STAT(2) | System Calls Manual | STAT(2) |
stat
, lstat
,
fstatat
, fstat
—
get file status
#include
<sys/stat.h>
int
stat
(const
char *path, struct stat
*sb);
int
lstat
(const
char *path, struct stat
*sb);
int
fstat
(int
fd, struct stat
*sb);
#include
<sys/stat.h>
#include <fcntl.h>
int
fstatat
(int
fd, const char
*path, struct stat
*sb, int flag);
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 identical to stat
() except when the
named file is a symbolic link, in which case lstat
()
returns information about the link itself, not the file the link
references.
The
fstatat
()
function is equivalent to either the stat
() or
lstat
() function depending on the value of
flag (see below), except that where
path specifies a relative path, the file whose
information is returned is determined relative to the directory associated
with file descriptor fd instead of the current working
directory.
If
fstatat
()
is passed the special value AT_FDCWD
(defined in
<fcntl.h>
) in the
fd parameter, the current working directory is used
and the behavior is identical to a call to stat
() or
lstat
(), depending on whether or not the
AT_SYMLINK_NOFOLLOW
bit is set in
flag.
The flag argument is the bitwise OR of zero or more of the following values:
AT_SYMLINK_NOFOLLOW
The
fstat
()
function obtains the same information about an open file known by the file
descriptor fd.
The sb argument is a pointer to
a stat
()
structure as defined by
<sys/stat.h>
(shown below)
and into which information is placed concerning the file.
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_atim; /* time of last access */ struct timespec st_mtim; /* time of last data modification */ struct timespec st_ctim; /* time of last file status change */ 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 */ u_int32_t st_flags; /* user defined flags for file */ u_int32_t st_gen; /* file generation number */ };
The time-related fields of struct stat
are
represented in struct timespec
format, which has
nanosecond precision. However, the actual precision is generally limited by
the file system holding the file. The fields are as follows:
In addition, all the time fields are set to the current time when a file system object is first created by the mkdir(2), mkfifo(2), mknod(2), open(2), and symlink(2) system calls.
For compatibility with previous standards,
st_atime, st_mtime, and
st_ctime macros are provided that expand to the
tv_secs member of their respective
struct timespec
member. Deprecated macros are also
provided for some transitional names: st_atimensec,
st_mtimensec, st_ctimensec,
st_atimespec, st_mtimespec, and
st_ctimespec
The size-related fields of the struct stat
are as follows:
The status information word st_mode has the following bits:
#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 */
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.
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 */
For a list of access modes, see
<sys/stat.h>
,
access(2), and
chmod(2).
Upon successful completion, the value 0 is returned; otherwise the value -1 is returned and the global variable errno is set to indicate the error.
stat
(), lstat
(),
and fstatat
() will fail if:
ENOTDIR
]ENAMETOOLONG
]NAME_MAX
characters, or an entire pathname (including the terminating NUL) exceeded
PATH_MAX
bytes.ENOENT
]EACCES
]ELOOP
]EFAULT
]EIO
]Additionally, fstatat
() will fail if:
EINVAL
]AT_SYMLINK_NOFOLLOW
.EBADF
]AT_FDCWD
nor a valid file descriptor.ENOTDIR
]EACCES
]fstat
() will fail if:
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.
The fstat
(),
fstatat
(), lstat
(), and
stat
() functions are intended to conform to
IEEE Std 1003.1-2008 (“POSIX.1”).
The stat
() and
fstat
() system calls first appeared in
Version 1 AT&T UNIX. The
<sys/stat.h>
header file and
the struct stat were introduced in
Version 7 AT&T UNIX.
An lstat
() function call appeared in
4.2BSD. The fstatat
()
function appeared in OpenBSD 5.0.
The file generation number, st_gen, is only available to the superuser.
Certain programs written when the timestamps were just of type
time_t
assumed that the members were consecutive
(and could therefore be treated as an array and have their address passed
directly to utime(3)). The
transition to timestamps of type struct timespec
broke them irrevocably.
Applying fstat
() to a pipe or socket fails
to fill in a unique device and inode number pair. Applying
fstat
() to a socket also fails to fill in the time
fields.
January 19, 2015 | OpenBSD-5.8 |