1/*
2 * Copyright (c) 2003, 2016, 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.
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23 */
24
25#ifndef SHARE_VM_CLASSFILE_STACKMAPTABLE_HPP
26#define SHARE_VM_CLASSFILE_STACKMAPTABLE_HPP
27
28#include "classfile/stackMapFrame.hpp"
29#include "classfile/verifier.hpp"
30#include "memory/allocation.hpp"
31#include "oops/constantPool.hpp"
32#include "oops/method.hpp"
33#include "utilities/bytes.hpp"
34#include "utilities/globalDefinitions.hpp"
35
36class StackMapReader;
37
38// StackMapTable class is the StackMap table used by type checker
39class StackMapTable : public StackObj {
40 private:
41  // Logically, the _frame_count (as well as many fields in the StackFrame)
42  // should be a u2, but if we defined the variable as that type it will
43  // be difficult to detect/recover from overflow or underflow conditions.
44  // Widening the type and making it signed will help detect these.
45  int32_t              _code_length;
46  int32_t              _frame_count;     // Stackmap frame count
47  StackMapFrame**       _frame_array;
48
49 public:
50  StackMapTable(StackMapReader* reader, StackMapFrame* init_frame,
51                u2 max_locals, u2 max_stack,
52                char* code_data, int code_len, TRAPS);
53
54  inline int32_t get_frame_count() const { return _frame_count; }
55  inline int get_offset(int index) const {
56    return _frame_array[index]->offset();
57  }
58
59  // Match and/or update current_frame to the frame in stackmap table with
60  // specified offset. Return true if the two frames match.
61  bool match_stackmap(
62    StackMapFrame* current_frame, int32_t offset,
63    bool match, bool update, ErrorContext* ctx, TRAPS) const;
64  // Match and/or update current_frame to the frame in stackmap table with
65  // specified offset and frame index. Return true if the two frames match.
66  bool match_stackmap(
67    StackMapFrame* current_frame, int32_t offset, int32_t frame_index,
68    bool match, bool update, ErrorContext* ctx, TRAPS) const;
69
70  // Check jump instructions. Make sure there are no uninitialized
71  // instances on backward branch.
72  void check_jump_target(StackMapFrame* frame, int32_t target, TRAPS) const;
73
74  // The following methods are only used inside this class.
75
76  // Returns the frame array index where the frame with offset is stored.
77  int get_index_from_offset(int32_t offset) const;
78
79  void print_on(outputStream* str) const;
80};
81
82class StackMapStream : StackObj {
83 private:
84  Array<u1>* _data;
85  int _index;
86 public:
87  StackMapStream(Array<u1>* ah)
88    : _data(ah), _index(0) {
89  }
90  u1 get_u1(TRAPS) {
91    if (_data == NULL || _index >= _data->length()) {
92      stackmap_format_error("access beyond the end of attribute", CHECK_0);
93    }
94    return _data->at(_index++);
95  }
96  u2 get_u2(TRAPS) {
97    if (_data == NULL || _index >= _data->length() - 1) {
98      stackmap_format_error("access beyond the end of attribute", CHECK_0);
99    }
100    u2 res = Bytes::get_Java_u2(_data->adr_at(_index));
101    _index += 2;
102    return res;
103  }
104  bool at_end() {
105    return (_data == NULL) || (_index == _data->length());
106  }
107  static void stackmap_format_error(const char* msg, TRAPS);
108};
109
110class StackMapReader : StackObj {
111 private:
112  // information about the class and method
113  constantPoolHandle  _cp;
114  ClassVerifier* _verifier;
115  StackMapStream* _stream;
116  char* _code_data;
117  int32_t _code_length;
118
119  // information get from the attribute
120  int32_t  _frame_count;       // frame count
121
122  int32_t chop(VerificationType* locals, int32_t length, int32_t chops);
123  VerificationType parse_verification_type(u1* flags, TRAPS);
124  void check_verification_type_array_size(
125      int32_t size, int32_t max_size, TRAPS) {
126    if (size < 0 || size > max_size) {
127      // Since this error could be caused someone rewriting the method
128      // but not knowing to update the stackmap data, we call the the
129      // verifier's error method, which may not throw an exception and
130      // failover to the old verifier instead.
131      _verifier->class_format_error(
132        "StackMapTable format error: bad type array size");
133    }
134  }
135
136  enum {
137    SAME_LOCALS_1_STACK_ITEM_EXTENDED = 247,
138    SAME_EXTENDED = 251,
139    FULL = 255
140  };
141
142 public:
143  // Constructor
144  StackMapReader(ClassVerifier* v, StackMapStream* stream, char* code_data,
145                 int32_t code_len, TRAPS) :
146                 _verifier(v), _stream(stream),
147                 _code_data(code_data), _code_length(code_len) {
148    methodHandle m = v->method();
149    if (m->has_stackmap_table()) {
150      _cp = constantPoolHandle(THREAD, m->constants());
151      _frame_count = _stream->get_u2(CHECK);
152    } else {
153      // There's no stackmap table present. Frame count and size are 0.
154      _frame_count = 0;
155    }
156  }
157
158  inline int32_t get_frame_count() const                { return _frame_count; }
159  StackMapFrame* next(StackMapFrame* pre_frame, bool first,
160                      u2 max_locals, u2 max_stack, TRAPS);
161
162  void check_end(TRAPS) {
163    if (!_stream->at_end()) {
164      StackMapStream::stackmap_format_error("wrong attribute size", CHECK);
165    }
166  }
167};
168
169#endif // SHARE_VM_CLASSFILE_STACKMAPTABLE_HPP
170