xref: /dragonfly/lib/libc/sys/stat.2 (revision dcd37f7d)
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32.\"     @(#)stat.2	8.4 (Berkeley) 5/1/95
33.\" $FreeBSD: src/lib/libc/sys/stat.2,v 1.16.2.7 2001/12/14 18:34:01 ru Exp $
34.\" $DragonFly: src/lib/libc/sys/stat.2,v 1.6 2008/09/28 16:33:35 swildner Exp $
35.\"
36.Dd August 1, 2009
37.Dt STAT 2
38.Os
39.Sh NAME
40.Nm stat ,
41.Nm lstat ,
42.Nm fstat ,
43.Nm fstatat
44.Nd get file status
45.Sh LIBRARY
46.Lb libc
47.Sh SYNOPSIS
48.In sys/types.h
49.In sys/stat.h
50.Ft int
51.Fn stat "const char *path" "struct stat *sb"
52.Ft int
53.Fn lstat "const char *path" "struct stat *sb"
54.Ft int
55.Fn fstat "int fd" "struct stat *sb"
56.Ft int
57.Fn fstatat "int fd" "const char *path" "struct stat *buf" "int flag"
58.Sh DESCRIPTION
59The
60.Fn stat
61system call obtains information about the file pointed to by
62.Fa path .
63Read, write or execute
64permission of the named file is not required, but all directories
65listed in the path name leading to the file must be searchable.
66.Pp
67.Fn Lstat
68is like
69.Fn stat
70except in the case where the named file is a symbolic link,
71in which case
72.Fn lstat
73returns information about the link,
74while
75.Fn stat
76returns information about the file the link references.
77.Pp
78The
79.Fn fstat
80system call obtains the same information about an open file
81known by the file descriptor
82.Fa fd .
83.Pp
84The
85.Fn fstatat
86system call is equivalent to
87.Fn stat
88and
89.Fn lstat
90except in the case where the
91.Fa path
92specifies a relative path.
93In this case the status is retrieved from a file relative to
94the directory associated with the file descriptor
95.Fa fd
96instead of the current working directory.
97.Pp
98The values for the
99.Fa flag
100are constructed by a bitwise-inclusive OR of flags from the following list,
101defined in
102.In fcntl.h :
103.Bl -tag -width indent
104.It Dv AT_SYMLINK_NOFOLLOW
105If
106.Fa path
107names a symbolic link, the status of the symbolic link is returned.
108.El
109.Pp
110If
111.Fn fstatat
112is passed the special value
113.Dv AT_FDCWD
114in the
115.Fa fd
116parameter, the current working directory is used and the behavior is
117identical to a call to
118.Fn stat
119or
120.Fn lstat
121respectively, depending on whether or not the
122.Dv AT_SYMLINK_NOFOLLOW
123bit is set in
124.Fa flag .
125.Pp
126The
127.Fa sb
128argument is a pointer to a
129.Vt stat
130structure
131as defined by
132.In sys/stat.h
133(shown below)
134and into which information is placed concerning the file.
135.Bd -literal
136struct stat {
137    dev_t     st_dev;               /* inode's device */
138    ino_t     st_ino;               /* inode's number */
139    mode_t    st_mode;              /* inode protection mode */
140    nlink_t   st_nlink;             /* number of hard links */
141    uid_t     st_uid;               /* user ID of the file's owner */
142    gid_t     st_gid;               /* group ID of the file's group */
143    dev_t     st_rdev;              /* device type */
144#ifndef _POSIX_SOURCE
145    struct timespec st_atimespec;  /* time of last access */
146    struct timespec st_mtimespec;  /* time of last data modification */
147    struct timespec st_ctimespec;  /* time of last file status change */
148#else
149    time_t    st_atime;             /* time of last access */
150    long      st_atimensec;         /* nsec of last access */
151    time_t    st_mtime;             /* time of last data modification */
152    long      st_mtimensec;         /* nsec of last data modification */
153    time_t    st_ctime;             /* time of last file status change */
154    long      st_ctimensec;         /* nsec of last file status change */
155#endif
156    off_t     st_size;              /* file size, in bytes */
157    int64_t   st_blocks;            /* blocks allocated for file */
158    u_int32_t st_blksize;           /* optimal blocksize for I/O */
159    u_int32_t st_flags;             /* user defined flags for file */
160    u_int32_t st_gen;               /* file generation number */
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