1 /* 2 * Copyright (c) 1997, 2013, 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/bytes.hpp" 29 #include "utilities/top.hpp" 30 31 // Input stream for reading .class file 32 // 33 // The entire input stream is present in a buffer allocated by the caller. 34 // The caller is responsible for deallocating the buffer and for using 35 // ResourceMarks appropriately when constructing streams. 36 37 class ClassFileStream: public ResourceObj { 38 private: 39 u1* _buffer_start; // Buffer bottom 40 u1* _buffer_end; // Buffer top (one past last element) 41 u1* _current; // Current buffer position 42 char* _source; // Source of stream (directory name, ZIP/JAR archive name) 43 bool _need_verify; // True if verification is on for the class file 44 45 void truncated_file_error(TRAPS); 46 public: 47 // Constructor 48 ClassFileStream(u1* buffer, int length, char* source); 49 50 // Buffer access 51 u1* buffer() const { return _buffer_start; } 52 int length() const { return _buffer_end - _buffer_start; } 53 u1* current() const { return _current; } 54 void set_current(u1* pos) { _current = pos; } 55 char* source() const { return _source; } 56 void set_verify(bool flag) { _need_verify = flag; } 57 58 void check_truncated_file(bool b, TRAPS) { 59 if (b) { 60 truncated_file_error(THREAD); 61 } 62 } 63 64 void guarantee_more(int size, TRAPS) { 65 size_t remaining = (size_t)(_buffer_end - _current); 66 unsigned int usize = (unsigned int)size; 67 check_truncated_file(usize > remaining, CHECK); 68 } 69 70 // Read u1 from stream 71 u1 get_u1(TRAPS); 72 u1 get_u1_fast() { 73 return *_current++; 74 } 75 76 // Read u2 from stream 77 u2 get_u2(TRAPS); 78 u2 get_u2_fast() { 79 u2 res = Bytes::get_Java_u2(_current); 80 _current += 2; 81 return res; 82 } 83 84 // Read u4 from stream 85 u4 get_u4(TRAPS); 86 u4 get_u4_fast() { 87 u4 res = Bytes::get_Java_u4(_current); 88 _current += 4; 89 return res; 90 } 91 92 // Read u8 from stream 93 u8 get_u8(TRAPS); 94 u8 get_u8_fast() { 95 u8 res = Bytes::get_Java_u8(_current); 96 _current += 8; 97 return res; 98 } 99 100 // Get direct pointer into stream at current position. 101 // Returns NULL if length elements are not remaining. The caller is 102 // responsible for calling skip below if buffer contents is used. 103 u1* get_u1_buffer() { 104 return _current; 105 } 106 107 u2* get_u2_buffer() { 108 return (u2*) _current; 109 } 110 111 // Skip length u1 or u2 elements from stream 112 void skip_u1(int length, TRAPS); 113 void skip_u1_fast(int length) { 114 _current += length; 115 } 116 117 void skip_u2(int length, TRAPS); 118 void skip_u2_fast(int length) { 119 _current += 2 * length; 120 } 121 122 void skip_u4(int length, TRAPS); 123 void skip_u4_fast(int length) { 124 _current += 4 * length; 125 } 126 127 // Tells whether eos is reached 128 bool at_eos() const { return _current == _buffer_end; } 129 }; 130 131 #endif // SHARE_VM_CLASSFILE_CLASSFILESTREAM_HPP