#include <sys/fcntl.h>

sys/fcntl.h

includes: sys/_types.h, sys/cdefs.h, Availability.h, sys/_types/_size_t.h, sys/_types/_mode_t.h, sys/_types/_off_t.h, sys/_types/_pid_t.h, sys/_types/_o_sync.h, sys/_types/_o_dsync.h, sys/_types/_seek_set.h, sys/_types/_s_ifmt.h, sys/_types/_timespec.h, sys/_types/_filesec_t.h

140 macros · 16 functions · 13 structs · 10 typedefs · 1 enum

macroO_RDONLY

File status flags: these are used by open(2), fcntl(2). They are also used (indirectly) in the kernel file structure f_flags, which is a superset of the open/fcntl flags. Open flags and f_flags are inter-convertible using OFLAGS(fflags) and FFLAGS(oflags). Open/fcntl flags begin with O_; kernel-internal flags begin with F. open-only flags

#define O_RDONLY 0x0000

open for reading only

macroO_WRONLY

#define O_WRONLY 0x0001

open for writing only

macroO_RDWR

#define O_RDWR 0x0002

open for reading and writing

macroO_ACCMODE

#define O_ACCMODE 0x0003

mask for above modes

macroFREAD

Kernel encoding of open mode; separate read and write bits that are independently testable: 1 greater than the above. XXX FREAD and FWRITE are excluded from the #ifdef KERNEL so that TIOCFLUSH, which was documented to use FREAD/FWRITE, continues to work.

#define FREAD 0x00000001

macroFWRITE

#define FWRITE 0x00000002

macroO_NONBLOCK

#define O_NONBLOCK 0x00000004

no delay

macroO_APPEND

#define O_APPEND 0x00000008

set append mode

macroO_SHLOCK

#define O_SHLOCK 0x00000010

open with shared file lock

macroO_EXLOCK

#define O_EXLOCK 0x00000020

open with exclusive file lock

macroO_ASYNC

#define O_ASYNC 0x00000040

signal pgrp when data ready

macroO_FSYNC

#define O_FSYNC O_SYNC

source compatibility: do not use

macroO_NOFOLLOW

#define O_NOFOLLOW 0x00000100

don't follow symlinks

macroO_CREAT

#define O_CREAT 0x00000200

create if nonexistant

macroO_TRUNC

#define O_TRUNC 0x00000400

truncate to zero length

macroO_EXCL

#define O_EXCL 0x00000800

error if already exists

macroO_RESOLVE_BENEATH

#define O_RESOLVE_BENEATH 0x00001000

only for open(2), same value as FMARK

macroO_UNIQUE

#define O_UNIQUE 0x00002000

only for open(2), same value as FDEFER

macroO_EVTONLY

#define O_EVTONLY 0x00008000

descriptor requested for event notifications only

macroO_NOCTTY

#define O_NOCTTY 0x00020000

don't assign controlling terminal

macroO_DIRECTORY

#define O_DIRECTORY 0x00100000

macroO_SYMLINK

#define O_SYMLINK 0x00200000

allow open of a symlink

macroO_CLOEXEC

#define O_CLOEXEC 0x01000000

implicitly set FD_CLOEXEC

macroO_NOFOLLOW_ANY

#define O_NOFOLLOW_ANY 0x20000000

no symlinks allowed in path

macroO_EXEC

#define O_EXEC 0x40000000

open file for execute only

macroO_SEARCH

#define O_SEARCH (O_EXEC | O_DIRECTORY)

open directory for search only

macroAT_FDCWD

Descriptor value for the current working directory

#define AT_FDCWD -2

macroAT_EACCESS

Flags for the at functions

#define AT_EACCESS 0x0010

Use effective ids in access check

macroAT_SYMLINK_NOFOLLOW

#define AT_SYMLINK_NOFOLLOW 0x0020

Act on the symlink itself not the target

macroAT_SYMLINK_FOLLOW

#define AT_SYMLINK_FOLLOW 0x0040

Act on target of symlink

macroAT_REMOVEDIR

#define AT_REMOVEDIR 0x0080

Path refers to directory

macroAT_REALDEV

#define AT_REALDEV 0x0200

Return real device inodes resides on for fstatat(2)

