hotspot/src/share/vm/memory/filemap.hpp
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     1 /*
       
     2  * Copyright 2003-2006 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
       
    20  * CA 95054 USA or visit www.sun.com if you need additional information or
       
    21  * have any questions.
       
    22  *
       
    23  */
       
    24 
       
    25 // Layout of the file:
       
    26 //  header: dump of archive instance plus versioning info, datestamp, etc.
       
    27 //   [magic # = 0xF00BABA2]
       
    28 //  ... padding to align on page-boundary
       
    29 //  read-write space from CompactingPermGenGen
       
    30 //  read-only space from CompactingPermGenGen
       
    31 //  misc data (block offset table, string table, symbols, dictionary, etc.)
       
    32 //  tag(666)
       
    33 
       
    34 static const int JVM_SHARED_JARS_MAX = 128;
       
    35 static const int JVM_SPACENAME_MAX = 128;
       
    36 static const int JVM_IDENT_MAX = 256;
       
    37 static const int JVM_ARCH_MAX = 12;
       
    38 
       
    39 
       
    40 
       
    41 class FileMapInfo : public CHeapObj {
       
    42 private:
       
    43   enum {
       
    44     _invalid_version = -1,
       
    45     _current_version = 1
       
    46   };
       
    47 
       
    48   bool  _file_open;
       
    49   int   _fd;
       
    50   long  _file_offset;
       
    51 
       
    52   // FileMapHeader describes the shared space data in the file to be
       
    53   // mapped.  This structure gets written to a file.  It is not a class, so
       
    54   // that the compilers don't add any compiler-private data to it.
       
    55 
       
    56   struct FileMapHeader {
       
    57     int    _magic;                    // identify file type.
       
    58     int    _version;                  // (from enum, above.)
       
    59     size_t _alignment;                // how shared archive should be aligned
       
    60 
       
    61     struct space_info {
       
    62       int    _file_offset;   // sizeof(this) rounded to vm page size
       
    63       char*  _base;          // copy-on-write base address
       
    64       size_t _capacity;      // for validity checking
       
    65       size_t _used;          // for setting space top on read
       
    66       bool   _read_only;     // read only space?
       
    67       bool   _allow_exec;    // executable code in space?
       
    68     } _space[CompactingPermGenGen::n_regions];
       
    69 
       
    70     // The following fields are all sanity checks for whether this archive
       
    71     // will function correctly with this JVM and the bootclasspath it's
       
    72     // invoked with.
       
    73     char  _arch[JVM_ARCH_MAX];            // architecture
       
    74     char  _jvm_ident[JVM_IDENT_MAX];      // identifier for jvm
       
    75     int   _num_jars;              // Number of jars in bootclasspath
       
    76 
       
    77     // Per jar file data:  timestamp, size.
       
    78 
       
    79     struct {
       
    80       time_t _timestamp;          // jar timestamp.
       
    81       long   _filesize;           // jar file size.
       
    82     } _jar[JVM_SHARED_JARS_MAX];
       
    83   } _header;
       
    84   const char* _full_path;
       
    85 
       
    86   static FileMapInfo* _current_info;
       
    87 
       
    88   bool  init_from_file(int fd);
       
    89   void  align_file_position();
       
    90 
       
    91 public:
       
    92   FileMapInfo() {
       
    93     _file_offset = 0;
       
    94     _file_open = false;
       
    95     _header._version = _invalid_version;
       
    96   }
       
    97 
       
    98   static int current_version()        { return _current_version; }
       
    99   void   populate_header(size_t alignment);
       
   100   bool   validate();
       
   101   void   invalidate();
       
   102   int    version()                    { return _header._version; }
       
   103   size_t alignment()                  { return _header._alignment; }
       
   104   size_t space_capacity(int i)        { return _header._space[i]._capacity; }
       
   105   char*  region_base(int i)           { return _header._space[i]._base; }
       
   106   struct FileMapHeader* header()      { return &_header; }
       
   107 
       
   108   static void set_current_info(FileMapInfo* info)  { _current_info = info; }
       
   109   static FileMapInfo* current_info()  { return _current_info; }
       
   110   static void assert_mark(bool check);
       
   111 
       
   112   // File manipulation.
       
   113   bool  initialize();
       
   114   bool  open_for_read();
       
   115   void  open_for_write();
       
   116   void  write_header();
       
   117   void  write_space(int i, CompactibleSpace* space, bool read_only);
       
   118   void  write_region(int region, char* base, size_t size,
       
   119                      size_t capacity, bool read_only, bool allow_exec);
       
   120   void  write_bytes(const void* buffer, int count);
       
   121   void  write_bytes_aligned(const void* buffer, int count);
       
   122   bool  map_space(int i, ReservedSpace rs, ContiguousSpace *space);
       
   123   char* map_region(int i, ReservedSpace rs);
       
   124   char* map_region(int i, bool address_must_match);
       
   125   void  unmap_region(int i);
       
   126   void  close();
       
   127   bool  is_open() { return _file_open; }
       
   128 
       
   129   // JVM/TI RedefineClasses() support:
       
   130   // Remap the shared readonly space to shared readwrite, private.
       
   131   bool  remap_shared_readonly_as_readwrite();
       
   132 
       
   133   // Errors.
       
   134   static void fail_stop(const char *msg, ...);
       
   135   void fail_continue(const char *msg, ...);
       
   136 
       
   137   // Return true if given address is in the mapped shared space.
       
   138   bool is_in_shared_space(const void* p);
       
   139 };