1 /*
   2  * Copyright (c) 2003, 2017, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/classLoader.hpp"
  27 #include "classfile/compactHashtable.inline.hpp"
  28 #include "classfile/sharedClassUtil.hpp"
  29 #include "classfile/symbolTable.hpp"
  30 #include "classfile/systemDictionaryShared.hpp"
  31 #include "classfile/altHashing.hpp"
  32 #if INCLUDE_ALL_GCS
  33 #include "gc/g1/g1CollectedHeap.hpp"
  34 #endif
  35 #include "logging/log.hpp"
  36 #include "logging/logMessage.hpp"
  37 #include "memory/filemap.hpp"
  38 #include "memory/metadataFactory.hpp"
  39 #include "memory/oopFactory.hpp"
  40 #include "oops/objArrayOop.hpp"
  41 #include "prims/jvmtiExport.hpp"
  42 #include "runtime/arguments.hpp"
  43 #include "runtime/java.hpp"
  44 #include "runtime/os.hpp"
  45 #include "runtime/vm_version.hpp"
  46 #include "services/memTracker.hpp"
  47 #include "utilities/defaultStream.hpp"
  48 
  49 # include <sys/stat.h>
  50 # include <errno.h>
  51 
  52 #ifndef O_BINARY       // if defined (Win32) use binary files.
  53 #define O_BINARY 0     // otherwise do nothing.
  54 #endif
  55 
  56 extern address JVM_FunctionAtStart();
  57 extern address JVM_FunctionAtEnd();
  58 
  59 // Complain and stop. All error conditions occurring during the writing of
  60 // an archive file should stop the process.  Unrecoverable errors during
  61 // the reading of the archive file should stop the process.
  62 
  63 static void fail(const char *msg, va_list ap) {
  64   // This occurs very early during initialization: tty is not initialized.
  65   jio_fprintf(defaultStream::error_stream(),
  66               "An error has occurred while processing the"
  67               " shared archive file.\n");
  68   jio_vfprintf(defaultStream::error_stream(), msg, ap);
  69   jio_fprintf(defaultStream::error_stream(), "\n");
  70   // Do not change the text of the below message because some tests check for it.
  71   vm_exit_during_initialization("Unable to use shared archive.", NULL);
  72 }
  73 
  74 
  75 void FileMapInfo::fail_stop(const char *msg, ...) {
  76         va_list ap;
  77   va_start(ap, msg);
  78   fail(msg, ap);        // Never returns.
  79   va_end(ap);           // for completeness.
  80 }
  81 
  82 
  83 // Complain and continue.  Recoverable errors during the reading of the
  84 // archive file may continue (with sharing disabled).
  85 //
  86 // If we continue, then disable shared spaces and close the file.
  87 
  88 void FileMapInfo::fail_continue(const char *msg, ...) {
  89   va_list ap;
  90   va_start(ap, msg);
  91   MetaspaceShared::set_archive_loading_failed();
  92   if (PrintSharedArchiveAndExit && _validating_classpath_entry_table) {
  93     // If we are doing PrintSharedArchiveAndExit and some of the classpath entries
  94     // do not validate, we can still continue "limping" to validate the remaining
  95     // entries. No need to quit.
  96     tty->print("[");
  97     tty->vprint(msg, ap);
  98     tty->print_cr("]");
  99   } else {
 100     if (RequireSharedSpaces) {
 101       fail(msg, ap);
 102     } else {
 103       if (log_is_enabled(Info, cds)) {
 104         ResourceMark rm;
 105         outputStream* logstream = Log(cds)::info_stream();
 106         logstream->print("UseSharedSpaces: ");
 107         logstream->vprint_cr(msg, ap);
 108       }
 109     }
 110     UseSharedSpaces = false;
 111     assert(current_info() != NULL, "singleton must be registered");
 112     current_info()->close();
 113   }
 114   va_end(ap);
 115 }
 116 
 117 // Fill in the fileMapInfo structure with data about this VM instance.
 118 
 119 // This method copies the vm version info into header_version.  If the version is too
 120 // long then a truncated version, which has a hash code appended to it, is copied.
 121 //
 122 // Using a template enables this method to verify that header_version is an array of
 123 // length JVM_IDENT_MAX.  This ensures that the code that writes to the CDS file and
 124 // the code that reads the CDS file will both use the same size buffer.  Hence, will
 125 // use identical truncation.  This is necessary for matching of truncated versions.
 126 template <int N> static void get_header_version(char (&header_version) [N]) {
 127   assert(N == JVM_IDENT_MAX, "Bad header_version size");
 128 
 129   const char *vm_version = VM_Version::internal_vm_info_string();
 130   const int version_len = (int)strlen(vm_version);
 131 
 132   if (version_len < (JVM_IDENT_MAX-1)) {
 133     strcpy(header_version, vm_version);
 134 
 135   } else {
 136     // Get the hash value.  Use a static seed because the hash needs to return the same
 137     // value over multiple jvm invocations.
 138     unsigned int hash = AltHashing::murmur3_32(8191, (const jbyte*)vm_version, version_len);
 139 
 140     // Truncate the ident, saving room for the 8 hex character hash value.
 141     strncpy(header_version, vm_version, JVM_IDENT_MAX-9);
 142 
 143     // Append the hash code as eight hex digits.
