1 /*
   2  * Copyright (c) 2003, 2014, 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/sharedClassUtil.hpp"
  28 #include "classfile/symbolTable.hpp"
  29 #include "classfile/systemDictionaryShared.hpp"
  30 #include "classfile/altHashing.hpp"
  31 #include "memory/filemap.hpp"
  32 #include "memory/metadataFactory.hpp"
  33 #include "memory/oopFactory.hpp"
  34 #include "oops/objArrayOop.hpp"
  35 #include "runtime/arguments.hpp"
  36 #include "runtime/java.hpp"
  37 #include "runtime/os.hpp"
  38 #include "services/memTracker.hpp"
  39 #include "utilities/defaultStream.hpp"
  40 
  41 # include <sys/stat.h>
  42 # include <errno.h>
  43 
  44 #ifndef O_BINARY       // if defined (Win32) use binary files.
  45 #define O_BINARY 0     // otherwise do nothing.
  46 #endif
  47 
  48 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
  49 extern address JVM_FunctionAtStart();
  50 extern address JVM_FunctionAtEnd();
  51 
  52 // Complain and stop. All error conditions occurring during the writing of
  53 // an archive file should stop the process.  Unrecoverable errors during
  54 // the reading of the archive file should stop the process.
  55 
  56 static void fail(const char *msg, va_list ap) {
  57   // This occurs very early during initialization: tty is not initialized.
  58   jio_fprintf(defaultStream::error_stream(),
  59               "An error has occurred while processing the"
  60               " shared archive file.\n");
  61   jio_vfprintf(defaultStream::error_stream(), msg, ap);
  62   jio_fprintf(defaultStream::error_stream(), "\n");
  63   // Do not change the text of the below message because some tests check for it.
  64   vm_exit_during_initialization("Unable to use shared archive.", NULL);
  65 }
  66 
  67 
  68 void FileMapInfo::fail_stop(const char *msg, ...) {
  69         va_list ap;
  70   va_start(ap, msg);
  71   fail(msg, ap);        // Never returns.
  72   va_end(ap);           // for completeness.
  73 }
  74 
  75 
  76 // Complain and continue.  Recoverable errors during the reading of the
  77 // archive file may continue (with sharing disabled).
  78 //
  79 // If we continue, then disable shared spaces and close the file.
  80 
  81 void FileMapInfo::fail_continue(const char *msg, ...) {
  82   va_list ap;
  83   va_start(ap, msg);
  84   MetaspaceShared::set_archive_loading_failed();
  85   if (PrintSharedArchiveAndExit && _validating_classpath_entry_table) {
  86     // If we are doing PrintSharedArchiveAndExit and some of the classpath entries
  87     // do not validate, we can still continue "limping" to validate the remaining
  88     // entries. No need to quit.
  89     tty->print("[");
  90     tty->vprint(msg, ap);
  91     tty->print_cr("]");
  92   } else {
  93     if (RequireSharedSpaces) {
  94       fail(msg, ap);
  95     } else {
  96       if (PrintSharedSpaces) {
  97         tty->print_cr("UseSharedSpaces: %s", msg);
  98       }
  99     }
 100   }
 101   va_end(ap);
 102   UseSharedSpaces = false;
 103   assert(current_info() != NULL, "singleton must be registered");
 104   current_info()->close();
 105 }
 106 
 107 // Fill in the fileMapInfo structure with data about this VM instance.
 108 
 109 // This method copies the vm version info into header_version.  If the version is too
 110 // long then a truncated version, which has a hash code appended to it, is copied.
 111 //
 112 // Using a template enables this method to verify that header_version is an array of
 113 // length JVM_IDENT_MAX.  This ensures that the code that writes to the CDS file and
 114 // the code that reads the CDS file will both use the same size buffer.  Hence, will
 115 // use identical truncation.  This is necessary for matching of truncated versions.
 116 template <int N> static void get_header_version(char (&header_version) [N]) {
 117   assert(N == JVM_IDENT_MAX, "Bad header_version size");
 118 
 119   const char *vm_version = VM_Version::internal_vm_info_string();
 120   const int version_len = (int)strlen(vm_version);
 121 
 122   if (version_len < (JVM_IDENT_MAX-1)) {
 123     strcpy(header_version, vm_version);
 124 
 125   } else {
 126     // Get the hash value.  Use a static seed because the hash needs to return the same
 127     // value over multiple jvm invocations.
