89 lines
2.8 KiB
C++
89 lines
2.8 KiB
C++
/*
|
|
* Copyright (C) 2011 The Android Open Source Project
|
|
*
|
|
* Licensed under the Apache License, Version 2.0 (the "License");
|
|
* you may not use this file except in compliance with the License.
|
|
* You may obtain a copy of the License at
|
|
*
|
|
* http://www.apache.org/licenses/LICENSE-2.0
|
|
*
|
|
* Unless required by applicable law or agreed to in writing, software
|
|
* distributed under the License is distributed on an "AS IS" BASIS,
|
|
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
* See the License for the specific language governing permissions and
|
|
* limitations under the License.
|
|
*/
|
|
|
|
#ifndef ART_LIBARTBASE_BASE_SCOPED_FLOCK_H_
|
|
#define ART_LIBARTBASE_BASE_SCOPED_FLOCK_H_
|
|
|
|
#include <memory>
|
|
#include <string>
|
|
|
|
#include <android-base/unique_fd.h>
|
|
|
|
#include "macros.h"
|
|
#include "os.h"
|
|
#include "unix_file/fd_file.h"
|
|
|
|
namespace art {
|
|
|
|
class LockedFile;
|
|
class LockedFileCloseNoFlush;
|
|
|
|
// A scoped File object that calls Close without flushing.
|
|
typedef std::unique_ptr<LockedFile, LockedFileCloseNoFlush> ScopedFlock;
|
|
|
|
class LockedFile : public unix_file::FdFile {
|
|
public:
|
|
// Attempts to acquire an exclusive file lock (see flock(2)) on the file
|
|
// at filename, and blocks until it can do so.
|
|
//
|
|
// It is an error if its inode changed (usually due to a new file being
|
|
// created at the same path) between attempts to lock it. In blocking mode,
|
|
// locking will be retried if the file changed. In non-blocking mode, false
|
|
// is returned and no attempt is made to re-acquire the lock.
|
|
//
|
|
// The file is opened with the provided flags.
|
|
static ScopedFlock Open(const char* filename, int flags, bool block,
|
|
std::string* error_msg);
|
|
|
|
// Calls Open(filename, O_CREAT | O_RDWR, true, errror_msg)
|
|
static ScopedFlock Open(const char* filename, std::string* error_msg);
|
|
|
|
// Attempt to acquire an exclusive file lock (see flock(2)) on 'file'.
|
|
// Returns true if the lock could be acquired or false if an error
|
|
// occured.
|
|
static ScopedFlock DupOf(const int fd, const std::string& path,
|
|
const bool read_only_mode, std::string* error_message);
|
|
|
|
// Release a lock held on this file, if any.
|
|
void ReleaseLock();
|
|
|
|
private:
|
|
// Constructors should not be invoked directly, use one of the factory
|
|
// methods instead.
|
|
explicit LockedFile(FdFile&& other) : FdFile(std::move(other)) {
|
|
}
|
|
|
|
// Constructors should not be invoked directly, use one of the factory
|
|
// methods instead.
|
|
LockedFile(int fd, const std::string& path, bool check_usage, bool read_only_mode)
|
|
: FdFile(fd, path, check_usage, read_only_mode) {
|
|
}
|
|
};
|
|
|
|
class LockedFileCloseNoFlush {
|
|
public:
|
|
void operator()(LockedFile* ptr) {
|
|
ptr->ReleaseLock();
|
|
UNUSED(ptr->Close());
|
|
|
|
delete ptr;
|
|
}
|
|
};
|
|
|
|
} // namespace art
|
|
|
|
#endif // ART_LIBARTBASE_BASE_SCOPED_FLOCK_H_
|