/*

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 *

 */

class StackMapReader;

// StackMapTable class is the StackMap table used by type checker

class StackMapTable : public StackObj {

 private:

  // Logically, the _frame_count (as well as many fields in the StackFrame)

  // should be a u2, but if we defined the variable as that type it will

  // be difficult to detect/recover from overflow or underflow conditions.

  // Widening the type and making it signed will help detect these.

  int32_t              _code_length;

  int32_t              _frame_count;     // Stackmap frame count

  StackMapFrame**       _frame_array;

 public:

  StackMapTable(StackMapReader* reader, StackMapFrame* init_frame,

                u2 max_locals, u2 max_stack,

                char* code_data, int code_len, TRAPS);

  inline int32_t get_frame_count() const { return _frame_count; }

  inline int get_offset(int index) const {

    return _frame_array[index]->offset();

  }

  // Match and/or update current_frame to the frame in stackmap table with

  // specified offset. Return true if the two frames match.

  bool match_stackmap(

    StackMapFrame* current_frame, int32_t offset,

    bool match, bool update, TRAPS) const;

  // Match and/or update current_frame to the frame in stackmap table with

  // specified offset and frame index. Return true if the two frames match.

  bool match_stackmap(

    StackMapFrame* current_frame, int32_t offset, int32_t frame_index,

    bool match, bool update, TRAPS) const;

  // Check jump instructions. Make sure there are no uninitialized

  // instances on backward branch.

  void check_jump_target(StackMapFrame* frame, int32_t target, TRAPS) const;

  // The following methods are only used inside this class.

  // Returns the frame array index where the frame with offset is stored.

  int get_index_from_offset(int32_t offset) const;

  // Make sure that there's no uninitialized object exist on backward branch.

  void check_new_object(

    const StackMapFrame* frame, int32_t target, TRAPS) const;

  // Debugging

  void print() const PRODUCT_RETURN;

};

class StackMapStream : StackObj {

 private:

  typeArrayHandle _data;

  int _index;

 public:

  StackMapStream(typeArrayHandle ah)

    : _data(ah), _index(0) {

  }

  u1 get_u1(TRAPS) {

    if (_data == NULL || _index >= _data->length()) {

      stackmap_format_error("access beyond the end of attribute", CHECK_0);

    }

    return _data->byte_at(_index++);

  }

  u2 get_u2(TRAPS) {

    if (_data == NULL || _index >= _data->length() - 1) {

      stackmap_format_error("access beyond the end of attribute", CHECK_0);

    }

    u2 res = Bytes::get_Java_u2((u1*)_data->byte_at_addr(_index));

    _index += 2;

    return res;

  }

  bool at_end() {

    return (_data == NULL) || (_index == _data->length());

  }

  static void stackmap_format_error(const char* msg, TRAPS);

};

class StackMapReader : StackObj {

 private:

  // information about the class and method

  constantPoolHandle  _cp;

  ClassVerifier* _verifier;

  StackMapStream* _stream;

  char* _code_data;

  int32_t _code_length;

  // information get from the attribute

  int32_t  _frame_count;       // frame count

  int32_t chop(VerificationType* locals, int32_t length, int32_t chops);

  VerificationType parse_verification_type(u1* flags, TRAPS);

  void check_verification_type_array_size(

      int32_t size, int32_t max_size, TRAPS) {

    if (size < 0 || size > max_size) {

      // Since this error could be caused someone rewriting the method

      // but not knowing to update the stackmap data, we call the the

      // verifier's error method, which may not throw an exception and

      // failover to the old verifier instead.

      _verifier->class_format_error(

        "StackMapTable format error: bad type array size");

    }

  }

  enum {

    SAME_LOCALS_1_STACK_ITEM_EXTENDED = 247,

    SAME_EXTENDED = 251,

    FULL = 255

  };

 public:

  // Constructor

  StackMapReader(ClassVerifier* v, StackMapStream* stream, char* code_data,

                 int32_t code_len, TRAPS) :

                 _verifier(v), _stream(stream),

                 _code_data(code_data), _code_length(code_len) {

    methodHandle m = v->method();

    if (m->has_stackmap_table()) {

      _cp = constantPoolHandle(THREAD, m->constants());

      _frame_count = _stream->get_u2(CHECK);

    } else {

      // There's no stackmap table present. Frame count and size are 0.

      _frame_count = 0;

    }

  }

  inline int32_t get_frame_count() const                { return _frame_count; }

  StackMapFrame* next(StackMapFrame* pre_frame, bool first,

                      u2 max_locals, u2 max_stack, TRAPS);

  void check_end(TRAPS) {

    if (!_stream->at_end()) {

      StackMapStream::stackmap_format_error("wrong attribute size", CHECK);

    }

  }

};