1 // Copyright 2011 The Chromium Authors 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 #include <stdint.h> 10 11 #include "base/files/file_util.h" 12 #include "base/files/memory_mapped_file.h" 13 #include "base/logging.h" 14 15 namespace base { 16 EvictFileFromSystemCache(const FilePath & file)17bool EvictFileFromSystemCache(const FilePath& file) { 18 // There aren't any really direct ways to purge a file from the UBC. From 19 // talking with Amit Singh, the safest is to mmap the file with MAP_FILE (the 20 // default) + MAP_SHARED, then do an msync to invalidate the memory. The next 21 // open should then have to load the file from disk. 22 23 int64_t length; 24 if (!GetFileSize(file, &length)) { 25 DLOG(ERROR) << "failed to get size of " << file.value(); 26 return false; 27 } 28 29 // When a file is empty, we do not need to evict it from cache. 30 // In fact, an attempt to map it to memory will result in error. 31 if (length == 0) { 32 DLOG(WARNING) << "file size is zero, will not attempt to map to memory"; 33 return true; 34 } 35 36 MemoryMappedFile mapped_file; 37 if (!mapped_file.Initialize(file)) { 38 DLOG(WARNING) << "failed to memory map " << file.value(); 39 return false; 40 } 41 42 if (msync(const_cast<uint8_t*>(mapped_file.data()), mapped_file.length(), 43 MS_INVALIDATE) != 0) { 44 DLOG(WARNING) << "failed to invalidate memory map of " << file.value() 45 << ", errno: " << errno; 46 return false; 47 } 48 49 return true; 50 } 51 52 } // namespace base 53