2 * Copyright 2016 Facebook, Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
21 #include <sys/types.h>
25 #include <folly/Portability.h>
26 #include <folly/Range.h>
27 #include <folly/portability/Unistd.h>
32 * A File represents an open file.
37 * Creates an empty File object, for late initialization.
42 * Create a File object from an existing file descriptor.
43 * Takes ownership of the file descriptor if ownsFd is true.
45 explicit File(int fd, bool ownsFd = false);
48 * Open and create a file object. Throws on error.
50 explicit File(const char* name, int flags = O_RDONLY, mode_t mode = 0666);
52 const std::string& name, int flags = O_RDONLY, mode_t mode = 0666);
53 explicit File(StringPiece name, int flags = O_RDONLY, mode_t mode = 0666);
58 * Create and return a temporary, owned file (uses tmpfile()).
60 static File temporary();
63 * Return the file descriptor, or -1 if the file was closed.
65 int fd() const { return fd_; }
68 * Returns 'true' iff the file was successfully opened.
70 explicit operator bool() const {
75 * Duplicate file descriptor and return File that owns it.
80 * If we own the file descriptor, close the file and throw on error.
81 * Otherwise, do nothing.
86 * Closes the file (if owned). Returns true on success, false (and sets
92 * Returns and releases the file descriptor; no longer owned by this File.
93 * Returns -1 if the File object didn't wrap a file.
95 int release() noexcept;
98 * Swap this File with another.
100 void swap(File& other);
103 File(File&&) noexcept;
104 File& operator=(File&&);
106 // FLOCK (INTERPROCESS) LOCKS
108 // NOTE THAT THESE LOCKS ARE flock() LOCKS. That is, they may only be used
109 // for inter-process synchronization -- an attempt to acquire a second lock
110 // on the same file descriptor from the same process may succeed. Attempting
111 // to acquire a second lock on a different file descriptor for the same file
112 // should fail, but some systems might implement flock() using fcntl() locks,
113 // in which case it will succeed.
119 bool try_lock_shared();
120 void unlock_shared();
124 bool doTryLock(int op);
127 File(const File&) = delete;
128 File& operator=(const File&) = delete;
134 void swap(File& a, File& b);