry
  jshort _app_module_paths_start_index; // Index of first module path entry
  jshort _num_module_paths;             // number of module path entries
  jshort _max_used_path_index;          // max path index referenced during CDS dump
  bool   _verify_local;                 // BytecodeVerificationLocal setting
  bool   _verify_remote;                // BytecodeVerificationRemote setting
  bool   _has_platform_or_app_classes;  // Archive contains app classes
  char*  _requested_base_address;       // Archive relocation is not necessary if we map with this base address.
  char*  _mapped_base_address;          // Actual base address where archive is mapped.

  bool   _allow_archiving_with_java_agent; // setting of the AllowArchivingWithJavaAgent option
  bool   _use_optimized_module_handling;// No module-relation VM options were specified, so we can skip
                                        // some expensive operations.
  bool   _use_full_module_graph;        // Can we use the full archived module graph?
  size_t _ptrmap_size_in_bits;          // Size of pointer relocation bitmap
  narrowOop _heap_obj_roots;            // An objArray that stores all the roots of archived heap objects
  char* from_mapped_offset(size_t offset) const {
    return mapped_base_address() + offset;
  }
  void set_as_offset(char* p, size_t *offset);
public:
  // Accessors -- fields declared in CDSFileMapHeaderBase
  unsigned int magic()                    const { return _magic; }
  int crc()                               const { return _crc; }
  int version()                           const { return _version; }

  void set_crc(int crc_value)                   { _crc = crc_value; }
  void set_version(int v)                       { _version = v; }

  // Accessors -- fields declared in FileMapHeader

  size_t header_size()                     const { return _header_size; }
  size_t core_region_alignment()           const { return _core_region_alignment; }
  int obj_alignment()                      const { return _obj_alignment; }
  address narrow_oop_base()                const { return _narrow_oop_base; }
  int narrow_oop_shift()                   const { return _narrow_oop_shift; }
  bool compact_strings()                   const { return _compact_strings; }
  uintx max_heap_size()                    const { return _max_heap_size; }
  CompressedOops::Mode narrow_oop_mode()   const { return _narrow_oop_mode; }
  int narrow_klass_shift()                 const { return _narrow_klass_shift; }
  address narrow_klass_base()              const { return (address)mapped_base_address(); }
  char* cloned_vtables()                   const { return from_mapped_offset(_cloned_vtables_offset); }
  char* serialized_data()                  const { return from_mapped_offset(_serialized_data_offset); }
  address heap_begin()                     const { return _heap_begin; }
  address heap_end()                       const { return _heap_end; }
  bool base_archive_is_default()           const { return _base_archive_is_default; }
  const char* jvm_ident()                  const { return _jvm_ident; }
  size_t base_archive_name_size()          const { return _base_archive_name_size; }
  char* requested_base_address()           const { return _requested_base_address; }
  char* mapped_base_address()              const { return _mapped_base_address; }
  bool has_platform_or_app_classes()       const { return _has_platform_or_app_classes; }
  size_t ptrmap_size_in_bits()             const { return _ptrmap_size_in_bits; }
  bool compressed_oops()                   const { return _compressed_oops; }
  bool compressed_class_pointers()         const { return _compressed_class_ptrs; }
  // FIXME: These should really return int
  jshort max_used_path_index()             const { return _max_used_path_index; }
  jshort app_module_paths_start_index()    const { return _app_module_paths_start_index; }
  jshort app_class_paths_start_index()     const { return _app_class_paths_start_index; }
  jshort num_module_paths()                const { return _num_module_paths; }
  narrowOop heap_obj_roots()               const { return _heap_obj_roots; }

  void set_has_platform_or_app_classes(bool v)   { _has_platform_or_app_classes = v; }
  void set_cloned_vtables(char* p)               { set_as_offset(p, &_cloned_vtables_offset); }
  void set_serialized_data(char* p)              { set_as_offset(p, &_serialized_data_offset); }
  void set_base_archive_name_size(size_t s)      { _base_archive_name_size = s; }
  void set_base_archive_is_default(bool b)       { _base_archive_is_default = b; }
  void set_header_size(size_t s)                 { _header_size = s; }
  void set_ptrmap_size_in_bits(size_t s)         { _ptrmap_size_in_bits = s; }
  void set_mapped_base_address(char* p)          { _mapped_base_address = p; }
  void set_heap_obj_roots(narrowOop r)           { _heap_obj_roots = r; }

  void set_shared_path_table(SharedPathTable table) {
    set_as_offset((char*)table.table(), &_shared_path_table_offset);
    _shared_path_table_size = table.size();
  }

  void set_requested_base(char* b) {
    _requested_base_address = b;
    _mapped_base_address = 0;
  }

