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.
  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
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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 
  36 class StackMapReader;
  37 
  38 // StackMapTable class is the StackMap table used by type checker
  39 class 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 
  82 class 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 
 110 class 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 
 147   inline int32_t get_frame_count() const                { return _frame_count; }
 148   StackMapFrame* next(StackMapFrame* pre_frame, bool first,
 149                       u2 max_locals, u2 max_stack, TRAPS);
 150 
 151   void check_end(TRAPS) {
 152     if (!_stream->at_end()) {
 153       StackMapStream::stackmap_format_error("wrong attribute size", CHECK);
 154     }
 155   }
 156 };
 157 
 158 #endif // SHARE_VM_CLASSFILE_STACKMAPTABLE_HPP