[apple/xnu.git] / bsd / man / man2 / stat.2

.\"	$OpenBSD: stat.2,v 1.3 1997/02/13 05:20:55 millert Exp $
.\"
.\" Copyright (c) 1980, 1991, 1993, 1994
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	This product includes software developed by the University of
.\"	California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\"     @(#)stat.2	8.3 (Berkeley) 4/19/94
.\"
.Dd April 19, 1994
.Dt STAT 2
.Os BSD 4
.Sh NAME
.Nm fstat ,
.Nm lstat ,
.Nm stat
.Nd get file status
.Sh SYNOPSIS
.Fd #include <sys/stat.h>
.Ft int
.Fo fstat
.Fa "int fildes"
.Fa "struct stat *buf"
.Fc
.Ft int
.Fo lstat
.Fa "const char *restrict path"
.Fa "struct stat *restrict buf"
.Fc
.Ft int
.Fo stat
.Fa "const char *restrict path"
.Fa "struct stat *restrict buf"
.Fc
.Sh DESCRIPTION
The
.Fn stat
family of functions obtain information about a file. The 
.Fn stat 
function obtains information about the file pointed to by
.Fa path .
Read, write or execute
permission of the named file is not required, but all directories
listed in the path name leading to the file must be searchable.
.Pp
.Fn Lstat
is like
.Fn stat
except in the case where the named file is a symbolic link,
in which case
.Fn lstat
returns information about the link,
while
.Fn stat
returns information about the file the link references.
Unlike other filesystem objects,
symbolic links do not have an owner, group, access mode, times, etc.
Instead, these attributes are taken from the directory that
contains the link.
The only attributes returned from an
.Fn lstat
that refer to the symbolic link itself are the file type (S_IFLNK),
size, blocks, and link count (always 1).
.Pp
The
.Fn fstat
obtains the same information about an open file
known by the file descriptor
.Fa fildes .
.Pp
The
.Fa buf
argument is a pointer to a
.Fa stat
structure 
as defined by
.Aq Pa sys/stat.h
and into which information is placed concerning the file.
.Bd -literal
struct stat {
    dev_t           st_dev;           /* ID of device containing file */
    mode_t          st_mode;          /* Mode of file (see below) */
    nlink_t         st_nlink;         /* Number of hard links */
    ino_t 	    st_ino;           /* File serial number */
    uid_t           st_uid;           /* User ID of the file */
    gid_t           st_gid;           /* Group ID of the file */
    dev_t           st_rdev;          /* Device ID */
    struct timespec st_atimespec;     /* time of last access */
    struct timespec st_mtimespec;     /* time of last data modification */
    struct timespec st_ctimespec;     /* time of last status change */
    struct timespec st_birthtimespec; /* time of file creation(birth) */
    off_t           st_size;          /* file size, in bytes */
    blkcnt_t        st_blocks;        /* blocks allocated for file */
    blksize_t       st_blksize;       /* optimal blocksize for I/O */
    uint32_t        st_flags;         /* user defined flags for file */
    uint32_t        st_gen;           /* file generation number */
    int32_t         st_lspare;        /* RESERVED: DO NOT USE! */
    int64_t         st_qspare[2];     /* RESERVED: DO NOT USE! */
};


.Ed
.Pp
The time-related fields of
.Fa struct stat
are as follows:
.Bl -tag -width XXXst_birthtime
.It st_atime
Time when file data last accessed.
Changed by the
.Xr mknod 2 ,
.Xr utimes 2
and
.Xr read 2
system calls.
.It st_mtime
Time when file data last modified.
Changed by the
.Xr mknod 2 ,
.Xr utimes 2
and
.Xr write 2
system calls.
.It st_ctime
Time when file status was last changed (inode data modification).
Changed by the
.Xr chmod 2 ,
.Xr chown 2 ,
.Xr link 2 ,
.Xr mknod 2 ,
.Xr rename 2 ,
.Xr unlink 2 ,
.Xr utimes 2
and
.Xr write 2
system calls.
.It st_birthtime
Time of file creation. Only set once when the file is created.
On filesystems where birthtime is not available, this field holds the
.Fa ctime
instead.
.El
.Pp
The size-related fields of the structures are as follows:
.Bl -tag -width XXXst_blksize
.It st_blksize
The optimal I/O block size for the file.
