Added member data to classes to support download resumption.

content/browser/download/base_file.h

 // Copyright (c) 2011 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 CONTENT_BROWSER_DOWNLOAD_BASE_FILE_H_
 #define CONTENT_BROWSER_DOWNLOAD_BASE_FILE_H_
 #pragma once
 
 #include <string>
 
@@ skipping 14 matching lines @@
 }
 
 // File being downloaded and saved to disk. This is a base class
 // for DownloadFile and SaveFile, which keep more state information.
 class CONTENT_EXPORT BaseFile {
  public:
   BaseFile(const FilePath& full_path,
            const GURL& source_url,
            const GURL& referrer_url,
            int64 received_bytes,
+           const std::string& initial_hash,

[Randy Smith (Not in Mondays), 2011/11/16 18:29:27]

In the cases in which we specify an initial_hash, we're going to want to be
specifying an existing file and an offset within that file at which to start,
correct?  Should those be here as well/how are you planning to specify those?

[ahendrickson, 2011/11/19 20:18:03]

Those are already here.

file_stream will be used to specify the location of the file that already has
data, or for restarts the location that we've already decided on.

received_bytes will be non-zero for files that already have data (continued).

[Randy Smith (Not in Mondays), 2011/11/21 02:10:16]

file_stream is fairly often not set; are you making the design decision to set
it always on the continuation pathway?  I'm uncomfortable with that, both
because I don't like that file stream is here (I don't understand the use cases
in which the download system needs to be passed a file descriptor rather than a
file name) and because it represents yet more conditionals as we go through the
code.  
D'oh; right.

[ahendrickson, 2011/11/21 20:34:46]

My mistake; the file is specified in full_path, not file_stream.

BaseFile doesn't know the difference between the intermediate and final files.

When we discover an existing download item, we will set DownloadCreateInfo's
save_info.file_path to the current file name that we are writing to.  When
DownloadFile is constructed, it uses that value to open the file.

            const linked_ptr<net::FileStream>& file_stream);
   virtual ~BaseFile();
 
   // If calculate_hash is true, sha256 hash will be calculated.
   // Returns net::OK on success, or a network error code on failure.
   net::Error Initialize(bool calculate_hash);
 
   // Write a new chunk of data to the file.
   // Returns net::OK on success (all bytes written to the file),
   // or a network error code on failure.
@@ skipping 12 matching lines @@
   // 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 in_progress() const { return file_stream_ != NULL; }
   int64 bytes_so_far() const { return bytes_so_far_; }
 
-  // Set |hash| with sha256 digest for the file.
+  // Gets |hash| with sha256 digest for the file.  May be partial.
   // Returns true if digest is successfully calculated.
   virtual bool GetSha256Hash(std::string* hash);
 
   // Returns true if the given hash is considered empty.  An empty hash is
   // a string of size kSha256HashLen that contains only zeros (initial value
   // for the hash).
   static bool IsEmptySha256Hash(const std::string& hash);
 
   virtual std::string DebugString() const;
 
@@ skipping 39 matching lines @@
   unsigned char sha256_hash_[kSha256HashLen];
 
   // Indicates that this class no longer owns the associated file, and so
   // won't delete it on destruction.
   bool detached_;
 
   DISALLOW_COPY_AND_ASSIGN(BaseFile);
 };
 
 #endif  // CONTENT_BROWSER_DOWNLOAD_BASE_FILE_H_