xref: /dragonfly/lib/libc/sys/stat.2 (revision 4662ec71)
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28.\"     @(#)stat.2	8.4 (Berkeley) 5/1/95
29.\" $FreeBSD: src/lib/libc/sys/stat.2,v 1.16.2.7 2001/12/14 18:34:01 ru Exp $
30.\" $DragonFly: src/lib/libc/sys/stat.2,v 1.6 2008/09/28 16:33:35 swildner Exp $
31.\"
32.Dd August 1, 2009
33.Dt STAT 2
34.Os
35.Sh NAME
36.Nm stat ,
37.Nm lstat ,
38.Nm fstat ,
39.Nm fstatat
40.Nd get file status
41.Sh LIBRARY
42.Lb libc
43.Sh SYNOPSIS
44.In sys/types.h
45.In sys/stat.h
46.Ft int
47.Fn stat "const char *path" "struct stat *sb"
48.Ft int
49.Fn lstat "const char *path" "struct stat *sb"
50.Ft int
51.Fn fstat "int fd" "struct stat *sb"
52.Ft int
53.Fn fstatat "int fd" "const char *path" "struct stat *buf" "int flag"
54.Sh DESCRIPTION
55The
56.Fn stat
57system call obtains information about the file pointed to by
58.Fa path .
59Read, write or execute
60permission of the named file is not required, but all directories
61listed in the path name leading to the file must be searchable.
62.Pp
63.Fn Lstat
64is like
65.Fn stat
66except in the case where the named file is a symbolic link,
67in which case
68.Fn lstat
69returns information about the link,
70while
71.Fn stat
72returns information about the file the link references.
73.Pp
74The
75.Fn fstat
76system call obtains the same information about an open file
77known by the file descriptor
78.Fa fd .
79.Pp
80The
81.Fn fstatat
82system call is equivalent to
83.Fn stat
84and
85.Fn lstat
86except in the case where the
87.Fa path
88specifies a relative path.
89In this case the status is retrieved from a file relative to
90the directory associated with the file descriptor
91.Fa fd
92instead of the current working directory.
93.Pp
94The values for the
95.Fa flag
96are constructed by a bitwise-inclusive OR of flags from the following list,
97defined in
98.In fcntl.h :
99.Bl -tag -width indent
100.It Dv AT_SYMLINK_NOFOLLOW
101If
102.Fa path
103names a symbolic link, the status of the symbolic link is returned.
104.El
105.Pp
106If
107.Fn fstatat
108is passed the special value
109.Dv AT_FDCWD
110in the
111.Fa fd
112parameter, the current working directory is used and the behavior is
113identical to a call to
114.Fn stat
115or
116.Fn lstat
117respectively, depending on whether or not the
118.Dv AT_SYMLINK_NOFOLLOW
119bit is set in
120.Fa flag .
121.Pp
122The
123.Fa sb
124argument is a pointer to a
125.Vt stat
126structure
127as defined by
128.In sys/stat.h
129(shown below)
130and into which information is placed concerning the file.
131.Bd -literal
132struct stat {
133    ino_t     st_ino;               /* inode's number */
134    nlink_t   st_nlink;             /* number of hard links */
135    dev_t     st_dev;               /* inode's device */
136    mode_t    st_mode;              /* inode protection mode */
137    uint16_t  st_padding1;
138    uid_t     st_uid;               /* user ID of the file's owner */
139    gid_t     st_gid;               /* group ID of the file's group */
140    dev_t     st_rdev;              /* device type */
141#ifndef _POSIX_SOURCE
142    struct timespec st_atimespec;  /* time of last access */
143    struct timespec st_mtimespec;  /* time of last data modification */
144    struct timespec st_ctimespec;  /* time of last file status change */
145#else
146    time_t    st_atime;             /* time of last access */
147    long      st_atimensec;         /* nsec of last access */
148    time_t    st_mtime;             /* time of last data modification */
149    long      st_mtimensec;         /* nsec of last data modification */
150    time_t    st_ctime;             /* time of last file status change */
151    long      st_ctimensec;         /* nsec of last file status change */
152#endif
153    off_t     st_size;              /* file size, in bytes */
154    int64_t   st_blocks;            /* blocks allocated for file */
155    u_int32_t st_blksize;           /* optimal blocksize for I/O */
156    u_int32_t st_flags;             /* user defined flags for file */
157    u_int32_t st_gen;               /* file generation number */
158    int32_t   st_lspare;
159    int64_t   st_qspare1;           /* was recursive change detect */
160    int64_t   st_qspare2;
161};
162.Ed
163.Pp
164The time-related fields of
165.Vt struct stat
166are as follows:
167.Bl -tag -width ".Fa st_mtime"
168.It Fa st_atime
169Time when file data last accessed.
170Changed by the
171.Xr execve 2 ,
172.Xr mknod 2 ,
173.Xr mmap 2 ,
174.Xr read 2
175and
176.Xr utimes 2
177system calls.