 144     sprintf(&header_version[JVM_IDENT_MAX-9], "%08x", hash);
 145     header_version[JVM_IDENT_MAX-1] = 0;  // Null terminate.
 146   }
 147 }
 148 
 149 FileMapInfo::FileMapInfo() {
 150   assert(_current_info == NULL, "must be singleton"); // not thread safe
 151   _current_info = this;
 152   memset(this, 0, sizeof(FileMapInfo));
 153   _file_offset = 0;
 154   _file_open = false;
 155   _header = SharedClassUtil::allocate_file_map_header();
 156   _header->_version = _invalid_version;
 157 }
 158 
 159 FileMapInfo::~FileMapInfo() {
 160   assert(_current_info == this, "must be singleton"); // not thread safe
 161   _current_info = NULL;
 162 }
 163 
 164 void FileMapInfo::populate_header(size_t alignment) {
 165   _header->populate(this, alignment);
 166 }
 167 
 168 size_t FileMapInfo::FileMapHeader::data_size() {
 169   return SharedClassUtil::file_map_header_size() - sizeof(FileMapInfo::FileMapHeaderBase);
 170 }
 171 
 172 void FileMapInfo::FileMapHeader::populate(FileMapInfo* mapinfo, size_t alignment) {
 173   _magic = 0xf00baba2;
 174   _version = _current_version;
 175   _alignment = alignment;
 176   _obj_alignment = ObjectAlignmentInBytes;
 177   _compact_strings = CompactStrings;
 178   _narrow_oop_mode = Universe::narrow_oop_mode();
 179   _narrow_oop_shift = Universe::narrow_oop_shift();
 180   _max_heap_size = MaxHeapSize;
 181   _narrow_klass_base = Universe::narrow_klass_base();
 182   _narrow_klass_shift = Universe::narrow_klass_shift();
 183   _classpath_entry_table_size = mapinfo->_classpath_entry_table_size;
 184   _classpath_entry_table = mapinfo->_classpath_entry_table;
 185   _classpath_entry_size = mapinfo->_classpath_entry_size;
 186 
 187   // The following fields are for sanity checks for whether this archive
 188   // will function correctly with this JVM and the bootclasspath it's
 189   // invoked with.
 190 
 191   // JVM version string ... changes on each build.
 192   get_header_version(_jvm_ident);
 193 }
 194 
 195 void FileMapInfo::allocate_classpath_entry_table() {
 196   int bytes = 0;
 197   int count = 0;
 198   char* strptr = NULL;
 199   char* strptr_max = NULL;
 200   Thread* THREAD = Thread::current();
 201 
 202   ClassLoaderData* loader_data = ClassLoaderData::the_null_class_loader_data();
 203   size_t entry_size = SharedClassUtil::shared_class_path_entry_size();
 204 
 205   for (int pass=0; pass<2; pass++) {
 206 
 207     // Process the modular java runtime image first
 208     ClassPathEntry* jrt_entry = ClassLoader::get_jrt_entry();
 209     assert(jrt_entry != NULL,
 210            "No modular java runtime image present when allocating the CDS classpath entry table");
 211     const char *name = jrt_entry->name();
 212     int name_bytes = (int)(strlen(name) + 1);
 213     if (pass == 0) {
 214       count++;
 215       bytes += (int)entry_size;
 216       bytes += name_bytes;
 217       log_info(class, path)("add main shared path for modular java runtime image %s", name);
 218     } else {
 219       // The java runtime image is always in slot 0 on the shared class path.
 220       SharedClassPathEntry* ent = shared_classpath(0);
 221       struct stat st;
 222       if (os::stat(name, &st) == 0) {
 223         ent->_timestamp = st.st_mtime;
 224         ent->_filesize = st.st_size;
 225       }
 226       if (ent->_filesize == 0) {
 227         // unknown
 228         ent->_filesize = -2;
 229       }
 230       ent->_name = strptr;
 231       assert(strptr + name_bytes <= strptr_max, "miscalculated buffer size");
 232       strncpy(strptr, name, (size_t)name_bytes); // name_bytes includes trailing 0.
 233       strptr += name_bytes;
 234     }
 235 
 236     // Walk the appended entries, which includes the entries added for the classpath.
 237     ClassPathEntry *cpe = ClassLoader::classpath_entry(1);
 238 
 239     // Since the java runtime image is always in slot 0 on the shared class path, the
 240     // appended entries are started at slot 1 immediately after.
 241     for (int cur_entry = 1 ; cpe != NULL; cpe = cpe->next(), cur_entry++) {
 242       const char *name = cpe->name();
 243       int name_bytes = (int)(strlen(name) + 1);
 244       assert(!cpe->is_jrt(), "A modular java runtime image is present on the list of appended entries");
 245 
 246       if (pass == 0) {
 247         count ++;
 248         bytes += (int)entry_size;
 249         bytes += name_bytes;
 250         log_info(class, path)("add main shared path (%s) %s", (cpe->is_jar_file() ? "jar" : "dir"), name);
 251       } else {
 252         SharedClassPathEntry* ent = shared_classpath(cur_entry);
 253         if (cpe->is_jar_file()) {
 254           struct stat st;
 255           if (os::stat(name, &st) != 0) {
 256             // The file/dir must exist, or it would not have been added
 257             // into ClassLoader::classpath_entry().
 258             //
 259             // If we can't access a jar file in the boot path, then we can't
 260             // make assumptions about where classes get loaded from.