.It st_blocks
The actual number of blocks allocated for the file in 512-byte units.
As short symbolic links are stored in the inode, this number may
be zero.
.El
.Pp
The status information word
.Fa st_mode
has the following bits:
.Bd -literal
#define S_IFMT 0170000           /* type of file */
#define        S_IFIFO  0010000  /* named pipe (fifo) */
#define        S_IFCHR  0020000  /* character special */
#define        S_IFDIR  0040000  /* directory */
#define        S_IFBLK  0060000  /* block special */
#define        S_IFREG  0100000  /* regular */
#define        S_IFLNK  0120000  /* symbolic link */
#define        S_IFSOCK 0140000  /* socket */
#define        S_IFWHT  0160000  /* whiteout */
#define S_ISUID 0004000  /* set user id on execution */
#define S_ISGID 0002000  /* set group id on execution */
#define S_ISVTX 0001000  /* save swapped text even after use */
#define S_IRUSR 0000400  /* read permission, owner */
#define S_IWUSR 0000200  /* write permission, owner */
#define S_IXUSR 0000100  /* execute/search permission, owner */
.Ed
.Pp
For a list of access modes, see
.Aq Pa sys/stat.h ,
.Xr access 2
and
.Xr chmod 2 .
.Pp
For a list of the file flags in the
.Fa st_flags
field, see
.Aq Pa sys/stat.h
and
.Xr chflags 2 .
.Sh RETURN VALUES
Upon successful completion a value of 0 is returned.
Otherwise, a value of -1 is returned and
.Va errno
is set to indicate the error.
.Sh COMPATIBILITY
Previous versions of the system used different types for the
.Li st_dev ,
.Li st_uid ,
.Li st_gid ,
.Li st_rdev ,
.Li st_size ,
.Li st_blksize
and
.Li st_blocks
fields.
.Sh ERRORS
.Bl -tag -width Er
The
.Fn fstat
system call will fail if:
.\" ===========
.It Bq Er EBADF
.Fa fildes
is not a valid open file descriptor.
.\" ===========
.It Bq Er EFAULT
.Fa Sb
points to an invalid address.
.\" ===========
.It Bq Er EIO
An I/O error occurs while reading from or writing to the file system.
.El
.Pp
The
.Fn lstat
and
.Fn stat
system calls will fail if:
.Bl -tag -width Er
.\" ===========
.It Bq Er EACCES
Search permission is denied for a component of the path prefix.
.\" ===========
.It Bq Er EFAULT
.Fa Sb
or
.Em name
points to an invalid address.
.\" ===========
.It Bq Er EIO
An I/O error occurs while reading from or writing to the file system.
.\" ===========
.It Bq Er ELOOP
Too many symbolic links are encountered in translating the pathname.
This is taken to be indicative of a looping symbolic link.
.\" ===========
.It Bq Er ENAMETOOLONG
A component of a pathname exceeds
.Dv {NAME_MAX}
characters, or an entire path name exceeds
.Dv {PATH_MAX}
characters.
.\" ===========
.It Bq Er ENOENT
The named file does not exist.
.\" ===========
.It Bq Er ENOTDIR
A component of the path prefix is not a directory.
.El
.Pp
The
.Fn fstat ,
.Fn lstat ,
and
.Fn stat
system calls will fail if:
.Bl -tag -width Er
.\" ===========
.It Bq Er EOVERFLOW
The file size in bytes 
or the number of blocks allocated to the file
or the file serial number cannot be represented correctly
in the structure pointed to by
.Fa buf .
.El
.Sh CAVEATS
The file generation number,
.Fa st_gen ,
is only available to the super-user.
.Sh SEE ALSO
.Xr chflags 2 ,
.Xr chmod 2 ,
.Xr chown 2 ,
.Xr utimes 2 ,
.Xr compat 5 ,
.Xr symlink 7
.Sh BUGS
Applying
.Xr fstat
to a socket (and thus to a pipe)
returns a zero'd buffer,
except for the blocksize field,
and a unique device and inode number.
.Sh STANDARDS
The
.Fn stat
and
.Fn fstat
function calls are expected to conform to 
.St -p1003.1-88 .
.Sh HISTORY
An
.Fn lstat
function call appeared in
.Bx 4.2 .
