aboutsummaryrefslogtreecommitdiffstats
path: root/lib/libc/sys/stat.2
blob: 4759d297e8da300e4604e9ee3fa3d83bbf9bf21a (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
.\" Copyright (c) 1980, 1991, 1993, 1994
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\"     @(#)stat.2	8.4 (Berkeley) 5/1/95
.\" $FreeBSD$
.\"
.Dd September 23, 2020
.Dt STAT 2
.Os
.Sh NAME
.Nm stat ,
.Nm lstat ,
.Nm fstat ,
.Nm fstatat
.Nd get file status
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In sys/stat.h
.Ft int
.Fn stat "const char * restrict path" "struct stat * restrict sb"
.Ft int
.Fn lstat "const char * restrict path" "struct stat * restrict sb"
.Ft int
.Fn fstat "int fd" "struct stat *sb"
.Ft int
.Fn fstatat "int fd" "const char *path" "struct stat *sb" "int flag"
.Sh DESCRIPTION
The
.Fn stat
system call obtains information about the file pointed to by
.Fa 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.
.Pp
The
.Fn lstat
system call is like
.Fn stat
except when the named file is a symbolic link,
in which case
.Fn lstat
returns information about the link,
while
.Fn stat
returns information about the file the link references.
.Pp
The
.Fn fstat
system call obtains the same information about an open file
known by the file descriptor
.Fa fd .
.Pp
The
.Fn fstatat
system call is equivalent to
.Fn stat
and
.Fn lstat
except when the
.Fa path
specifies a relative path, or the
.Dv AT_BENEATH
flag is provided.
For
.Fn fstatat
and relative
.Fa path ,
the status is retrieved from a file relative to
the directory associated with the file descriptor
.Fa fd
instead of the current working directory.
For
.Dv AT_BENEATH
and absolute
.Fa path ,
the status is retrieved from a file specified by the
.Fa path ,
but additional permission checks are performed, see below.
.Pp
The values for the
.Fa flag
are constructed by a bitwise-inclusive OR of flags from this list,
defined in
.In fcntl.h :
.Bl -tag -width indent
.It Dv AT_SYMLINK_NOFOLLOW
If
.Fa path
names a symbolic link, the status of the symbolic link is returned.
.It Dv AT_BENEATH
Only stat files and directories below the topping directory.
See the description of the
.Dv O_BENEATH
flag in the
.Xr open 2
manual page.
.It Dv AT_RESOLVE_BENEATH
Only walks paths below the topping directory.
See the description of the
.Dv O_RESOLVE_BENEATH
flag in the
.Xr open 2
manual page.
.El
.Pp
If
.Fn fstatat
is passed the special value
.Dv AT_FDCWD
in the
.Fa fd
parameter, the current working directory is used and the behavior is
identical to a call to
.Fn stat
or
.Fn lstat
respectively, depending on whether or not the
.Dv AT_SYMLINK_NOFOLLOW
bit is set in
.Fa flag .
.Pp
When
.Fn fstatat
is called with an absolute
.Fa path
without the
.Dv AT_BENEATH
flag, it ignores the
.Fa fd
argument.
When
.Dv AT_BENEATH
is specified with an absolute
.Fa path ,
a directory passed by the
.Fa fd
argument is used as the topping point for the resolution.
.Pp
The
.Fa sb
argument is a pointer to a
.Vt stat
structure
as defined by
.In sys/stat.h
and into which information is placed concerning the file.
.Pp
The fields of
.Vt "struct stat"
related to the file system are:
.Bl -tag -width ".Va st_nlink"
.It Va st_dev
Numeric ID of the device containing the file.
.It Va st_ino
The file's inode number.
.It Va st_nlink
Number of hard links to the file.
.It Va st_flags
Flags enabled for the file.
See
.Xr chflags 2
for the list of flags and their description.
.El
.Pp
The
.Va st_dev
and
.Va st_ino
fields together identify the file uniquely within the system.
.Pp
The time-related fields of
.Vt "struct stat"
are:
.Bl -tag -width ".Va st_birthtim"
.It Va st_atim
Time when file data was last accessed.
