Download resumption - Preliminary

content/browser/download/download_resource_handler.cc

 // Copyright (c) 2012 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/download_resource_handler.h"
 
 #include <string>
 
 #include "base/bind.h"
 #include "base/logging.h"
@@ skipping 154 matching lines @@
 
   // Get the last modified time and etag.
   const net::HttpResponseHeaders* headers = request_->response_headers();
   if (headers) {
     std::string last_modified_hdr;
     std::string etag;
     if (headers->EnumerateHeader(NULL, "Last-Modified", &last_modified_hdr))
       info->last_modified = last_modified_hdr;
     if (headers->EnumerateHeader(NULL, "ETag", &etag))
       info->etag = etag;
+
+    int status = headers->response_code();
+    if (status == 200) {  // Continue with download:
+      // Downloading the full file, even if we asked for a range.
+      // If there is a temporary file and |received_bytes == 0|, delete it.
+      save_info_->offset = 0;
+      save_info_->hash_state = "";
+    }
   }
 
   std::string content_type_header;
   if (!response->head.headers ||
       !response->head.headers->GetMimeType(&content_type_header))
     content_type_header = "";
   info->original_mime_type = content_type_header;
 
   if (!response->head.headers ||
       !response->head.headers->EnumerateHeader(
@@ skipping 130 matching lines @@
     // stack cancelled the request.  There aren't that many things that
     // could do this to a download request (whose lifetime is separated from
     // the tab from which it came).  We map this to USER_CANCELLED as the
     // case we know about (system suspend because of laptop close) corresponds
     // to a user action.
     // TODO(ahendrickson) -- Find a better set of codes to use here, as
     // CANCELED/ERR_ABORTED can occur for reasons other than user cancel.
     reason = DOWNLOAD_INTERRUPT_REASON_USER_CANCELED;
   }
 
-  if (status.is_success()) {
-    if (response_code >= 400) {
+  if (status.is_success() &&
+      (reason == DOWNLOAD_INTERRUPT_REASON_NONE) &&
+      request_->response_headers()) {
+    // Handle server's response codes.
+    if ((response_code >= 0) && ((response_code % 100) != 2)) {
       switch(response_code) {
-        case 404:  // File Not Found.
+        // Continue with download:
+        case 200:   // Downloading the full file, even if we asked for a
+                    // range.
+        case 206:   // Partial content.  Leave alone.
+          break;
+        case 204:   // No content.  File not present.
+        case 404:   // File Not Found.
           reason = DOWNLOAD_INTERRUPT_REASON_SERVER_BAD_CONTENT;
           break;
-        case 416:  // Range Not Satisfiable.
-          reason = DOWNLOAD_INTERRUPT_REASON_SERVER_NO_RANGE;
-          break;
-        case 412:  // Precondition Failed.
+        case 412:   // Precondition failed.  Fails 'If-Unmodified-Since' or
+                    // 'If-Match'.
           reason = DOWNLOAD_INTERRUPT_REASON_SERVER_PRECONDITION;
           break;
-        default:
+        case 416:  // Range Not Satisfiable.
+          // Retry by downloading from the start automatically:
+          // If we haven't received data when we get this error, we won't.
+          reason = DOWNLOAD_INTERRUPT_REASON_SERVER_NO_RANGE;
+          reason = DOWNLOAD_INTERRUPT_REASON_SERVER_PRECONDITION;
+          break;
+        default:    // All other errors.
           reason = DOWNLOAD_INTERRUPT_REASON_SERVER_FAILED;
           break;
       }
     }
   }
 
   RecordAcceptsRanges(accept_ranges_, bytes_read_);
   RecordNetworkBlockage(
       base::TimeTicks::Now() - download_start_time_, total_pause_time_);
 
@@ skipping 88 matching lines @@
 
   // Remove output stream callback if a stream exists.
   if (stream_writer_.get())
     stream_writer_->RegisterCallback(base::Closure());
 
   UMA_HISTOGRAM_TIMES("SB2.DownloadDuration",
                       base::TimeTicks::Now() - download_start_time_);
 }
 
 }  // namespace content