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

chrome/browser/download/base_file.cc

Index: chrome/browser/download/base_file.cc
===================================================================
--- chrome/browser/download/base_file.cc	(revision 70630)
+++ chrome/browser/download/base_file.cc	(working copy)
@@ -6,7 +6,11 @@
 
 #include "base/file_util.h"
 #include "base/logging.h"
+#include "base/string_number_conversions.h"
+#include "base/string_util.h"
 #include "base/stringprintf.h"
+#include "base/third_party/nss/blapi.h"
+#include "base/third_party/nss/sha256.h"
 #include "net/base/file_stream.h"
 #include "net/base/net_errors.h"
 #include "chrome/browser/browser_thread.h"
@@ -23,14 +27,17 @@
                    const GURL& source_url,
                    const GURL& referrer_url,
                    int64 received_bytes,
-                   const linked_ptr<net::FileStream>& file_stream)
+                   const linked_ptr<net::FileStream>& file_stream,
+                   bool calculate_hash)
     : full_path_(full_path),
       path_renamed_(false),
       source_url_(source_url),
       referrer_url_(referrer_url),
       file_stream_(file_stream),
       bytes_so_far_(received_bytes),
-      power_save_blocker_(true) {
+      power_save_blocker_(true),
+      calculate_hash_(calculate_hash),
+      sha_context_(NULL) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
 }
 
@@ -43,6 +50,12 @@
 
 bool BaseFile::Initialize() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
+
+  if (calculate_hash_) {
+    sha_context_.reset(new SHA256Context);
+    SHA256_Begin(sha_context_.get());
+  }
+
   if (!full_path_.empty() ||
       download_util::CreateTemporaryFileForDownload(&full_path_))
     return Open();
@@ -59,6 +72,12 @@
   if (data_len == 0)
     return true;
 
+  if (calculate_hash_) {
+    SHA256_Update(sha_context_.get(),

[Paweł Hajdan Jr., 2011/01/11 08:28:21]

Hmm, I wonder if we should somehow check result of file_stream_->Write below. If
that one fails, the calculated hash will get out of sync with real contents on
disk.

[lzheng, 2011/01/12 02:11:54]

Done.

+                  reinterpret_cast<const unsigned char*>(data),
+                  data_len);
+  }
+
   bytes_so_far_ += data_len;
 
   // TODO(phajdan.jr): handle errors on file writes. http://crbug.com/58355
@@ -140,8 +159,19 @@
 void BaseFile::Finish() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
   Close();
+  if (calculate_hash_) {
+    SHA256_End(sha_context_.get(), sha256_hash_, NULL, kSha256HashLen_);
+  }
 }
 
+bool BaseFile::GetSha256Hash(std::string* hash) {
+  if (!calculate_hash_)
+    return false;
+  *hash =
+      StringToLowerASCII(base::HexEncode(sha256_hash_, sizeof(sha256_hash_)));

[Randy Smith (Not in Mondays), 2011/01/11 18:29:51]

This means that the hash can be grabbed at any time during the download process,
and it'll be the hash to this point but not completed?  That seems like not what
you'd like; wouldn't you prefer GetSha256Hash to return false if the downloading
hasn't yet completed?

+  return true;
+}
+
 void BaseFile::AnnotateWithSourceInformation() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
 #if defined(OS_WIN)