/*

 * Copyright (c) 2003, 2012, Oracle and/or its affiliates. All rights reserved.

 * 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.

 *

 */

#include "precompiled.hpp"

#include "classfile/stackMapTable.hpp"

#include "classfile/verifier.hpp"

#include "memory/resourceArea.hpp"

#include "oops/oop.inline.hpp"

#include "runtime/fieldType.hpp"

#include "runtime/handles.inline.hpp"

StackMapTable::StackMapTable(StackMapReader* reader, StackMapFrame* init_frame,

                             u2 max_locals, u2 max_stack,

                             char* code_data, int code_len, TRAPS) {

  _code_length = code_len;

  _frame_count = reader->get_frame_count();

  if (_frame_count > 0) {

    _frame_array = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD,

                                                StackMapFrame*, _frame_count);

    StackMapFrame* pre_frame = init_frame;

    for (int32_t i = 0; i < _frame_count; i++) {

      StackMapFrame* frame = reader->next(

        pre_frame, i == 0, max_locals, max_stack,

        CHECK_VERIFY(pre_frame->verifier()));

      _frame_array[i] = frame;

      int offset = frame->offset();

      if (offset >= code_len || code_data[offset] == 0) {

        frame->verifier()->verify_error(

            ErrorContext::bad_stackmap(i, frame),

            "StackMapTable error: bad offset");

        return;

      }

      pre_frame = frame;

    }

  }

  reader->check_end(CHECK);

}

// This method is only called by method in StackMapTable.

int StackMapTable::get_index_from_offset(int32_t offset) const {

  int i = 0;

  for (; i < _frame_count; i++) {

    if (_frame_array[i]->offset() == offset) {

      return i;

    }

  }

  return i;  // frame with offset doesn't exist in the array

}

bool StackMapTable::match_stackmap(

    StackMapFrame* frame, int32_t target,

    bool match, bool update, ErrorContext* ctx, TRAPS) const {

  int index = get_index_from_offset(target);

  return match_stackmap(frame, target, index, match, update, ctx, THREAD);

}

// 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.

//

// The values of match and update are:                  _match__update_

//

// checking a branch target/exception handler:           true   false

// linear bytecode verification following an

// unconditional branch:                                 false  true

// linear bytecode verification not following an

// unconditional branch:                                 true   true

bool StackMapTable::match_stackmap(

    StackMapFrame* frame, int32_t target, int32_t frame_index,

    bool match, bool update, ErrorContext* ctx, TRAPS) const {

  if (frame_index < 0 || frame_index >= _frame_count) {

    *ctx = ErrorContext::missing_stackmap(frame->offset());

    frame->verifier()->verify_error(

        *ctx, "Expecting a stackmap frame at branch target %d", target);

    return false;

  }

  StackMapFrame *stackmap_frame = _frame_array[frame_index];

  bool result = true;

  if (match) {

    // when checking handler target, match == true && update == false

    bool is_exception_handler = !update;

    // Has direct control flow from last instruction, need to match the two

    // frames.

    result = frame->is_assignable_to(stackmap_frame, is_exception_handler,

        ctx, CHECK_VERIFY_(frame->verifier(), result));

  }

  if (update) {

    // Use the frame in stackmap table as current frame

    int lsize = stackmap_frame->locals_size();

    int ssize = stackmap_frame->stack_size();

    if (frame->locals_size() > lsize || frame->stack_size() > ssize) {

      // Make sure unused type array items are all _bogus_type.

      frame->reset();

    }

    frame->set_locals_size(lsize);

    frame->copy_locals(stackmap_frame);

    frame->set_stack_size(ssize);

    frame->copy_stack(stackmap_frame);

    frame->set_flags(stackmap_frame->flags());

  }

  return result;

}

void StackMapTable::check_jump_target(

    StackMapFrame* frame, int32_t target, TRAPS) const {

  ErrorContext ctx;

  bool match = match_stackmap(

    frame, target, true, false, &ctx, CHECK_VERIFY(frame->verifier()));

  if (!match || (target < 0 || target >= _code_length)) {

    frame->verifier()->verify_error(ctx,

        "Inconsistent stackmap frames at branch target %d", target);

    return;

  }

  // check if uninitialized objects exist on backward branches

  check_new_object(frame, target, CHECK_VERIFY(frame->verifier()));

}

void StackMapTable::check_new_object(

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

  if (frame->offset() > target && frame->has_new_object()) {

    frame->verifier()->verify_error(

        ErrorContext::bad_code(frame->offset()),

        "Uninitialized object exists on backward branch %d", target);

    return;

  }

}

void StackMapTable::print_on(outputStream* str) const {

  str->indent().print_cr("StackMapTable: frame_count = %d", _frame_count);

  str->indent().print_cr("table = { ");

  {

    streamIndentor si(str);

    for (int32_t i = 0; i < _frame_count; ++i) {

      _frame_array[i]->print_on(str);

    }

  }

  str->print_cr(" }");

}

int32_t StackMapReader::chop(

    VerificationType* locals, int32_t length, int32_t chops) {

  if (locals == NULL) return -1;

  int32_t pos = length - 1;

  for (int32_t i=0; i<chops; i++) {

    if (locals[pos].is_category2_2nd()) {

      pos -= 2;

