STAT(2) | System Calls Manual | STAT(2) |
stat
, lstat
,
fstatat
, fstat
,
S_ISBLK
, S_ISCHR
,
S_ISDIR
, S_ISFIFO
,
S_ISLNK
, S_ISREG
,
S_ISSOCK
—
#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);
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).
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:
EBADF
]EFAULT
]EIO
]The fstat
(),
fstatat
(), lstat
(), and
stat
() functions are intended to conform to
IEEE Std 1003.1-2008 (“POSIX.1”).
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.
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.
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.October 28, 2017 | OpenBSD-current |