1 /* 2 * Copyright (c) 1997, 2005, 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 // Input stream for reading .class file 26 // 27 // The entire input stream is present in a buffer allocated by the caller. 28 // The caller is responsible for deallocating the buffer and for using 29 // ResourceMarks appropriately when constructing streams. 30 31 class ClassFileStream: public ResourceObj { 32 private: 33 u1* _buffer_start; // Buffer bottom 34 u1* _buffer_end; // Buffer top (one past last element) 35 u1* _current; // Current buffer position 36 char* _source; // Source of stream (directory name, ZIP/JAR archive name) 37 bool _need_verify; // True if verification is on for the class file 38 39 void truncated_file_error(TRAPS); 40 public: 41 // Constructor 42 ClassFileStream(u1* buffer, int length, char* source); 43 44 // Buffer access 45 u1* buffer() const { return _buffer_start; } 46 int length() const { return _buffer_end - _buffer_start; } 47 u1* current() const { return _current; } 48 void set_current(u1* pos) { _current = pos; } 49 char* source() const { return _source; } 50 void set_verify(bool flag) { _need_verify = flag; } 51 52 void check_truncated_file(bool b, TRAPS) { 53 if (b) { 54 truncated_file_error(THREAD); 55 } 56 } 57 58 void guarantee_more(int size, TRAPS) { 59 size_t remaining = (size_t)(_buffer_end - _current); 60 unsigned int usize = (unsigned int)size; 61 check_truncated_file(usize > remaining, CHECK); 62 } 63 64 // Read u1 from stream 65 u1 get_u1(TRAPS); 66 u1 get_u1_fast() { 67 return *_current++; 68 } 69 70 // Read u2 from stream 71 u2 get_u2(TRAPS); 72 u2 get_u2_fast() { 73 u2 res = Bytes::get_Java_u2(_current); 74 _current += 2; 75 return res; 76 } 77 78 // Read u4 from stream 79 u4 get_u4(TRAPS); 80 u4 get_u4_fast() { 81 u4 res = Bytes::get_Java_u4(_current); 82 _current += 4; 83 return res; 84 } 85 86 // Read u8 from stream 87 u8 get_u8(TRAPS); 88 u8 get_u8_fast() { 89 u8 res = Bytes::get_Java_u8(_current); 90 _current += 8; 91 return res; 92 } 93 94 // Get direct pointer into stream at current position. 95 // Returns NULL if length elements are not remaining. The caller is 96 // responsible for calling skip below if buffer contents is used. 97 u1* get_u1_buffer() { 98 return _current; 99 } 100 101 u2* get_u2_buffer() { 102 return (u2*) _current; 103 } 104 105 // Skip length u1 or u2 elements from stream 106 void skip_u1(int length, TRAPS); 107 void skip_u1_fast(int length) { 108 _current += length; 109 } 110 111 void skip_u2(int length, TRAPS); 112 void skip_u2_fast(int length) { 113 _current += 2 * length; 114 } 115 116 // Tells whether eos is reached 117 bool at_eos() const { return _current == _buffer_end; } 118 };