macroAT_FDONLY

#define AT_FDONLY 0x0400

Use only the fd and Ignore the path for fstatat(2)

macroAT_SYMLINK_NOFOLLOW_ANY

#define AT_SYMLINK_NOFOLLOW_ANY 0x0800

Path should not contain any symlinks

macroAT_RESOLVE_BENEATH

#define AT_RESOLVE_BENEATH 0x2000

Path must reside in the hierarchy beneath the starting directory

macroAT_NODELETEBUSY

#define AT_NODELETEBUSY 0x4000

Don't delete busy files

macroAT_UNIQUE

#define AT_UNIQUE 0x8000

prevent a path lookup from succeeding on a vnode with multiple links

macroO_DP_GETRAWENCRYPTED

Data Protection Flags

#define O_DP_GETRAWENCRYPTED 0x0001

macroO_DP_GETRAWUNENCRYPTED

#define O_DP_GETRAWUNENCRYPTED 0x0002

macroO_DP_AUTHENTICATE

#define O_DP_AUTHENTICATE 0x0004

macroAUTH_OPEN_NOAUTHFD

Descriptor value for openat_authenticated_np() to skip authentication with another fd

#define AUTH_OPEN_NOAUTHFD -1

macroFAPPEND

The O_* flags used to have only F* names, which were used in the kernel and by fcntl. We retain the F* names for the kernel f_flags field and for backward compatibility for fcntl.

#define FAPPEND O_APPEND

kernel/compat

macroFASYNC

#define FASYNC O_ASYNC

kernel/compat

macroFFSYNC

#define FFSYNC O_FSYNC

kernel

macroFFDSYNC

#define FFDSYNC O_DSYNC

kernel

macroFNONBLOCK

#define FNONBLOCK O_NONBLOCK

kernel

macroFNDELAY

#define FNDELAY O_NONBLOCK

compat

macroO_NDELAY

#define O_NDELAY O_NONBLOCK

compat

macroCPF_OVERWRITE

#define CPF_OVERWRITE 0x0001

macroCPF_IGNORE_MODE

#define CPF_IGNORE_MODE 0x0002

macroCPF_MASK

#define CPF_MASK (CPF_OVERWRITE|CPF_IGNORE_MODE)

macroF_DUPFD

command values

#define F_DUPFD 0

duplicate file descriptor

macroF_GETFD

#define F_GETFD 1

get file descriptor flags

macroF_SETFD

#define F_SETFD 2

set file descriptor flags

macroF_GETFL

#define F_GETFL 3

get file status flags

macroF_SETFL

#define F_SETFL 4

set file status flags

macroF_GETOWN

#define F_GETOWN 5

get SIGIO/SIGURG proc/pgrp

macroF_SETOWN

#define F_SETOWN 6

set SIGIO/SIGURG proc/pgrp

macroF_GETLK

#define F_GETLK 7

get record locking information

macroF_SETLK

#define F_SETLK 8

set record locking information

macroF_SETLKW

#define F_SETLKW 9

F_SETLK; wait if blocked

macroF_SETLKWTIMEOUT

#define F_SETLKWTIMEOUT 10

F_SETLK; wait if blocked, return on timeout

macroF_FLUSH_DATA

#define F_FLUSH_DATA 40

macroF_CHKCLEAN

#define F_CHKCLEAN 41

Used for regression test

macroF_PREALLOCATE

#define F_PREALLOCATE 42

Preallocate storage

macroF_SETSIZE

#define F_SETSIZE 43

Truncate a file. Equivalent to calling truncate(2)

