chrome/browser/media_galleries/fileapi/safe_media_metadata_parser.h

   1 // Copyright 2014 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 #ifndef CHROME_BROWSER_MEDIA_GALLERIES_FILEAPI_SAFE_MEDIA_METADATA_PARSER_H_
   6 #define CHROME_BROWSER_MEDIA_GALLERIES_FILEAPI_SAFE_MEDIA_METADATA_PARSER_H_
   7
   8 #include <string>
   9 #include <vector>
  10
  11 #include "base/callback.h"
  12 #include "base/compiler_specific.h"
  13 #include "base/memory/scoped_ptr.h"
  14 #include "base/memory/weak_ptr.h"
  15 #include "chrome/common/extensions/api/media_galleries.h"
  16 #include "chrome/common/media_galleries/metadata_types.h"
  17 #include "content/public/browser/utility_process_host.h"
  18 #include "content/public/browser/utility_process_host_client.h"
  19
  20 namespace IPC {
  21 class Message;
  22 }
  23
  24 class Profile;
  25
  26 namespace metadata {
  27
  28 // Parses the media metadata of a Blob safely in a utility process. This class
  29 // expects the MIME type of the Blob to be already determined. It spawns a
  30 // utility process to do further MIME-type specific metadata extraction.
  31 // All public methods and callbacks of this class run on the UI thread.
  32 class SafeMediaMetadataParser : public content::UtilityProcessHostClient {
  33  public:
  34   // |metadata_dictionary| is owned by the callback.
  35   typedef base::Callback<
  36       void(bool parse_success,
  37            scoped_ptr<base::DictionaryValue> metadata_dictionary,
  38            scoped_ptr<std::vector<AttachedImage> > attached_images)>
  39       DoneCallback;
  40
  41   SafeMediaMetadataParser(Profile* profile, const std::string& blob_uuid,
  42                           int64 blob_size, const std::string& mime_type,
  43                           bool get_attached_images);
  44
  45   // Should be called on the UI thread. |callback| also runs on the UI thread.
  46   void Start(const DoneCallback& callback);
  47
  48  private:
  49   enum ParserState {
  50     INITIAL_STATE,
  51     STARTED_PARSING_STATE,
  52     FINISHED_PARSING_STATE,
  53   };
  54
  55   // Private because content::UtilityProcessHostClient is ref-counted.
  56   ~SafeMediaMetadataParser() override;
  57
  58   // Launches the utility process.  Must run on the IO thread.
  59   void StartWorkOnIOThread(const DoneCallback& callback);
  60
  61   // Notification from the utility process when it finishes parsing metadata.
  62   // Runs on the IO thread.
  63   void OnParseMediaMetadataFinished(
  64       bool parse_success, const base::DictionaryValue& metadata_dictionary,
  65       const std::vector<AttachedImage>& attached_images);
  66
  67   // Sequence of functions that bounces from the IO thread to the UI thread to
  68   // read the blob data, then sends the data back to the utility process.
  69   void OnUtilityProcessRequestBlobBytes(int64 request_id, int64 byte_start,
  70                                         int64 length);
  71   void StartBlobReaderOnUIThread(int64 request_id, int64 byte_start,
  72                                  int64 length);
  73   void OnBlobReaderDoneOnUIThread(int64 request_id,
  74                                   scoped_ptr<std::string> data,
  75                                   int64 /* blob_total_size */);
  76   void FinishRequestBlobBytes(int64 request_id, scoped_ptr<std::string> data);
  77
  78   // UtilityProcessHostClient implementation.
  79   // Runs on the IO thread.
  80   void OnProcessCrashed(int exit_code) override;
  81   bool OnMessageReceived(const IPC::Message& message) override;
  82
  83   // All member variables are only accessed on the IO thread.
  84   Profile* const profile_;
  85   const std::string blob_uuid_;
  86   const int64 blob_size_;
  87   const std::string mime_type_;
  88   bool get_attached_images_;
  89
  90   DoneCallback callback_;
  91
  92   base::WeakPtr<content::UtilityProcessHost> utility_process_host_;
  93
  94   // Verifies the messages from the utility process came at the right time.
  95   // Initialized on the UI thread, but only accessed on the IO thread.
  96   ParserState parser_state_;
  97
  98   DISALLOW_COPY_AND_ASSIGN(SafeMediaMetadataParser);
  99 };
 100
 101 }  // namespace metadata
 102
 103 #endif  // CHROME_BROWSER_MEDIA_GALLERIES_FILEAPI_SAFE_MEDIA_METADATA_PARSER_H_