[net/cache] Avoid the cache for responses exceeding 2GB.

net/http/mock_http_cache.cc

Index: net/http/mock_http_cache.cc
diff --git a/net/http/mock_http_cache.cc b/net/http/mock_http_cache.cc
index 682aff529ada0053bdc0e46d7fea8e7c0f18d40e..16f0b32750dee9adf24bcc2770a5796da38b99d9 100644
--- a/net/http/mock_http_cache.cc
+++ b/net/http/mock_http_cache.cc
@@ -20,6 +20,16 @@ namespace net {
 
 namespace {
 
+#if DCHECK_IS_ON()
+// During testing, we are going to limit the size of a cache entry to this many
+// bytes using DCHECKs in order to prevent a test from causing unbounded memory
+// growth. In practice cache entry shouldn't come anywhere near this limit for
+// tests that use the mock cache. If they do, that's likely a problem with the
+// test. If a test requires using massive cache entries, they should use a real
+// cache backend instead.
+const int kMaxMockCacheEntrySize = 100000000;

[gavinp, 2016/06/28 14:24:43]

Nit: I have trouble counting zeroes this quickly. Could we write this as 100 *
1000 * 1000, for speedy reading?

[asanka, 2016/06/28 16:55:38]

Done. :-)

+#endif
+
 // We can override the test mode for a given operation by setting this global
 // variable.
 int g_test_mode = 0;
@@ -139,6 +149,7 @@ int MockDiskEntry::WriteData(int index,
   if (offset < 0 || offset > static_cast<int>(data_[index].size()))
     return ERR_FAILED;
 
+  DCHECK(offset + buf_len < kMaxMockCacheEntrySize);

[gavinp, 2016/06/28 14:24:43]

DCHECK_LT?

[asanka, 2016/06/28 16:55:38]

Done here and on L223.

   data_[index].resize(offset + buf_len);
   if (buf_len)
     memcpy(&data_[index][offset], buf->data(), buf_len);
@@ -208,8 +219,10 @@ int MockDiskEntry::WriteSparseData(int64_t offset,
   DCHECK(offset < std::numeric_limits<int32_t>::max());
   int real_offset = static_cast<int>(offset);
 
-  if (static_cast<int>(data_[1].size()) < real_offset + buf_len)
+  if (static_cast<int>(data_[1].size()) < real_offset + buf_len) {
+    DCHECK(real_offset + buf_len < kMaxMockCacheEntrySize);
     data_[1].resize(real_offset + buf_len);
+  }
 
   memcpy(&data_[1][real_offset], buf->data(), buf_len);
   if (MockHttpCache::GetTestMode(test_mode_) & TEST_MODE_SYNC_CACHE_WRITE)