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      1 /*
      2  * Copyright (C) 2017 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #include "dex_file_exception_helpers.h"
     18 
     19 #include "code_item_accessors-inl.h"
     20 
     21 namespace art {
     22 
     23 CatchHandlerIterator::CatchHandlerIterator(const CodeItemDataAccessor& accessor, uint32_t address) {
     24   handler_.address_ = -1;
     25   int32_t offset = -1;
     26 
     27   // Short-circuit the overwhelmingly common cases.
     28   switch (accessor.TriesSize()) {
     29     case 0:
     30       break;
     31     case 1: {
     32       const DexFile::TryItem* tries = accessor.TryItems().begin();
     33       uint32_t start = tries->start_addr_;
     34       if (address >= start) {
     35         uint32_t end = start + tries->insn_count_;
     36         if (address < end) {
     37           offset = tries->handler_off_;
     38         }
     39       }
     40       break;
     41     }
     42     default: {
     43       const DexFile::TryItem* try_item = accessor.FindTryItem(address);
     44       offset = try_item != nullptr ? try_item->handler_off_ : -1;
     45       break;
     46     }
     47   }
     48   Init(accessor, offset);
     49 }
     50 
     51 CatchHandlerIterator::CatchHandlerIterator(const CodeItemDataAccessor& accessor,
     52                                            const DexFile::TryItem& try_item) {
     53   handler_.address_ = -1;
     54   Init(accessor, try_item.handler_off_);
     55 }
     56 
     57 void CatchHandlerIterator::Init(const CodeItemDataAccessor& accessor, int32_t offset) {
     58   if (offset >= 0) {
     59     Init(accessor.GetCatchHandlerData(offset));
     60   } else {
     61     // Not found, initialize as empty
     62     current_data_ = nullptr;
     63     remaining_count_ = -1;
     64     catch_all_ = false;
     65     DCHECK(!HasNext());
     66   }
     67 }
     68 
     69 void CatchHandlerIterator::Init(const uint8_t* handler_data) {
     70   current_data_ = handler_data;
     71   remaining_count_ = DecodeSignedLeb128(&current_data_);
     72 
     73   // If remaining_count_ is non-positive, then it is the negative of
     74   // the number of catch types, and the catches are followed by a
     75   // catch-all handler.
     76   if (remaining_count_ <= 0) {
     77     catch_all_ = true;
     78     remaining_count_ = -remaining_count_;
     79   } else {
     80     catch_all_ = false;
     81   }
     82   Next();
     83 }
     84 
     85 void CatchHandlerIterator::Next() {
     86   if (remaining_count_ > 0) {
     87     handler_.type_idx_ = dex::TypeIndex(DecodeUnsignedLeb128(&current_data_));
     88     handler_.address_  = DecodeUnsignedLeb128(&current_data_);
     89     remaining_count_--;
     90     return;
     91   }
     92 
     93   if (catch_all_) {
     94     handler_.type_idx_ = dex::TypeIndex(DexFile::kDexNoIndex16);
     95     handler_.address_  = DecodeUnsignedLeb128(&current_data_);
     96     catch_all_ = false;
     97     return;
     98   }
     99 
    100   // no more handler
    101   remaining_count_ = -1;
    102 }
    103 
    104 }  // namespace art
    105