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 "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
38 class ClassPathEntry;
39
40 class 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
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 no_verification;
56 static const bool verify;
57
58 ClassFileStream(const u1* buffer,
59 int length,
60 const char* source,
61 bool verify_stream = verify); // to be verified by default
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
82 void check_truncated_file(bool b, TRAPS) const {
83 if (b) {
84 truncated_file_error(THREAD);
85 }
86 }
87
88 void guarantee_more(int size, TRAPS) const {
89 size_t remaining = (size_t)(_buffer_end - _current);
90 unsigned int usize = (unsigned int)size;
91 check_truncated_file(usize > remaining, CHECK);
92 }
93
94 // Read u1 from stream
95 u1 get_u1(TRAPS) const;
96 u1 get_u1_fast() const {
97 return *_current++;
98 }
99
100 // Read u2 from stream
101 u2 get_u2(TRAPS) const;
102 u2 get_u2_fast() const {
103 u2 res = Bytes::get_Java_u2((address)_current);
104 _current += 2;
105 return res;
106 }
107
108 // Read u4 from stream
109 u4 get_u4(TRAPS) const;
110 u4 get_u4_fast() const {
111 u4 res = Bytes::get_Java_u4((address)_current);
112 _current += 4;
113 return res;
114 }
115
116 // Read u8 from stream
117 u8 get_u8(TRAPS) const;
118 u8 get_u8_fast() const {
119 u8 res = Bytes::get_Java_u8((address)_current);
120 _current += 8;
121 return res;
122 }
123
124 // Get direct pointer into stream at current position.
125 // Returns NULL if length elements are not remaining. The caller is
126 // responsible for calling skip below if buffer contents is used.
127 const u1* get_u1_buffer() const {
128 return _current;
129 }
130
131 const u2* get_u2_buffer() const {
132 return (const u2*) _current;
133 }
134
135 // Skip length u1 or u2 elements from stream
136 void skip_u1(int length, TRAPS) const;
137 void skip_u1_fast(int length) const {
138 _current += length;
139 }
140
141 void skip_u2(int length, TRAPS) const;
142 void skip_u2_fast(int length) const {
143 _current += 2 * length;
144 }
145
146 void skip_u4(int length, TRAPS) const;
147 void skip_u4_fast(int length) const {
148 _current += 4 * length;
149 }
150
151 // Tells whether eos is reached
152 bool at_eos() const { return _current == _buffer_end; }
153
154 uint64_t compute_fingerprint() const;
155 };
156
157 #endif // SHARE_VM_CLASSFILE_CLASSFILESTREAM_HPP