1 /*
   2  * Copyright (c) 2014, 2016, 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 #ifndef SHARE_VM_CLASSFILE_SHAREDPATHSMISCINFO_HPP
  26 #define SHARE_VM_CLASSFILE_SHAREDPATHSMISCINFO_HPP
  27 
  28 #include "classfile/classLoader.hpp"
  29 #include "runtime/os.hpp"
  30 
  31 // During dumping time, when processing class paths, we build up the dump-time
  32 // classpath. The JAR files that exist are stored in the list ClassLoader::_first_append_entry.
  33 // However, we need to store other "misc" information for run-time checking, such as
  34 //
  35 // + The values of Arguments::get_sysclasspath() used during dumping.
  36 //
  37 // + The meta-index file(s) used during dumping (incl modification time and size)
  38 //
  39 // + The class path elements specified during dumping but did not exist --
  40 //   these elements must also be specified at run time, and they also must not
  41 //   exist at run time.
  42 //
  43 // These misc items are stored in a linear buffer in SharedPathsMiscInfo.
  44 // The storage format is stream oriented to minimize its size.
  45 //
  46 // When writing the information to the archive file, SharedPathsMiscInfo is stored in
  47 // the archive file header. At run-time, this information is used only during initialization
  48 // (accessed using read() instead of mmap()), and is deallocated afterwards to save space.
  49 //
  50 // The SharedPathsMiscInfo class is used for both creating the the information (during
  51 // dumping time) and validation (at run time). Different constructors are used in the
  52 // two situations. See below.
  53 
  54 class SharedPathsMiscInfo : public CHeapObj<mtClass> {
  55 protected:
  56   char* _buf_start;
  57   char* _cur_ptr;
  58   char* _end_ptr;
  59   int   _buf_size;
  60   bool  _allocated;   // was _buf_start allocated by me?
  61   void ensure_size(size_t needed_bytes);
  62   void add_path(const char* path, int type);
  63 
  64   void write(const void* ptr, size_t size);
  65   bool read(void* ptr, size_t size);
  66 
  67 protected:
  68   static bool fail(const char* msg, const char* name = NULL);
  69   virtual bool check(jint type, const char* path);
  70 
  71 public:
  72   enum {
  73     INITIAL_BUF_SIZE = 128
  74   };
  75   // This constructor is used when creating the misc information (during dump)
  76   SharedPathsMiscInfo() {
  77     _buf_size = INITIAL_BUF_SIZE;
  78     _cur_ptr = _buf_start = NEW_C_HEAP_ARRAY(char, _buf_size, mtClass);
  79     _allocated = true;
  80   }
  81   // This constructor is used when validating the misc info (during run time)
  82   SharedPathsMiscInfo(char *buff, int size) {
  83     _cur_ptr = _buf_start = buff;
  84     _end_ptr = _buf_start + size;
  85     _buf_size = size;
  86     _allocated = false;
  87   }
  88   ~SharedPathsMiscInfo() {
  89     if (_allocated) {
  90       FREE_C_HEAP_ARRAY(char, _buf_start);
  91     }
  92   }
  93   int get_used_bytes() {
  94     return _cur_ptr - _buf_start;
  95   }
  96   void* buffer() {
  97     return _buf_start;
  98   }
  99 
 100   // writing --
 101 
 102   // The path must not exist at run-time
 103   void add_nonexist_path(const char* path) {
 104     add_path(path, NON_EXIST);
 105   }
 106 
 107   // The path must exist, and must contain exactly <num_entries> files/dirs
 108   void add_boot_classpath(const char* path) {
 109     add_path(path, BOOT);
 110   }
 111   int write_jint(jint num) {
 112     write(&num, sizeof(num));
 113     return 0;
 114   }
 115   void write_time(time_t t) {
 116     write(&t, sizeof(t));
 117   }
 118   void write_long(long l) {
 119     write(&l, sizeof(l));
 120   }
 121 
 122   bool dump_to_file(int fd) {
 123     int n = get_used_bytes();
 124     return (os::write(fd, _buf_start, n) == (size_t)n);
 125   }
 126 
 127   // reading --
 128 
 129   enum {
 130     BOOT      = 1,
 131     NON_EXIST = 2,
 132     REQUIRED  = 3
 133   };
 134 
 135   virtual const char* type_name(int type) {
 136     switch (type) {
 137     case BOOT:      return "BOOT";
 138     case NON_EXIST: return "NON_EXIST";
 139     case REQUIRED:  return "REQUIRED";
 140     default:        ShouldNotReachHere(); return "?";
 141     }
 142   }
 143 
 144   virtual void print_path(int type, const char* path);
 145 
 146   bool check();
 147   bool read_jint(jint *ptr) {
 148     return read(ptr, sizeof(jint));
 149   }
 150   bool read_long(long *ptr) {
 151     return read(ptr, sizeof(long));
 152   }
 153   bool read_time(time_t *ptr) {
 154     return read(ptr, sizeof(time_t));
 155   }
 156 };
 157 
 158 #endif // SHARE_VM_CLASSFILE_SHAREDPATHSMISCINFO_HPP