 128     unsigned int hash = AltHashing::murmur3_32(8191, (const jbyte*)vm_version, version_len);
 129 
 130     // Truncate the ident, saving room for the 8 hex character hash value.
 131     strncpy(header_version, vm_version, JVM_IDENT_MAX-9);
 132 
 133     // Append the hash code as eight hex digits.
 134     sprintf(&header_version[JVM_IDENT_MAX-9], "%08x", hash);
 135     header_version[JVM_IDENT_MAX-1] = 0;  // Null terminate.
 136   }
 137 }
 138 
 139 FileMapInfo::FileMapInfo() {
 140   assert(_current_info == NULL, "must be singleton"); // not thread safe
 141   _current_info = this;
 142   memset(this, 0, sizeof(FileMapInfo));
 143   _file_offset = 0;
 144   _file_open = false;
 145   _header = SharedClassUtil::allocate_file_map_header();
 146   _header->_version = _invalid_version;
 147 }
 148 
 149 FileMapInfo::~FileMapInfo() {
 150   assert(_current_info == this, "must be singleton"); // not thread safe
 151   _current_info = NULL;
 152 }
 153 
 154 void FileMapInfo::populate_header(size_t alignment) {
 155   _header->populate(this, alignment);
 156 }
 157 
 158 size_t FileMapInfo::FileMapHeader::data_size() {
 159   return SharedClassUtil::file_map_header_size() - sizeof(FileMapInfo::FileMapHeaderBase);
 160 }
 161 
 162 void FileMapInfo::FileMapHeader::populate(FileMapInfo* mapinfo, size_t alignment) {
 163   _magic = 0xf00baba2;
 164   _version = _current_version;
 165   _alignment = alignment;
 166   _obj_alignment = ObjectAlignmentInBytes;
 167   _classpath_entry_table_size = mapinfo->_classpath_entry_table_size;
 168   _classpath_entry_table = mapinfo->_classpath_entry_table;
 169   _classpath_entry_size = mapinfo->_classpath_entry_size;
 170 
 171   // The following fields are for sanity checks for whether this archive
 172   // will function correctly with this JVM and the bootclasspath it's
 173   // invoked with.
 174 
 175   // JVM version string ... changes on each build.
 176   get_header_version(_jvm_ident);
 177 }
 178 
 179 void FileMapInfo::allocate_classpath_entry_table() {
 180   int bytes = 0;
 181   int count = 0;
 182   char* strptr = NULL;
 183   char* strptr_max = NULL;
 184   Thread* THREAD = Thread::current();
 185 
 186   ClassLoaderData* loader_data = ClassLoaderData::the_null_class_loader_data();
 187   size_t entry_size = SharedClassUtil::shared_class_path_entry_size();
 188 
 189   for (int pass=0; pass<2; pass++) {
 190     ClassPathEntry *cpe = ClassLoader::classpath_entry(0);
 191 
 192     for (int cur_entry = 0 ; cpe != NULL; cpe = cpe->next(), cur_entry++) {
 193       const char *name = cpe->name();
 194       int name_bytes = (int)(strlen(name) + 1);
 195 
 196       if (pass == 0) {
 197         count ++;
 198         bytes += (int)entry_size;
 199         bytes += name_bytes;
 200         if (TraceClassPaths || (TraceClassLoading && Verbose)) {
 201           tty->print_cr("[Add main shared path (%s) %s]", (cpe->is_jar_file() ? "jar" : "dir"), name);
 202         }
 203       } else {
 204         SharedClassPathEntry* ent = shared_classpath(cur_entry);
 205         if (cpe->is_jar_file()) {
 206           struct stat st;
 207           if (os::stat(name, &st) != 0) {
 208             // The file/dir must exist, or it would not have been added
 209             // into ClassLoader::classpath_entry().
 210             //
 211             // If we can't access a jar file in the boot path, then we can't
 212             // make assumptions about where classes get loaded from.
