Added member data to classes to support download resumption.

content/browser/download/base_file.cc

 // 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.
 
 #include "content/browser/download/base_file.h"
 
 #include "base/file_util.h"
 #include "base/format_macros.h"
 #include "base/logging.h"
 #include "base/stringprintf.h"
@@ skipping 175 matching lines @@
 
 }  // namespace
 
 // This will initialize the entire array to zero.
 const unsigned char BaseFile::kEmptySha256Hash[] = { 0 };
 
 BaseFile::BaseFile(const FilePath& full_path,
                    const GURL& source_url,
                    const GURL& referrer_url,
                    int64 received_bytes,
+                   const std::string& initial_hash,
                    const linked_ptr<net::FileStream>& file_stream)
     : full_path_(full_path),
       source_url_(source_url),
       referrer_url_(referrer_url),
       file_stream_(file_stream),
       bytes_so_far_(received_bytes),
       power_save_blocker_(PowerSaveBlocker::kPowerSaveBlockPreventSystemSleep),
       calculate_hash_(false),
       detached_(false) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
-  memcpy(sha256_hash_, kEmptySha256Hash, kSha256HashLen);
+  if (initial_hash.empty() || IsEmptySha256Hash(initial_hash))
+    memcpy(sha256_hash_, kEmptySha256Hash, kSha256HashLen);
+  else
+    memcpy(sha256_hash_, initial_hash.c_str(), kSha256HashLen);
   if (file_stream_.get())
     file_stream_->EnableErrorStatistics();
 }
 
 BaseFile::~BaseFile() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
   if (detached_)
     Close();
   else
     Cancel();  // Will delete the file.
@@ skipping 154 matching lines @@
   Close();
 
   if (!full_path_.empty())
     file_util::Delete(full_path_, false);
 }
 
 void BaseFile::Finish() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
 
   if (calculate_hash_)
     secure_hash_->Finish(sha256_hash_, kSha256HashLen);

[Randy Smith (Not in Mondays), 2011/11/16 21:40:25]

I may be repenting my earlier comments; I hadn't realized that we transformed
the continuing hash into a completed value.  Doesn't this mean that
GetSha256Hash() won't work at intermediate stages?  So does the current code
actually transmit the intermediate hash values?

[ahendrickson, 2011/11/19 20:18:04]

You are correct -- GetSha256Hash() will only work properly for the final hash
value.

I have another CL that will allow saving the state of the algorithm, and
restoring it later.  It uses Pickle's to serialize & deserialize the state.

[Randy Smith (Not in Mondays), 2011/11/21 02:10:17]

*nod*; makes sense.  I'd hold this CL until that one lands (as this CL promises
functionality it can't currently deliver).

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

The CL has landed! $-)

 
   Close();
 }
 
 bool BaseFile::GetSha256Hash(std::string* hash) {
   DCHECK(!detached_);
   hash->assign(reinterpret_cast<const char*>(sha256_hash_),
                sizeof(sha256_hash_));
-  return (calculate_hash_ && !in_progress());
+  return (calculate_hash_);
 }
 
 bool BaseFile::IsEmptySha256Hash(const std::string& hash) {
   return (hash.size() == kSha256HashLen &&
           0 == memcmp(hash.data(), kEmptySha256Hash, sizeof(kSha256HashLen)));
 }
 
 void BaseFile::AnnotateWithSourceInformation() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
   DCHECK(!detached_);
@@ skipping 63 matching lines @@
 std::string BaseFile::DebugString() const {
   return base::StringPrintf("{ source_url_ = \"%s\""
                             " full_path_ = \"%" PRFilePath "\""
                             " bytes_so_far_ = %" PRId64
                             " detached_ = %c }",
                             source_url_.spec().c_str(),
                             full_path_.value().c_str(),
                             bytes_so_far_,
                             detached_ ? 'T' : 'F');
 }