base/test/test_file_util_mac.cc

   1 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "base/test/test_file_util.h"
   6
   7 #include <sys/mman.h>
   8 #include <errno.h>
   9
  10 #include "base/files/file_util.h"
  11 #include "base/files/memory_mapped_file.h"
  12 #include "base/logging.h"
  13
  14 namespace base {
  15
  16 bool EvictFileFromSystemCache(const FilePath& file) {
  17   // There aren't any really direct ways to purge a file from the UBC.  From
  18   // talking with Amit Singh, the safest is to mmap the file with MAP_FILE (the
  19   // default) + MAP_SHARED, then do an msync to invalidate the memory.  The next
  20   // open should then have to load the file from disk.
  21
  22   int64 length;
  23   if (!GetFileSize(file, &length)) {
  24     DLOG(ERROR) << "failed to get size of " << file.value();
  25     return false;
  26   }
  27
  28   // When a file is empty, we do not need to evict it from cache.
  29   // In fact, an attempt to map it to memory will result in error.
  30   if (length == 0) {
  31     DLOG(WARNING) << "file size is zero, will not attempt to map to memory";
  32     return true;
  33   }
  34
  35   MemoryMappedFile mapped_file;
  36   if (!mapped_file.Initialize(file)) {
  37     DLOG(WARNING) << "failed to memory map " << file.value();
  38     return false;
  39   }
  40
  41   if (msync(const_cast<uint8*>(mapped_file.data()), mapped_file.length(),
  42             MS_INVALIDATE) != 0) {
  43     DLOG(WARNING) << "failed to invalidate memory map of " << file.value()
  44                   << ", errno: " << errno;
  45     return false;
  46   }
  47
  48   return true;
  49 }
  50
  51 }  // namespace base