macroF_RDADVISE

#define F_RDADVISE 44

Issue an advisory read async with no copy to user

macroF_RDAHEAD

#define F_RDAHEAD 45

turn read ahead off/on for this fd

macroF_NOCACHE

46,47 used to be F_READBOOTSTRAP and F_WRITEBOOTSTRAP

#define F_NOCACHE 48

turn data caching off/on for this fd

macroF_LOG2PHYS

#define F_LOG2PHYS 49

file offset to device offset

macroF_GETPATH

#define F_GETPATH 50

return the full path of the fd

macroF_FULLFSYNC

#define F_FULLFSYNC 51

fsync + ask the drive to flush to the media

macroF_PATHPKG_CHECK

#define F_PATHPKG_CHECK 52

find which component (if any) is a package

macroF_FREEZE_FS

#define F_FREEZE_FS 53

"freeze" all fs operations

macroF_THAW_FS

#define F_THAW_FS 54

"thaw" all fs operations

macroF_GLOBAL_NOCACHE

#define F_GLOBAL_NOCACHE 55

turn data caching off/on (globally) for this file

macroF_ADDSIGS

#define F_ADDSIGS 59

add detached signatures

macroF_ADDFILESIGS

#define F_ADDFILESIGS 61

add signature from same file (used by dyld for shared libs)

macroF_NODIRECT

#define F_NODIRECT 62

used in conjunction with F_NOCACHE to indicate that DIRECT, synchonous writes

macroF_GETPROTECTIONCLASS

#define F_GETPROTECTIONCLASS 63

Get the protection class of a file from the EA, returns int

macroF_SETPROTECTIONCLASS

#define F_SETPROTECTIONCLASS 64

Set the protection class of a file for the EA, requires int

macroF_LOG2PHYS_EXT

#define F_LOG2PHYS_EXT 65

file offset to device offset, extended

macroF_GETLKPID

#define F_GETLKPID 66

See man fcntl(2) F_GETLK Similar to F_GETLK but in addition l_pid is treated as an input parameter which is used as a matching value when searching locks on the file so that only locks owned by the process with pid l_pid are returned. However, any flock(2) type lock will also be found with the returned value of l_pid set to -1 (as with F_GETLK).

macroF_SETBACKINGSTORE

#define F_SETBACKINGSTORE 70

Mark the file as being the backing store for another filesystem

macroF_GETPATH_MTMINFO

#define F_GETPATH_MTMINFO 71

return the full path of the FD, but error in specific mtmd circumstances

macroF_GETCODEDIR

#define F_GETCODEDIR 72

Returns the code directory, with associated hashes, to the caller

macroF_SETNOSIGPIPE

#define F_SETNOSIGPIPE 73

No SIGPIPE generated on EPIPE

macroF_GETNOSIGPIPE

#define F_GETNOSIGPIPE 74

Status of SIGPIPE for this fd

macroF_TRANSCODEKEY

#define F_TRANSCODEKEY 75

For some cases, we need to rewrap the key for AKS/MKB

macroF_SINGLE_WRITER

#define F_SINGLE_WRITER 76

file being written to a by single writer... if throttling enabled, writes

macroF_GETPROTECTIONLEVEL

#define F_GETPROTECTIONLEVEL 77

Get the protection version number for this filesystem

macroF_FINDSIGS

#define F_FINDSIGS 78

Add detached code signatures (used by dyld for shared libs)

macroF_ADDFILESIGS_FOR_DYLD_SIM

#define F_ADDFILESIGS_FOR_DYLD_SIM 83

Add signature from same file, only if it is signed by Apple (used by dyld for simulator)

macroF_BARRIERFSYNC

#define F_BARRIERFSYNC 85

fsync + issue barrier to drive

macroF_OFD_SETLK

#define F_OFD_SETLK 90

Acquire or release open file description lock

macroF_OFD_SETLKW

#define F_OFD_SETLKW 91

(as F_OFD_SETLK but blocking if conflicting lock)

macroF_OFD_GETLK

#define F_OFD_GETLK 92

Examine OFD lock

macroF_OFD_SETLKWTIMEOUT

#define F_OFD_SETLKWTIMEOUT 93

(as F_OFD_SETLKW but return if timeout)

macroF_ADDFILESIGS_RETURN

#define F_ADDFILESIGS_RETURN 97

Add signature from same file, return end offset in structure on success

macroF_CHECK_LV

#define F_CHECK_LV 98

Check if Library Validation allows this Mach-O file to be mapped into the calling process

