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
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
use crate::errno::Errno;
use libc::{self, c_char, c_int, c_uint, size_t, ssize_t};
use std::ffi::OsString;
#[cfg(not(target_os = "redox"))]
use std::os::raw;
use std::os::unix::ffi::OsStringExt;
use std::os::unix::io::RawFd;
// For splice and copy_file_range
#[cfg(any(
    target_os = "android",
    target_os = "freebsd",
    target_os = "linux"
))]
use std::{
    os::unix::io::{AsFd, AsRawFd},
    ptr,
};

#[cfg(feature = "fs")]
use crate::{sys::stat::Mode, NixPath, Result};

#[cfg(any(
    target_os = "linux",
    target_os = "android",
    target_os = "emscripten",
    target_os = "fuchsia",
    target_os = "wasi",
    target_env = "uclibc",
    target_os = "freebsd"
))]
#[cfg(feature = "fs")]
pub use self::posix_fadvise::{posix_fadvise, PosixFadviseAdvice};

#[cfg(not(target_os = "redox"))]
#[cfg(any(feature = "fs", feature = "process"))]
libc_bitflags! {
    #[cfg_attr(docsrs, doc(cfg(any(feature = "fs", feature = "process"))))]
    pub struct AtFlags: c_int {
        AT_REMOVEDIR;
        AT_SYMLINK_FOLLOW;
        AT_SYMLINK_NOFOLLOW;
        #[cfg(any(target_os = "android", target_os = "linux"))]
        AT_NO_AUTOMOUNT;
        #[cfg(any(target_os = "android", target_os = "linux"))]
        AT_EMPTY_PATH;
        #[cfg(not(target_os = "android"))]
        AT_EACCESS;
    }
}