Commit	Line	Data
9bccf70c A	1	.\" $OpenBSD: stat.2,v 1.3 1997/02/13 05:20:55 millert Exp $
	2	.\"
	3	.\" Copyright (c) 1980, 1991, 1993, 1994
	4	.\" The Regents of the University of California. All rights reserved.
	5	.\"
	6	.\" Redistribution and use in source and binary forms, with or without
	7	.\" modification, are permitted provided that the following conditions
	8	.\" are met:
	9	.\" 1. Redistributions of source code must retain the above copyright
	10	.\" notice, this list of conditions and the following disclaimer.
	11	.\" 2. Redistributions in binary form must reproduce the above copyright
	12	.\" notice, this list of conditions and the following disclaimer in the
	13	.\" documentation and/or other materials provided with the distribution.
	14	.\" 3. All advertising materials mentioning features or use of this software
	15	.\" must display the following acknowledgement:
	16	.\" This product includes software developed by the University of
	17	.\" California, Berkeley and its contributors.
	18	.\" 4. Neither the name of the University nor the names of its contributors
	19	.\" may be used to endorse or promote products derived from this software
	20	.\" without specific prior written permission.
	21	.\"
	22	.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	23	.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	24	.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	25	.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	26	.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	27	.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	28	.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	29	.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	30	.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	31	.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	32	.\" SUCH DAMAGE.
	33	.\"
	34	.\" @(#)stat.2 8.3 (Berkeley) 4/19/94
	35	.\"
	36	.Dd April 19, 1994
	37	.Dt STAT 2
	38	.Os BSD 4
	39	.Sh NAME
2d21ac55	40	.Nm fstat ,
9bccf70c	41	.Nm lstat ,
593a1d5f	42	.Nm stat
9bccf70c A	43	.Nd get file status
9bccf70c A	44	.Sh SYNOPSIS
9bccf70c A	45	.Fd #include <sys/stat.h>
9bccf70c A	46	.Ft int
2d21ac55 A	47	.Fo fstat
	48	.Fa "int fildes"
	49	.Fa "struct stat *buf"
	50	.Fc
	51	.Ft int
2d21ac55 A	52	.Fo lstat
	53	.Fa "const char *restrict path"
	54	.Fa "struct stat *restrict buf"
	55	.Fc
9bccf70c	56	.Ft int
2d21ac55 A	57	.Fo stat
	58	.Fa "const char *restrict path"
	59	.Fa "struct stat *restrict buf"
	60	.Fc
9bccf70c A	61	.Sh DESCRIPTION
	62	The
	63	.Fn stat
593a1d5f	64	family of functions obtain information about a file. The
2d21ac55	65	.Fn stat
9bccf70c A	66	function obtains information about the file pointed to by
	67	.Fa path .
	68	Read, write or execute
	69	permission of the named file is not required, but all directories
	70	listed in the path name leading to the file must be searchable.
	71	.Pp
	72	.Fn Lstat
	73	is like
	74	.Fn stat
	75	except in the case where the named file is a symbolic link,
	76	in which case
	77	.Fn lstat
	78	returns information about the link,
	79	while
	80	.Fn stat
	81	returns information about the file the link references.
	82	Unlike other filesystem objects,
	83	symbolic links do not have an owner, group, access mode, times, etc.
	84	Instead, these attributes are taken from the directory that
	85	contains the link.
	86	The only attributes returned from an
	87	.Fn lstat
	88	that refer to the symbolic link itself are the file type (S_IFLNK),
	89	size, blocks, and link count (always 1).
	90	.Pp
	91	The
	92	.Fn fstat
	93	obtains the same information about an open file
	94	known by the file descriptor
2d21ac55	95	.Fa fildes .
9bccf70c A	96	.Pp
9bccf70c A	97	The
2d21ac55	98	.Fa buf
9bccf70c	99	argument is a pointer to a
2d21ac55	100	.Fa stat
2d21ac55	101	structure
9bccf70c A	102	as defined by
9bccf70c A	103	.Aq Pa sys/stat.h
9bccf70c A	104	and into which information is placed concerning the file.
