Fix content verification code for undreadable and deleted files.

extensions/browser/content_verify_job.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 "extensions/browser/content_verify_job.h"
 
 #include <algorithm>
 
 #include "base/metrics/histogram_macros.h"
 #include "base/stl_util.h"
@@ skipping 116 matching lines @@
     return;
   if (g_test_delegate) {
     FailureReason reason =
         g_test_delegate->DoneReading(hash_reader_->extension_id());
     if (reason != NONE)
       DispatchFailureCallback(reason);
     return;
   }
   done_reading_ = true;
   if (hashes_ready_) {
-    if (!FinishBlock())
+    if (!FinishBlock()) {
       DispatchFailureCallback(HASH_MISMATCH);
-    else if (g_test_observer)
+    } else if (g_test_observer) {
       g_test_observer->JobFinished(hash_reader_->extension_id(),
-                                   hash_reader_->relative_path(), failed_);
+                                   hash_reader_->relative_path(), NONE);
+    }
   }
 }
 
 bool ContentVerifyJob::FinishBlock() {
-  if (current_hash_byte_count_ <= 0)
+  if (!done_reading_ && current_hash_byte_count_ == 0)
     return true;
+  if (!current_hash_) {
+    // This happens when we fail to read the resource. Compute empty content's
+    // hash in this case.
+    current_hash_ = crypto::SecureHash::Create(crypto::SecureHash::SHA256);
+  }
   std::string final(crypto::kSHA256Length, 0);
   current_hash_->Finish(base::string_as_array(& final), final.size());
   current_hash_.reset();
   current_hash_byte_count_ = 0;
 
   int block = current_block_++;
 
   const std::string* expected_hash = NULL;
   if (!hash_reader_->GetHashForBlock(block, &expected_hash) ||
-      *expected_hash != final)
+      *expected_hash != final) {
     return false;
+  }
 
   return true;
 }
 
 void ContentVerifyJob::OnHashesReady(bool success) {
   if (!success && !g_test_delegate) {
-    if (!hash_reader_->content_exists()) {
+    // TODO(lazyboy): Make ContentHashReader::Init return an enum instead of
+    // bool. This should make the following checks on |hash_reader_| easier
+    // to digest and will avoid future bugs from creeping up.
+    if (!hash_reader_->have_verified_contents() ||
+        !hash_reader_->have_computed_hashes()) {
+      DispatchFailureCallback(MISSING_ALL_HASHES);
+      return;
+    }
+
+    if (hash_reader_->file_missing_from_verified_contents()) {
       // Ignore verification of non-existent resources.
+      if (g_test_observer) {
+        g_test_observer->JobFinished(hash_reader_->extension_id(),
+                                     hash_reader_->relative_path(), NONE);
+      }
       return;
-    } else if (hash_reader_->have_verified_contents() &&
-               hash_reader_->have_computed_hashes()) {
-      DispatchFailureCallback(NO_HASHES_FOR_FILE);
-    } else {
-      DispatchFailureCallback(MISSING_ALL_HASHES);
     }
+    DispatchFailureCallback(NO_HASHES_FOR_FILE);
     return;
   }
 
   hashes_ready_ = true;
   if (!queue_.empty()) {
     std::string tmp;
     queue_.swap(tmp);
     BytesRead(tmp.size(), base::string_as_array(&tmp));
   }
   if (done_reading_) {
     ScopedElapsedTimer timer(&time_spent_);
     if (!FinishBlock()) {
       DispatchFailureCallback(HASH_MISMATCH);
     } else if (g_test_observer) {
       g_test_observer->JobFinished(hash_reader_->extension_id(),
-                                   hash_reader_->relative_path(), failed_);
+                                   hash_reader_->relative_path(), NONE);
     }
   }
 }
 
 // static
 void ContentVerifyJob::SetDelegateForTests(TestDelegate* delegate) {
   DCHECK(delegate == nullptr || g_test_delegate == nullptr)
       << "SetDelegateForTests does not support interleaving. Delegates should "
       << "be set and then cleared one at a time.";
   g_test_delegate = delegate;
 }
 
 // static
 void ContentVerifyJob::SetObserverForTests(TestObserver* observer) {
   g_test_observer = observer;
 }
 
 void ContentVerifyJob::DispatchFailureCallback(FailureReason reason) {
   DCHECK(!failed_);
   failed_ = true;
   if (!failure_callback_.is_null()) {
     VLOG(1) << "job failed for " << hash_reader_->extension_id() << " "
             << hash_reader_->relative_path().MaybeAsASCII()
             << " reason:" << reason;
     failure_callback_.Run(reason);
     failure_callback_.Reset();
   }
-  if (g_test_observer)
-    g_test_observer->JobFinished(
-        hash_reader_->extension_id(), hash_reader_->relative_path(), failed_);
+  if (g_test_observer) {
+    g_test_observer->JobFinished(hash_reader_->extension_id(),
+                                 hash_reader_->relative_path(), reason);
+  }
 }
 
 }  // namespace extensions