1 /*
   2  * Copyright (c) 1997, 2019, 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 "utilities/top.hpp"
  29 #ifdef TARGET_ARCH_x86
  30 # include "bytes_x86.hpp"
  31 #endif
  32 #ifdef TARGET_ARCH_sparc
  33 # include "bytes_sparc.hpp"
  34 #endif
  35 #ifdef TARGET_ARCH_zero
  36 # include "bytes_zero.hpp"
  37 #endif
  38 #ifdef TARGET_ARCH_arm
  39 # include "bytes_arm.hpp"
  40 #endif
  41 #ifdef TARGET_ARCH_ppc
  42 # include "bytes_ppc.hpp"
  43 #endif
  44 
  45 // Input stream for reading .class file
  46 //
  47 // The entire input stream is present in a buffer allocated by the caller.
  48 // The caller is responsible for deallocating the buffer and for using
  49 // ResourceMarks appropriately when constructing streams.
  50 
  51 class ClassFileStream: public ResourceObj {
  52  private:
  53   u1*   _buffer_start; // Buffer bottom
  54   u1*   _buffer_end;   // Buffer top (one past last element)
  55   u1*   _current;      // Current buffer position
  56   const char* _source; // Source of stream (directory name, ZIP/JAR archive name)
  57   bool  _need_verify;  // True if verification is on for the class file
  58 
  59   void truncated_file_error(TRAPS);
  60  protected:
  61   const u1* clone_buffer() const;
  62   const char* const clone_source() const;
  63  public:
  64   // Constructor
  65   ClassFileStream(u1* buffer, int length, const char* source);
  66 
  67   virtual const ClassFileStream* clone() const;
  68 
  69   // Buffer access
  70   u1* buffer() const           { return _buffer_start; }
  71   int length() const           { return _buffer_end - _buffer_start; }
  72   u1* current() const          { return _current; }
  73   void set_current(u1* pos)    { _current = pos; }
  74   // for relative positioning
  75   juint current_offset() const {
  76     return (juint)(_current - _buffer_start);
  77   }
  78   const char* source() const   { return _source; }
  79   void set_verify(bool flag)   { _need_verify = flag; }
  80 
  81   void check_truncated_file(bool b, TRAPS) {
  82     if (b) {
  83       truncated_file_error(THREAD);
  84     }
  85   }
  86 
  87   void guarantee_more(int size, TRAPS) {
  88     size_t remaining = (size_t)(_buffer_end - _current);
  89     unsigned int usize = (unsigned int)size;
  90     check_truncated_file(usize > remaining, CHECK);
  91   }
  92 
  93   // Read u1 from stream
  94   u1 get_u1(TRAPS);
  95   u1 get_u1_fast() {
  96     return *_current++;
  97   }
  98 
  99   // Read u2 from stream
 100   u2 get_u2(TRAPS);
 101   u2 get_u2_fast() {
 102     u2 res = Bytes::get_Java_u2(_current);
 103     _current += 2;
 104     return res;
 105   }
 106 
 107   // Read u4 from stream
 108   u4 get_u4(TRAPS);
 109   u4 get_u4_fast() {
 110     u4 res = Bytes::get_Java_u4(_current);
 111     _current += 4;
 112     return res;
 113   }
 114 
 115   // Read u8 from stream
 116   u8 get_u8(TRAPS);
 117   u8 get_u8_fast() {
 118     u8 res = Bytes::get_Java_u8(_current);
 119     _current += 8;
 120     return res;
 121   }
 122 
 123   // Get direct pointer into stream at current position.
 124   // Returns NULL if length elements are not remaining. The caller is
 125   // responsible for calling skip below if buffer contents is used.
 126   u1* get_u1_buffer() {
 127     return _current;
 128   }
 129 
 130   u2* get_u2_buffer() {
 131     return (u2*) _current;
 132   }
 133 
 134   // Skip length u1 or u2 elements from stream
 135   void skip_u1(int length, TRAPS);
 136   void skip_u1_fast(int length) {
 137     _current += length;
 138   }
 139 
 140   void skip_u2(int length, TRAPS);
 141   void skip_u2_fast(int length) {
 142     _current += 2 * length;
 143   }
 144 
 145   void skip_u4(int length, TRAPS);
 146   void skip_u4_fast(int length) {
 147     _current += 4 * length;
 148   }
 149 
 150   // Tells whether eos is reached
 151   bool at_eos() const          { return _current == _buffer_end; }
 152 };
 153 
 154 #endif // SHARE_VM_CLASSFILE_CLASSFILESTREAM_HPP