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_CLASSFILE_CLASSFILESTREAM_HPP
26#define SHARE_CLASSFILE_CLASSFILESTREAM_HPP
27
28#include "memory/allocation.hpp"
29#include "utilities/bytes.hpp"
30#include "utilities/exceptions.hpp"
31
32// Input stream for reading .class file
33//
34// The entire input stream is present in a buffer allocated by the caller.
35// The caller is responsible for deallocating the buffer and for using
36// ResourceMarks appropriately when constructing streams.
37
38class ClassPathEntry;
39
40class ClassFileStream: public ResourceObj {
41 private:
42 const u1* const _buffer_start; // Buffer bottom
43 const u1* const _buffer_end; // Buffer top (one past last element)
44 mutable const u1* _current; // Current buffer position
45 const char* const _source; // Source of stream (directory name, ZIP/JAR archive name)
46 bool _need_verify; // True if verification is on for the class file
47 bool _from_boot_loader_modules_image; // True if this was created by ClassPathImageEntry.
48 void truncated_file_error(TRAPS) const ;
49
50 protected:
51 const u1* clone_buffer() const;
52 const char* const clone_source() const;
53
54 public:
55 static const bool verify;
56
57 ClassFileStream(const u1* buffer,
58 int length,
59 const char* source,
60 bool verify_stream = verify, // to be verified by default
61 bool from_boot_loader_modules_image = false);
62
63 virtual const ClassFileStream* clone() const;
64
65 // Buffer access
66 const u1* buffer() const { return _buffer_start; }
67 int length() const { return _buffer_end - _buffer_start; }
68 const u1* current() const { return _current; }
69 void set_current(const u1* pos) const {
70 assert(pos >= _buffer_start && pos <= _buffer_end, "invariant");
71 _current = pos;
72 }
73
74 // for relative positioning
75 juint current_offset() const {
76 return (juint)(_current - _buffer_start);
77 }
78 const char* source() const { return _source; }
79 bool need_verify() const { return _need_verify; }
80 void set_verify(bool flag) { _need_verify = flag; }
81 bool from_boot_loader_modules_image() const { return _from_boot_loader_modules_image; }
82
83 void check_truncated_file(bool b, TRAPS) const {
84 if (b) {
85 truncated_file_error(THREAD);
86 }
87 }
88
89 void guarantee_more(int size, TRAPS) const {
90 size_t remaining = (size_t)(_buffer_end - _current);
91 unsigned int usize = (unsigned int)size;
92 check_truncated_file(usize > remaining, CHECK);
93 }
94
95 // Read u1 from stream
96 u1 get_u1_fast() const {
97 return *_current++;
98 }
99 u1 get_u1(TRAPS) const {
100 if (_need_verify) {
101 guarantee_more(1, CHECK_0);
102 } else {
103 assert(1 <= _buffer_end - _current, "buffer overflow");
104 }
105 return get_u1_fast();
106 }
107
108 // Read u2 from stream
109 u2 get_u2_fast() const {
110 u2 res = Bytes::get_Java_u2((address)_current);
111 _current += 2;
112 return res;
113 }
114 u2 get_u2(TRAPS) const {
115 if (_need_verify) {
116 guarantee_more(2, CHECK_0);
117 } else {
118 assert(2 <= _buffer_end - _current, "buffer overflow");
119 }
120 return get_u2_fast();
121 }
122
123 // Read u4 from stream
124 u4 get_u4_fast() const {
125 u4 res = Bytes::get_Java_u4((address)_current);
126 _current += 4;
127 return res;
128 }
129
130 // Read u8 from stream
131 u8 get_u8_fast() const {
132 u8 res = Bytes::get_Java_u8((address)_current);
133 _current += 8;
134 return res;
135 }
136
137 // Skip length elements from stream
138 void skip_u1(int length, TRAPS) const {
139 if (_need_verify) {
140 guarantee_more(length, CHECK);
141 }
142 skip_u1_fast(length);
143 }
144 void skip_u1_fast(int length) const {
145 _current += length;
146 }
147
148 void skip_u2_fast(int length) const {
149 _current += 2 * length;
150 }
151
152 void skip_u4_fast(int length) const {
153 _current += 4 * length;
154 }
155
156 // Tells whether eos is reached
157 bool at_eos() const { return _current == _buffer_end; }
158
159 uint64_t compute_fingerprint() const;
160};
161
162#endif // SHARE_CLASSFILE_CLASSFILESTREAM_HPP
163