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.\" @(#)stat.2 8.3 (Berkeley) 4/19/94
.\"
.Dd May 15, 2008
.Dt STAT 2
.Os BSD 4
.Sh NAME
.Nm fstat ,
.Nm fstat64 ,
.Nm lstat ,
.Nm lstat64 ,
.Nm stat ,
.Nm stat64
.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 TRANSITIIONAL SYNOPSIS (NOW DEPRECATED)
.Ft int
.br
.Fo fstat64
.Fa "int fildes"
.Fa "struct stat64 *buf"
.Fc ;
.sp
.Ft int
.br
.Fo lstat64
.Fa "const char *restrict path"
.Fa "struct stat64 *restrict buf"
.Fc ;
.sp
.Ft int
.br
.Fo stat64
.Fa "const char *restrict path"
.Fa "struct stat64 *restrict buf"
.Fc ;
.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 like
.Fn stat
except in the case where the named file is a symbolic link;
.Fn lstat
returns information about the link,
while
.Fn stat
returns information about the file the link references.
Unlike other filesystem objects,
symbolic links may not have an owner, group, access mode, times, etc.
Instead, these attributes may be taken from the directory that
contains the link.
In this case, 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.
When the macro
.Dv _DARWIN_FEATURE_64_BIT_INODE
is not defined (see below for more information about this macro), the
.Fa stat
structure is defined as:
.Bd -literal
struct stat { /* when _DARWIN_FEATURE_64_BIT_INODE is NOT defined */
dev_t st_dev; /* device inode resides on */
ino_t st_ino; /* inode's number */
mode_t st_mode; /* inode protection mode */
nlink_t st_nlink; /* number of hard links to the file */
uid_t st_uid; /* user-id of owner */
gid_t st_gid; /* group-id of owner */
dev_t st_rdev; /* device type, for special file inode */
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 */
quad_t st_blocks; /* blocks allocated for file */
u_long st_blksize;/* optimal file sys I/O ops blocksize */
u_long st_flags; /* user defined flags for file */
u_long st_gen; /* file generation number */
};
.Ed
.Pp
However, when the macro
.Dv _DARWIN_FEATURE_64_BIT_INODE
is defined, the
.Fa stat
structure will now be defined as:
.Bd -literal
struct stat { /* when _DARWIN_FEATURE_64_BIT_INODE is defined */
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. This field is
only available in the 64 bit inode variants. 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 _DARWIN_FEATURE_64_BIT_INODE
In order to accommodate advanced capabilities of newer file systems, the
.Fa struct stat ,
.Fa struct statfs ,
and
.Fa struct dirent
data structures were updated in Mac OSX 10.5.
.Pp
The most obvious change is the increased size of
.Fa ino_t
from 32 bits to 64 bits. As a consequence, storing an ino_t in an int is
no longer safe, and file formats storing ino_t as 32-bit values may need to
be updated. There are other changes as well, such as the widening of
.Fa f_fstypename ,
.Fa f_mntonname ,
and
.Fa f_mntfromname
in
.Fa struct statfs .
Please refer to
.Xr stat 2
and
.Xr dir 5
for more detail on the specific changes to the other affected data structures.
.Pp
On platforms that existed before these updates were available, ABI
compatibility is achieved by providing two implementations for related
functions: one using the legacy data structures and one using the updated
data structures. Variants which make use of the newer structures have their
symbols suffixed with $INODE64. These $INODE64 suffixes are automatically
appended by the compiler tool-chain and should not be used directly.
.Pp
Platforms that were released after these updates only have the newer variants
available to them. These platforms have the macro
.Dv _DARWIN_FEATURE_ONLY_64_BIT_INODE
defined.
.Pp
The
.Dv _DARWIN_FEATURE_64_BIT_INODE
macro should not be set directly. Instead, developers should make use of the
.Dv _DARWIN_NO_64_BIT_INODE
or
.Dv _DARWIN_USE_64_BIT_INODE
macros when the default variant is not desired. The following table details
the effects of defining these macros for different deployment targets.
.Pp
.TS
center;
c s s s
l | c s s
c | c c c
c | c c c
l | c c c.
T{
.Dv _DARWIN_FEATURE_ONLY_64_BIT_INODE Sy not defined
T}
=
Deployment Target
user defines: < 10.5 10.5 > 10.5
_
T{
.Em (none)
T} 32-bit 32-bit 64-bit
T{
.Dv _DARWIN_NO_64_BIT_INODE
T} 32-bit 32-bit 32-bit
T{
.Dv _DARWIN_USE_64_BIT_INODE
T} 32-bit 64-bit 64-bit
_
.T&
c s s s
c s s s
c | l s s
c | c c c
l | c c c.
T{
.Dv _DARWIN_FEATURE_ONLY_64_BIT_INODE Sy defined
T}
=
user defines: Any Deployment Target
_
T{
.Em (none)
T} 64-bit-only
T{
.Dv _DARWIN_NO_64_BIT_INODE
T} T{
.Em (error)
T}
T{
.Dv _DARWIN_USE_64_BIT_INODE
T} 64-bit-only
_
.TE
.Pp
.Bl -tag -width 64-bit-only -offset indent
.It 32-bit
32-bit inode values are enabled, and the legacy structures involving the
.Vt ino_t
type are in use.
The macro
.Dv _DARWIN_FEATURE_64_BIT_INODE
is not defined.
.It 64-bit
64-bit inode values are enabled, and the expanded structures involving the
.Vt ino_t
type are in use.
The macro
.Dv _DARWIN_FEATURE_64_BIT_INODE
is defined, and loader symbols will contain the
.Li $INODE64
suffix.
.It 64-bit-only
Like 64-bit, except loader symbols do not have the
.Li $INODE64
suffix.
.It Em (error)
A compile time error is generated.
.El
.Pp
Due to the increased benefits of the larger structure, it is highly
recommended that developers not define
.Dv _DARWIN_NO_64_BIT_INODE
and make use of
.Dv _DARWIN_USE_64_BIT_INODE
when targeting Mac OSX 10.5.
.Pp
In addition to the $INODE64 suffixed symbols, variants suffixed with 64 are
also available for related functions. These functions were provided as a way
for developers to use the updated structures in code that also made use of
the legacy structures. The enlarged stat structures were also prefixed with
64 to distinguish them from their legacy variants. These functions have been
deprecated and should be avoided.
.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.
.br
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 TRANSITIONAL DESCRIPTION (NOW DEPRECATED)
The
.Fa fstat64 ,
.Fa lstat64
and
.Fa stat64
routines are equivalent to their corresponding non-64-suffixed routine,
when 64-bit inodes are in effect.
They were added before there was support for the symbol variants, and so are
now deprecated.
Instead of using these, set the
.Dv _DARWIN_USE_64_BIT_INODE
macro before including header files to force 64-bit inode support.
.Pp
The
.Fa stat64
structure used by these deprecated routines is the same as the
.Fa stat
structure when 64-bit inodes are in effect (see above).
.Sh SEE ALSO
.Xr chflags 2 ,
.Xr chmod 2 ,
.Xr chown 2 ,
.Xr utimes 2 ,
.Xr compat 5 ,
.Xr statfs 2 ,
.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 .
The
.Fn stat64 ,
.Fn fstat64 ,
and
.Fn lstat64
system calls first appeared in Mac OS X 10.5 (Leopard) and are now deprecated
in favor of the corresponding symbol variants.