1 /*

     2  * Copyright (c) 1997, 2015, 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_CLASSFILESTREAM_HPP

    26 #define SHARE_VM_CLASSFILE_CLASSFILESTREAM_HPP

    27 

    28 #include "memory/allocation.hpp"

    29 #include "utilities/bytes.hpp"

    30 #include "utilities/exceptions.hpp"

    31 

    32 // Input stream for reading .class file

    33 //

    34 // The entire input stream is present in a buffer allocated by the caller.

    35 // The caller is responsible for deallocating the buffer and for using

    36 // ResourceMarks appropriately when constructing streams.

    37 

    38 class ClassPathEntry;

    39 

    40 class ClassFileStream: public ResourceObj {

    41  private:

    42   const u1* const _buffer_start; // Buffer bottom

    43   const u1* const _buffer_end;   // Buffer top (one past last element)

    44   mutable const u1* _current;    // Current buffer position

    45   const char* const _source;     // Source of stream (directory name, ZIP/JAR archive name)

    46   bool _need_verify;             // True if verification is on for the class file

    47 

    48   void truncated_file_error(TRAPS) const ;

    49 

    50  protected:

    51   const u1* clone_buffer() const;

    52   const char* const clone_source() const;

    53 

    54  public:

    55   static const bool no_verification;

    56   static const bool verify;

    57 

    58   ClassFileStream(const u1* buffer,

    59                   int length,

    60                   const char* source,

    61                   bool verify_stream = verify); // to be verified by default

    62 

    63   virtual const ClassFileStream* clone() const;

    64 

    65   // Buffer access

    66   const u1* buffer() const { return _buffer_start; }

    67   int length() const { return _buffer_end - _buffer_start; }

    68   const u1* current() const { return _current; }

    69   void set_current(const u1* pos) const {

    70     assert(pos >= _buffer_start && pos <= _buffer_end, "invariant");

    71     _current = pos;

    72   }

    73 

    74   // for relative positioning

    75   juint current_offset() const {

    76     return (juint)(_current - _buffer_start);

    77   }

    78   const char* source() const { return _source; }

    79   bool need_verify() const { return _need_verify; }

    80   void set_verify(bool flag) { _need_verify = flag; }

    81 

    82   void check_truncated_file(bool b, TRAPS) const {

    83     if (b) {

    84       truncated_file_error(THREAD);

    85     }

    86   }

    87 

    88   void guarantee_more(int size, TRAPS) const {

    89     size_t remaining = (size_t)(_buffer_end - _current);

    90     unsigned int usize = (unsigned int)size;

    91     check_truncated_file(usize > remaining, CHECK);

    92   }

    93 

    94   // Read u1 from stream

    95   u1 get_u1(TRAPS) const;

    96   u1 get_u1_fast() const {

    97     return *_current++;

    98   }

    99 

   100   // Read u2 from stream

   101   u2 get_u2(TRAPS) const;

   102   u2 get_u2_fast() const {

   103     u2 res = Bytes::get_Java_u2((address)_current);

   104     _current += 2;

   105     return res;

   106   }

   107 

   108   // Read u4 from stream

   109   u4 get_u4(TRAPS) const;

   110   u4 get_u4_fast() const {

   111     u4 res = Bytes::get_Java_u4((address)_current);

   112     _current += 4;

   113     return res;

   114   }

   115 

   116   // Read u8 from stream

   117   u8 get_u8(TRAPS) const;

   118   u8 get_u8_fast() const {

   119     u8 res = Bytes::get_Java_u8((address)_current);

   120     _current += 8;

   121     return res;

   122   }

   123 

   124   // Skip length u1 or u2 elements from stream

   125   void skip_u1(int length, TRAPS) const;

   126   void skip_u1_fast(int length) const {

   127     _current += length;

   128   }

   129 

   130   void skip_u2(int length, TRAPS) const;

   131   void skip_u2_fast(int length) const {

   132     _current += 2 * length;

   133   }

   134 

   135   void skip_u4(int length, TRAPS) const;

   136   void skip_u4_fast(int length) const {

   137     _current += 4 * length;

   138   }

   139 

   140   // Tells whether eos is reached

   141   bool at_eos() const { return _current == _buffer_end; }

   142 

   143   uint64_t compute_fingerprint() const;

   144 };

   145 

   146 #endif // SHARE_VM_CLASSFILE_CLASSFILESTREAM_HPP