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 "utilities/top.hpp"
  29 #ifdef TARGET_ARCH_x86
  30 # include "bytes_x86.hpp"
  31 #endif
  32 #ifdef TARGET_ARCH_aarch64
  33 # include "bytes_aarch64.hpp"
  34 #endif
  35 #ifdef TARGET_ARCH_sparc
  36 # include "bytes_sparc.hpp"
  37 #endif
  38 #ifdef TARGET_ARCH_zero
  39 # include "bytes_zero.hpp"
  40 #endif
  41 #ifdef TARGET_ARCH_arm
  42 # include "bytes_arm.hpp"
  43 #endif
  44 #ifdef TARGET_ARCH_ppc
  45 # include "bytes_ppc.hpp"
  46 #endif
  47 
  48 // Input stream for reading .class file
  49 //
  50 // The entire input stream is present in a buffer allocated by the caller.
  51 // The caller is responsible for deallocating the buffer and for using
  52 // ResourceMarks appropriately when constructing streams.
  53 
  54 class ClassFileStream: public ResourceObj {
  55  private:
  56   u1*   _buffer_start; // Buffer bottom
  57   u1*   _buffer_end;   // Buffer top (one past last element)
  58   u1*   _current;      // Current buffer position
  59   const char* _source; // Source of stream (directory name, ZIP/JAR archive name)
  60   bool  _need_verify;  // True if verification is on for the class file
  61 
  62   void truncated_file_error(TRAPS);
  63 
  64 #if INCLUDE_JFR
  65   u1* clone_buffer() const;
  66   const char* const clone_source() const;
  67 #endif
  68 
  69  public:
  70   // Constructor
  71   ClassFileStream(u1* buffer, int length, const char* source, bool need_verify = false);
  72 
  73   // Buffer access
  74   u1* buffer() const           { return _buffer_start; }
  75   int length() const           { return _buffer_end - _buffer_start; }
  76   u1* current() const          { return _current; }
  77   void set_current(u1* pos)    { _current = pos; }
  78   // for relative positioning
  79   juint current_offset() const {
  80     return (juint)(_current - _buffer_start);
  81   }
  82   const char* source() const   { return _source; }
  83   void set_verify(bool flag)   { _need_verify = flag; }
  84 
  85   void check_truncated_file(bool b, TRAPS) {
  86     if (b) {
  87       truncated_file_error(THREAD);
  88     }
  89   }
  90 
  91   void guarantee_more(int size, TRAPS) {
  92     size_t remaining = (size_t)(_buffer_end - _current);
  93     unsigned int usize = (unsigned int)size;
  94     check_truncated_file(usize > remaining, CHECK);
  95   }
  96 
  97   // Read u1 from stream
  98   u1 get_u1(TRAPS);
  99   u1 get_u1_fast() {
 100     return *_current++;
 101   }
 102 
 103   // Read u2 from stream
 104   u2 get_u2(TRAPS);
 105   u2 get_u2_fast() {
 106     u2 res = Bytes::get_Java_u2(_current);
 107     _current += 2;
 108     return res;
 109   }
 110 
 111   // Read u4 from stream
 112   u4 get_u4(TRAPS);
 113   u4 get_u4_fast() {
 114     u4 res = Bytes::get_Java_u4(_current);
 115     _current += 4;
 116     return res;
 117   }
 118 
 119   // Read u8 from stream
 120   u8 get_u8(TRAPS);
 121   u8 get_u8_fast() {
 122     u8 res = Bytes::get_Java_u8(_current);
 123     _current += 8;
 124     return res;
 125   }
 126 
 127   // Get direct pointer into stream at current position.
 128   // Returns NULL if length elements are not remaining. The caller is
 129   // responsible for calling skip below if buffer contents is used.
 130   u1* get_u1_buffer() {
 131     return _current;
 132   }
 133 
 134   u2* get_u2_buffer() {
 135     return (u2*) _current;
 136   }
 137 
 138   // Skip length u1 or u2 elements from stream
 139   void skip_u1(int length, TRAPS);
 140   void skip_u1_fast(int length) {
 141     _current += length;
 142   }
 143 
 144   void skip_u2(int length, TRAPS);
 145   void skip_u2_fast(int length) {
 146     _current += 2 * length;
 147   }
 148 
 149   void skip_u4(int length, TRAPS);
 150   void skip_u4_fast(int length) {
 151     _current += 4 * length;
 152   }
 153 
 154   // Tells whether eos is reached
 155   bool at_eos() const          { return _current == _buffer_end; }
 156 
 157 #if INCLUDE_JFR
 158   ClassFileStream* clone() const;
 159 
 160   bool need_verify() const { return _need_verify; }
 161 #endif
 162 };
 163 
 164 #endif // SHARE_VM_CLASSFILE_CLASSFILESTREAM_HPP