    } else {

      pos --;

    }

    if (pos<0 && i<(chops-1)) return -1;

  }

  return pos+1;

}

VerificationType StackMapReader::parse_verification_type(u1* flags, TRAPS) {

  u1 tag = _stream->get_u1(THREAD);

  if (tag < (u1)ITEM_UninitializedThis) {

    return VerificationType::from_tag(tag);

  }

  if (tag == ITEM_Object) {

    u2 class_index = _stream->get_u2(THREAD);

    int nconstants = _cp->length();

    if ((class_index <= 0 || class_index >= nconstants) ||

        (!_cp->tag_at(class_index).is_klass() &&

         !_cp->tag_at(class_index).is_unresolved_klass())) {

      _stream->stackmap_format_error("bad class index", THREAD);

      return VerificationType::bogus_type();

    }

    return VerificationType::reference_type(_cp->klass_name_at(class_index));

  }

  if (tag == ITEM_UninitializedThis) {

    if (flags != NULL) {

      *flags |= FLAG_THIS_UNINIT;

    }

    return VerificationType::uninitialized_this_type();

  }

  if (tag == ITEM_Uninitialized) {

    u2 offset = _stream->get_u2(THREAD);

    if (offset >= _code_length ||

        _code_data[offset] != ClassVerifier::NEW_OFFSET) {

      ResourceMark rm(THREAD);

      _verifier->class_format_error(

        "StackMapTable format error: bad offset for Uninitialized");

      return VerificationType::bogus_type();

    }

    return VerificationType::uninitialized_type(offset);

  }

  _stream->stackmap_format_error("bad verification type", THREAD);

  return VerificationType::bogus_type();

}

StackMapFrame* StackMapReader::next(

    StackMapFrame* pre_frame, bool first, u2 max_locals, u2 max_stack, TRAPS) {

  StackMapFrame* frame;

  int offset;

  VerificationType* locals = NULL;

  u1 frame_type = _stream->get_u1(THREAD);

  if (frame_type < 64) {

    // same_frame

    if (first) {

      offset = frame_type;

      // Can't share the locals array since that is updated by the verifier.

      if (pre_frame->locals_size() > 0) {

        locals = NEW_RESOURCE_ARRAY_IN_THREAD(

          THREAD, VerificationType, pre_frame->locals_size());

      }

    } else {

      offset = pre_frame->offset() + frame_type + 1;

      locals = pre_frame->locals();

    }

    frame = new StackMapFrame(

      offset, pre_frame->flags(), pre_frame->locals_size(), 0,

      max_locals, max_stack, locals, NULL, _verifier);

    if (first && locals != NULL) {

      frame->copy_locals(pre_frame);

    }

    return frame;

  }

  if (frame_type < 128) {

    // same_locals_1_stack_item_frame

    if (first) {

      offset = frame_type - 64;

      // Can't share the locals array since that is updated by the verifier.

      if (pre_frame->locals_size() > 0) {

        locals = NEW_RESOURCE_ARRAY_IN_THREAD(

          THREAD, VerificationType, pre_frame->locals_size());

      }

    } else {

      offset = pre_frame->offset() + frame_type - 63;

      locals = pre_frame->locals();

    }

    VerificationType* stack = NEW_RESOURCE_ARRAY_IN_THREAD(

      THREAD, VerificationType, 2);

    u2 stack_size = 1;

    stack[0] = parse_verification_type(NULL, CHECK_VERIFY_(_verifier, NULL));

    if (stack[0].is_category2()) {

      stack[1] = stack[0].to_category2_2nd();

      stack_size = 2;

    }

    check_verification_type_array_size(

      stack_size, max_stack, CHECK_VERIFY_(_verifier, NULL));

    frame = new StackMapFrame(

      offset, pre_frame->flags(), pre_frame->locals_size(), stack_size,

      max_locals, max_stack, locals, stack, _verifier);

    if (first && locals != NULL) {

      frame->copy_locals(pre_frame);

    }

    return frame;

  }

  u2 offset_delta = _stream->get_u2(THREAD);

  if (frame_type < SAME_LOCALS_1_STACK_ITEM_EXTENDED) {

    // reserved frame types

    _stream->stackmap_format_error(

      "reserved frame type", CHECK_VERIFY_(_verifier, NULL));

  }

  if (frame_type == SAME_LOCALS_1_STACK_ITEM_EXTENDED) {

    // same_locals_1_stack_item_frame_extended

    if (first) {

      offset = offset_delta;

      // Can't share the locals array since that is updated by the verifier.

      if (pre_frame->locals_size() > 0) {

        locals = NEW_RESOURCE_ARRAY_IN_THREAD(

          THREAD, VerificationType, pre_frame->locals_size());

      }

    } else {

      offset = pre_frame->offset() + offset_delta + 1;

      locals = pre_frame->locals();

