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65392c8478
This is a flag that causes open () to create a new, unnamed file in the
same filesystem as the given directory. The file descriptor can be
simply used in the creating process as a temporary file, or shared with
children processes via fork (), or sent over a Unix socket. The file can
be left anonymous, in which case it will be deleted from the backing
file system once all copies of the file descriptor are closed, or given
a permanent name with a linkat () call, such as the following:
int fd = open ("/tmp", O_TMPFILE | O_RDWR, 0700);
/* Do something with the file... */
linkat (fd, "", AT_FDCWD, "/tmp/filename", AT_EMPTY_PATH);
In between creating the file and linking it to the file system, it is
possible to set the file content, mode, ownership, author, and other
attributes, so that the file visibly appears in the file system (perhaps
replacing another file) atomically, with all of its attributes already
set up.
The Hurd support for O_TMPFILE directly exposes the dir_mkfile RPC to
user programs. Previously, dir_mkfile was used by glibc internally, in
particular for implementing tmpfile (), but not exposed to user programs
through a Unix-level API.
O_TMPFILE was initially introduced by Linux. This implementation is
intended to be compatible with the Linux implementation, except that the
O_EXCL flag is not given the special meaning when used together with
O_TMPFILE, unlike on Linux.
Signed-off-by: Sergey Bugaev <bugaevc@gmail.com>
Message-Id: <20230130125216.6254-3-bugaevc@gmail.com>
235 lines
8.5 KiB
C
235 lines
8.5 KiB
C
/* O_*, F_*, FD_* bit values for GNU.
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Copyright (C) 1993-2023 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#ifndef _FCNTL_H
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# error "Never use <bits/fcntl.h> directly; include <fcntl.h> instead."
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#endif
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#include <sys/types.h>
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/* File access modes. These are understood by io servers; they can be
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passed in `dir_lookup', and are returned by `io_get_openmodes'.
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Consequently they can be passed to `open', `hurd_file_name_lookup', and
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`file_name_lookup'; and are returned by `fcntl' with the F_GETFL
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command. */
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/* In GNU, read and write are bits (unlike BSD). */
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#ifdef __USE_GNU
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# define O_READ O_RDONLY /* Open for reading. */
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# define O_WRITE O_WRONLY /* Open for writing. */
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# define O_EXEC 0x0004 /* Open for execution. */
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# define O_NORW 0 /* Open without R/W access. */
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#endif
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/* POSIX.1 standard names. */
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#define O_RDONLY 0x0001 /* Open read-only. */
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#define O_WRONLY 0x0002 /* Open write-only. */
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#define O_RDWR (O_RDONLY|O_WRONLY) /* Open for reading and writing. */
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#define O_ACCMODE O_RDWR /* Mask for file access modes. */
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#define O_LARGEFILE 0
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/* File name translation flags. These are understood by io servers;
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they can be passed in `dir_lookup', and consequently to `open',
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`hurd_file_name_lookup', and `file_name_lookup'. */
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#define O_CREAT 0x0010 /* Create file if it doesn't exist. */
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#define O_EXCL 0x0020 /* Fail if file already exists. */
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#ifdef __USE_GNU
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# define O_NOLINK 0x0040 /* No name mappings on final component. */
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# define O_NOTRANS 0x0080 /* No translator on final component. */
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#endif
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#ifdef __USE_XOPEN2K8
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# define O_NOFOLLOW 0x00100000 /* Produce ENOENT if file is a symlink. */
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# define O_DIRECTORY 0x00200000 /* Produce ENOTDIR if not a directory. */
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#endif
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/* I/O operating modes. These are understood by io servers; they can be
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passed in `dir_lookup' and set or fetched with `io_*_openmodes'.
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Consequently they can be passed to `open', `hurd_file_name_lookup',
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`file_name_lookup', and `fcntl' with the F_SETFL command; and are
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returned by `fcntl' with the F_GETFL command. */
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#define O_APPEND 0x0100 /* Writes always append to the file. */
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#define O_ASYNC 0x0200 /* Send SIGIO to owner when data is ready. */
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#define O_FSYNC 0x0400 /* Synchronous writes. */
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#define O_SYNC O_FSYNC
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#ifdef __USE_GNU
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# define O_NOATIME 0x0800 /* Don't set access time on read (owner). */
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#endif
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#ifdef __USE_MISC
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# define O_SHLOCK 0x00020000 /* Open with shared file lock. */
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# define O_EXLOCK 0x00040000 /* Open with exclusive file lock. */
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#endif
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/* These are lesser flavors of partial synchronization that are
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implied by our one flag (O_FSYNC). */
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#if defined __USE_POSIX199309 || defined __USE_UNIX98
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# define O_DSYNC O_SYNC /* Synchronize data. */
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# define O_RSYNC O_SYNC /* Synchronize read operations. */
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#endif
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/* The name O_NONBLOCK is unfortunately overloaded; it is both a file name
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translation flag and an I/O operating mode. O_NDELAY is the deprecated
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BSD name for the same flag, overloaded in the same way.
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When used in `dir_lookup' (and consequently `open', `hurd_file_name_lookup',
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or `file_name_lookup'), O_NONBLOCK says the open should return immediately
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instead of blocking for any significant length of time (e.g., to wait
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for carrier detect on a serial line). It is also saved as an I/O
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operating mode, and after open has the following meaning.
