chrome/utility/media_galleries/iapps_xml_utils.cc

   1 // Copyright 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "chrome/utility/media_galleries/iapps_xml_utils.h"
   6
   7 #include "base/logging.h"
   8 #include "base/stl_util.h"
   9 #include "base/strings/string_number_conversions.h"
  10 #include "third_party/libxml/chromium/libxml_utils.h"
  11
  12 namespace iapps {
  13
  14 bool SkipToNextElement(XmlReader* reader) {
  15   if (!reader->SkipToElement()) {
  16     // SkipToElement returns false if the current node is an end element,
  17     // try to advance to the next element and then try again.
  18     if (!reader->Read() || !reader->SkipToElement())
  19       return false;
  20   }
  21   return true;
  22 }
  23
  24 bool SeekToNodeAtCurrentDepth(XmlReader* reader, const std::string& name) {
  25   int depth = reader->Depth();
  26   do {
  27     if (!SkipToNextElement(reader) || reader->Depth() < depth)
  28       return false;
  29     DCHECK_EQ(depth, reader->Depth());
  30     if (reader->NodeName() == name)
  31       return true;
  32   } while (reader->Next());
  33
  34   return false;
  35 }
  36
  37 bool SeekInDict(XmlReader* reader, const std::string& key) {
  38   DCHECK_EQ("dict", reader->NodeName());
  39
  40   int dict_content_depth = reader->Depth() + 1;
  41   // Advance past the dict node and into the body of the dictionary.
  42   if (!reader->Read())
  43     return false;
  44
  45   while (reader->Depth() >= dict_content_depth) {
  46     if (!SeekToNodeAtCurrentDepth(reader, "key"))
  47       return false;
  48     std::string found_key;
  49     if (!reader->ReadElementContent(&found_key))
  50       return false;
  51     DCHECK_EQ(dict_content_depth, reader->Depth());
  52     if (found_key == key)
  53       return true;
  54   }
  55   return false;
  56 }
  57
  58 // Seek to the start of a tag and read the value into |result| if the node's
  59 // name is |node_name|.
  60 bool ReadSimpleValue(XmlReader* reader, const std::string& node_name,
  61                      std::string* result) {
  62   if (!iapps::SkipToNextElement(reader))
  63       return false;
  64   if (reader->NodeName() != node_name)
  65     return false;
  66   return reader->ReadElementContent(result);
  67 }
  68
  69 bool ReadString(XmlReader* reader, std::string* result) {
  70   return ReadSimpleValue(reader, "string", result);
  71 }
  72
  73 bool ReadInteger(XmlReader* reader, uint64* result) {
  74   std::string value;
  75   if (!ReadSimpleValue(reader, "integer", &value))
  76     return false;
  77   return base::StringToUint64(value, result);
  78 }
  79
  80 std::string ReadPlatformFileAsString(const base::PlatformFile file) {
  81   std::string result;
  82   if (file == base::kInvalidPlatformFileValue)
  83     return result;
  84
  85   // A "reasonable" artificial limit.
  86   // TODO(vandebo): Add a UMA to figure out what common values are.
  87   const int64 kMaxLibraryFileSize = 150 * 1024 * 1024;
  88   base::PlatformFileInfo file_info;
  89   if (!base::GetPlatformFileInfo(file, &file_info) ||
  90       file_info.size > kMaxLibraryFileSize) {
  91     base::ClosePlatformFile(file);
  92     return result;
  93   }
  94
  95   result.resize(file_info.size);
  96   int bytes_read =
  97       base::ReadPlatformFile(file, 0, string_as_array(&result), file_info.size);
  98   if (bytes_read != file_info.size)
  99     result.clear();
 100
 101   base::ClosePlatformFile(file);
 102   return result;
 103 }
 104
 105 }  // namespace iapps