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.\" $OpenBSD: stat.2,v 1.24 2007/11/05 14:52:46 jmc 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. 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 $Mdocdate: November 5 2007 $
.Dt STAT 2
.Os
.Sh NAME
.Nm stat ,
.Nm lstat ,
.Nm fstat
.Nd get file status
.Sh SYNOPSIS
.Fd #include <sys/types.h>
.Fd #include <sys/stat.h>
.Ft int
.Fn stat "const char *path" "struct stat *sb"
.Ft int
.Fn lstat "const char *path" "struct stat *sb"
.Ft int
.Fn fstat "int fd" "struct stat *sb"
.Sh DESCRIPTION
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
The
.Fn lstat
function is identical to
.Fn stat
except when the named file is a symbolic link,
in which case
.Fn lstat
returns information about the link itself, not the file the link references.
Unlike other file system 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
.Pq Dv S_IFLNK ,
size, blocks, and link count (always 1).
.Pp
The
.Fn fstat
function obtains the same information about an open file
known by the file descriptor
.Fa fd .
.Pp
The
.Fa sb
argument is a pointer to a
.Fn stat
structure
as defined by
.Aq Pa sys/stat.h
(shown below)
and into which information is placed concerning the file.
.Bd -literal
struct stat {
dev_t st_dev; /* inode's device */
ino_t st_ino; /* inode's number */
mode_t st_mode; /* inode protection mode */
nlink_t st_nlink; /* number of hard links */
uid_t st_uid; /* user ID of the file's owner */
gid_t st_gid; /* group ID of the file's group */
dev_t st_rdev; /* device type */
struct timespec st_atimespec; /* time of last access */
struct timespec st_mtimespec; /* time of last data modification */
struct timespec st_ctimespec; /* time of last file status change */
off_t st_size; /* file size, in bytes */
int64_t st_blocks; /* blocks allocated for file */
u_int32_t st_blksize;/* optimal blocksize for I/O */
u_int32_t st_flags; /* user defined flags for file */
u_int32_t st_gen; /* file generation number */
};
.Ed
.Pp
The time-related fields of
.Li struct stat
are as follows:
.Bl -tag -width XXXst_mtime
.It Fa st_atime
Time when file data was last accessed.
Changed by the
.Xr mknod 2 ,
.Xr utimes 2 ,
and
.Xr read 2
system calls.
.It Fa st_mtime
Time when file data was last modified.
Changed by the
.Xr mknod 2 ,
.Xr utimes 2 ,
and
.Xr write 2
system calls.
.It Fa 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.
.El
.Pp
The size-related fields of the
.Li struct stat
are as follows:
.Bl -tag -width XXXst_blksize
.It Fa st_blksize
The optimal I/O block size for the file.
.It Fa 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 -offset indent
#define S_IFMT 0170000 /* type of file mask */
#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_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_IRWXU 0000700 /* RWX mask for owner */
#define S_IRUSR 0000400 /* R for owner */
#define S_IWUSR 0000200 /* W for owner */
#define S_IXUSR 0000100 /* X for owner */
#define S_IRWXG 0000070 /* RWX mask for group */
#define S_IRGRP 0000040 /* R for group */
#define S_IWGRP 0000020 /* W for group */
#define S_IXGRP 0000010 /* X for group */
#define S_IRWXO 0000007 /* RWX mask for other */
#define S_IROTH 0000004 /* R for other */
#define S_IWOTH 0000002 /* W for other */
#define S_IXOTH 0000001 /* X for other */
.Ed
.Pp
The following macros test a file's type.
If the file is of that type, a non-zero value is returned;
otherwise, 0 is returned.
.Bd -literal -offset indent
S_ISBLK(st_mode m) /* block special */
S_ISCHR(st_mode m) /* char special */
S_ISDIR(st_mode m) /* directory */
S_ISFIFO(st_mode m) /* fifo */
S_ISLNK(st_mode m) /* symbolic link */
S_ISREG(st_mode m) /* regular file */
S_ISSOCK(st_mode m) /* socket */
.Ed
.Pp
For a list of access modes, see
.Aq Pa sys/stat.h ,
.Xr access 2 ,
and
.Xr chmod 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 ERRORS
.Fn stat
and
.Fn lstat
will fail if:
.Bl -tag -width Er
.It Bq Er ENOTDIR
A component of the path prefix is not a directory.
.It Bq Er ENAMETOOLONG
A component of a pathname exceeded
.Dv NAME_MAX
characters, or an entire path name exceeded
.Dv PATH_MAX
characters.
.It Bq Er ENOENT
The named file does not exist.
.It Bq Er EACCES
Search permission is denied for a component of the path prefix.
.It Bq Er ELOOP
Too many symbolic links were encountered in translating the pathname.
.It Bq Er EFAULT
.Fa sb
or
.Em name
points to an invalid address.
.It Bq Er EIO
An I/O error occurred while reading from or writing to the file system.
.El
.Pp
.Fn fstat
will fail if:
.Bl -tag -width Er
.It Bq Er EBADF
.Fa fd
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 occurred while reading from or writing to the file system.
.El
.Sh SEE ALSO
.Xr chmod 2 ,
.Xr chown 2 ,
.Xr utimes 2 ,
.Xr symlink 7
.Sh STANDARDS
Previous versions of the system used different types for the
.Fa st_dev ,
.Fa st_uid ,
.Fa st_gid ,
.Fa st_rdev ,
.Fa st_size ,
.Fa st_blksize ,
and
.Fa st_blocks
fields.
.Pp
The
.Fn stat
and
.Fn fstat
function calls are expected to conform to
.St -p1003.1-88 .
.Sh HISTORY
A
.Fn stat
function appeared in
.At v2 .
An
.Fn lstat
function call appeared in
.Bx 4.2 .
.Sh CAVEATS
The file generation number,
.Fa st_gen ,
is only available to the superuser.
.Pp
The fields in the stat structure currently marked
.Fa st_spare1 ,
.Fa st_spare2 ,
and
.Fa st_spare3
are present in preparation for inode time stamps expanding to 64 bits.
This, however, can break certain programs that
depend on the time stamps being contiguous (in calls to
.Xr utimes 2 ) .
.Sh BUGS
Applying
.Fn fstat
to a socket (and thus to a pipe)
returns a zeroed buffer,
except for the blocksize field,
and a unique device and inode number.
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