Changed implicitly by syscalls such as
.Xr read 2
and
.Xr readv 2 ,
and explicitly by
.Xr utimes 2 .
.It Va st_mtim
Time when file data was last modified.
Changed implicitly by syscalls such as
.Xr truncate 2 ,
.Xr write 2 ,
and
.Xr writev 2 ,
and explicitly by
.Xr utimes 2 .
Also, any syscall which modifies directory content changes the
.Va st_mtim
for the affected directory.
For instance,
.Xr creat 2 ,
.Xr mkdir 2 ,
.Xr rename 2 ,
.Xr link 2 ,
and
.Xr unlink 2 .
.It Va st_ctim
Time when file status was last changed (inode data modification).
Changed implicitly by any syscall that affects file metadata, including
.Va st_mtim ,
such as
.Xr chflags 2 ,
.Xr chmod 2 ,
.Xr chown 2 ,
.Xr truncate 2 ,
.Xr utimes 2 ,
and
.Xr write 2 .
Also, any syscall which modifies directory content changes the
.Va st_ctim
for the affected directory.
For instance,
.Xr creat 2 ,
.Xr mkdir 2 ,
.Xr rename 2 ,
.Xr link 2 ,
and
.Xr unlink 2 .
.It Va st_birthtim
Time when the inode was created.
.El
.Pp
These time-related macros are defined for compatibility:
.Bd -literal
#define	st_atime		st_atim.tv_sec
#define	st_mtime		st_mtim.tv_sec
#define	st_ctime		st_ctim.tv_sec
#ifndef _POSIX_SOURCE
#define	st_birthtime		st_birthtim.tv_sec
#endif

#ifndef _POSIX_SOURCE
#define	st_atimespec		st_atim
#define	st_mtimespec		st_mtim
#define	st_ctimespec		st_ctim
#define	st_birthtimespec	st_birthtim
#endif
.Ed
.Pp
Size-related fields of the
.Vt "struct stat"
are:
.Bl -tag -width ".Va st_blksize"
.It Va st_size
File size in bytes.
.It Va st_blksize
Optimal I/O block size for the file.
.It Va st_blocks
Actual number of blocks allocated for the file in 512-byte units.
As short symbolic links are stored in the inode, this number may
be zero.
.El
.Pp
The access-related fields of
.Vt "struct stat"
are:
.Bl -tag -width ".Va st_mode"
.It Va st_uid
User ID of the file's owner.
.It Va st_gid
Group ID of the file.
.It Va st_mode
Status of the file (see below).
.El
.Pp
The status information word
.Fa st_mode
has these bits:
.Bd -literal
#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_IFWHT  0160000  /* whiteout */
#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  /* read permission, owner */
#define S_IWUSR  0000200  /* write permission, owner */
#define S_IXUSR  0000100  /* execute/search permission, owner */
#define S_IRWXG  0000070  /* RWX mask for group */
#define S_IRGRP  0000040  /* read permission, group */
#define S_IWGRP  0000020  /* write permission, group */
#define S_IXGRP  0000010  /* execute/search permission, group */
#define S_IRWXO  0000007  /* RWX mask for other */
#define S_IROTH  0000004  /* read permission, other */
#define S_IWOTH  0000002  /* write permission, other */
#define S_IXOTH  0000001  /* execute/search permission, other */
.Ed
.Pp
For a list of access modes, see
.In sys/stat.h ,
.Xr access 2
and
.Xr chmod 2 .
These macros are available to test whether a
.Va st_mode
value passed in the
.Fa m
argument corresponds to a file of the specified type:
.Bl -tag -width ".Fn S_ISFIFO m"
.It Fn S_ISBLK m
Test for a block special file.
.It Fn S_ISCHR m
Test for a character special file.
.It Fn S_ISDIR m
Test for a directory.
.It Fn S_ISFIFO m
Test for a pipe or FIFO special file.
.It Fn S_ISLNK m
Test for a symbolic link.
.It Fn S_ISREG m
Test for a regular file.
