Unify the error checking of crypto::Encryptor and add WARN_UNUSED_RESULT to prevent misuse.

crypto/encryptor_unittest.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 "crypto/encryptor.h"
 
 #include <string>
 
 #include "base/memory/scoped_ptr.h"
 #include "base/string_number_conversions.h"
@@ skipping 60 matching lines @@
 }
 
 TEST(EncryptorTest, CTRCounter) {
   const int kCounterSize = 16;
   const char kTest1[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
   uint8 buf[16];
 
   // Increment 10 times.
   crypto::Encryptor::Counter counter1(std::string(kTest1, kCounterSize));
   for (int i = 0; i < 10; ++i)
-    counter1.Increment();
+    EXPECT_TRUE(counter1.Increment());
   counter1.Write(buf);
   EXPECT_EQ(0, memcmp(buf, kTest1, 15));
   EXPECT_TRUE(buf[15] == 10);
 
   // Check corner cases.
   const char kTest2[] = {0, 0, 0, 0, 0, 0, 0, 0,
                          0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff};
   const char kExpect2[] = {0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0};
   crypto::Encryptor::Counter counter2(std::string(kTest2, kCounterSize));
-  counter2.Increment();
+  EXPECT_TRUE(counter2.Increment());
   counter2.Write(buf);
   EXPECT_EQ(0, memcmp(buf, kExpect2, kCounterSize));
 
   const char kTest3[] = {0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
                          0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff};
   const char kExpect3[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
   crypto::Encryptor::Counter counter3(std::string(kTest3, kCounterSize));
-  counter3.Increment();
+  EXPECT_TRUE(counter3.Increment());
   counter3.Write(buf);
   EXPECT_EQ(0, memcmp(buf, kExpect3, kCounterSize));
 }
 
 #endif
 
 // TODO(wtc): add more known-answer tests.  Test vectors are available from
 // http://www.ietf.org/rfc/rfc3602
 // http://csrc.nist.gov/publications/nistpubs/800-38a/sp800-38a.pdf
 // http://gladman.plushost.co.uk/oldsite/AES/index.php
@@ skipping 164 matching lines @@
   crypto::Encryptor encryptor;
   // The IV must be exactly as long a the cipher block size.
   EXPECT_EQ(16U, iv.size());
   EXPECT_TRUE(encryptor.Init(sym_key.get(), crypto::Encryptor::CBC, iv));
 
   std::string ciphertext;
   EXPECT_TRUE(encryptor.Encrypt(plaintext, &ciphertext));
   EXPECT_EQ(expected_ciphertext_hex, base::HexEncode(ciphertext.data(),
                                                      ciphertext.size()));
 }