chrome/utility/media_galleries/iapps_xml_utils.cc

// Copyright 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "chrome/utility/media_galleries/iapps_xml_utils.h"

#include "base/logging.h"
#include "base/stl_util.h"
#include "base/strings/string_number_conversions.h"
#include "third_party/libxml/chromium/libxml_utils.h"

namespace iapps {

bool SkipToNextElement(XmlReader* reader) {
  if (!reader->SkipToElement()) {
    // SkipToElement returns false if the current node is an end element,
    // try to advance to the next element and then try again.
    if (!reader->Read() || !reader->SkipToElement())
      return false;
  }
  return true;
}

bool SeekToNodeAtCurrentDepth(XmlReader* reader, const std::string& name) {
  int depth = reader->Depth();
  do {
    if (!SkipToNextElement(reader) || reader->Depth() < depth)
      return false;
    DCHECK_EQ(depth, reader->Depth());
    if (reader->NodeName() == name)
      return true;
  } while (reader->Next());

  return false;
}

bool SeekInDict(XmlReader* reader, const std::string& key) {
  DCHECK_EQ("dict", reader->NodeName());

  int dict_content_depth = reader->Depth() + 1;
  // Advance past the dict node and into the body of the dictionary.
  if (!reader->Read())
    return false;

  while (reader->Depth() >= dict_content_depth) {
    if (!SeekToNodeAtCurrentDepth(reader, "key"))
      return false;
    std::string found_key;
    if (!reader->ReadElementContent(&found_key))
      return false;
    DCHECK_EQ(dict_content_depth, reader->Depth());
    if (found_key == key)
      return true;
  }
  return false;
}

// Seek to the start of a tag and read the value into |result| if the node's
// name is |node_name|.
bool ReadSimpleValue(XmlReader* reader, const std::string& node_name,
                     std::string* result) {
  if (!iapps::SkipToNextElement(reader))
      return false;
  if (reader->NodeName() != node_name)
    return false;
  return reader->ReadElementContent(result);
}

bool ReadString(XmlReader* reader, std::string* result) {
  return ReadSimpleValue(reader, "string", result);
}

bool ReadInteger(XmlReader* reader, uint64* result) {
  std::string value;
  if (!ReadSimpleValue(reader, "integer", &value))
    return false;
  return base::StringToUint64(value, result);
}

std::string ReadPlatformFileAsString(const base::PlatformFile file) {
  std::string result;
  if (file == base::kInvalidPlatformFileValue)
    return result;

  // A "reasonable" artificial limit.
  // TODO(vandebo): Add a UMA to figure out what common values are.
  const int64 kMaxLibraryFileSize = 150 * 1024 * 1024;
  base::PlatformFileInfo file_info;
  if (!base::GetPlatformFileInfo(file, &file_info) ||
      file_info.size > kMaxLibraryFileSize) {
    base::ClosePlatformFile(file);
    return result;
  }

  result.resize(file_info.size);
  int bytes_read =
      base::ReadPlatformFile(file, 0, string_as_array(&result), file_info.size);
  if (bytes_read != file_info.size)
    result.clear();

  base::ClosePlatformFile(file);
  return result;
}

}  // namespace iapps