 213             FileMapInfo::fail_stop("Unable to open jar file %s.", name);
 214           }
 215 
 216           EXCEPTION_MARK; // The following call should never throw, but would exit VM on error.
 217           SharedClassUtil::update_shared_classpath(cpe, ent, st.st_mtime, st.st_size, THREAD);
 218         } else {
 219           ent->_filesize  = -1;
 220           if (!os::dir_is_empty(name)) {
 221             ClassLoader::exit_with_path_failure("Cannot have non-empty directory in archived classpaths", name);
 222           }
 223         }
 224         ent->_name = strptr;
 225         if (strptr + name_bytes <= strptr_max) {
 226           strncpy(strptr, name, (size_t)name_bytes); // name_bytes includes trailing 0.
 227           strptr += name_bytes;
 228         } else {
 229           assert(0, "miscalculated buffer size");
 230         }
 231       }
 232     }
 233 
 234     if (pass == 0) {
 235       EXCEPTION_MARK; // The following call should never throw, but would exit VM on error.
 236       Array<u8>* arr = MetadataFactory::new_array<u8>(loader_data, (bytes + 7)/8, THREAD);
 237       strptr = (char*)(arr->data());
 238       strptr_max = strptr + bytes;
 239       SharedClassPathEntry* table = (SharedClassPathEntry*)strptr;
 240       strptr += entry_size * count;
 241 
 242       _classpath_entry_table_size = count;
 243       _classpath_entry_table = table;
 244       _classpath_entry_size = entry_size;
 245     }
 246   }
 247 }
 248 
 249 bool FileMapInfo::validate_classpath_entry_table() {
 250   _validating_classpath_entry_table = true;
 251 
 252   int count = _header->_classpath_entry_table_size;
 253 
 254   _classpath_entry_table = _header->_classpath_entry_table;
 255   _classpath_entry_size = _header->_classpath_entry_size;
 256 
 257   for (int i=0; i<count; i++) {
 258     SharedClassPathEntry* ent = shared_classpath(i);
 259     struct stat st;
 260     const char* name = ent->_name;
 261     bool ok = true;
 262     if (TraceClassPaths || (TraceClassLoading && Verbose)) {
 263       tty->print_cr("[Checking shared classpath entry: %s]", name);
 264     }
 265     if (os::stat(name, &st) != 0) {
 266       fail_continue("Required classpath entry does not exist: %s", name);
 267       ok = false;
 268     } else if (ent->is_dir()) {
 269       if (!os::dir_is_empty(name)) {
 270         fail_continue("directory is not empty: %s", name);
 271         ok = false;
 272       }
 273     } else {
 274       if (ent->_timestamp != st.st_mtime ||
 275           ent->_filesize != st.st_size) {
 276         ok = false;
 277         if (PrintSharedArchiveAndExit) {
 278           fail_continue(ent->_timestamp != st.st_mtime ?
 279                         "Timestamp mismatch" :
 280                         "File size mismatch");
 281         } else {
 282           fail_continue("A jar file is not the one used while building"
 283                         " the shared archive file: %s", name);
 284         }
 285       }
 286     }
 287     if (ok) {
 288       if (TraceClassPaths || (TraceClassLoading && Verbose)) {
 289         tty->print_cr("[ok]");
 290       }
 291     } else if (!PrintSharedArchiveAndExit) {
 292       _validating_classpath_entry_table = false;
 293       return false;
 294     }
 295   }
 296 
 297   _classpath_entry_table_size = _header->_classpath_entry_table_size;
 298   _validating_classpath_entry_table = false;
 299   return true;
 300 }
 301 
 302 
 303 // Read the FileMapInfo information from the file.
 304 
 305 bool FileMapInfo::init_from_file(int fd) {
 306   size_t sz = _header->data_size();
 307   char* addr = _header->data();
 308   size_t n = os::read(fd, addr, (unsigned int)sz);
 309   if (n != sz) {
 310     fail_continue("Unable to read the file header.");
 311     return false;
 312   }
 313   if (_header->_version != current_version()) {
 314     fail_continue("The shared archive file has the wrong version.");
 315     return false;
 316   }
 317 
 318   size_t info_size = _header->_paths_misc_info_size;
 319   _paths_misc_info = NEW_C_HEAP_ARRAY_RETURN_NULL(char, info_size, mtClass);
 320   if (_paths_misc_info == NULL) {
 321     fail_continue("Unable to read the file header.");
 322     return false;
 323   }
 324   n = os::read(fd, _paths_misc_info, (unsigned int)info_size);
 325   if (n != info_size) {
 326     fail_continue("Unable to read the shared path info header.");
 327     FREE_C_HEAP_ARRAY(char, _paths_misc_info, mtClass);
 328     _paths_misc_info = NULL;
 329     return false;
 330   }
 331 
 332   size_t len = lseek(fd, 0, SEEK_END);
 333   struct FileMapInfo::FileMapHeader::space_info* si =
 334     &_header->_space[MetaspaceShared::mc];
 335   if (si->_file_offset >= len || len - si->_file_offset < si->_used) {
 336     fail_continue("The shared archive file has been truncated.");
 337     return false;
 338   }
 339 
 340   _file_offset += (long)n;
 341   return true;
 342 }
 343 
 344 
 345 // Read the FileMapInfo information from the file.
