stat(2) BSD System Calls Manual stat(2)
NAME
fstat, fstat64, lstat, lstat64, stat, stat64 -- get file status
SYNOPSIS
#include <sys/stat.h>
int
fstat(int fildes, struct stat *buf);
int
lstat(const char *restrict path, struct stat *restrict buf);
int
stat(const char *restrict path, struct stat *restrict buf);
TRANSITIIONAL SYNOPSIS (NOW DEPRECATED)
int
fstat64(int fildes, struct stat64 *buf);
int
lstat64(const char *restrict path, struct stat64 *restrict buf);
int
stat64(const char *restrict path, struct stat64 *restrict buf);
DESCRIPTION
The stat() function obtains information about the file pointed to by
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.
The lstat() function is like stat() except in the case where the named
file is a symbolic link; lstat() returns information about the link,
while 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 lstat() that refer to the symbolic link
itself are the file type (S_IFLNK), size, blocks, and link count (always
1).
The fstat() obtains the same information about an open file known by the
file descriptor fildes.
The buf argument is a pointer to a stat structure as defined by
<sys/stat.h> and into which information is placed concerning the file.
When the macro _DARWIN_FEATURE_64_BIT_INODE is not defined (the ino_t
type is 32-bits), the stat structure is defined as:
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 or 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 */
};
However, when the macro _DARWIN_FEATURE_64_BIT_INODE is defined, the
ino_t type will be 64-bits (force 64-bit inode mode by defining the
_DARWIN_USE_64_BIT_INODE macro before including header files). This will
cause symbol variants of the stat family, with the $INODE64 suffixes, to
be automatically linked in. In addition, the stat structure will now be
defined as:
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! */
};
The time-related fields of struct stat are as follows:
st_atime Time when file data last accessed. Changed by the
mknod(2), utimes(2) and read(2) system calls.
st_mtime Time when file data last modified. Changed by the
mknod(2), utimes(2) and write(2) system calls.
st_ctime Time when file status was last changed (inode data modi-
fication). Changed by the chmod(2), chown(2), link(2),
mknod(2), rename(2), unlink(2), utimes(2) and write(2)
system calls.
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 ctime instead.
The size-related fields of the structures are as follows:
st_blksize The optimal I/O block size for the file.
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.
The status information word st_mode has the following bits:
#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 */
For a list of access modes, see <sys/stat.h>, access(2) and chmod(2).
For a list of the file flags in the st_flags field, see <sys/stat.h> and
chflags(2).
RETURN VALUES
Upon successful completion a value of 0 is returned. Otherwise, a value
of -1 is returned and errno is set to indicate the error.
COMPATIBILITY
Previous versions of the system used different types for the st_dev,
st_uid, st_gid, st_rdev, st_size, st_blksize and st_blocks fields.
ERRORS
The fstat() system call will fail if:
[EBADF] fildes is not a valid open file descriptor.
[EFAULT] Sb points to an invalid address.
[EIO] An I/O error occurs while reading from or writing to
the file system.
The lstat() and stat() system calls will fail if:
[EACCES] Search permission is denied for a component of the
path prefix.
[EFAULT] Sb or name points to an invalid address.
[EIO] An I/O error occurs while reading from or writing to
the file system.
[ELOOP] Too many symbolic links are encountered in translating
the pathname. This is taken to be indicative of a
looping symbolic link.
[ENAMETOOLONG] A component of a pathname exceeds {NAME_MAX} charac-
ters, or an entire path name exceeds {PATH_MAX} char-
acters.
[ENOENT] The named file does not exist.
[ENOTDIR] A component of the path prefix is not a directory.
The fstat(), lstat(), and stat() system calls will fail if:
[EOVERFLOW] The file size in bytes or the number of blocks allo-
cated to the file or the file serial number cannot be
represented correctly in the structure pointed to by
buf.
CAVEATS
The file generation number, st_gen, is only available to the super-user.
The fields in the stat structure currently marked st_spare1, st_spare2,
and 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 utimes(2)).
TRANSITIONAL DESCRIPTION (NOW DEPRECATED)
The fstat64, lstat64 and stat64 routines are equivalent to their corre-
sponding 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 _DARWIN_USE_64_BIT_INODE
macro before including header files to force 64-bit inode support.
The stat64 structure used by these deprecated routines is the same as the
stat structure when 64-bit inodes are in effect (see above).
SEE ALSO
chflags(2), chmod(2), chown(2), utimes(2), compat(5), symlink(7)
BUGS
Applying 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.
STANDARDS
The stat() and fstat() function calls are expected to conform to IEEE Std
1003.1-1988 (``POSIX.1'').
HISTORY
An lstat() function call appeared in 4.2BSD. The stat64(), fstat64(),
and lstat64() system calls first appeared in Mac OS X 10.5 (Leopard) and
are now deprecated in favor of the corresponding symbol variants.
4th Berkeley Distribution May 15, 2008 4th Berkeley Distribution
Mac OS X 10.6 - Generated Thu Sep 17 20:10:13 CDT 2009