1 //===--- FileSystemStatCache.cpp - Caching for 'stat' calls ---------------===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This file defines the FileSystemStatCache interface. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #include "clang/Basic/FileSystemStatCache.h" 15 #include "llvm/System/Path.h" 16 using namespace clang; 17 18 #if defined(_MSC_VER) 19 #define S_ISDIR(s) (_S_IFDIR & s) 20 #endif 21 22 /// FileSystemStatCache::get - Get the 'stat' information for the specified 23 /// path, using the cache to accellerate it if possible. This returns true if 24 /// the path does not exist or false if it exists. 25 /// 26 /// If FileDescriptor is non-null, then this lookup should only return success 27 /// for files (not directories). If it is null this lookup should only return 28 /// success for directories (not files). On a successful file lookup, the 29 /// implementation can optionally fill in FileDescriptor with a valid 30 /// descriptor and the client guarantees that it will close it. 31 bool FileSystemStatCache::get(const char *Path, struct stat &StatBuf, 32 int *FileDescriptor, FileSystemStatCache *Cache) { 33 LookupResult R; 34 35 if (Cache) 36 R = Cache->getStat(Path, StatBuf, FileDescriptor); 37 else 38 R = ::stat(Path, &StatBuf) != 0 ? CacheMissing : CacheExists; 39 40 if (R == CacheMissing) return true; 41 42 bool isForDir = FileDescriptor == 0; 43 return S_ISDIR(StatBuf.st_mode) != isForDir; 44 } 45 46 47 MemorizeStatCalls::LookupResult 48 MemorizeStatCalls::getStat(const char *Path, struct stat &StatBuf, 49 int *FileDescriptor) { 50 LookupResult Result = statChained(Path, StatBuf, FileDescriptor); 51 52 // Do not cache failed stats, it is easy to construct common inconsistent 53 // situations if we do, and they are not important for PCH performance (which 54 // currently only needs the stats to construct the initial FileManager 55 // entries). 56 if (Result == CacheMissing) 57 return Result; 58 59 // Cache file 'stat' results and directories with absolutely paths. 60 if (!S_ISDIR(StatBuf.st_mode) || llvm::sys::Path(Path).isAbsolute()) 61 StatCalls[Path] = StatBuf; 62 63 return Result; 64 } 65