 261             FileMapInfo::fail_stop("Unable to open jar file %s.", name);
 262           }
 263 
 264           EXCEPTION_MARK; // The following call should never throw, but would exit VM on error.
 265           SharedClassUtil::update_shared_classpath(cpe, ent, st.st_mtime, st.st_size, THREAD);
 266         } else {
 267           struct stat st;
 268           if (os::stat(name, &st) == 0) {
 269             if ((st.st_mode & S_IFMT) == S_IFDIR) {
 270               if (!os::dir_is_empty(name)) {
 271                 ClassLoader::exit_with_path_failure(
 272                   "Cannot have non-empty directory in archived classpaths", name);
 273               }
 274               ent->_filesize = -1;
 275             }
 276           }
 277           if (ent->_filesize == 0) {
 278             // unknown
 279             ent->_filesize = -2;
 280           }
 281         }
 282         ent->_name = strptr;
 283         if (strptr + name_bytes <= strptr_max) {
 284           strncpy(strptr, name, (size_t)name_bytes); // name_bytes includes trailing 0.
 285           strptr += name_bytes;
 286         } else {
 287           assert(0, "miscalculated buffer size");
 288         }
 289       }
 290     }
 291 
 292     if (pass == 0) {
 293       EXCEPTION_MARK; // The following call should never throw, but would exit VM on error.
 294       Array<u8>* arr = MetadataFactory::new_array<u8>(loader_data, (bytes + 7)/8, THREAD);
 295       strptr = (char*)(arr->data());
 296       strptr_max = strptr + bytes;
 297       SharedClassPathEntry* table = (SharedClassPathEntry*)strptr;
 298       strptr += entry_size * count;
 299 
 300       _classpath_entry_table_size = count;
 301       _classpath_entry_table = table;
 302       _classpath_entry_size = entry_size;
 303     }
 304   }
 305 }
 306 
 307 bool FileMapInfo::validate_classpath_entry_table() {
 308   _validating_classpath_entry_table = true;
 309 
 310   int count = _header->_classpath_entry_table_size;
 311 
 312   _classpath_entry_table = _header->_classpath_entry_table;
 313   _classpath_entry_size = _header->_classpath_entry_size;
 314 
 315   for (int i=0; i<count; i++) {
 316     SharedClassPathEntry* ent = shared_classpath(i);
 317     struct stat st;
 318     const char* name = ent->_name;
 319     bool ok = true;
 320     log_info(class, path)("checking shared classpath entry: %s", name);
 321     if (os::stat(name, &st) != 0) {
 322       fail_continue("Required classpath entry does not exist: %s", name);
 323       ok = false;
 324     } else if (ent->is_dir()) {
 325       if (!os::dir_is_empty(name)) {
 326         fail_continue("directory is not empty: %s", name);
 327         ok = false;
 328       }
 329     } else if (ent->is_jar_or_bootimage()) {
 330       if (ent->_timestamp != st.st_mtime ||
 331           ent->_filesize != st.st_size) {
 332         ok = false;
 333         if (PrintSharedArchiveAndExit) {
 334           fail_continue(ent->_timestamp != st.st_mtime ?
 335                         "Timestamp mismatch" :
 336                         "File size mismatch");
 337         } else {
 338           fail_continue("A jar/jimage file is not the one used while building"
 339                         " the shared archive file: %s", name);
 340         }
 341       }
 342     }
 343     if (ok) {
 344       log_info(class, path)("ok");
 345     } else if (!PrintSharedArchiveAndExit) {
 346       _validating_classpath_entry_table = false;
 347       return false;
 348     }
 349   }
 350 
 351   _classpath_entry_table_size = _header->_classpath_entry_table_size;
 352   _validating_classpath_entry_table = false;
 353   return true;
 354 }
 355 
 356 
 357 // Read the FileMapInfo information from the file.
 358 
 359 bool FileMapInfo::init_from_file(int fd) {
 360   size_t sz = _header->data_size();
 361   char* addr = _header->data();
 362   size_t n = os::read(fd, addr, (unsigned int)sz);
 363   if (n != sz) {
 364     fail_continue("Unable to read the file header.");
 365     return false;
 366   }
 367   if (_header->_version != current_version()) {
 368     fail_continue("The shared archive file has the wrong version.");
 369     return false;
 370   }
 371   _file_offset = (long)n;
 372 
 373   size_t info_size = _header->_paths_misc_info_size;
 374   _paths_misc_info = NEW_C_HEAP_ARRAY_RETURN_NULL(char, info_size, mtClass);
 375   if (_paths_misc_info == NULL) {
 376     fail_continue("Unable to read the file header.");
 377     return false;
 378   }
 379   n = os::read(fd, _paths_misc_info, (unsigned int)info_size);
 380   if (n != info_size) {
 381     fail_continue("Unable to read the shared path info header.");
 382     FREE_C_HEAP_ARRAY(char, _paths_misc_info);
 383     _paths_misc_info = NULL;
 384     return false;
 385   }
 386 
 387   size_t len = lseek(fd, 0, SEEK_END);
 388   struct FileMapInfo::FileMapHeader::space_info* si =
 389     &_header->_space[MetaspaceShared::mc];
 390   if (si->_file_offset >= len || len - si->_file_offset < si->_used) {
 391     fail_continue("The shared archive file has been truncated.");
 392     return false;
 393   }
 394 
 395   _file_offset += (long)n;
 396   return true;
 397 }
 398 
 399 
 400 // Read the FileMapInfo information from the file.