  SharedPathTable shared_path_table() const {
    return SharedPathTable((Array<u8>*)from_mapped_offset(_shared_path_table_offset),
                           _shared_path_table_size);
  }

  bool validate();
  int compute_crc();

  FileMapRegion* space_at(int i) {
    assert(is_valid_region(i), "invalid region");
    return FileMapRegion::cast(&_space[i]);
  }

  void populate(FileMapInfo* info, size_t core_region_alignment);

  static bool is_valid_region(int region) {
    return (0 <= region && region < NUM_CDS_REGIONS);
  }

  void print(outputStream* st);
};

class FileMapInfo : public CHeapObj<mtInternal> {
private:
  friend class ManifestStream;
  friend class VMStructs;
  friend class ArchiveBuilder;
  friend class CDSOffsets;
  friend class FileMapHeader;

  bool           _is_static;
  bool           _file_open;
  bool           _is_mapped;
  int            _fd;
  size_t         _file_offset;
  const char*    _full_path;
  const char*    _base_archive_name;
  FileMapHeader* _header;

  // 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
  // mapped.  This structure gets written to a file.  It is not a class, so
  // that the compilers don't add any compiler-private data to it.

  static FileMapInfo* _current_info;
  static FileMapInfo* _dynamic_archive_info;
  static bool _heap_pointers_need_patching;
  static bool _memory_mapping_failed;
  static GrowableArray<const char*>* _non_existent_class_paths;

  FileMapHeader *header() const       { return _header; }

public:
  static bool get_base_archive_name_from_header(const char* archive_name,
                                                int* size, char** base_archive_name);
  static bool check_archive(const char* archive_name, bool is_static);
  static SharedPathTable shared_path_table() {
    return _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, bool use_copy = true);

  void log_paths(const char* msg, int start_idx, int end_idx);

  FileMapInfo(bool is_static);
  ~FileMapInfo();

  // Accessors
  int    compute_header_crc()  const { return header()->compute_crc(); }
  void   set_header_crc(int crc)     { header()->set_crc(crc); }
  int    space_crc(int i)      const { return space_at(i)->crc(); }
  void   populate_header(size_t core_region_alignment);
  bool   validate_header();
  void   invalidate();
  int    crc()                 const { return header()->crc(); }
  int    version()             const { return header()->version(); }
  unsigned int magic()         const { return header()->magic(); }
  address narrow_oop_base()    const { return header()->narrow_oop_base(); }
  int     narrow_oop_shift()   const { return header()->narrow_oop_shift(); }
  uintx   max_heap_size()      const { return header()->max_heap_size(); }
  address narrow_klass_base()  const { return header()->narrow_klass_base(); }
  int     narrow_klass_shift() const { return header()->narrow_klass_shift(); }
  size_t  core_region_alignment() const { return header()->core_region_alignment(); }

  void   set_header_base_archive_name_size(size_t size)      { header()->set_base_archive_name_size(size); }
  void   set_header_base_archive_is_default(bool is_default) { header()->set_base_archive_is_default(is_default); }

  CompressedOops::Mode narrow_oop_mode()      const { return header()->narrow_oop_mode(); }
  jshort app_module_paths_start_index()       const { return header()->app_module_paths_start_index(); }
  jshort app_class_paths_start_index()        const { return header()->app_class_paths_start_index(); }

  char* cloned_vtables()                      const { return header()->cloned_vtables(); }
  void  set_cloned_vtables(char* p)           const { header()->set_cloned_vtables(p); }
  char* serialized_data()                     const { return header()->serialized_data(); }
  void  set_serialized_data(char* p)          const { header()->set_serialized_data(p); }

  bool  is_file_position_aligned() const;
  void  align_file_position();

  bool is_static()                            const { return _is_static; }
  bool is_mapped()                            const { return _is_mapped; }
  void set_is_mapped(bool v)                        { _is_mapped = v; }
  const char* full_path()                     const { return _full_path; }

