Disk Cache: Make sure that an entry that pretends to be

"clean" is not really dirty.

If for some reason an entry is left on disk with a pointer
on the rankings node but without the dirty flag set, we now
recognize it as dirty the next time we read it from disk.

BUG=3987
TEST=DiskCacheTest.Backend_NotMarkedButDirty


Review URL: http://codereview.chromium.org/57024

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@12820 0039d316-1c4b-4281-b951-d872f2087c98

net/data/cache_tests/dirty_entry/contents.txt

+Index header:
+num_entries: 2
+num_bytes: 27
+this_id: 1
+table_len: 64k
+
+head: 0x90000001
+tail: 0x90000000
+
+Address: 0xa0010002
+Address: 0xa0010003
+
+-------------------------------
+
+entry:
+Address: 0xa0010002
+hash: 0x687d1422
+next: 0
+rankings_node: 0x90000000
+key_len: 13
+long_key: 0
+data_size: 0's
+data_addr: 0's
+key: "the first key"
+
+rankings:
+Address: 0x90000000
+next: 0x90000000
+prev: 0x90000001
+contents: 0xa0010002
+dirty: 0
+pointer: 0
+
+-------------------------------
+
+entry:
+Address: 0xa0010003
+hash: 0x63909ecb
+next: 0
+rankings_node: 0x90000001
+key_len: 14
+long_key: 0
+data_size: 0's
+data_addr: 0's
+key: "some other key"
+
+rankings:
+Address: 0x90000001
+next: 0x90000000
+prev: 0x90000001
+contents: 0xa0010003
+dirty: 0
+pointer: 0x0169dc48       <- Invalid.
+
+================================
+
+Generated with:
+
+disk_cache::Entry *entry;
+ASSERT_TRUE(cache_->CreateEntry("the first key", &entry));
+entry->Close();
+
+ASSERT_TRUE(cache_->CreateEntry("some other key", &entry));
+entry->Close();                                              <---- Edit value*
+
+* Edit the value with the debugger before it is saved to disk (break on
+the destructor of EntryImpl and skip the line that clears "pointer")
\ No newline at end of file

net/disk_cache/backend_unittest.cc

@@ -817,6 +817,23 @@ TEST_F(DiskCacheTest, Backend_InvalidEntry) {
   delete cache;
 }
 
+// We want to be able to deal with abnormal dirty entries.
+TEST_F(DiskCacheTest, Backend_NotMarkedButDirty) {
+  ASSERT_TRUE(CopyTestCache(L"dirty_entry"));
+  std::wstring path = GetCachePath();
+  disk_cache::Backend* cache = disk_cache::CreateCacheBackend(path, false, 0,
+                                                              net::DISK_CACHE);
+  ASSERT_TRUE(NULL != cache);
+
+  disk_cache::Entry *entry1, *entry2;
+  ASSERT_TRUE(cache->OpenEntry("the first key", &entry1));
+  EXPECT_FALSE(cache->OpenEntry("some other key", &entry2));
+  entry1->Close();
+
+  delete cache;
+  EXPECT_TRUE(CheckCacheIntegrity(path));
+}
+
 // We want to be able to deal with messed up entries on disk.
 TEST_F(DiskCacheTest, Backend_InvalidRankings) {
   ASSERT_TRUE(CopyTestCache(L"bad_rankings"));

net/disk_cache/entry_impl.cc

@@ -539,6 +539,9 @@ EntryImpl* EntryImpl::Update(EntryImpl* entry) {
 
 bool EntryImpl::IsDirty(int32 current_id) {
   DCHECK(node_.HasData());
+  if (node_.Data()->pointer && !node_.Data()->dirty)
+    return true;
+
   return node_.Data()->dirty && current_id != node_.Data()->dirty;
 }