 401 bool FileMapInfo::open_for_read() {
 402   _full_path = Arguments::GetSharedArchivePath();
 403   int fd = open(_full_path, O_RDONLY | O_BINARY, 0);
 404   if (fd < 0) {
 405     if (errno == ENOENT) {
 406       // Not locating the shared archive is ok.
 407       fail_continue("Specified shared archive not found.");
 408     } else {
 409       fail_continue("Failed to open shared archive file (%s).",
 410                     os::strerror(errno));
 411     }
 412     return false;
 413   }
 414 
 415   _fd = fd;
 416   _file_open = true;
 417   return true;
 418 }
 419 
 420 
 421 // Write the FileMapInfo information to the file.
 422 
 423 void FileMapInfo::open_for_write() {
 424  _full_path = Arguments::GetSharedArchivePath();
 425   if (log_is_enabled(Info, cds)) {
 426     ResourceMark rm;
 427     LogMessage(cds) msg;
 428     stringStream info_stream;
 429     info_stream.print_cr("Dumping shared data to file: ");
 430     info_stream.print_cr("   %s", _full_path);
 431     msg.info("%s", info_stream.as_string());
 432   }
 433 
 434 #ifdef _WINDOWS  // On Windows, need WRITE permission to remove the file.
 435   chmod(_full_path, _S_IREAD | _S_IWRITE);
 436 #endif
 437 
 438   // Use remove() to delete the existing file because, on Unix, this will
 439   // allow processes that have it open continued access to the file.
 440   remove(_full_path);
 441   int fd = open(_full_path, O_RDWR | O_CREAT | O_TRUNC | O_BINARY, 0444);
 442   if (fd < 0) {
 443     fail_stop("Unable to create shared archive file %s: (%s).", _full_path,
 444               os::strerror(errno));
 445   }
 446   _fd = fd;
 447   _file_offset = 0;
 448   _file_open = true;
 449 }
 450 
 451 
 452 // Write the header to the file, seek to the next allocation boundary.
 453 
 454 void FileMapInfo::write_header() {
 455   int info_size = ClassLoader::get_shared_paths_misc_info_size();
 456 
 457   _header->_paths_misc_info_size = info_size;
 458 
 459   align_file_position();
 460   size_t sz = _header->data_size();
 461   char* addr = _header->data();
 462   write_bytes(addr, (int)sz); // skip the C++ vtable
 463   write_bytes(ClassLoader::get_shared_paths_misc_info(), info_size);
 464   align_file_position();
 465 }
 466 
 467 
 468 // Dump shared spaces to file.
 469 
 470 void FileMapInfo::write_space(int i, Metaspace* space, bool read_only) {
 471   align_file_position();
 472   size_t used = space->used_bytes_slow(Metaspace::NonClassType);
 473   size_t capacity = space->capacity_bytes_slow(Metaspace::NonClassType);
 474   struct FileMapInfo::FileMapHeader::space_info* si = &_header->_space[i];
 475   write_region(i, (char*)space->bottom(), used, capacity, read_only, false);
 476 }
 477 
 478 
 479 // Dump region to file.
 480 
 481 void FileMapInfo::write_region(int region, char* base, size_t size,
 482                                size_t capacity, bool read_only,
 483                                bool allow_exec) {
 484   struct FileMapInfo::FileMapHeader::space_info* si = &_header->_space[region];
 485 
 486   if (_file_open) {
 487     guarantee(si->_file_offset == _file_offset, "file offset mismatch.");
 488     log_info(cds)("Shared file region %d: " SIZE_FORMAT_HEX_W(6)
 489                   " bytes, addr " INTPTR_FORMAT " file offset " SIZE_FORMAT_HEX_W(6),
 490                   region, size, p2i(base), _file_offset);
 491   } else {
 492     si->_file_offset = _file_offset;
 493   }
 494   if (MetaspaceShared::is_string_region(region)) {
 495     assert((base - (char*)Universe::narrow_oop_base()) % HeapWordSize == 0, "Sanity");
 496     if (base != NULL) {
 497       si->_addr._offset = (intx)oopDesc::encode_heap_oop_not_null((oop)base);
 498     } else {
 499       si->_addr._offset = 0;
 500     }
 501   } else {
 502     si->_addr._base = base;
 503   }
 504   si->_used = size;
 505   si->_capacity = capacity;
 506   si->_read_only = read_only;
 507   si->_allow_exec = allow_exec;
 508   si->_crc = ClassLoader::crc32(0, base, (jint)size);
 509   write_bytes_aligned(base, (int)size);
 510 }
 511 
 512 // Write the string space. The string space contains one or multiple GC(G1) regions.
 513 // When the total string space size is smaller than one GC region of the dump time,
 514 // only one string region is used for shared strings.
 515 //
 516 // If the total string space size is bigger than one GC region, there would be more
 517 // than one GC regions allocated for shared strings. The first/bottom GC region might
 518 // be a partial GC region with the empty portion at the higher address within that region.
 519 // The non-empty portion of the first region is written into the archive as one string
 520 // region. The rest are consecutive full GC regions if they exist, which can be written
 521 // out in one chunk as another string region.