macroF_PUNCHHOLE

#define F_PUNCHHOLE 99

Deallocate a range of the file

macroF_TRIM_ACTIVE_FILE

#define F_TRIM_ACTIVE_FILE 100

Trim an active file

macroF_SPECULATIVE_READ

#define F_SPECULATIVE_READ 101

Asynchronous advisory read fcntl for regular and compressed file

macroF_GETPATH_NOFIRMLINK

#define F_GETPATH_NOFIRMLINK 102

return the full path without firmlinks of the fd

macroF_ADDFILESIGS_INFO

#define F_ADDFILESIGS_INFO 103

Add signature from same file, return information

macroF_ADDFILESUPPL

#define F_ADDFILESUPPL 104

Add supplemental signature from same file with fd reference to original

macroF_GETSIGSINFO

#define F_GETSIGSINFO 105

Look up code signature information attached to a file or slice

macroF_SETLEASE

#define F_SETLEASE 106

Acquire or release lease

macroF_GETLEASE

#define F_GETLEASE 107

Retrieve lease information

macroF_SETLEASE_ARG

#define F_SETLEASE_ARG(t, oc) ((t) | ((oc) << 2))

macroF_TRANSFEREXTENTS

#define F_TRANSFEREXTENTS 110

Transfer allocated extents beyond leof to a different file

macroF_ATTRIBUTION_TAG

#define F_ATTRIBUTION_TAG 111

Based on flags, query/set/delete a file's attribution tag

macroF_NOCACHE_EXT

#define F_NOCACHE_EXT 112

turn data caching off/on for this fd and relax size and alignment restrictions for write

macroF_ADDSIGS_MAIN_BINARY

#define F_ADDSIGS_MAIN_BINARY 113

add detached signatures for main binary -- development only

macroFCNTL_FS_SPECIFIC_BASE

FS-specific fcntl()'s numbers begin at 0x00010000 and go up

#define FCNTL_FS_SPECIFIC_BASE 0x00010000

macroF_DUPFD_CLOEXEC

#define F_DUPFD_CLOEXEC 67

mark the dup with FD_CLOEXEC

macroFD_CLOEXEC

file descriptor flags (F_GETFD, F_SETFD)

#define FD_CLOEXEC 1

close-on-exec flag

macroF_RDLCK

record locking flags (F_GETLK, F_SETLK, F_SETLKW)

#define F_RDLCK 1

shared or read lock

macroF_UNLCK

#define F_UNLCK 2

unlock

macroF_WRLCK

#define F_WRLCK 3

exclusive or write lock

macroF_ALLOCATECONTIG

#define F_ALLOCATECONTIG 0x00000002

allocate contigious space

macroF_ALLOCATEALL

#define F_ALLOCATEALL 0x00000004

allocate all requested space or no space at all

macroF_ALLOCATEPERSIST

#define F_ALLOCATEPERSIST 0x00000008

do not free space upon close(2)

macroF_PEOFPOSMODE

#define F_PEOFPOSMODE 3

Make it past all of the SEEK pos modes so that

macroF_VOLPOSMODE

we can keep them in sync should we desire

#define F_VOLPOSMODE 4

specify volume starting postion

structflock

Advisory file segment locking data type - information passed to system by user

size 24, align 8

off_t	l_start	starting offset
off_t	l_len	len = 0 means until end of file
pid_t	l_pid	lock owner
short	l_type	lock type: read/write, etc.
short	l_whence	type of l_start

structflocktimeout

Advisory file segment locking with time out - Information passed to system by user for F_SETLKWTIMEOUT

size 40, align 8

struct flock	fl	flock passed for file locking
struct timespec	timeout	timespec struct for timeout

structradvisory

size 16, align 8

off_t	ra_offset
int	ra_count

macroUSER_FSIGNATURES_CDHASH_LEN

detached code signatures data type - information passed by user to system used by F_ADDSIGS and F_ADDFILESIGS. F_ADDFILESIGS is a shortcut for files that contain their own signature and doesn't require mapping of the file in order to load the signature.

