minix/external/bsd/llvm/dist/clang/lib/Basic/FileSystemStatCache.cpp
Lionel Sambuc f4a2713ac8 Importing netbsd clang -- pristine
Change-Id: Ia40e9ffdf29b5dab2f122f673ff6802a58bc690f
2014-07-28 17:05:57 +02:00

136 lines
4.8 KiB
C++

//===--- FileSystemStatCache.cpp - Caching for 'stat' calls ---------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines the FileSystemStatCache interface.
//
//===----------------------------------------------------------------------===//
#include "clang/Basic/FileSystemStatCache.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/Path.h"
// FIXME: This is terrible, we need this for ::close.
#if !defined(_MSC_VER) && !defined(__MINGW32__)
#include <unistd.h>
#include <sys/uio.h>
#else
#include <io.h>
#endif
using namespace clang;
#if defined(_MSC_VER)
#define S_ISDIR(s) ((_S_IFDIR & s) !=0)
#endif
void FileSystemStatCache::anchor() { }
static void copyStatusToFileData(const llvm::sys::fs::file_status &Status,
FileData &Data) {
Data.Size = Status.getSize();
Data.ModTime = Status.getLastModificationTime().toEpochTime();
Data.UniqueID = Status.getUniqueID();
Data.IsDirectory = is_directory(Status);
Data.IsNamedPipe = Status.type() == llvm::sys::fs::file_type::fifo_file;
Data.InPCH = false;
}
/// FileSystemStatCache::get - Get the 'stat' information for the specified
/// path, using the cache to accelerate it if possible. This returns true if
/// the path does not exist or false if it exists.
///
/// If isFile is true, then this lookup should only return success for files
/// (not directories). If it is false this lookup should only return
/// success for directories (not files). On a successful file lookup, the
/// implementation can optionally fill in FileDescriptor with a valid
/// descriptor and the client guarantees that it will close it.
bool FileSystemStatCache::get(const char *Path, FileData &Data, bool isFile,
int *FileDescriptor, FileSystemStatCache *Cache) {
LookupResult R;
bool isForDir = !isFile;
// If we have a cache, use it to resolve the stat query.
if (Cache)
R = Cache->getStat(Path, Data, isFile, FileDescriptor);
else if (isForDir || !FileDescriptor) {
// If this is a directory or a file descriptor is not needed and we have
// no cache, just go to the file system.
llvm::sys::fs::file_status Status;
if (llvm::sys::fs::status(Path, Status)) {
R = CacheMissing;
} else {
R = CacheExists;
copyStatusToFileData(Status, Data);
}
} else {
// Otherwise, we have to go to the filesystem. We can always just use
// 'stat' here, but (for files) the client is asking whether the file exists
// because it wants to turn around and *open* it. It is more efficient to
// do "open+fstat" on success than it is to do "stat+open".
//
// Because of this, check to see if the file exists with 'open'. If the
// open succeeds, use fstat to get the stat info.
llvm::error_code EC = llvm::sys::fs::openFileForRead(Path, *FileDescriptor);
if (EC) {
// If the open fails, our "stat" fails.
R = CacheMissing;
} else {
// Otherwise, the open succeeded. Do an fstat to get the information
// about the file. We'll end up returning the open file descriptor to the
// client to do what they please with it.
llvm::sys::fs::file_status Status;
if (!llvm::sys::fs::status(*FileDescriptor, Status)) {
R = CacheExists;
copyStatusToFileData(Status, Data);
} else {
// fstat rarely fails. If it does, claim the initial open didn't
// succeed.
R = CacheMissing;
::close(*FileDescriptor);
*FileDescriptor = -1;
}
}
}
// If the path doesn't exist, return failure.
if (R == CacheMissing) return true;
// If the path exists, make sure that its "directoryness" matches the clients
// demands.
if (Data.IsDirectory != isForDir) {
// If not, close the file if opened.
if (FileDescriptor && *FileDescriptor != -1) {
::close(*FileDescriptor);
*FileDescriptor = -1;
}
return true;
}
return false;
}
MemorizeStatCalls::LookupResult
MemorizeStatCalls::getStat(const char *Path, FileData &Data, bool isFile,
int *FileDescriptor) {
LookupResult Result = statChained(Path, Data, isFile, FileDescriptor);
// Do not cache failed stats, it is easy to construct common inconsistent
// situations if we do, and they are not important for PCH performance (which
// currently only needs the stats to construct the initial FileManager
// entries).
if (Result == CacheMissing)
return Result;
// Cache file 'stat' results and directories with absolutely paths.
if (!Data.IsDirectory || llvm::sys::path::is_absolute(Path))
StatCalls[Path] = Data;
return Result;
}