Add support to sha256 hash the downloaded file....

chrome/browser/download/base_file.h

 // Copyright (c) 2010 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.
 
 #ifndef CHROME_BROWSER_DOWNLOAD_BASE_FILE_H_
 #define CHROME_BROWSER_DOWNLOAD_BASE_FILE_H_
 #pragma once
 
 #include <string>
 
 #include "base/file_path.h"
 #include "base/linked_ptr.h"
+#include "base/scoped_ptr.h"
+#include "base/third_party/nss/blapi.h"
 #include "chrome/browser/power_save_blocker.h"
 #include "googleurl/src/gurl.h"
 
 namespace net {
 class FileStream;
 }
 
 // File being downloaded and saved to disk. This is a base class
 // for DownloadFile and SaveFile, which keep more state information.
 class BaseFile {
  public:
   BaseFile(const FilePath& full_path,
            const GURL& source_url,
            const GURL& referrer_url,
            int64 received_bytes,
            const linked_ptr<net::FileStream>& file_stream);
   ~BaseFile();
 
-  bool Initialize();
+  // If calculate_hash is true, sha256 hash will be calculated.
+  bool Initialize(bool calculate_hash);
 
   // Write a new chunk of data to the file. Returns true on success (all bytes
   // written to the file).
   bool AppendDataToFile(const char* data, size_t data_len);
 
   // Rename the download file. Returns true on success.
   // |path_renamed_| is set to true only if |is_final_rename| is true.
   // Marked virtual for testing.
   virtual bool Rename(const FilePath& full_path, bool is_final_rename);
 
   // Abort the download and automatically close the file.
   void Cancel();
 
   // Indicate that the download has finished. No new data will be received.
   void Finish();
 
   // Informs the OS that this file came from the internet.
   void AnnotateWithSourceInformation();
 
   FilePath full_path() const { return full_path_; }
   bool path_renamed() const { return path_renamed_; }
   bool in_progress() const { return file_stream_ != NULL; }
   int64 bytes_so_far() const { return bytes_so_far_; }
 
+  // Set |hash| with sha256 digest for the file.
+  // Returns true if digest is successfully calculated.
+  virtual bool GetSha256Hash(std::string* hash);
+
   virtual std::string DebugString() const;
 
  protected:
   bool Open();
   void Close();
 
   // Full path to the file including the file name.
   FilePath full_path_;
 
   // Whether the download is still using its initial temporary path.
   bool path_renamed_;
 
  private:
+  static const size_t kSha256HashLen = 32;
+
   // Source URL for the file being downloaded.
   GURL source_url_;
 
   // The URL where the download was initiated.
   GURL referrer_url_;
 
   // OS file stream for writing
   linked_ptr<net::FileStream> file_stream_;
 
   // Amount of data received up so far, in bytes.
   int64 bytes_so_far_;
 
   // RAII handle to keep the system from sleeping while we're downloading.
   PowerSaveBlocker power_save_blocker_;
 
+  // Indicates if sha256 hash should be calculated for the file.
+  bool calculate_hash_;
+
+  // Used to calculate sha256 hash for the file when calculate_hash_
+  // is set.
+  scoped_ptr<SHA256Context> sha_context_;
+
+  unsigned char sha256_hash_[kSha256HashLen];
+
   DISALLOW_COPY_AND_ASSIGN(BaseFile);
 };
 
 #endif  // CHROME_BROWSER_DOWNLOAD_BASE_FILE_H_