Fix for 0-length file problem in content verification

extensions/browser/computed_hashes_unittest.cc

 // Copyright 2014 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 "base/base64.h"
 #include "base/files/file_path.h"
 #include "base/files/scoped_temp_dir.h"
 #include "crypto/sha2.h"
 #include "extensions/browser/computed_hashes.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
+namespace {
+
+// Helper to return base64 encode result by value.
+std::string Base64Encode(std::string data) {

[Ken Rockot(use gerrit already), 2014/08/05 23:10:32]

nit: Might as well pass |data| as a const ref?

[asargent_no_longer_on_chrome, 2014/08/06 04:47:33]

Good catch, done. 

+  std::string result;
+  base::Base64Encode(data, &result);
+  return result;
+}
+
+}  // namespace
+
 namespace extensions {
 
 TEST(ComputedHashes, ComputedHashes) {
   base::ScopedTempDir scoped_dir;
   ASSERT_TRUE(scoped_dir.CreateUniqueTempDir());
   base::FilePath computed_hashes =
       scoped_dir.path().AppendASCII("computed_hashes.json");
 
   // We'll add hashes for 2 files, one of which uses a subdirectory
   // path. The first file will have a list of 1 block hash, and the
@@ skipping 31 matching lines @@
 
   // Finally make sure that we can retrieve the hashes for the subdir
   // path even when that path contains forward slashes (on windows).
   base::FilePath path2_fwd_slashes =
       base::FilePath::FromUTF8Unsafe("foo/bar.txt");
   block_size = 0;
   EXPECT_TRUE(reader.GetHashes(path2_fwd_slashes, &block_size, &read_hashes2));
   EXPECT_EQ(hashes2, read_hashes2);
 }
 
+// Note: the expected hashes used in this test were generated using linux
+// command line tools. E.g., from a bash prompt:
+//  $ printf "hello world" | openssl dgst -sha256 -binary | base64
+//
+// The file with multiple-blocks expectations were generated by doing:
+// $ for i in `seq 500 ; do printf "hello world" ; done > hello.txt
+// $ dd if=hello.txt bs=4096 count=1 | openssl dgst -sha256 -binary | base64
+// $ dd if=hello.txt skip=1 bs=4096 count=1 | \
+//   openssl dgst -sha256 -binary | base64
+TEST(ComputedHashes, ComputeHashesForContent) {
+  const int block_size = 4096;
+
+  // Simple short input.
+  std::string content1 = "hello world";
+  std::string content1_expected_hash =
+      "uU0nuZNNPgilLlLX2n2r+sSE7+N6U4DukIj3rOLvzek=";
+  std::vector<std::string> hashes1;
+  ComputedHashes::ComputeHashesForContent(content1, block_size, &hashes1);
+  ASSERT_EQ(1u, hashes1.size());
+  EXPECT_EQ(content1_expected_hash, Base64Encode(hashes1[0]));
+
+  // Multiple blocks input.
+  std::string content2;
+  for (int i = 0; i < 500; i++)
+    content2 += "hello world";
+  const char* content2_expected_hashes[] = {
+      "bvtt5hXo8xvHrlzGAhhoqPL/r+4zJXHx+6wAvkv15V8=",
+      "lTD45F7P6I/HOdi8u7FLRA4qzAYL+7xSNVeusG6MJI0="};
+  std::vector<std::string> hashes2;
+  ComputedHashes::ComputeHashesForContent(content2, block_size, &hashes2);
+  ASSERT_EQ(2u, hashes2.size());
+  EXPECT_EQ(content2_expected_hashes[0], Base64Encode(hashes2[0]));
+  EXPECT_EQ(content2_expected_hashes[1], Base64Encode(hashes2[1]));
+
+  // Now an empty input.
+  std::string content3;
+  std::vector<std::string> hashes3;
+  ComputedHashes::ComputeHashesForContent(content3, block_size, &hashes3);
+  ASSERT_EQ(1u, hashes3.size());
+  ASSERT_EQ(std::string("47DEQpj8HBSa+/TImW+5JCeuQeRkm5NMpJWZG3hSuFU="),
+            Base64Encode(hashes3[0]));
+}
+
 }  // namespace extensions