.It Fn S_ISSOCK m
Test for a socket.
.It Fn S_ISWHT m
Test for a whiteout.
.El
.Pp
The macros evaluate to a non-zero value if the test is true
or to the value 0 if the test is false.
.Sh RETURN VALUES
.Rv -std
.Sh COMPATIBILITY
Previous versions of the system used different types for the
.Va st_dev ,
.Va st_uid ,
.Va st_gid ,
.Va st_rdev ,
.Va st_size ,
.Va st_blksize
and
.Va st_blocks
fields.
.Sh ERRORS
The
.Fn stat
and
.Fn lstat
system calls will fail if:
.Bl -tag -width Er
.It Bq Er EACCES
Search permission is denied for a component of the path prefix.
.It Bq Er EFAULT
The
.Fa sb
or
.Fa path
argument
points to an invalid address.
.It Bq Er EIO
An I/O error occurred while reading from or writing to the file system.
.It Bq Er EINTEGRITY
Corrupted data was detected while reading from the file system.
.It Bq Er ELOOP
Too many symbolic links were encountered in translating the pathname.
.It Bq Er ENAMETOOLONG
A component of a pathname exceeded 255 characters,
or an entire path name exceeded 1023 characters.
.It Bq Er ENOENT
The named file does not exist.
.It Bq Er ENOTDIR
A component of the path prefix is not a directory.
.It Bq Er EOVERFLOW
The file size in bytes cannot be
represented correctly in the structure pointed to by
.Fa sb .
.El
.Pp
The
.Fn fstat
system call will fail if:
.Bl -tag -width Er
.It Bq Er EBADF
The
.Fa fd
argument
is not a valid open file descriptor.
.It Bq Er EFAULT
The
.Fa sb
argument
points to an invalid address.
.It Bq Er EIO
An I/O error occurred while reading from or writing to the file system.
.It Bq Er EINTEGRITY
Corrupted data was detected while reading from the file system.
.It Bq Er EOVERFLOW
The file size in bytes cannot be
represented correctly in the structure pointed to by
.Fa sb .
.El
.Pp
In addition to the errors returned by the
.Fn lstat ,
the
.Fn fstatat
may fail if:
.Bl -tag -width Er
.It Bq Er EBADF
The
.Fa path
argument does not specify an absolute path and the
.Fa fd
argument is neither
.Dv AT_FDCWD
nor a valid file descriptor open for searching.
.It Bq Er EINVAL
The value of the
.Fa flag
argument is not valid.
.It Bq Er ENOTDIR
The
.Fa path
argument is not an absolute path and
.Fa fd
is neither
.Dv AT_FDCWD
nor a file descriptor associated with a directory.
.It Bq Er ENOTCAPABLE
.Fa path
is an absolute path,
or contained a ".." component leading to a
directory outside of the directory hierarchy specified by
.Fa fd ,
and the process is in capability mode.
.It Bq Er ENOTCAPABLE
The
.Dv AT_BENEATH
flag was provided to
.Fn fstatat ,
and the absolute
.Fa path
does not have its tail fully contained under the topping directory,
or the relative
.Fa path
escapes it.
.El
.Sh SEE ALSO
.Xr access 2 ,
.Xr chmod 2 ,
.Xr chown 2 ,
.Xr fhstat 2 ,
.Xr statfs 2 ,
.Xr utimes 2 ,
.Xr sticky 7 ,
.Xr symlink 7
.Sh STANDARDS
The
.Fn stat
and
.Fn fstat
system calls are expected to conform to
.St -p1003.1-90 .
The
.Fn fstatat
system call follows The Open Group Extended API Set 2 specification.
.Sh HISTORY
The
.Fn stat
and
.Fn fstat
system calls appeared in
.At v1 .
The
.Fn lstat
system call appeared in
.Bx 4.2 .
The
.Fn fstatat
system call appeared in
.Fx 8.0 .
.Sh BUGS
Applying
.Fn fstat
to a socket
returns a zeroed buffer,
except for the blocksize field,
and a unique device and inode number.