 522 void FileMapInfo::write_string_regions(GrowableArray<MemRegion> *regions) {
 523   for (int i = MetaspaceShared::first_string;
 524            i < MetaspaceShared::first_string + MetaspaceShared::max_strings; i++) {
 525     char* start = NULL;
 526     size_t size = 0;
 527     if (regions->is_nonempty()) {
 528       if (i == MetaspaceShared::first_string) {
 529         MemRegion first = regions->first();
 530         start = (char*)first.start();
 531         size = first.byte_size();
 532       } else {
 533         int len = regions->length();
 534         if (len > 1) {
 535           start = (char*)regions->at(1).start();
 536           size = (char*)regions->at(len - 1).end() - start;
 537         }
 538       }
 539     }
 540     write_region(i, start, size, size, false, false);
 541   }
 542 }
 543 
 544 
 545 // Dump bytes to file -- at the current file position.
 546 
 547 void FileMapInfo::write_bytes(const void* buffer, int nbytes) {
 548   if (_file_open) {
 549     int n = ::write(_fd, buffer, nbytes);
 550     if (n != nbytes) {
 551       // It is dangerous to leave the corrupted shared archive file around,
 552       // close and remove the file. See bug 6372906.
 553       close();
 554       remove(_full_path);
 555       fail_stop("Unable to write to shared archive file.");
 556     }
 557   }
 558   _file_offset += nbytes;
 559 }
 560 
 561 
 562 // Align file position to an allocation unit boundary.
 563 
 564 void FileMapInfo::align_file_position() {
 565   size_t new_file_offset = align_size_up(_file_offset,
 566                                          os::vm_allocation_granularity());
 567   if (new_file_offset != _file_offset) {
 568     _file_offset = new_file_offset;
 569     if (_file_open) {
 570       // Seek one byte back from the target and write a byte to insure
 571       // that the written file is the correct length.
 572       _file_offset -= 1;
 573       if (lseek(_fd, (long)_file_offset, SEEK_SET) < 0) {
 574         fail_stop("Unable to seek.");
 575       }
 576       char zero = 0;
 577       write_bytes(&zero, 1);
 578     }
 579   }
 580 }
 581 
 582 
 583 // Dump bytes to file -- at the current file position.
 584 
 585 void FileMapInfo::write_bytes_aligned(const void* buffer, int nbytes) {
 586   align_file_position();
 587   write_bytes(buffer, nbytes);
 588   align_file_position();
 589 }
 590 
 591 
 592 // Close the shared archive file.  This does NOT unmap mapped regions.
 593 
 594 void FileMapInfo::close() {
 595   if (_file_open) {
 596     if (::close(_fd) < 0) {
 597       fail_stop("Unable to close the shared archive file.");
 598     }
 599     _file_open = false;
 600     _fd = -1;
 601   }
 602 }
 603 
 604 
 605 // JVM/TI RedefineClasses() support:
 606 // Remap the shared readonly space to shared readwrite, private.
 607 bool FileMapInfo::remap_shared_readonly_as_readwrite() {
 608   int idx = 0;
 609   struct FileMapInfo::FileMapHeader::space_info* si = &_header->_space[idx];
 610   if (!si->_read_only) {
 611     // the space is already readwrite so we are done
 612     return true;
 613   }
 614   size_t used = si->_used;
 615   size_t size = align_size_up(used, os::vm_allocation_granularity());
 616   if (!open_for_read()) {
 617     return false;
 618   }
 619   char *addr = _header->region_addr(idx);
 620   char *base = os::remap_memory(_fd, _full_path, si->_file_offset,
 621                                 addr, size, false /* !read_only */,
 622                                 si->_allow_exec);
 623   close();
 624   if (base == NULL) {
 625     fail_continue("Unable to remap shared readonly space (errno=%d).", errno);
 626     return false;
 627   }
 628   if (base != addr) {
 629     fail_continue("Unable to remap shared readonly space at required address.");
 630     return false;
 631   }
 632   si->_read_only = false;
 633   return true;
 634 }
 635 
 636 // Map the whole region at once, assumed to be allocated contiguously.
 637 ReservedSpace FileMapInfo::reserve_shared_memory() {
 638   struct FileMapInfo::FileMapHeader::space_info* si = &_header->_space[0];
 639   char* requested_addr = _header->region_addr(0);
 640 
 641   size_t size = FileMapInfo::shared_spaces_size();
 642 
 643   // Reserve the space first, then map otherwise map will go right over some
 644   // other reserved memory (like the code cache).
 645   ReservedSpace rs(size, os::vm_allocation_granularity(), false, requested_addr);
 646   if (!rs.is_reserved()) {
 647     fail_continue("Unable to reserve shared space at required address "
 648                   INTPTR_FORMAT, p2i(requested_addr));
 649     return rs;
 650   }
 651   // the reserved virtual memory is for mapping class data sharing archive
 652   MemTracker::record_virtual_memory_type((address)rs.base(), mtClassShared);
 653 
 654   return rs;
 655 }
 656 
 657 // Memory map a region in the address space.
