1    :  // Copyright 2012 Google Inc.
   2    :  //
   3    :  // Licensed under the Apache License, Version 2.0 (the "License");
   4    :  // you may not use this file except in compliance with the License.
   5    :  // You may obtain a copy of the License at
   6    :  //
   7    :  //     http://www.apache.org/licenses/LICENSE-2.0
   8    :  //
   9    :  // Unless required by applicable law or agreed to in writing, software
  10    :  // distributed under the License is distributed on an "AS IS" BASIS,
  11    :  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  12    :  // See the License for the specific language governing permissions and
  13    :  // limitations under the License.
  14    :  
  15    :  #include "syzygy/block_graph/transforms/trim_transform.h"
  16    :  
  17    :  namespace block_graph {
  18    :  namespace transforms {
  19    :  
  20    :  namespace {
  21    :  
  22    :  // Returns the length of the initialized data for the given block.
  23  E :  size_t InitializedDataSize(const BlockGraph::Block* block) {
  24  E :    size_t size = 0;
  25    :  
  26  E :    if (!block->references().empty()) {
  27    :      // NOTE: This relies on ReferenceMap being sorted by the offset!
  28    :      BlockGraph::Block::ReferenceMap::const_iterator ref =
  29  E :          --block->references().end();
  30  E :      size = ref->first + ref->second.size();
  31  E :    }
  32    :  
  33    :    // If we have no data it consists of implicit zeros.
  34  E :    if (block->data() == NULL || block->data_size() <= size)
  35  E :      return size;
  36    :  
  37    :    // If we do have data then we peel off any explicit zeros at the end of the
  38    :    // buffer.
  39  E :    const uint8* data = block->data() + block->data_size() - 1;
  40  E :    for (size_t i = block->data_size(); i > size; --i, --data) {
  41  E :      if (*data != 0)
  42  E :        return i;
  43  E :    }
  44    :  
  45  E :    return size;
  46  E :  }
  47    :  
  48    :  }  // namespace
  49    :  
  50    :  const char TrimTransform::kTransformName[] = "TrimTransform";
  51    :  
  52    :  bool TrimTransform::OnBlock(BlockGraph* /* block_graph */,
  53  E :                              BlockGraph::Block* block) {
  54  E :    DCHECK(block != NULL);
  55    :  
  56  E :    size_t init_size = InitializedDataSize(block);
  57  E :    if (init_size != block->data_size())
  58  E :      block->ResizeData(init_size);
  59    :  
  60  E :    return true;
  61  E :  }
  62    :  
  63    :  }  // namespace transforms
  64    :  }  // namespace block_graph