#define USER_FSIGNATURES_CDHASH_LEN 20

structfsignatures

size 56, align 8

off_t	fs_file_start
void *	fs_blob_start
size_t	fs_blob_size
size_t	fs_fsignatures_size	The following fields are only applicable to F_ADDFILESIGS_INFO (64bit only). Prior to F_ADDFILESIGS_INFO, this struct ended after fs_blob_size. input: size of this struct (for compatibility)
char[20]	fs_cdhash	output: cdhash
int	fs_hash_type	output: hash algorithm type for cdhash

typedeffsignatures_t

typedef struct fsignatures fsignatures_t;

structfsupplement

size 32, align 8

off_t	fs_file_start	offset of Mach-O image in FAT file
off_t	fs_blob_start	offset of signature in Mach-O image
size_t	fs_blob_size	signature blob size
int	fs_orig_fd	address of original image

typedeffsupplement_t

typedef struct fsupplement fsupplement_t;

structfchecklv

DYLD needs to check if the object is allowed to be combined into the main binary. This is done between the code signature is loaded and dyld is doing all the work to process the LOAD commands. While this could be done in F_ADDFILESIGS.* family the hook into the MAC module doesn't say no when LV isn't enabled and then that is cached on the vnode, and the MAC module never gets change once a process that library validation enabled.

size 24, align 8

off_t	lv_file_start
size_t	lv_error_message_size
void *	lv_error_message

typedeffchecklv_t

typedef struct fchecklv fchecklv_t;

macroGETSIGSINFO_PLATFORM_BINARY

At this time F_GETSIGSINFO can only indicate platformness. As additional requestable information is defined, new keys will be added and the fgetsigsinfo_t structure will be lengthened to add space for the additional information

#define GETSIGSINFO_PLATFORM_BINARY 1

structfgetsigsinfo

fgetsigsinfo_t used by F_GETSIGSINFO command

size 16, align 8

off_t	fg_file_start	IN: Offset in the file to look for a signature, -1 for any signature
int	fg_info_request	IN: Key indicating the info requested
int	fg_sig_is_platform	OUT: 1 if the signature is a plat form binary, 0 if not

typedeffgetsigsinfo_t

typedef struct fgetsigsinfo fgetsigsinfo_t;

macroLOCK_SH

lock operations for flock(2)

#define LOCK_SH 0x01

shared file lock

macroLOCK_EX

#define LOCK_EX 0x02

exclusive file lock

macroLOCK_NB

#define LOCK_NB 0x04

don't block when locking

macroLOCK_UN

#define LOCK_UN 0x08

unlock file

structfstore

size 32, align 8

unsigned int	fst_flags	IN: flags word
int	fst_posmode	IN: indicates use of offset field
off_t	fst_offset	IN: start of the region
off_t	fst_length	IN: size of the region
off_t	fst_bytesalloc	OUT: number of bytes allocated

typedeffstore_t

typedef struct fstore fstore_t;

structfpunchhole

fpunchhole_t used by F_PUNCHHOLE

size 24, align 8

unsigned int	fp_flags	unused
unsigned int	reserved	(to maintain 8-byte alignment)
off_t	fp_offset	IN: start of the region
off_t	fp_length	IN: size of the region

typedeffpunchhole_t

typedef struct fpunchhole fpunchhole_t;

structftrimactivefile

factive_file_trim_t used by F_TRIM_ACTIVE_FILE

size 16, align 8

off_t	fta_offset	IN: start of the region
off_t	fta_length	IN: size of the region

typedefftrimactivefile_t

typedef struct ftrimactivefile ftrimactivefile_t;

structfspecread

fspecread_t used by F_SPECULATIVE_READ

size 24, align 8

unsigned int	fsr_flags	IN: flags word
unsigned int	reserved	to maintain 8-byte alignment
off_t	fsr_offset	IN: start of the region
off_t	fsr_length	IN: size of the region

typedeffspecread_t

typedef struct fspecread fspecread_t;

macroATTRIBUTION_NAME_MAX

fattributiontag_t used by F_ATTRIBUTION_TAG

#define ATTRIBUTION_NAME_MAX 255

structfattributiontag

size 272, align 8

unsigned int	ft_flags	IN: flags word
unsigned long long	ft_hash	OUT: hash of attribution tag name
char[255]	ft_attribution_name	IN/OUT: attribution tag name associated with the file

typedeffattributiontag_t

typedef struct fattributiontag fattributiontag_t;

macroF_CREATE_TAG

ft_flags (F_ATTRIBUTION_TAG)