 658 static const char* shared_region_name[] = { "ReadOnly", "ReadWrite", "MiscData", "MiscCode",
 659                                             "String1", "String2", "OptionalData" };
 660 
 661 char* FileMapInfo::map_region(int i) {
 662   assert(!MetaspaceShared::is_string_region(i), "sanity");
 663   struct FileMapInfo::FileMapHeader::space_info* si = &_header->_space[i];
 664   size_t used = si->_used;
 665   size_t alignment = os::vm_allocation_granularity();
 666   size_t size = align_size_up(used, alignment);
 667   char *requested_addr = _header->region_addr(i);
 668 
 669   // If a tool agent is in use (debugging enabled), we must map the address space RW
 670   if (JvmtiExport::can_modify_any_class() || JvmtiExport::can_walk_any_space()) {
 671     si->_read_only = false;
 672   }
 673 
 674   // map the contents of the CDS archive in this memory
 675   char *base = os::map_memory(_fd, _full_path, si->_file_offset,
 676                               requested_addr, size, si->_read_only,
 677                               si->_allow_exec);
 678   if (base == NULL || base != requested_addr) {
 679     fail_continue("Unable to map %s shared space at required address.", shared_region_name[i]);
 680     return NULL;
 681   }
 682 #ifdef _WINDOWS
 683   // This call is Windows-only because the memory_type gets recorded for the other platforms
 684   // in method FileMapInfo::reserve_shared_memory(), which is not called on Windows.
 685   MemTracker::record_virtual_memory_type((address)base, mtClassShared);
 686 #endif
 687 
 688   return base;
 689 }
 690 
 691 static MemRegion *string_ranges = NULL;
 692 static int num_ranges = 0;
 693 bool FileMapInfo::map_string_regions() {
 694 #if INCLUDE_ALL_GCS
 695   if (UseG1GC && UseCompressedOops && UseCompressedClassPointers) {
 696     // Check that all the narrow oop and klass encodings match the archive
 697     if (narrow_oop_mode() != Universe::narrow_oop_mode() ||
 698         narrow_oop_shift() != Universe::narrow_oop_shift() ||
 699         narrow_klass_base() != Universe::narrow_klass_base() ||
 700         narrow_klass_shift() != Universe::narrow_klass_shift()) {
 701       if (log_is_enabled(Info, cds) && _header->_space[MetaspaceShared::first_string]._used > 0) {
 702         log_info(cds)("Shared string data from the CDS archive is being ignored. "
 703                       "The current CompressedOops/CompressedClassPointers encoding differs from "
 704                       "that archived due to heap size change. The archive was dumped using max heap "
 705                       "size " UINTX_FORMAT "M.", max_heap_size()/M);
 706       }
 707     } else {
 708       string_ranges = new MemRegion[MetaspaceShared::max_strings];
 709       struct FileMapInfo::FileMapHeader::space_info* si;
 710 
 711       for (int i = MetaspaceShared::first_string;
 712                i < MetaspaceShared::first_string + MetaspaceShared::max_strings; i++) {
 713         si = &_header->_space[i];
 714         size_t used = si->_used;
 715         if (used > 0) {
 716           size_t size = used;
 717           char* requested_addr = (char*)((void*)oopDesc::decode_heap_oop_not_null(
 718                                                  (narrowOop)si->_addr._offset));
 719           string_ranges[num_ranges] = MemRegion((HeapWord*)requested_addr, size / HeapWordSize);
 720           num_ranges ++;
 721         }
 722       }
 723 
 724       if (num_ranges == 0) {
 725         StringTable::ignore_shared_strings(true);
 726         return true; // no shared string data
 727       }
 728 
 729       // Check that ranges are within the java heap
 730       if (!G1CollectedHeap::heap()->check_archive_addresses(string_ranges, num_ranges)) {
 731         fail_continue("Unable to allocate shared string space: range is not "
 732                       "within java heap.");
 733         return false;
 734       }
 735 
 736       // allocate from java heap
 737       if (!G1CollectedHeap::heap()->alloc_archive_regions(string_ranges, num_ranges)) {
 738         fail_continue("Unable to allocate shared string space: range is "
 739                       "already in use.");
 740         return false;
 741       }
 742 
 743       // Map the string data. No need to call MemTracker::record_virtual_memory_type()
 744       // for mapped string regions as they are part of the reserved java heap, which
 745       // is already recorded.
 746       for (int i = 0; i < num_ranges; i++) {
 747         si = &_header->_space[MetaspaceShared::first_string + i];
 748         char* addr = (char*)string_ranges[i].start();
 749         char* base = os::map_memory(_fd, _full_path, si->_file_offset,
 750                                     addr, string_ranges[i].byte_size(), si->_read_only,
 751                                     si->_allow_exec);
 752         if (base == NULL || base != addr) {
 753           // dealloc the string regions from java heap
 754           dealloc_string_regions();
 755           fail_continue("Unable to map shared string space at required address.");
 756           return false;
 757         }
 758       }
 759 
 760       if (!verify_string_regions()) {
 761         // dealloc the string regions from java heap
 762         dealloc_string_regions();
 763         fail_continue("Shared string regions are corrupt");
 764         return false;
 765       }
 766 
 767       // the shared string data is mapped successfully
 768       return true;
 769     }
 770   } else {
 771     if (log_is_enabled(Info, cds) && _header->_space[MetaspaceShared::first_string]._used > 0) {
 772       log_info(cds)("Shared string data from the CDS archive is being ignored. UseG1GC, "
 773                     "UseCompressedOops and UseCompressedClassPointers are required.");
 774     }
 775   }
 776 
 777   // if we get here, the shared string data is not mapped
 778   assert(string_ranges == NULL && num_ranges == 0, "sanity");
 779   StringTable::ignore_shared_strings(true);
 780 #endif
 781   return true;
 782 }
 783 
 784 bool FileMapInfo::verify_string_regions() {
 785   for (int i = MetaspaceShared::first_string;
 786            i < MetaspaceShared::first_string + MetaspaceShared::max_strings; i++) {
 787     if (!verify_region_checksum(i)) {
 788       return false;
 789     }
 790   }
 791   return true;
 792 }
 793 
 794 void FileMapInfo::fixup_string_regions() {
 795 #if INCLUDE_ALL_GCS
 796   // If any string regions were found, call the fill routine to make them parseable.