 346 bool FileMapInfo::open_for_read() {
 347   _full_path = Arguments::GetSharedArchivePath();
 348   int fd = open(_full_path, O_RDONLY | O_BINARY, 0);
 349   if (fd < 0) {
 350     if (errno == ENOENT) {
 351       // Not locating the shared archive is ok.
 352       fail_continue("Specified shared archive not found.");
 353     } else {
 354       fail_continue("Failed to open shared archive file (%s).",
 355                     strerror(errno));
 356     }
 357     return false;
 358   }
 359 
 360   _fd = fd;
 361   _file_open = true;
 362   return true;
 363 }
 364 
 365 
 366 // Write the FileMapInfo information to the file.
 367 
 368 void FileMapInfo::open_for_write() {
 369  _full_path = Arguments::GetSharedArchivePath();
 370   if (PrintSharedSpaces) {
 371     tty->print_cr("Dumping shared data to file: ");
 372     tty->print_cr("   %s", _full_path);
 373   }
 374 
 375 #ifdef _WINDOWS  // On Windows, need WRITE permission to remove the file.
 376   chmod(_full_path, _S_IREAD | _S_IWRITE);
 377 #endif
 378 
 379   // Use remove() to delete the existing file because, on Unix, this will
 380   // allow processes that have it open continued access to the file.
 381   remove(_full_path);
 382   int fd = open(_full_path, O_RDWR | O_CREAT | O_TRUNC | O_BINARY, 0444);
 383   if (fd < 0) {
 384     fail_stop("Unable to create shared archive file %s.", _full_path);
 385   }
 386   _fd = fd;
 387   _file_offset = 0;
 388   _file_open = true;
 389 }
 390 
 391 
 392 // Write the header to the file, seek to the next allocation boundary.
 393 
 394 void FileMapInfo::write_header() {
 395   int info_size = ClassLoader::get_shared_paths_misc_info_size();
 396 
 397   _header->_paths_misc_info_size = info_size;
 398 
 399   align_file_position();
 400   size_t sz = _header->data_size();
 401   char* addr = _header->data();
 402   write_bytes(addr, (int)sz); // skip the C++ vtable
 403   write_bytes(ClassLoader::get_shared_paths_misc_info(), info_size);
 404   align_file_position();
 405 }
 406 
 407 
 408 // Dump shared spaces to file.
 409 
 410 void FileMapInfo::write_space(int i, Metaspace* space, bool read_only) {
 411   align_file_position();
 412   size_t used = space->used_bytes_slow(Metaspace::NonClassType);
 413   size_t capacity = space->capacity_bytes_slow(Metaspace::NonClassType);
 414   struct FileMapInfo::FileMapHeader::space_info* si = &_header->_space[i];
 415   write_region(i, (char*)space->bottom(), used, capacity, read_only, false);
 416 }
 417 
 418 
 419 // Dump region to file.
 420 
 421 void FileMapInfo::write_region(int region, char* base, size_t size,
 422                                size_t capacity, bool read_only,
 423                                bool allow_exec) {
 424   struct FileMapInfo::FileMapHeader::space_info* si = &_header->_space[region];
 425 
 426   if (_file_open) {
 427     guarantee(si->_file_offset == _file_offset, "file offset mismatch.");
 428     if (PrintSharedSpaces) {
 429       tty->print_cr("Shared file region %d: 0x%6x bytes, addr " INTPTR_FORMAT
 430                     " file offset 0x%6x", region, size, base, _file_offset);
 431     }
 432   } else {
 433     si->_file_offset = _file_offset;
 434   }
 435   si->_base = base;
 436   si->_used = size;
 437   si->_capacity = capacity;
 438   si->_read_only = read_only;
 439   si->_allow_exec = allow_exec;
 440   si->_crc = ClassLoader::crc32(0, base, (jint)size);
 441   write_bytes_aligned(base, (int)size);
 442 }
 443 
 444 
 445 // Dump bytes to file -- at the current file position.