	105	.Bd -literal
	106	struct stat {
2d21ac55 A	107	dev_t st_dev; /* ID of device containing file */
	108	mode_t st_mode; /* Mode of file (see below) */
	109	nlink_t st_nlink; /* Number of hard links */
593a1d5f	110	ino_t st_ino; /* File serial number */
2d21ac55 A	111	uid_t st_uid; /* User ID of the file */
	112	gid_t st_gid; /* Group ID of the file */
	113	dev_t st_rdev; /* Device ID */
	114	struct timespec st_atimespec; /* time of last access */
	115	struct timespec st_mtimespec; /* time of last data modification */
	116	struct timespec st_ctimespec; /* time of last status change */
	117	struct timespec st_birthtimespec; /* time of file creation(birth) */
	118	off_t st_size; /* file size, in bytes */
	119	blkcnt_t st_blocks; /* blocks allocated for file */
	120	blksize_t st_blksize; /* optimal blocksize for I/O */
	121	uint32_t st_flags; /* user defined flags for file */
	122	uint32_t st_gen; /* file generation number */
	123	int32_t st_lspare; /* RESERVED: DO NOT USE! */
	124	int64_t st_qspare[2]; /* RESERVED: DO NOT USE! */
	125	};
	126
	127
9bccf70c A	128	.Ed
	129	.Pp
	130	The time-related fields of
	131	.Fa struct stat
	132	are as follows:
2d21ac55	133	.Bl -tag -width XXXst_birthtime
9bccf70c A	134	.It st_atime
	135	Time when file data last accessed.
	136	Changed by the
	137	.Xr mknod 2 ,
	138	.Xr utimes 2
	139	and
	140	.Xr read 2
	141	system calls.
	142	.It st_mtime
	143	Time when file data last modified.
	144	Changed by the
	145	.Xr mknod 2 ,
	146	.Xr utimes 2
	147	and
	148	.Xr write 2
	149	system calls.
	150	.It st_ctime
	151	Time when file status was last changed (inode data modification).
	152	Changed by the
	153	.Xr chmod 2 ,
	154	.Xr chown 2 ,
	155	.Xr link 2 ,
	156	.Xr mknod 2 ,
	157	.Xr rename 2 ,
	158	.Xr unlink 2 ,
	159	.Xr utimes 2
	160	and
	161	.Xr write 2
	162	system calls.
2d21ac55	163	.It st_birthtime
593a1d5f A	164	Time of file creation. Only set once when the file is created.
593a1d5f A	165	On filesystems where birthtime is not available, this field holds the
2d21ac55 A	166	.Fa ctime
2d21ac55 A	167	instead.
9bccf70c A	168	.El
9bccf70c A	169	.Pp
2d21ac55	170	The size-related fields of the structures are as follows:
9bccf70c A	171	.Bl -tag -width XXXst_blksize
	172	.It st_blksize
	173	The optimal I/O block size for the file.
	174	.It st_blocks
	175	The actual number of blocks allocated for the file in 512-byte units.
	176	As short symbolic links are stored in the inode, this number may
	177	be zero.
	178	.El
	179	.Pp
	180	The status information word
	181	.Fa st_mode
	182	has the following bits:
	183	.Bd -literal
	184	#define S_IFMT 0170000 /* type of file */
	185	#define S_IFIFO 0010000 /* named pipe (fifo) */
	186	#define S_IFCHR 0020000 /* character special */
	187	#define S_IFDIR 0040000 /* directory */
	188	#define S_IFBLK 0060000 /* block special */
	189	#define S_IFREG 0100000 /* regular */
	190	#define S_IFLNK 0120000 /* symbolic link */
	191	#define S_IFSOCK 0140000 /* socket */
	192	#define S_IFWHT 0160000 /* whiteout */
	193	#define S_ISUID 0004000 /* set user id on execution */
	194	#define S_ISGID 0002000 /* set group id on execution */
	195	#define S_ISVTX 0001000 /* save swapped text even after use */
	196	#define S_IRUSR 0000400 /* read permission, owner */
	197	#define S_IWUSR 0000200 /* write permission, owner */
	198	#define S_IXUSR 0000100 /* execute/search permission, owner */
	199	.Ed
	200	.Pp
	201	For a list of access modes, see
	202	.Aq Pa sys/stat.h ,
	203	.Xr access 2
	204	and
	205	.Xr chmod 2 .