 797   // Note that string_ranges may be non-NULL even if no ranges were found.
 798   if (num_ranges != 0) {
 799     assert(string_ranges != NULL, "Null string_ranges array with non-zero count");
 800     G1CollectedHeap::heap()->fill_archive_regions(string_ranges, num_ranges);
 801   }
 802 #endif
 803 }
 804 
 805 bool FileMapInfo::verify_region_checksum(int i) {
 806   if (!VerifySharedSpaces) {
 807     return true;
 808   }
 809 
 810   size_t sz = _header->_space[i]._used;
 811 
 812   if (sz == 0) {
 813     return true; // no data
 814   }
 815   if (MetaspaceShared::is_string_region(i) && StringTable::shared_string_ignored()) {
 816     return true; // shared string data are not mapped
 817   }
 818   const char* buf = _header->region_addr(i);
 819   int crc = ClassLoader::crc32(0, buf, (jint)sz);
 820   if (crc != _header->_space[i]._crc) {
 821     fail_continue("Checksum verification failed.");
 822     return false;
 823   }
 824   return true;
 825 }
 826 
 827 // Unmap a memory region in the address space.
 828 
 829 void FileMapInfo::unmap_region(int i) {
 830   assert(!MetaspaceShared::is_string_region(i), "sanity");
 831   struct FileMapInfo::FileMapHeader::space_info* si = &_header->_space[i];
 832   size_t used = si->_used;
 833   size_t size = align_size_up(used, os::vm_allocation_granularity());
 834 
 835   if (used == 0) {
 836     return;
 837   }
 838 
 839   char* addr = _header->region_addr(i);
 840   if (!os::unmap_memory(addr, size)) {
 841     fail_stop("Unable to unmap shared space.");
 842   }
 843 }
 844 
 845 // dealloc the archived string region from java heap
 846 void FileMapInfo::dealloc_string_regions() {
 847 #if INCLUDE_ALL_GCS
 848   if (num_ranges > 0) {
 849     assert(string_ranges != NULL, "Null string_ranges array with non-zero count");
 850     G1CollectedHeap::heap()->dealloc_archive_regions(string_ranges, num_ranges);
 851   }
 852 #endif
 853 }
 854 
 855 void FileMapInfo::assert_mark(bool check) {
 856   if (!check) {
 857     fail_stop("Mark mismatch while restoring from shared file.");
 858   }
 859 }
 860 
 861 
 862 FileMapInfo* FileMapInfo::_current_info = NULL;
 863 SharedClassPathEntry* FileMapInfo::_classpath_entry_table = NULL;
 864 int FileMapInfo::_classpath_entry_table_size = 0;
 865 size_t FileMapInfo::_classpath_entry_size = 0x1234baad;
 866 bool FileMapInfo::_validating_classpath_entry_table = false;
 867 
 868 // Open the shared archive file, read and validate the header
 869 // information (version, boot classpath, etc.).  If initialization
 870 // fails, shared spaces are disabled and the file is closed. [See
 871 // fail_continue.]
 872 //
 873 // Validation of the archive is done in two steps:
 874 //
 875 // [1] validate_header() - done here. This checks the header, including _paths_misc_info.
 876 // [2] validate_classpath_entry_table - this is done later, because the table is in the RW
 877 //     region of the archive, which is not mapped yet.