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When used in `io_*_openmodes' (and consequently `fcntl' with the F_SETFL
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command), the O_NONBLOCK flag means to do nonblocking i/o: any i/o
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operation that would block for any significant length of time will instead
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fail with EAGAIN. */
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#define O_NONBLOCK 0x0008 /* Non-blocking open or non-blocking I/O. */
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#ifdef __USE_MISC
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# define O_NDELAY O_NONBLOCK /* Deprecated. */
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#endif
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#ifdef __USE_GNU
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/* Mask of bits which are understood by io servers. */
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# define O_HURD (0xffff | O_EXLOCK | O_SHLOCK)
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#endif
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/* Open-time action flags. These are understood by `hurd_file_name_lookup'
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and consequently by `open' and `file_name_lookup'. They are not preserved
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once the file has been opened. */
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#define O_TRUNC 0x00010000 /* Truncate file to zero length. */
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#ifdef __USE_XOPEN2K8
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# define O_CLOEXEC 0x00400000 /* Set FD_CLOEXEC. */
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#endif
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#ifdef __USE_GNU
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# define O_TMPFILE 0x00800000 /* Make a new unnamed file. */
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#endif
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/* Controlling terminal flags. These are understood only by `open',
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and are not preserved once the file has been opened. */
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#ifdef __USE_GNU
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# define O_IGNORE_CTTY 0x00080000 /* Don't do any ctty magic at all. */
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#endif
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/* `open' never assigns a controlling terminal in GNU. */
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#define O_NOCTTY 0 /* Don't assign a controlling terminal. */
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#ifdef __USE_MISC
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/* Flags for TIOCFLUSH. */
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# define FREAD O_RDONLY
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# define FWRITE O_WRONLY
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/* Traditional BSD names the O_* bits. */
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# define FASYNC O_ASYNC
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# define FCREAT O_CREAT
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# define FEXCL O_EXCL
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# define FTRUNC O_TRUNC
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# define FNOCTTY O_NOCTTY
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# define FFSYNC O_FSYNC
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# define FSYNC O_SYNC
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# define FAPPEND O_APPEND
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# define FNONBLOCK O_NONBLOCK
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# define FNDELAY O_NDELAY
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#endif
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/* Values for the second argument to `fcntl'. */
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#define F_DUPFD 0 /* Duplicate file descriptor. */
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#define F_GETFD 1 /* Get file descriptor flags. */
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#define F_SETFD 2 /* Set file descriptor flags. */
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#define F_GETFL 3 /* Get file status flags. */
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#define F_SETFL 4 /* Set file status flags. */
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#if defined __USE_UNIX98 || defined __USE_XOPEN2K8
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# define F_GETOWN 5 /* Get owner (receiver of SIGIO). */
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# define F_SETOWN 6 /* Set owner (receiver of SIGIO). */
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#endif
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#ifdef __USE_FILE_OFFSET64
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# define F_GETLK F_GETLK64
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# define F_SETLK F_SETLK64
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# define F_SETLKW F_SETLKW64
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#else
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# define F_GETLK 7 /* Get record locking info. */
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# define F_SETLK 8 /* Set record locking info (non-blocking). */
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# define F_SETLKW 9 /* Set record locking info (blocking). */
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#endif
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#define F_GETLK64 10 /* Get record locking info. */
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#define F_SETLK64 11 /* Set record locking info (non-blocking). */
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#define F_SETLKW64 12 /* Set record locking info (blocking). */
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#ifdef __USE_XOPEN2K8
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# define F_DUPFD_CLOEXEC 1030 /* Duplicate, set FD_CLOEXEC on new one. */
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#endif
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/* File descriptor flags used with F_GETFD and F_SETFD. */
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#define FD_CLOEXEC 1 /* Close on exec. */
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#include <bits/types.h>
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/* The structure describing an advisory lock. This is the type of the third
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argument to `fcntl' for the F_GETLK, F_SETLK, and F_SETLKW requests. */
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struct flock
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{
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int l_type; /* Type of lock: F_RDLCK, F_WRLCK, or F_UNLCK. */
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int l_whence; /* Where `l_start' is relative to (like `lseek'). */
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#ifndef __USE_FILE_OFFSET64
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__off_t l_start; /* Offset where the lock begins. */
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__off_t l_len; /* Size of the locked area; zero means until EOF. */
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#else
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__off64_t l_start; /* Offset where the lock begins. */
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__off64_t l_len; /* Size of the locked area; zero means until EOF. */
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#endif
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__pid_t l_pid; /* Process holding the lock. */
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};
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#ifdef __USE_LARGEFILE64
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struct flock64
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{
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int l_type; /* Type of lock: F_RDLCK, F_WRLCK, or F_UNLCK. */
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int l_whence; /* Where `l_start' is relative to (like `lseek'). */
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__off64_t l_start; /* Offset where the lock begins. */
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__off64_t l_len; /* Size of the locked area; zero means until EOF. */
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__pid_t l_pid; /* Process holding the lock. */
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};
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#endif
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/* Values for the `l_type' field of a `struct flock'. */
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#define F_RDLCK 1 /* Read lock. */
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#define F_WRLCK 2 /* Write lock. */
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#define F_UNLCK 3 /* Remove lock. */
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/* Advise to `posix_fadvise'. */
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#ifdef __USE_XOPEN2K
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# define POSIX_FADV_NORMAL 0 /* No further special treatment. */
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# define POSIX_FADV_RANDOM 1 /* Expect random page references. */
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# define POSIX_FADV_SEQUENTIAL 2 /* Expect sequential page references. */
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# define POSIX_FADV_WILLNEED 3 /* Will need these pages. */
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# define POSIX_FADV_DONTNEED 4 /* Don't need these pages. */
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# define POSIX_FADV_NOREUSE 5 /* Data will be accessed once. */
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#endif
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