Fixing a crash in disk_cache::SparseControl::UpdateRange()

TEST=net_unittests --gtest_filter=DiskCacheEntryTest::PArtialSparseEntry

If we do a partial write with the following criteria, disk_cache::SparseControl
will crash:

1. first_byte and last_byte in the same 1KB block
2. first_byte % 1024 != 0
3. (first_byte >> 10) % 32 == 31

Review URL: http://codereview.chromium.org/176067

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@25134 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 6 insertions, 1 deletions

diff --git a/net/disk_cache/entry_unittest.cc b/net/disk_cache/entry_unittest.cc
index 1c81995..f65f593 100644
--- a/net/disk_cache/entry_unittest.cc
+++ b/net/disk_cache/entry_unittest.cc
@@ -1216,12 +1216,17 @@ void DiskCacheEntryTest::PartialSparseEntry() {
   // We should be able to deal with IO that is not aligned to the block size
   // of a sparse entry, at least to write a big range without leaving holes.
   const int kSize = 4 * 1024;
+  const int kSmallSize = 128;
   scoped_refptr<net::IOBuffer> buf1 = new net::IOBuffer(kSize);
   CacheTestFillBuffer(buf1->data(), kSize, false);
 
-  // The first write is just to extend the entry.
+  // The first write is just to extend the entry. The third write occupies
+  // a 1KB block partially, it may not be written internally depending on the
+  // implementation.
   EXPECT_EQ(kSize, entry->WriteSparseData(20000, buf1, kSize, NULL));
   EXPECT_EQ(kSize, entry->WriteSparseData(500, buf1, kSize, NULL));
+  EXPECT_EQ(kSmallSize,
+            entry->WriteSparseData(1080321, buf1, kSmallSize, NULL));
   entry->Close();
   ASSERT_TRUE(cache_->OpenEntry(key, &entry));