#define F_CREATE_TAG 0x00000001

macroF_DELETE_TAG

#define F_DELETE_TAG 0x00000002

macroF_QUERY_TAG

#define F_QUERY_TAG 0x00000004

structlog2phys

size 20, align 4

unsigned int	l2p_flags	unused so far
off_t	l2p_contigbytes	F_LOG2PHYS: unused so far
off_t	l2p_devoffset	F_LOG2PHYS_EXT: IN: number of bytes to be queried OUT: number of contiguous bytes at this position F_LOG2PHYS: OUT: bytes into device

macroO_POPUP

#define O_POPUP 0x80000000

force window to popup on open

macroO_ALERT

#define O_ALERT 0x20000000

small, clean popup window

enumfilesec_property_t

underlying type unsigned int

FILESEC_OWNER	1
FILESEC_GROUP	2
FILESEC_UUID	3
FILESEC_MODE	4
FILESEC_ACL	5
FILESEC_GRPUUID	6
FILESEC_ACL_RAW	100	XXX these are private to the implementation
FILESEC_ACL_ALLOCSIZE	101

typedeffilesec_property_t

typedef enum filesec_property_t filesec_property_t;

macroFILESEC_GUID

XXX backwards compatibility

#define FILESEC_GUID FILESEC_UUID

functionopen

__DARWIN_ALIAS_C(open)
int open(const char *, int, ...)

functionopenat

__DARWIN_NOCANCEL(openat) __OSX_AVAILABLE_STARTING(__MAC_10_10, __IPHONE_8_0)
int openat(int, const char *, int, ...)

functioncreat

__DARWIN_ALIAS_C(creat)
int creat(const char *, mode_t)

man page · June 2, 1993

creat(2) — create a new file

functionfcntl

__DARWIN_ALIAS_C(fcntl)
int fcntl(int, int, ...)

man page · August 12, 2021

fcntl(2) — file control

functionopenx_np

int openx_np(const char *, int, filesec_t)

functionopen_dprotected_np

int open_dprotected_np(const char *, int, int, int, ...)

data-protected non-portable open(2) : int open_dprotected_np(user_addr_t path, int flags, int class, int dpflags, int mode)

functionopenat_dprotected_np

int openat_dprotected_np(int, const char *, int, int, int, ...)

functionopenat_authenticated_np

int openat_authenticated_np(int, const char *, int, int)

man page · October 22, 2025

openat_authenticated_np(2) — open files with authenticated volume verification

functionflock

int flock(int, int)

man page · December 11, 1993

flock(2) — "apply or remove an advisory lock on an open file"

functionfilesec_init

filesec_t filesec_init(void)

functionfilesec_dup

filesec_t filesec_dup(filesec_t)

functionfilesec_free

void filesec_free(filesec_t)

functionfilesec_get_property

int filesec_get_property(filesec_t, filesec_property_t, void *)

functionfilesec_query_property

int filesec_query_property(filesec_t, filesec_property_t, int *)

functionfilesec_set_property

int filesec_set_property(filesec_t, filesec_property_t, const void *)

functionfilesec_unset_property

__OSX_AVAILABLE_STARTING(__MAC_10_6, __IPHONE_3_2)
int filesec_unset_property(filesec_t, filesec_property_t)

macro_FILESEC_UNSET_PROPERTY

#define _FILESEC_UNSET_PROPERTY ((void *)0)

macro_FILESEC_REMOVE_ACL

#define _FILESEC_REMOVE_ACL ((void *)1)