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 /*

  * 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.

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  */

 #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;

 }