 446 
 447 void FileMapInfo::write_bytes(const void* buffer, int nbytes) {
 448   if (_file_open) {
 449     int n = ::write(_fd, buffer, nbytes);
 450     if (n != nbytes) {
 451       // It is dangerous to leave the corrupted shared archive file around,
 452       // close and remove the file. See bug 6372906.
 453       close();
 454       remove(_full_path);
 455       fail_stop("Unable to write to shared archive file.", NULL);
 456     }
 457   }
 458   _file_offset += nbytes;
 459 }
 460 
 461 
 462 // Align file position to an allocation unit boundary.
 463 
 464 void FileMapInfo::align_file_position() {
 465   size_t new_file_offset = align_size_up(_file_offset,
 466                                          os::vm_allocation_granularity());
 467   if (new_file_offset != _file_offset) {
 468     _file_offset = new_file_offset;
 469     if (_file_open) {
 470       // Seek one byte back from the target and write a byte to insure
 471       // that the written file is the correct length.
 472       _file_offset -= 1;
 473       if (lseek(_fd, (long)_file_offset, SEEK_SET) < 0) {
 474         fail_stop("Unable to seek.", NULL);
 475       }
 476       char zero = 0;
 477       write_bytes(&zero, 1);
 478     }
 479   }
 480 }
 481 
 482 
 483 // Dump bytes to file -- at the current file position.
 484 
 485 void FileMapInfo::write_bytes_aligned(const void* buffer, int nbytes) {
 486   align_file_position();
 487   write_bytes(buffer, nbytes);
 488   align_file_position();
 489 }
 490 
 491 
 492 // Close the shared archive file.  This does NOT unmap mapped regions.
 493 
 494 void FileMapInfo::close() {
 495   if (_file_open) {
 496     if (::close(_fd) < 0) {
 497       fail_stop("Unable to close the shared archive file.");
 498     }
 499     _file_open = false;
 500     _fd = -1;
 501   }
 502 }
 503 
 504 
 505 // JVM/TI RedefineClasses() support:
 506 // Remap the shared readonly space to shared readwrite, private.
 507 bool FileMapInfo::remap_shared_readonly_as_readwrite() {
 508   struct FileMapInfo::FileMapHeader::space_info* si = &_header->_space[0];
 509   if (!si->_read_only) {
 510     // the space is already readwrite so we are done
 511     return true;
 512   }
 513   size_t used = si->_used;
 514   size_t size = align_size_up(used, os::vm_allocation_granularity());
 515   if (!open_for_read()) {
 516     return false;
 517   }
 518   char *base = os::remap_memory(_fd, _full_path, si->_file_offset,
 519                                 si->_base, size, false /* !read_only */,
 520                                 si->_allow_exec);
 521   close();
 522   if (base == NULL) {
 523     fail_continue("Unable to remap shared readonly space (errno=%d).", errno);
 524     return false;
 525   }
 526   if (base != si->_base) {
 527     fail_continue("Unable to remap shared readonly space at required address.");
 528     return false;
 529   }
 530   si->_read_only = false;
 531   return true;
 532 }
 533 
 534 // Map the whole region at once, assumed to be allocated contiguously.
 535 ReservedSpace FileMapInfo::reserve_shared_memory() {
 536   struct FileMapInfo::FileMapHeader::space_info* si = &_header->_space[0];
 537   char* requested_addr = si->_base;
 538 
 539   size_t size = FileMapInfo::shared_spaces_size();
 540 
 541   // Reserve the space first, then map otherwise map will go right over some
 542   // other reserved memory (like the code cache).
 543   ReservedSpace rs(size, os::vm_allocation_granularity(), false, requested_addr);
 544   if (!rs.is_reserved()) {
 545     fail_continue(err_msg("Unable to reserve shared space at required address " INTPTR_FORMAT, requested_addr));
 546     return rs;
 547   }
 548   // the reserved virtual memory is for mapping class data sharing archive
 549   MemTracker::record_virtual_memory_type((address)rs.base(), mtClassShared);
 550 
 551   return rs;
 552 }
 553 
 554 // Memory map a region in the address space.