#[cfg(any(feature = "fs", feature = "term"))]
libc_bitflags!(
    /// Configuration options for opened files.
    #[cfg_attr(docsrs, doc(cfg(any(feature = "fs", feature = "term"))))]
    pub struct OFlag: c_int {
        /// Mask for the access mode of the file.
        O_ACCMODE;
        /// Use alternate I/O semantics.
        #[cfg(target_os = "netbsd")]
        #[cfg_attr(docsrs, doc(cfg(all())))]
        O_ALT_IO;
        /// Open the file in append-only mode.
        O_APPEND;
        /// Generate a signal when input or output becomes possible.
        #[cfg(not(any(target_os = "aix",
                      target_os = "illumos",
                      target_os = "solaris",
                      target_os = "haiku")))]
        #[cfg_attr(docsrs, doc(cfg(all())))]
        O_ASYNC;
        /// Closes the file descriptor once an `execve` call is made.
        ///
        /// Also sets the file offset to the beginning of the file.
        O_CLOEXEC;
        /// Create the file if it does not exist.
        O_CREAT;
        /// Try to minimize cache effects of the I/O for this file.
        #[cfg(any(target_os = "android",
                  target_os = "dragonfly",
                  target_os = "freebsd",
                  target_os = "linux",
                  target_os = "netbsd"))]
        #[cfg_attr(docsrs, doc(cfg(all())))]
        O_DIRECT;
        /// If the specified path isn't a directory, fail.
        #[cfg(not(any(target_os = "illumos", target_os = "solaris")))]
        #[cfg_attr(docsrs, doc(cfg(all())))]
        O_DIRECTORY;
        /// Implicitly follow each `write()` with an `fdatasync()`.
        #[cfg(any(target_os = "android",
                  target_os = "ios",
                  target_os = "linux",
                  target_os = "macos",
                  target_os = "netbsd",
                  target_os = "openbsd"))]
        #[cfg_attr(docsrs, doc(cfg(all())))]
        O_DSYNC;
        /// Error out if a file was not created.
        O_EXCL;
        /// Open for execute only.
        #[cfg(target_os = "freebsd")]
        #[cfg_attr(docsrs, doc(cfg(all())))]
        O_EXEC;
        /// Open with an exclusive file lock.
        #[cfg(any(target_os = "dragonfly",
                  target_os = "freebsd",
                  target_os = "ios",
                  target_os = "macos",
                  target_os = "netbsd",
                  target_os = "openbsd",
                  target_os = "redox"))]
        #[cfg_attr(docsrs, doc(cfg(all())))]
        O_EXLOCK;
        /// Same as `O_SYNC`.
        #[cfg(any(target_os = "dragonfly",
                  target_os = "freebsd",
                  target_os = "ios",
                  all(target_os = "linux", not(target_env = "musl")),
                  target_os = "macos",
                  target_os = "netbsd",
                  target_os = "openbsd",
                  target_os = "redox"))]
        #[cfg_attr(docsrs, doc(cfg(all())))]
        O_FSYNC;
        /// Allow files whose sizes can't be represented in an `off_t` to be opened.
        #[cfg(any(target_os = "android", target_os = "linux"))]
        #[cfg_attr(docsrs, doc(cfg(all())))]
        O_LARGEFILE;
        /// Do not update the file last access time during `read(2)`s.
        #[cfg(any(target_os = "android", target_os = "linux"))]
        #[cfg_attr(docsrs, doc(cfg(all())))]
        O_NOATIME;
        /// Don't attach the device as the process' controlling terminal.
        #[cfg(not(target_os = "redox"))]
        #[cfg_attr(docsrs, doc(cfg(all())))]
        O_NOCTTY;
        /// Same as `O_NONBLOCK`.
        #[cfg(not(any(target_os = "redox", target_os = "haiku")))]
        #[cfg_attr(docsrs, doc(cfg(all())))]
        O_NDELAY;
        /// `open()` will fail if the given path is a symbolic link.
        O_NOFOLLOW;
        /// When possible, open the file in nonblocking mode.
        O_NONBLOCK;
        /// Don't deliver `SIGPIPE`.
        #[cfg(target_os = "netbsd")]
        #[cfg_attr(docsrs, doc(cfg(all())))]
        O_NOSIGPIPE;
        /// Obtain a file descriptor for low-level access.
        ///
        /// The file itself is not opened and other file operations will fail.
        #[cfg(any(target_os = "android", target_os = "linux", target_os = "redox"))]
        #[cfg_attr(docsrs, doc(cfg(all())))]
        O_PATH;
        /// Only allow reading.
        ///
        /// This should not be combined with `O_WRONLY` or `O_RDWR`.
        O_RDONLY;
        /// Allow both reading and writing.
        ///
        /// This should not be combined with `O_WRONLY` or `O_RDONLY`.
        O_RDWR;
        /// Similar to `O_DSYNC` but applies to `read`s instead.
        #[cfg(any(target_os = "linux", target_os = "netbsd", target_os = "openbsd"))]
        #[cfg_attr(docsrs, doc(cfg(all())))]
        O_RSYNC;
        /// Skip search permission checks.
        #[cfg(target_os = "netbsd")]
        #[cfg_attr(docsrs, doc(cfg(all())))]
        O_SEARCH;
        /// Open with a shared file lock.
        #[cfg(any(target_os = "dragonfly",
                  target_os = "freebsd",
                  target_os = "ios",
                  target_os = "macos",
                  target_os = "netbsd",
                  target_os = "openbsd",
                  target_os = "redox"))]
        #[cfg_attr(docsrs, doc(cfg(all())))]
        O_SHLOCK;
        /// Implicitly follow each `write()` with an `fsync()`.
        #[cfg(not(target_os = "redox"))]
        #[cfg_attr(docsrs, doc(cfg(all())))]
        O_SYNC;
        /// Create an unnamed temporary file.
        #[cfg(any(target_os = "android", target_os = "linux"))]
        #[cfg_attr(docsrs, doc(cfg(all())))]
        O_TMPFILE;
        /// Truncate an existing regular file to 0 length if it allows writing.
        O_TRUNC;
        /// Restore default TTY attributes.
        #[cfg(target_os = "freebsd")]
        #[cfg_attr(docsrs, doc(cfg(all())))]
        O_TTY_INIT;
        /// Only allow writing.
        ///
        /// This should not be combined with `O_RDONLY` or `O_RDWR`.
        O_WRONLY;
    }
);

feature! {
#![feature = "fs"]