  void set_requested_base(char* b)                  { header()->set_requested_base(b); }
  char* requested_base_address()           const    { return header()->requested_base_address(); }

  class DynamicArchiveHeader* dynamic_header() const {
    assert(!is_static(), "must be");
    return (DynamicArchiveHeader*)header();
  }

  void set_has_platform_or_app_classes(bool v) {
    header()->set_has_platform_or_app_classes(v);
  }
  bool has_platform_or_app_classes() const {
    return header()->has_platform_or_app_classes();
  }

  static FileMapInfo* current_info() {
    CDS_ONLY(return _current_info;)
    NOT_CDS(return NULL;)
  }

  static void set_current_info(FileMapInfo* info) {
    CDS_ONLY(_current_info = info;)
  }

  static FileMapInfo* dynamic_info() {
    CDS_ONLY(return _dynamic_archive_info;)
    NOT_CDS(return NULL;)
  }

  static void assert_mark(bool check);

  // File manipulation.
  bool  initialize() NOT_CDS_RETURN_(false);
  bool  open_for_read();
  void  open_for_write(const char* path = NULL);
  void  write_header();
  void  write_region(int region, char* base, size_t size,
                     bool read_only, bool allow_exec);
  char* write_bitmap_region(const CHeapBitMap* ptrmap,
                            GrowableArray<ArchiveHeapOopmapInfo>* closed_oopmaps,
                            GrowableArray<ArchiveHeapOopmapInfo>* open_oopmaps,
                            size_t &size_in_bytes);
  size_t write_archive_heap_regions(GrowableArray<MemRegion> *heap_mem,
                                    GrowableArray<ArchiveHeapOopmapInfo> *oopmaps,
                                    int first_region_id, int max_num_regions);
  void  write_bytes(const void* buffer, size_t count);
  void  write_bytes_aligned(const void* buffer, size_t count);
  size_t  read_bytes(void* buffer, size_t count);
  MapArchiveResult map_regions(int regions[], int num_regions, char* mapped_base_address, ReservedSpace rs);
  void  unmap_regions(int regions[], int num_regions);
  void  map_heap_regions() NOT_CDS_JAVA_HEAP_RETURN;
  void  fixup_mapped_heap_regions() NOT_CDS_JAVA_HEAP_RETURN;
  void  patch_archived_heap_embedded_pointers() NOT_CDS_JAVA_HEAP_RETURN;
  void  patch_archived_heap_embedded_pointers(MemRegion* ranges, int num_ranges,
                                              int first_region_idx) NOT_CDS_JAVA_HEAP_RETURN;
  bool  has_heap_regions()  NOT_CDS_JAVA_HEAP_RETURN_(false);
  MemRegion get_heap_regions_range_with_current_oop_encoding_mode() NOT_CDS_JAVA_HEAP_RETURN_(MemRegion());
  void  unmap_region(int i);
  bool  verify_region_checksum(int i);
  void  close();
  bool  is_open() { return _file_open; }
  ReservedSpace reserve_shared_memory();

  // JVM/TI RedefineClasses() support:
  // Remap the shared readonly space to shared readwrite, private.
  bool  remap_shared_readonly_as_readwrite();

  // Errors.
  static void fail_stop(const char *msg, ...) ATTRIBUTE_PRINTF(1, 2);
  static void fail_continue(const char *msg, ...) ATTRIBUTE_PRINTF(1, 2);
  static bool memory_mapping_failed() {
    CDS_ONLY(return _memory_mapping_failed;)
    NOT_CDS(return false;)
  }
  bool is_in_shared_region(const void* p, int idx) NOT_CDS_RETURN_(false);

  // Stop CDS sharing and unmap CDS regions.
  static void stop_sharing_and_unmap(const char* msg);

  static void allocate_shared_path_table(TRAPS);
  static void copy_shared_path_table(ClassLoaderData* loader_data, TRAPS);
  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();
  void validate_non_existent_class_paths();
  static void set_shared_path_table(FileMapInfo* info) {
    _shared_path_table = info->header()->shared_path_table();
  }
  static void update_jar_manifest(ClassPathEntry *cpe, SharedClassPathEntry* ent, TRAPS);
  static int num_non_existent_class_paths();
  static void record_non_existent_class_path_entry(const char* path);