2d21ac55 A	206	.Pp
	207	For a list of the file flags in the
	208	.Fa st_flags
	209	field, see
	210	.Aq Pa sys/stat.h
	211	and
	212	.Xr chflags 2 .
9bccf70c A	213	.Sh RETURN VALUES
	214	Upon successful completion a value of 0 is returned.
	215	Otherwise, a value of -1 is returned and
	216	.Va errno
	217	is set to indicate the error.
	218	.Sh COMPATIBILITY
	219	Previous versions of the system used different types for the
	220	.Li st_dev ,
	221	.Li st_uid ,
	222	.Li st_gid ,
	223	.Li st_rdev ,
	224	.Li st_size ,
	225	.Li st_blksize
	226	and
	227	.Li st_blocks
	228	fields.
	229	.Sh ERRORS
2d21ac55 A	230	.Bl -tag -width Er
	231	The
	232	.Fn fstat
	233	system call will fail if:
	234	.\" ===========
	235	.It Bq Er EBADF
	236	.Fa fildes
	237	is not a valid open file descriptor.
	238	.\" ===========
	239	.It Bq Er EFAULT
	240	.Fa Sb
	241	points to an invalid address.
	242	.\" ===========
	243	.It Bq Er EIO
	244	An I/O error occurs while reading from or writing to the file system.
	245	.El
	246	.Pp
	247	The
9bccf70c	248	.Fn lstat
2d21ac55 A	249	and
	250	.Fn stat
	251	system calls will fail if:
9bccf70c	252	.Bl -tag -width Er
2d21ac55	253	.\" ===========
9bccf70c A	254	.It Bq Er EACCES
9bccf70c A	255	Search permission is denied for a component of the path prefix.
2d21ac55	256	.\" ===========
9bccf70c A	257	.It Bq Er EFAULT
	258	.Fa Sb
	259	or
	260	.Em name
	261	points to an invalid address.
2d21ac55	262	.\" ===========
9bccf70c	263	.It Bq Er EIO
2d21ac55 A	264	An I/O error occurs while reading from or writing to the file system.
	265	.\" ===========
	266	.It Bq Er ELOOP
	267	Too many symbolic links are encountered in translating the pathname.
	268	This is taken to be indicative of a looping symbolic link.
	269	.\" ===========
	270	.It Bq Er ENAMETOOLONG
	271	A component of a pathname exceeds
	272	.Dv {NAME_MAX}
	273	characters, or an entire path name exceeds
	274	.Dv {PATH_MAX}
	275	characters.
	276	.\" ===========
	277	.It Bq Er ENOENT
	278	The named file does not exist.
	279	.\" ===========
	280	.It Bq Er ENOTDIR
	281	A component of the path prefix is not a directory.
9bccf70c A	282	.El
9bccf70c A	283	.Pp
2d21ac55 A	284	The
	285	.Fn fstat ,
	286	.Fn lstat ,
	287	and
	288	.Fn stat
	289	system calls will fail if:
9bccf70c	290	.Bl -tag -width Er
2d21ac55 A	291	.\" ===========
	292	.It Bq Er EOVERFLOW
	293	The file size in bytes
	294	or the number of blocks allocated to the file
	295	or the file serial number cannot be represented correctly
	296	in the structure pointed to by
	297	.Fa buf .
9bccf70c A	298	.El
	299	.Sh CAVEATS
	300	The file generation number,
	301	.Fa st_gen ,
	302	is only available to the super-user.
9bccf70c	303	.Sh SEE ALSO
2d21ac55	304	.Xr chflags 2 ,
9bccf70c A	305	.Xr chmod 2 ,
9bccf70c A	306	.Xr chown 2 ,
2d21ac55 A	307	.Xr utimes 2 ,
2d21ac55 A	308	.Xr compat 5 ,
9bccf70c A	309	.Xr symlink 7
	310	.Sh BUGS
	311	Applying
	312	.Xr fstat
	313	to a socket (and thus to a pipe)
	314	returns a zero'd buffer,
	315	except for the blocksize field,
	316	and a unique device and inode number.
	317	.Sh STANDARDS
	318	The
	319	.Fn stat
	320	and
	321	.Fn fstat
	322	function calls are expected to conform to
	323	.St -p1003.1-88 .
	324	.Sh HISTORY
	325	An
	326	.Fn lstat
	327	function call appeared in
	328	.Bx 4.2 .