xref: /freebsd-13.1/lib/libc/sys/stat.2 (revision dfd1ff19)
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32.\"     @(#)stat.2	8.4 (Berkeley) 5/1/95
33.\" $FreeBSD$
34.\"
35.Dd November 15, 2004
36.Dt STAT 2
37.Os
38.Sh NAME
39.Nm stat ,
40.Nm lstat ,
41.Nm fstat
42.Nd get file status
43.Sh LIBRARY
44.Lb libc
45.Sh SYNOPSIS
46.In sys/types.h
47.In sys/stat.h
48.Ft int
49.Fn stat "const char *path" "struct stat *sb"
50.Ft int
51.Fn lstat "const char *path" "struct stat *sb"
52.Ft int
53.Fn fstat "int fd" "struct stat *sb"
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
63The
64.Fn lstat
65system call is like
66.Fn stat
67except in the case where the named file is a symbolic link,
68in which case
69.Fn lstat
70returns information about the link,
71while
72.Fn stat
73returns information about the file the link references.
74.Pp
75The
76.Fn fstat
77system call obtains the same information about an open file
78known by the file descriptor
79.Fa fd .
80.Pp
81The
82.Fa sb
83argument is a pointer to a
84.Vt stat
85structure
86as defined by
87.In sys/stat.h
88and into which information is placed concerning the file.
89.Pp
90The fields of
91.Vt "struct stat"
92related to the file system are as follows:
93.Bl -tag -width ".Va st_nlink"
94.It Va st_dev
95The numeric ID of the device containing the file.
96.It Va st_ino
97The file's inode number.
98.It Va st_nlink
99The number of hard links to the file.
100.El
101.Pp
102The
103.Va st_dev
104and
105.Va st_ino
106fields together identify the file uniquely within the system.
107.Pp
108The time-related fields of
109.Vt "struct stat"
110are as follows:
111.Bl -tag -width ".Va st_birthtime"
112.It Va st_atime
113Time when file data last accessed.
114Changed by the
115.Xr mknod 2 ,
116.Xr utimes 2 ,
117.Xr read 2
118and
119.Xr readv 2
120system calls.
121.It Va st_mtime
122Time when file data last modified.
123Changed by the
124.Xr mkdir 2 ,
125.Xr mkfifo 2 ,
126.Xr mknod 2 ,
127.Xr utimes 2 ,
128.Xr write 2
129and
130.Xr writev 2
131system calls.
132.It Va st_ctime
133Time when file status was last changed (inode data modification).
134Changed by the
135.Xr chflags 2 ,
136.Xr chmod 2 ,
137.Xr chown 2 ,
138.Xr creat 2 ,
139.Xr link 2 ,
140.Xr mkdir 2 ,
141.Xr mkfifo 2 ,
142.Xr mknod 2 ,
143.Xr rename 2 ,
144.Xr rmdir 2 ,
145.Xr symlink 2 ,
146.Xr truncate 2 ,
147.Xr unlink 2 ,
148.Xr utimes 2 ,
149.Xr write 2
150and
151.Xr writev 2
152system calls.
153.It Va st_birthtime
154Time when the inode was created.
155.El
156.Pp
157If
158.Dv _POSIX_SOURCE
159is not defined, the time-related fields are defined as:
160.Bd -literal
161#ifndef _POSIX_SOURCE
162#define st_atime st_atimespec.tv_sec
163#define st_mtime st_mtimespec.tv_sec
164#define st_ctime st_ctimespec.tv_sec
165#endif
166.Ed
167.Pp
168The size-related fields of the
169.Vt "struct stat"
170are as follows:
171.Bl -tag -width ".Va st_blksize"
172.It Va st_size
173The file size in bytes.
174.It Va st_blksize
175The optimal I/O block size for the file.
176.It Va st_blocks
177The actual number of blocks allocated for the file in 512-byte units.
178As short symbolic links are stored in the inode, this number may
179be zero.
180.El
181.Pp
182The access-related fields of
183.Vt "struct stat"
184are as follows:
185.Bl -tag -width ".Va st_mode"
186.It Va st_uid
187The user ID of the file's owner.
188.It Va st_gid
189The group ID of the file.
190.It Va st_mode
191Status of the file (see below).
