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 #include "precompiled.hpp"
  26 #include "classfile/classFileStream.hpp"
  27 #include "classfile/classLoader.hpp"
  28 #include "classfile/dictionary.hpp"
  29 #include "classfile/vmSymbols.hpp"
  30 #include "memory/resourceArea.hpp"
  31 
  32 const bool ClassFileStream::verify = true;
  33 const bool ClassFileStream::no_verification = false;
  34 
  35 void ClassFileStream::truncated_file_error(TRAPS) const {
  36   THROW_MSG(vmSymbols::java_lang_ClassFormatError(), "Truncated class file");
  37 }
  38 
  39 ClassFileStream::ClassFileStream(const u1* buffer,
  40                                  int length,
  41                                  const char* source,
  42                                  bool verify_stream,
  43                                  bool from_modules_image) :
  44   _buffer_start(buffer),
  45   _buffer_end(buffer + length),
  46   _current(buffer),
  47   _source(source),
  48   _need_verify(verify_stream),
  49   _from_modules_image(from_modules_image) {}
  50 
  51 const u1* ClassFileStream::clone_buffer() const {
  52   u1* const new_buffer_start = NEW_RESOURCE_ARRAY(u1, length());
  53   memcpy(new_buffer_start, _buffer_start, length());
  54   return new_buffer_start;
  55 }
  56 
  57 const char* const ClassFileStream::clone_source() const {
  58   const char* const src = source();
  59   char* source_copy = NULL;
  60   if (src != NULL) {
  61     size_t source_len = strlen(src);
  62     source_copy = NEW_RESOURCE_ARRAY(char, source_len + 1);
  63     strncpy(source_copy, src, source_len + 1);
  64   }
  65   return source_copy;
  66 }
  67 
  68 // Caller responsible for ResourceMark
  69 // clone stream with a rewound position
  70 const ClassFileStream* ClassFileStream::clone() const {
  71   const u1* const new_buffer_start = clone_buffer();
  72   return new ClassFileStream(new_buffer_start,
  73                              length(),
  74                              clone_source(),
  75                              need_verify(),
  76                              from_modules_image());
  77 }
  78 
  79 u1 ClassFileStream::get_u1(TRAPS) const {
  80   if (_need_verify) {
  81     guarantee_more(1, CHECK_0);
  82   } else {
  83     assert(1 <= _buffer_end - _current, "buffer overflow");
  84   }
  85   return *_current++;
  86 }
  87 
  88 u2 ClassFileStream::get_u2(TRAPS) const {
  89   if (_need_verify) {
  90     guarantee_more(2, CHECK_0);
  91   } else {
  92     assert(2 <= _buffer_end - _current, "buffer overflow");
  93   }
  94   const u1* tmp = _current;
  95   _current += 2;
  96   return Bytes::get_Java_u2((address)tmp);
  97 }
  98 
  99 u4 ClassFileStream::get_u4(TRAPS) const {
 100   if (_need_verify) {
 101     guarantee_more(4, CHECK_0);
 102   } else {
 103     assert(4 <= _buffer_end - _current, "buffer overflow");
 104   }
 105   const u1* tmp = _current;
 106   _current += 4;
 107   return Bytes::get_Java_u4((address)tmp);
 108 }
 109 
 110 u8 ClassFileStream::get_u8(TRAPS) const {
 111   if (_need_verify) {
 112     guarantee_more(8, CHECK_0);
 113   } else {
 114     assert(8 <= _buffer_end - _current, "buffer overflow");
 115   }
 116   const u1* tmp = _current;
 117   _current += 8;
 118   return Bytes::get_Java_u8((address)tmp);
 119 }
 120 
 121 void ClassFileStream::skip_u1(int length, TRAPS) const {
 122   if (_need_verify) {
 123     guarantee_more(length, CHECK);
 124   }
 125   _current += length;
 126 }
 127 
 128 void ClassFileStream::skip_u2(int length, TRAPS) const {
 129   if (_need_verify) {
 130     guarantee_more(length * 2, CHECK);
 131   }
 132   _current += length * 2;
 133 }
 134 
 135 void ClassFileStream::skip_u4(int length, TRAPS) const {
 136   if (_need_verify) {
 137     guarantee_more(length * 4, CHECK);
 138   }
 139   _current += length * 4;
 140 }
 141 
 142 uint64_t ClassFileStream::compute_fingerprint() const {
 143   int classfile_size = length();
 144   int classfile_crc = ClassLoader::crc32(0, (const char*)buffer(), length());
 145   uint64_t fingerprint = (uint64_t(classfile_size) << 32) | uint64_t(uint32_t(classfile_crc));
 146   assert(fingerprint != 0, "must not be zero");
 147 
 148   return fingerprint;
 149 }