 555 static const char* shared_region_name[] = { "ReadOnly", "ReadWrite", "MiscData", "MiscCode"};
 556 
 557 char* FileMapInfo::map_region(int i) {
 558   struct FileMapInfo::FileMapHeader::space_info* si = &_header->_space[i];
 559   size_t used = si->_used;
 560   size_t alignment = os::vm_allocation_granularity();
 561   size_t size = align_size_up(used, alignment);
 562   char *requested_addr = si->_base;
 563 
 564   // map the contents of the CDS archive in this memory
 565   char *base = os::map_memory(_fd, _full_path, si->_file_offset,
 566                               requested_addr, size, si->_read_only,
 567                               si->_allow_exec);
 568   if (base == NULL || base != si->_base) {
 569     fail_continue(err_msg("Unable to map %s shared space at required address.", shared_region_name[i]));
 570     return NULL;
 571   }
 572 #ifdef _WINDOWS
 573   // This call is Windows-only because the memory_type gets recorded for the other platforms
 574   // in method FileMapInfo::reserve_shared_memory(), which is not called on Windows.
 575   MemTracker::record_virtual_memory_type((address)base, mtClassShared);
 576 #endif
 577   return base;
 578 }
 579 
 580 bool FileMapInfo::verify_region_checksum(int i) {
 581   if (!VerifySharedSpaces) {
 582     return true;
 583   }
 584   const char* buf = _header->_space[i]._base;
 585   size_t sz = _header->_space[i]._used;
 586   int crc = ClassLoader::crc32(0, buf, (jint)sz);
 587   if (crc != _header->_space[i]._crc) {
 588     fail_continue("Checksum verification failed.");
 589     return false;
 590   }
 591   return true;
 592 }
 593 
 594 // Unmap a memory region in the address space.
 595 
 596 void FileMapInfo::unmap_region(int i) {
 597   struct FileMapInfo::FileMapHeader::space_info* si = &_header->_space[i];
 598   size_t used = si->_used;
 599   size_t size = align_size_up(used, os::vm_allocation_granularity());
 600   if (!os::unmap_memory(si->_base, size)) {
 601     fail_stop("Unable to unmap shared space.");
 602   }
 603 }
 604 
 605 
 606 void FileMapInfo::assert_mark(bool check) {
 607   if (!check) {
 608     fail_stop("Mark mismatch while restoring from shared file.", NULL);
 609   }
 610 }
 611 
 612 
 613 FileMapInfo* FileMapInfo::_current_info = NULL;
 614 SharedClassPathEntry* FileMapInfo::_classpath_entry_table = NULL;
 615 int FileMapInfo::_classpath_entry_table_size = 0;
 616 size_t FileMapInfo::_classpath_entry_size = 0x1234baad;
 617 bool FileMapInfo::_validating_classpath_entry_table = false;
 618 
 619 // Open the shared archive file, read and validate the header
 620 // information (version, boot classpath, etc.).  If initialization
 621 // fails, shared spaces are disabled and the file is closed. [See
 622 // fail_continue.]
 623 //
 624 // Validation of the archive is done in two steps:
 625 //
 626 // [1] validate_header() - done here. This checks the header, including _paths_misc_info.
 627 // [2] validate_classpath_entry_table - this is done later, because the table is in the RW
 628 //     region of the archive, which is not mapped yet.