#if INCLUDE_JVMTI
  static ClassFileStream* open_stream_for_jvmti(InstanceKlass* ik, Handle class_loader, TRAPS);
#endif

  static SharedClassPathEntry* shared_path(int index) {
    return _shared_path_table.path_at(index);
  }

  static const char* shared_path_name(int index) {
    assert(index >= 0, "Sanity");
    return shared_path(index)->name();
  }

  static int get_number_of_shared_paths() {
    return _shared_path_table.size();
  }

  static int get_module_shared_path_index(Symbol* location) NOT_CDS_RETURN_(-1);

  char* region_addr(int idx);

  // The offset of the first core region in the archive, relative to SharedBaseAddress
  size_t mapping_base_offset() const { return first_core_space()->mapping_offset(); }
  // The offset of the (exclusive) end of the last core region in this archive, relative to SharedBaseAddress
  size_t mapping_end_offset()  const { return last_core_space()->mapping_end_offset(); }

  char* mapped_base()    const { return first_core_space()->mapped_base(); }
  char* mapped_end()     const { return last_core_space()->mapped_end();   }

  // Non-zero if the archive needs to be mapped a non-default location due to ASLR.
  intx relocation_delta() const {
    return header()->mapped_base_address() - header()->requested_base_address();
  }

  FileMapRegion* first_core_space() const;
  FileMapRegion* last_core_space() const;

  FileMapRegion* space_at(int i) const {
    return header()->space_at(i);
  }

  void print(outputStream* st) {
    header()->print(st);
  }

  const char* vm_version() {
    return header()->jvm_ident();
  }

 private:
  void  seek_to_position(size_t pos);
  char* skip_first_path_entry(const char* path) NOT_CDS_RETURN_(NULL);
  int   num_paths(const char* path) NOT_CDS_RETURN_(0);
  GrowableArray<const char*>* create_path_array(const char* path) NOT_CDS_RETURN_(NULL);
  bool  classpath_failure(const char* msg, const char* name) NOT_CDS_RETURN_(false);
  bool  check_paths(int shared_path_start_idx, int num_paths,
                    GrowableArray<const char*>* rp_array) NOT_CDS_RETURN_(false);
  bool  validate_boot_class_paths() NOT_CDS_RETURN_(false);
  bool  validate_app_class_paths(int shared_app_paths_len) NOT_CDS_RETURN_(false);
  bool  map_heap_data(MemRegion **heap_mem, int first, int max, int* num,
                      bool is_open = false) NOT_CDS_JAVA_HEAP_RETURN_(false);
  bool  region_crc_check(char* buf, size_t size, int expected_crc) NOT_CDS_RETURN_(false);
  void  dealloc_archive_heap_regions(MemRegion* regions, int num) NOT_CDS_JAVA_HEAP_RETURN;
  void  map_heap_regions_impl() NOT_CDS_JAVA_HEAP_RETURN;
  char* map_bitmap_region();
  MapArchiveResult map_region(int i, intx addr_delta, char* mapped_base_address, ReservedSpace rs);
  bool  read_region(int i, char* base, size_t size);
  bool  relocate_pointers_in_core_regions(intx addr_delta);
  static size_t set_oopmaps_offset(GrowableArray<ArchiveHeapOopmapInfo> *oopmaps, size_t curr_size);
  static size_t write_oopmaps(GrowableArray<ArchiveHeapOopmapInfo> *oopmaps, size_t curr_offset, char* buffer);

  // The starting address of spc, as calculated with CompressedOop::decode_non_null()
  address start_address_as_decoded_with_current_oop_encoding_mode(FileMapRegion* spc) {
    return decode_start_address(spc, true);
  }

  // The starting address of spc, as calculated with HeapShared::decode_from_archive()
  address start_address_as_decoded_from_archive(FileMapRegion* spc) {
    return decode_start_address(spc, false);
  }

  address decode_start_address(FileMapRegion* spc, bool with_current_oop_encoding_mode);

#if INCLUDE_JVMTI
  static ClassPathEntry** _classpath_entries_for_jvmti;
  static ClassPathEntry* get_classpath_entry_for_jvmti(int i, TRAPS);
#endif
};

#endif // SHARE_CDS_FILEMAP_HPP