    }

    VerificationType* stack = NEW_RESOURCE_ARRAY_IN_THREAD(

      THREAD, VerificationType, 2);

    u2 stack_size = 1;

    stack[0] = parse_verification_type(NULL, CHECK_VERIFY_(_verifier, NULL));

    if (stack[0].is_category2()) {

      stack[1] = stack[0].to_category2_2nd();

      stack_size = 2;

    }

    check_verification_type_array_size(

      stack_size, max_stack, CHECK_VERIFY_(_verifier, NULL));

    frame = new StackMapFrame(

      offset, pre_frame->flags(), pre_frame->locals_size(), stack_size,

      max_locals, max_stack, locals, stack, _verifier);

    if (first && locals != NULL) {

      frame->copy_locals(pre_frame);

    }

    return frame;

  }

  if (frame_type <= SAME_EXTENDED) {

    // chop_frame or same_frame_extended

    locals = pre_frame->locals();

    int length = pre_frame->locals_size();

    int chops = SAME_EXTENDED - frame_type;

    int new_length = length;

    u1 flags = pre_frame->flags();

    if (chops != 0) {

      new_length = chop(locals, length, chops);

      check_verification_type_array_size(

        new_length, max_locals, CHECK_VERIFY_(_verifier, NULL));

      // Recompute flags since uninitializedThis could have been chopped.

      flags = 0;

      for (int i=0; i<new_length; i++) {

        if (locals[i].is_uninitialized_this()) {

          flags |= FLAG_THIS_UNINIT;

          break;

        }

      }

    }

    if (first) {

      offset = offset_delta;

      // Can't share the locals array since that is updated by the verifier.

      if (new_length > 0) {

        locals = NEW_RESOURCE_ARRAY_IN_THREAD(

          THREAD, VerificationType, new_length);

      } else {

        locals = NULL;

      }

    } else {

      offset = pre_frame->offset() + offset_delta + 1;

    }

    frame = new StackMapFrame(

      offset, flags, new_length, 0, max_locals, max_stack,

      locals, NULL, _verifier);

    if (first && locals != NULL) {

      frame->copy_locals(pre_frame);

    }

    return frame;

  } else if (frame_type < SAME_EXTENDED + 4) {

    // append_frame

    int appends = frame_type - SAME_EXTENDED;

    int real_length = pre_frame->locals_size();

    int new_length = real_length + appends*2;

    locals = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, VerificationType, new_length);

    VerificationType* pre_locals = pre_frame->locals();

    int i;

    for (i=0; i<pre_frame->locals_size(); i++) {

      locals[i] = pre_locals[i];

    }

    u1 flags = pre_frame->flags();

    for (i=0; i<appends; i++) {

      locals[real_length] = parse_verification_type(&flags, THREAD);

      if (locals[real_length].is_category2()) {

        locals[real_length + 1] = locals[real_length].to_category2_2nd();

        ++real_length;

      }

      ++real_length;

    }

    check_verification_type_array_size(

      real_length, max_locals, CHECK_VERIFY_(_verifier, NULL));

    if (first) {

      offset = offset_delta;

    } else {

      offset = pre_frame->offset() + offset_delta + 1;

    }

    frame = new StackMapFrame(

      offset, flags, real_length, 0, max_locals,

      max_stack, locals, NULL, _verifier);

    return frame;

  }

  if (frame_type == FULL) {

    // full_frame

    u1 flags = 0;

    u2 locals_size = _stream->get_u2(THREAD);

    int real_locals_size = 0;

    if (locals_size > 0) {

      locals = NEW_RESOURCE_ARRAY_IN_THREAD(

        THREAD, VerificationType, locals_size*2);

    }

    int i;

    for (i=0; i<locals_size; i++) {

      locals[real_locals_size] = parse_verification_type(&flags, THREAD);

      if (locals[real_locals_size].is_category2()) {

        locals[real_locals_size + 1] =

          locals[real_locals_size].to_category2_2nd();

        ++real_locals_size;

      }

      ++real_locals_size;

    }

    check_verification_type_array_size(

      real_locals_size, max_locals, CHECK_VERIFY_(_verifier, NULL));

    u2 stack_size = _stream->get_u2(THREAD);

    int real_stack_size = 0;

    VerificationType* stack = NULL;

    if (stack_size > 0) {

      stack = NEW_RESOURCE_ARRAY_IN_THREAD(

        THREAD, VerificationType, stack_size*2);

    }

    for (i=0; i<stack_size; i++) {

      stack[real_stack_size] = parse_verification_type(NULL, THREAD);

      if (stack[real_stack_size].is_category2()) {

        stack[real_stack_size + 1] = stack[real_stack_size].to_category2_2nd();

        ++real_stack_size;

      }

      ++real_stack_size;

    }

    check_verification_type_array_size(

      real_stack_size, max_stack, CHECK_VERIFY_(_verifier, NULL));

    if (first) {

      offset = offset_delta;

    } else {

      offset = pre_frame->offset() + offset_delta + 1;

    }

    frame = new StackMapFrame(

      offset, flags, real_locals_size, real_stack_size,

      max_locals, max_stack, locals, stack, _verifier);

    return frame;

  }

  _stream->stackmap_format_error(

    "reserved frame type", CHECK_VERIFY_(pre_frame->verifier(), NULL));

  return NULL;

}