 629 bool FileMapInfo::initialize() {
 630   assert(UseSharedSpaces, "UseSharedSpaces expected.");
 631 
 632   if (JvmtiExport::can_modify_any_class() || JvmtiExport::can_walk_any_space()) {
 633     fail_continue("Tool agent requires sharing to be disabled.");
 634     return false;
 635   }
 636 
 637   if (!open_for_read()) {
 638     return false;
 639   }
 640 
 641   init_from_file(_fd);
 642   if (!validate_header()) {
 643     return false;
 644   }
 645 
 646   SharedReadOnlySize =  _header->_space[0]._capacity;
 647   SharedReadWriteSize = _header->_space[1]._capacity;
 648   SharedMiscDataSize =  _header->_space[2]._capacity;
 649   SharedMiscCodeSize =  _header->_space[3]._capacity;
 650   return true;
 651 }
 652 
 653 int FileMapInfo::FileMapHeader::compute_crc() {
 654   char* header = data();
 655   // start computing from the field after _crc
 656   char* buf = (char*)&_crc + sizeof(int);
 657   size_t sz = data_size() - (buf - header);
 658   int crc = ClassLoader::crc32(0, buf, (jint)sz);
 659   return crc;
 660 }
 661 
 662 int FileMapInfo::compute_header_crc() {
 663   return _header->compute_crc();
 664 }
 665 
 666 bool FileMapInfo::FileMapHeader::validate() {
 667   if (_magic != (int)0xf00baba2) {
 668     FileMapInfo::fail_continue("The shared archive file has a bad magic number.");
 669     return false;
 670   }
 671   if (VerifySharedSpaces && compute_crc() != _crc) {
 672     fail_continue("Header checksum verification failed.");
 673     return false;
 674   }
 675   if (_version != current_version()) {
 676     FileMapInfo::fail_continue("The shared archive file is the wrong version.");
 677 
 678     return false;
 679   }
 680   char header_version[JVM_IDENT_MAX];
 681   get_header_version(header_version);
 682   if (strncmp(_jvm_ident, header_version, JVM_IDENT_MAX-1) != 0) {
 683     if (TraceClassPaths) {
 684       tty->print_cr("Expected: %s", header_version);
 685       tty->print_cr("Actual:   %s", _jvm_ident);
 686     }
 687     FileMapInfo::fail_continue("The shared archive file was created by a different"
 688                   " version or build of HotSpot");
 689     return false;
 690   }
 691   if (_obj_alignment != ObjectAlignmentInBytes) {
 692     FileMapInfo::fail_continue("The shared archive file's ObjectAlignmentInBytes of %d"
 693                   " does not equal the current ObjectAlignmentInBytes of %d.",
 694                   _obj_alignment, ObjectAlignmentInBytes);
 695     return false;
 696   }
 697 
 698   return true;
 699 }
 700 
 701 bool FileMapInfo::validate_header() {
 702   bool status = _header->validate();
 703 
 704   if (status) {
 705     if (!ClassLoader::check_shared_paths_misc_info(_paths_misc_info, _header->_paths_misc_info_size)) {
 706       if (!PrintSharedArchiveAndExit) {
 707         fail_continue("shared class paths mismatch (hint: enable -XX:+TraceClassPaths to diagnose the failure)");
 708         status = false;
 709       }
 710     }
 711   }
 712 
 713   if (_paths_misc_info != NULL) {
 714     FREE_C_HEAP_ARRAY(char, _paths_misc_info, mtClass);
 715     _paths_misc_info = NULL;
 716   }
 717   return status;
 718 }
 719 
 720 // The following method is provided to see whether a given pointer
 721 // falls in the mapped shared space.
 722 // Param:
 723 // p, The given pointer
 724 // Return:
 725 // True if the p is within the mapped shared space, otherwise, false.
 726 bool FileMapInfo::is_in_shared_space(const void* p) {
 727   for (int i = 0; i < MetaspaceShared::n_regions; i++) {
 728     if (p >= _header->_space[i]._base &&
 729         p < _header->_space[i]._base + _header->_space[i]._used) {
 730       return true;
 731     }
 732   }
 733 
 734   return false;
 735 }
 736 
 737 void FileMapInfo::print_shared_spaces() {
 738   gclog_or_tty->print_cr("Shared Spaces:");
 739   for (int i = 0; i < MetaspaceShared::n_regions; i++) {
 740     struct FileMapInfo::FileMapHeader::space_info* si = &_header->_space[i];
 741     gclog_or_tty->print("  %s " INTPTR_FORMAT "-" INTPTR_FORMAT,
 742                         shared_region_name[i],
 743                         si->_base, si->_base + si->_used);
 744   }
 745 }
 746 
 747 // Unmap mapped regions of shared space.
 748 void FileMapInfo::stop_sharing_and_unmap(const char* msg) {
 749   FileMapInfo *map_info = FileMapInfo::current_info();
 750   if (map_info) {
 751     map_info->fail_continue(msg);
 752     for (int i = 0; i < MetaspaceShared::n_regions; i++) {
 753       if (map_info->_header->_space[i]._base != NULL) {
 754         map_info->unmap_region(i);
 755         map_info->_header->_space[i]._base = NULL;
 756       }
 757     }
 758   } else if (DumpSharedSpaces) {
 759     fail_stop(msg, NULL);
 760   }
 761 }