// The conversion is not identical on all operating systems.
#[allow(clippy::useless_conversion)]
pub fn open<P: ?Sized + NixPath>(
    path: &P,
    oflag: OFlag,
    mode: Mode,
) -> Result<RawFd> {
    let fd = path.with_nix_path(|cstr| unsafe {
        libc::open(cstr.as_ptr(), oflag.bits(), mode.bits() as c_uint)
    })?;

    Errno::result(fd)
}

// The conversion is not identical on all operating systems.
#[allow(clippy::useless_conversion)]
#[cfg(not(target_os = "redox"))]
pub fn openat<P: ?Sized + NixPath>(
    dirfd: RawFd,
    path: &P,
    oflag: OFlag,
    mode: Mode,
) -> Result<RawFd> {
    let fd = path.with_nix_path(|cstr| unsafe {
        libc::openat(dirfd, cstr.as_ptr(), oflag.bits(), mode.bits() as c_uint)
    })?;
    Errno::result(fd)
}

#[cfg(not(target_os = "redox"))]
pub fn renameat<P1: ?Sized + NixPath, P2: ?Sized + NixPath>(
    old_dirfd: Option<RawFd>,
    old_path: &P1,
    new_dirfd: Option<RawFd>,
    new_path: &P2,
) -> Result<()> {
    let res = old_path.with_nix_path(|old_cstr| {
        new_path.with_nix_path(|new_cstr| unsafe {
            libc::renameat(
                at_rawfd(old_dirfd),
                old_cstr.as_ptr(),
                at_rawfd(new_dirfd),
                new_cstr.as_ptr(),
            )
        })
    })??;
    Errno::result(res).map(drop)
}
}

#[cfg(all(target_os = "linux", target_env = "gnu"))]
#[cfg(feature = "fs")]
libc_bitflags! {
    #[cfg_attr(docsrs, doc(cfg(feature = "fs")))]
    pub struct RenameFlags: u32 {
        RENAME_EXCHANGE;
        RENAME_NOREPLACE;
        RENAME_WHITEOUT;
    }
}

feature! {
#![feature = "fs"]
#[cfg(all(target_os = "linux", target_env = "gnu"))]
pub fn renameat2<P1: ?Sized + NixPath, P2: ?Sized + NixPath>(
    old_dirfd: Option<RawFd>,
    old_path: &P1,
    new_dirfd: Option<RawFd>,
    new_path: &P2,
    flags: RenameFlags,
) -> Result<()> {
    let res = old_path.with_nix_path(|old_cstr| {
        new_path.with_nix_path(|new_cstr| unsafe {
            libc::renameat2(
                at_rawfd(old_dirfd),
                old_cstr.as_ptr(),
                at_rawfd(new_dirfd),
                new_cstr.as_ptr(),
                flags.bits(),
            )
        })
    })??;
    Errno::result(res).map(drop)
}

fn wrap_readlink_result(mut v: Vec<u8>, len: ssize_t) -> Result<OsString> {
    unsafe { v.set_len(len as usize) }
    v.shrink_to_fit();
    Ok(OsString::from_vec(v.to_vec()))
}

fn readlink_maybe_at<P: ?Sized + NixPath>(
    dirfd: Option<RawFd>,
    path: &P,
    v: &mut Vec<u8>,
) -> Result<libc::ssize_t> {
    path.with_nix_path(|cstr| unsafe {
        match dirfd {
            #[cfg(target_os = "redox")]
            Some(_) => unreachable!(),
            #[cfg(not(target_os = "redox"))]
            Some(dirfd) => libc::readlinkat(
                dirfd,
                cstr.as_ptr(),
                v.as_mut_ptr() as *mut c_char,
                v.capacity() as size_t,
            ),
            None => libc::readlink(
                cstr.as_ptr(),
                v.as_mut_ptr() as *mut c_char,
                v.capacity() as size_t,
            ),
        }
    })
}

fn inner_readlink<P: ?Sized + NixPath>(
    dirfd: Option<RawFd>,
    path: &P,
) -> Result<OsString> {
    let mut v = Vec::with_capacity(libc::PATH_MAX as usize);