 878 bool FileMapInfo::initialize() {
 879   assert(UseSharedSpaces, "UseSharedSpaces expected.");
 880 
 881   if (!open_for_read()) {
 882     return false;
 883   }
 884 
 885   init_from_file(_fd);
 886   if (!validate_header()) {
 887     return false;
 888   }
 889 
 890   SharedReadOnlySize =  _header->_space[0]._capacity;
 891   SharedReadWriteSize = _header->_space[1]._capacity;
 892   SharedMiscDataSize =  _header->_space[2]._capacity;
 893   SharedMiscCodeSize =  _header->_space[3]._capacity;
 894   return true;
 895 }
 896 
 897 char* FileMapInfo::FileMapHeader::region_addr(int idx) {
 898   if (MetaspaceShared::is_string_region(idx)) {
 899     return (char*)((void*)oopDesc::decode_heap_oop_not_null(
 900               (narrowOop)_space[idx]._addr._offset));
 901   } else {
 902     return _space[idx]._addr._base;
 903   }
 904 }
 905 
 906 int FileMapInfo::FileMapHeader::compute_crc() {
 907   char* header = data();
 908   // start computing from the field after _crc
 909   char* buf = (char*)&_crc + sizeof(int);
 910   size_t sz = data_size() - (buf - header);
 911   int crc = ClassLoader::crc32(0, buf, (jint)sz);
 912   return crc;
 913 }
 914 
 915 bool FileMapInfo::FileMapHeader::validate() {
 916   if (VerifySharedSpaces && compute_crc() != _crc) {
 917     fail_continue("Header checksum verification failed.");
 918     return false;
 919   }
 920 
 921   if (!Arguments::has_jimage()) {
 922     FileMapInfo::fail_continue("The shared archive file cannot be used with an exploded module build.");
 923     return false;
 924   }
 925 
 926   if (_version != current_version()) {
 927     FileMapInfo::fail_continue("The shared archive file is the wrong version.");
 928     return false;
 929   }
 930   if (_magic != (int)0xf00baba2) {
 931     FileMapInfo::fail_continue("The shared archive file has a bad magic number.");
 932     return false;
 933   }
 934   char header_version[JVM_IDENT_MAX];
 935   get_header_version(header_version);
 936   if (strncmp(_jvm_ident, header_version, JVM_IDENT_MAX-1) != 0) {
 937     log_info(class, path)("expected: %s", header_version);
 938     log_info(class, path)("actual:   %s", _jvm_ident);
 939     FileMapInfo::fail_continue("The shared archive file was created by a different"
 940                   " version or build of HotSpot");
 941     return false;
 942   }
 943   if (_obj_alignment != ObjectAlignmentInBytes) {
 944     FileMapInfo::fail_continue("The shared archive file's ObjectAlignmentInBytes of %d"
 945                   " does not equal the current ObjectAlignmentInBytes of " INTX_FORMAT ".",
 946                   _obj_alignment, ObjectAlignmentInBytes);
 947     return false;
 948   }
 949   if (_compact_strings != CompactStrings) {
 950     FileMapInfo::fail_continue("The shared archive file's CompactStrings setting (%s)"
 951                   " does not equal the current CompactStrings setting (%s).",
 952                   _compact_strings ? "enabled" : "disabled",
 953                   CompactStrings   ? "enabled" : "disabled");
 954     return false;
 955   }
 956 
 957   return true;
 958 }
 959 
 960 bool FileMapInfo::validate_header() {
 961   bool status = _header->validate();
 962 
 963   if (status) {
 964     if (!ClassLoader::check_shared_paths_misc_info(_paths_misc_info, _header->_paths_misc_info_size)) {
 965       if (!PrintSharedArchiveAndExit) {
 966         fail_continue("shared class paths mismatch (hint: enable -Xlog:class+path=info to diagnose the failure)");
 967         status = false;
 968       }
 969     }
 970   }
 971 
 972   if (_paths_misc_info != NULL) {
 973     FREE_C_HEAP_ARRAY(char, _paths_misc_info);
 974     _paths_misc_info = NULL;
 975   }
 976   return status;
 977 }
 978 
 979 // The following method is provided to see whether a given pointer
 980 // falls in the mapped shared space.
 981 // Param:
 982 // p, The given pointer
 983 // Return:
 984 // True if the p is within the mapped shared space, otherwise, false.
 985 bool FileMapInfo::is_in_shared_space(const void* p) {
 986   for (int i = 0; i < MetaspaceShared::n_regions; i++) {
 987     char *base;
 988     if (MetaspaceShared::is_string_region(i) && _header->_space[i]._used == 0) {
 989       continue;
 990     }
 991     base = _header->region_addr(i);
 992     if (p >= base && p < base + _header->_space[i]._used) {
 993       return true;
 994     }
 995   }
 996 
 997   return false;
 998 }
 999 
1000 // Check if a given address is within one of the shared regions (ro, rw, md, mc)
1001 bool FileMapInfo::is_in_shared_region(const void* p, int idx) {
1002   assert((idx >= MetaspaceShared::ro) && (idx <= MetaspaceShared::mc), "invalid region index");
1003   char* base = _header->region_addr(idx);
1004   if (p >= base && p < base + _header->_space[idx]._used) {
1005     return true;
1006   }
1007   return false;
1008 }
1009 
1010 void FileMapInfo::print_shared_spaces() {
1011   tty->print_cr("Shared Spaces:");
1012   for (int i = 0; i < MetaspaceShared::n_regions; i++) {
1013     struct FileMapInfo::FileMapHeader::space_info* si = &_header->_space[i];
1014     char *base = _header->region_addr(i);
1015     tty->print("  %s " INTPTR_FORMAT "-" INTPTR_FORMAT,
1016                         shared_region_name[i],
1017                         p2i(base), p2i(base + si->_used));
1018   }
1019 }
1020 
1021 // Unmap mapped regions of shared space.
1022 void FileMapInfo::stop_sharing_and_unmap(const char* msg) {
1023   FileMapInfo *map_info = FileMapInfo::current_info();
1024   if (map_info) {
1025     map_info->fail_continue("%s", msg);
1026     for (int i = 0; i < MetaspaceShared::num_non_strings; i++) {
1027       char *addr = map_info->_header->region_addr(i);
1028       if (addr != NULL && !MetaspaceShared::is_string_region(i)) {
1029         map_info->unmap_region(i);
1030         map_info->_header->_space[i]._addr._base = NULL;
1031       }
1032     }
1033     // Dealloc the string regions only without unmapping. The string regions are part
1034     // of the java heap. Unmapping of the heap regions are managed by GC.
1035     map_info->dealloc_string_regions();
1036   } else if (DumpSharedSpaces) {
1037     fail_stop("%s", msg);
1038   }
1039 }