178.It Fa st_mtime
179Time when file data last modified.
180Changed by the
181.Xr mknod 2 ,
182.Xr utimes 2
183and
184.Xr write 2
185system calls.
186.It Fa st_ctime
187Time when file status was last changed (inode data modification).
188Changed by the
189.Xr chmod 2 ,
190.Xr chown 2 ,
191.Xr link 2 ,
192.Xr mknod 2 ,
193.Xr rename 2 ,
194.Xr unlink 2 ,
195.Xr utimes 2
196and
197.Xr write 2
198system calls.
199.El
200.Pp
201If
202.Dv _POSIX_SOURCE
203is not defined, the time-related fields are defined as:
204.Bd -literal
205#ifndef _POSIX_SOURCE
206#define st_atime st_atimespec.tv_sec
207#define st_mtime st_mtimespec.tv_sec
208#define st_ctime st_ctimespec.tv_sec
209#endif
210.Ed
211.Pp
212The size-related fields of the
213.Vt struct stat
214are as follows:
215.Bl -tag -width ".Fa st_blksize"
216.It Fa st_blksize
217The optimal I/O block size for the file.
218.It Fa st_blocks
219The actual number of blocks allocated for the file in 512-byte units.
220As short symbolic links are stored in the inode, this number may
221be zero.
222.El
223.Pp
224The status information word
225.Fa st_mode
226has the following bits:
227.Bd -literal
228#define S_IFMT 0170000           /* type of file */
229#define        S_IFIFO  0010000  /* named pipe (fifo) */
230#define        S_IFCHR  0020000  /* character special */
231#define        S_IFDIR  0040000  /* directory */
232#define        S_IFBLK  0060000  /* block special */
233#define        S_IFREG  0100000  /* regular */
234#define        S_IFLNK  0120000  /* symbolic link */
235#define        S_IFSOCK 0140000  /* socket */
236#define        S_IFWHT  0160000  /* whiteout */
237#define S_ISUID 0004000  /* set user id on execution */
238#define S_ISGID 0002000  /* set group id on execution */
239#define S_ISVTX 0001000  /* save swapped text even after use */
240#define S_IRUSR 0000400  /* read permission, owner */
241#define S_IWUSR 0000200  /* write permission, owner */
242#define S_IXUSR 0000100  /* execute/search permission, owner */
243.Ed
244.Pp
245For a list of access modes, see
246.In sys/stat.h ,
247.Xr access 2
248and
249.Xr chmod 2 .
250.Sh RETURN VALUES
251.Rv -std
252.Sh COMPATIBILITY
253Previous versions of the system used different types for the
254.Fa st_dev ,
255.Fa st_uid ,
256.Fa st_gid ,
257.Fa st_rdev ,
258.Fa st_size ,
259.Fa st_blksize
260and
261.Fa st_blocks
262fields.
263.Sh ERRORS
264.Fn Stat
265and
266.Fn lstat
267will fail if:
268.Bl -tag -width Er
269.It Bq Er EACCES
270Search permission is denied for a component of the path prefix.
271.It Bq Er EIO
272An I/O error occurred while reading from or writing to the file system.
273.It Bq Er ELOOP
274Too many symbolic links were encountered in translating the pathname.
275.It Bq Er ENAMETOOLONG
276A component of a pathname exceeded 255 characters,
277or an entire path name exceeded 1023 characters.
278.It Bq Er ENOENT
279The named file does not exist.
280.It Bq Er ENOTDIR
281A component of the path prefix is not a directory.
282.It Bq Er EFAULT
283.Fa sb
284or
285.Em name
286points to an invalid address.
287.El
288.Pp
289.Fn Fstat
290will fail if:
291.Bl -tag -width Er
292.It Bq Er EBADF
293.Fa fd
294is not a valid open file descriptor.
295.It Bq Er EFAULT
296.Fa sb
297points to an invalid address.
298.It Bq Er EIO
299An I/O error occurred while reading from or writing to the file system.
300.El
301.Sh SEE ALSO
302.Xr access 2 ,
303.Xr chmod 2 ,
304.Xr chown 2 ,
305.Xr statfs 2 ,
306.Xr statvfs 2 ,
307.Xr utimes 2 ,
308.Xr symlink 7
309.Sh STANDARDS
310The
311.Fn stat
312and
313.Fn fstat
314system calls are expected to conform to
315.St -p1003.1-90 .
316.Sh HISTORY
317A
318.Fn stat
319and a
320.Fn fstat
321system call appeared in
322.At v7 .
323A
324.Fn lstat
325system call appeared in
326.Bx 4.2 .
327The
328.Fn fstatat
329system call appeared in
330.Dx 2.3 .
331.Sh BUGS
332Applying
333.Fn fstat
334to a socket (and thus to a pipe)
335returns a zeroed buffer,
336except for the blocksize field,
337and a unique device and inode number.
338