192.El
193.Pp
194The status information word
195.Fa st_mode
196has the following bits:
197.Bd -literal
198#define S_IFMT   0170000  /* type of file */
199#define S_IFIFO  0010000  /* named pipe (fifo) */
200#define S_IFCHR  0020000  /* character special */
201#define S_IFDIR  0040000  /* directory */
202#define S_IFBLK  0060000  /* block special */
203#define S_IFREG  0100000  /* regular */
204#define S_IFLNK  0120000  /* symbolic link */
205#define S_IFSOCK 0140000  /* socket */
206#define S_IFWHT  0160000  /* whiteout */
207#define S_ISUID  0004000  /* set user id on execution */
208#define S_ISGID  0002000  /* set group id on execution */
209#define S_ISVTX  0001000  /* save swapped text even after use */
210#define S_IRUSR  0000400  /* read permission, owner */
211#define S_IWUSR  0000200  /* write permission, owner */
212#define S_IXUSR  0000100  /* execute/search permission, owner */
213.Ed
214.Pp
215For a list of access modes, see
216.In sys/stat.h ,
217.Xr access 2
218and
219.Xr chmod 2 .
220The following macros are available to test whether a
221.Va st_mode
222value passed in the
223.Fa m
224argument corresponds to a file of the specified type:
225.Bl -tag -width ".Fn S_ISFIFO m"
226.It Fn S_ISBLK m
227Test for a block special file.
228.It Fn S_ISCHR m
229Test for a character special file.
230.It Fn S_ISDIR m
231Test for a directory.
232.It Fn S_ISFIFO m
233Test for a pipe or FIFO special file.
234.It Fn S_ISLNK m
235Test for a symbolic link.
236.It Fn S_ISREG m
237Test for a regular file.
238.It Fn S_ISSOCK m
239Test for a socket.
240.It Fn S_ISWHT m
241Test for a whiteout.
242.El
243.Pp
244The macros evaluate to a non-zero value if the test is true
245or to the value 0 if the test is false.
246.Sh RETURN VALUES
247.Rv -std
248.Sh COMPATIBILITY
249Previous versions of the system used different types for the
250.Va st_dev ,
251.Va st_uid ,
252.Va st_gid ,
253.Va st_rdev ,
254.Va st_size ,
255.Va st_blksize
256and
257.Va st_blocks
258fields.
259.Sh ERRORS
260The
261.Fn stat
262and
263.Fn lstat
264system calls will fail if:
265.Bl -tag -width Er
266.It Bq Er EACCES
267Search permission is denied for a component of the path prefix.
268.It Bq Er EFAULT
269The
270.Fa sb
271or
272.Fa path
273argument
274points to an invalid address.
275.It Bq Er EIO
276An I/O error occurred while reading from or writing to the file system.
277.It Bq Er ELOOP
278Too many symbolic links were encountered in translating the pathname.
279.It Bq Er ENAMETOOLONG
280A component of a pathname exceeded 255 characters,
281or an entire path name exceeded 1023 characters.
282.It Bq Er ENOENT
283The named file does not exist.
284.It Bq Er ENOTDIR
285A component of the path prefix is not a directory.
286.It Bq Er EOVERFLOW
287The file size in bytes cannot be
288represented correctly in the structure pointed to by
289.Fa sb .
290.El
291.Pp
292.Bl -tag -width Er
293The
294.Fn fstat
295system call will fail if:
296.It Bq Er EBADF
297The
298.Fa fd
299argument
300is not a valid open file descriptor.
301.It Bq Er EFAULT
302The
303.Fa sb
304argument
305points to an invalid address.
306.It Bq Er EIO
307An I/O error occurred while reading from or writing to the file system.
308.It Bq Er EOVERFLOW
309The file size in bytes cannot be
310represented correctly in the structure pointed to by
311.Fa sb .
312.El
313.Sh SEE ALSO
314.Xr access 2 ,
315.Xr chmod 2 ,
316.Xr chown 2 ,
317.Xr fhstat 2 ,
318.Xr utimes 2 ,
319.Xr symlink 7 ,
320.Xr sticky 8
321.Sh STANDARDS
322The
323.Fn stat
324and
325.Fn fstat
326system calls are expected to conform to
327.St -p1003.1-90 .
328.Sh HISTORY
329The
330.Fn stat
331and
332.Fn fstat
333system calls appeared in
334.At v7 .
335The
336.Fn lstat
337system call appeared in
338.Bx 4.2 .
339.Sh BUGS
340Applying
341.Fn fstat
342to a socket (and thus to a pipe)
343returns a zeroed buffer,
344except for the blocksize field,
345and a unique device and inode number.
346