[HTTP Cache] Prevent memory backend from exceeding its max size

net/disk_cache/memory/mem_entry_impl.cc

 // Copyright (c) 2012 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 "net/disk_cache/memory/mem_entry_impl.h"
 
 #include <algorithm>
 #include <utility>
 
 #include "base/bind.h"
@@ skipping 63 matching lines @@
 
 MemEntryImpl::MemEntryImpl(MemBackendImpl* backend,
                            const std::string& key,
                            net::NetLog* net_log)
     : MemEntryImpl(backend,
                    key,
                    0,        // child_id
                    nullptr,  // parent
                    net_log) {
   Open();
+  // Just creating the entry (without any data) could cause the storage to
+  // grow beyond capacity, but we allow such infractions.
   backend_->ModifyStorageSize(GetStorageSize());
 }
 
 MemEntryImpl::MemEntryImpl(MemBackendImpl* backend,
                            int child_id,
                            MemEntryImpl* parent,
                            net::NetLog* net_log)
     : MemEntryImpl(backend,
                    std::string(),  // key
                    child_id,
@@ skipping 244 matching lines @@
   int max_file_size = backend_->MaxFileSize();
 
   // offset of buf_len could be negative numbers.
   if (offset > max_file_size || buf_len > max_file_size ||
       offset + buf_len > max_file_size) {
     return net::ERR_FAILED;
   }
 
   int old_data_size = data_[index].size();
   if (truncate || old_data_size < offset + buf_len) {
+    int delta = offset + buf_len - old_data_size;
+    backend_->ModifyStorageSize(delta);
+    if (backend_->HasExceededStorageSize()) {
+      backend_->ModifyStorageSize(-delta);
+      return net::ERR_INSUFFICIENT_RESOURCES;
+    }
+
     data_[index].resize(offset + buf_len);
 
     // Zero fill any hole.
     if (old_data_size < offset) {
       std::fill(data_[index].begin() + old_data_size,
                 data_[index].begin() + offset, 0);
     }
-
-    backend_->ModifyStorageSize(data_[index].size() - old_data_size);
   }
 
   UpdateStateOnUse(ENTRY_WAS_MODIFIED);
 
   if (!buf_len)
     return 0;
 
   std::copy(buf->data(), buf->data() + buf_len, data_[index].begin() + offset);
   return buf_len;
 }
@@ skipping 220 matching lines @@
          scanned_len += first_pos - current_child_offset;
          break;
       }
     }
     scanned_len += kMaxSparseEntrySize - current_child_offset;
   }
   return scanned_len;
 }
 
 }  // namespace disk_cache