/*
- * Copyright 2013 Facebook, Inc.
+ * Copyright 2017 Facebook, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* limitations under the License.
*/
-#ifndef FOLLY_FILE_H_
-#define FOLLY_FILE_H_
+#pragma once
+#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
-#include <fcntl.h>
+
+#include <string>
+
+#include <folly/Portability.h>
+#include <folly/Range.h>
+#include <folly/portability/Unistd.h>
namespace folly {
* Create a File object from an existing file descriptor.
* Takes ownership of the file descriptor if ownsFd is true.
*/
- /* implicit */ File(int fd,
- bool ownsFd = false);
+ explicit File(int fd, bool ownsFd = false);
/**
* Open and create a file object. Throws on error.
*/
- /* implicit */ File(const char* name,
- int flags = O_RDONLY,
- mode_t mode = 0644);
+ explicit File(const char* name, int flags = O_RDONLY, mode_t mode = 0666);
+ explicit File(
+ const std::string& name, int flags = O_RDONLY, mode_t mode = 0666);
+ explicit File(StringPiece name, int flags = O_RDONLY, mode_t mode = 0666);
~File();
*/
static File temporary();
- /**
- * Attempts to open the file at the given path. Returns an 'closed` File
- * instance on failure, which will evaluate to false.
- */
- static File tryOpen(const char* name,
- int flags = O_RDONLY,
- mode_t mode = 0644);
-
/**
* Return the file descriptor, or -1 if the file was closed.
*/
* Returns 'true' iff the file was successfully opened.
*/
explicit operator bool() const {
- return fd_ >= 0;
+ return fd_ != -1;
}
+ /**
+ * Duplicate file descriptor and return File that owns it.
+ */
+ File dup() const;
+
/**
* If we own the file descriptor, close the file and throw on error.
* Otherwise, do nothing.
bool closeNoThrow();
/**
- * Releases the file descriptor; no longer owned by this File.
+ * Returns and releases the file descriptor; no longer owned by this File.
+ * Returns -1 if the File object didn't wrap a file.
*/
- void release();
+ int release() noexcept;
/**
* Swap this File with another.
void swap(File& other);
// movable
- File(File&&);
+ File(File&&) noexcept;
File& operator=(File&&);
+ // FLOCK (INTERPROCESS) LOCKS
+ //
+ // NOTE THAT THESE LOCKS ARE flock() LOCKS. That is, they may only be used
+ // for inter-process synchronization -- an attempt to acquire a second lock
+ // on the same file descriptor from the same process may succeed. Attempting
+ // to acquire a second lock on a different file descriptor for the same file
+ // should fail, but some systems might implement flock() using fcntl() locks,
+ // in which case it will succeed.
+ void lock();
+ bool try_lock();
+ void unlock();
+
+ void lock_shared();
+ bool try_lock_shared();
+ void unlock_shared();
+
private:
+ void doLock(int op);
+ bool doTryLock(int op);
+
// unique
File(const File&) = delete;
File& operator=(const File&) = delete;
void swap(File& a, File& b);
-} // namespace folly
-#endif /* FOLLY_FILE_H_ */
+} // namespace folly