    {
        // simple case: result is strictly less than `PATH_MAX`
        let res = readlink_maybe_at(dirfd, path, &mut v)?;
        let len = Errno::result(res)?;
        debug_assert!(len >= 0);
        if (len as usize) < v.capacity() {
            return wrap_readlink_result(v, res);
        }
    }

    // Uh oh, the result is too long...
    // Let's try to ask lstat how many bytes to allocate.
    let mut try_size = {
        let reported_size = match dirfd {
            #[cfg(target_os = "redox")]
            Some(_) => unreachable!(),
            #[cfg(any(target_os = "android", target_os = "linux"))]
            Some(dirfd) => {
                let flags = if path.is_empty() {
                    AtFlags::AT_EMPTY_PATH
                } else {
                    AtFlags::empty()
                };
                super::sys::stat::fstatat(
                    dirfd,
                    path,
                    flags | AtFlags::AT_SYMLINK_NOFOLLOW,
                )
            }
            #[cfg(not(any(
                target_os = "android",
                target_os = "linux",
                target_os = "redox"
            )))]
            Some(dirfd) => super::sys::stat::fstatat(
                dirfd,
                path,
                AtFlags::AT_SYMLINK_NOFOLLOW,
            ),
            None => super::sys::stat::lstat(path),
        }
        .map(|x| x.st_size)
        .unwrap_or(0);

        if reported_size > 0 {
            // Note: even if `lstat`'s apparently valid answer turns out to be
            // wrong, we will still read the full symlink no matter what.
            reported_size as usize + 1
        } else {
            // If lstat doesn't cooperate, or reports an error, be a little less
            // precise.
            (libc::PATH_MAX as usize).max(128) << 1
        }
    };

    loop {
        {
            v.reserve_exact(try_size);
            let res = readlink_maybe_at(dirfd, path, &mut v)?;
            let len = Errno::result(res)?;
            debug_assert!(len >= 0);
            if (len as usize) < v.capacity() {
                return wrap_readlink_result(v, res);
            }
        }

        // Ugh! Still not big enough!
        match try_size.checked_shl(1) {
            Some(next_size) => try_size = next_size,
            // It's absurd that this would happen, but handle it sanely
            // anyway.
            None => break Err(Errno::ENAMETOOLONG),
        }
    }
}

pub fn readlink<P: ?Sized + NixPath>(path: &P) -> Result<OsString> {
    inner_readlink(None, path)
}

#[cfg(not(target_os = "redox"))]
pub fn readlinkat<P: ?Sized + NixPath>(
    dirfd: RawFd,
    path: &P,
) -> Result<OsString> {
    inner_readlink(Some(dirfd), path)
}

/// Computes the raw fd consumed by a function of the form `*at`.
#[cfg(not(target_os = "redox"))]
pub(crate) fn at_rawfd(fd: Option<RawFd>) -> raw::c_int {
    match fd {
        None => libc::AT_FDCWD,
        Some(fd) => fd,
    }
}
}

#[cfg(any(target_os = "android", target_os = "linux", target_os = "freebsd"))]
#[cfg(feature = "fs")]
libc_bitflags!(
    /// Additional flags for file sealing, which allows for limiting operations on a file.
    #[cfg_attr(docsrs, doc(cfg(feature = "fs")))]
    pub struct SealFlag: c_int {
        /// Prevents further calls to `fcntl()` with `F_ADD_SEALS`.
        F_SEAL_SEAL;
        /// The file cannot be reduced in size.
        F_SEAL_SHRINK;
        /// The size of the file cannot be increased.
        F_SEAL_GROW;
        /// The file contents cannot be modified.
        F_SEAL_WRITE;
    }
);

#[cfg(feature = "fs")]
libc_bitflags!(
    /// Additional configuration flags for `fcntl`'s `F_SETFD`.
    #[cfg_attr(docsrs, doc(cfg(feature = "fs")))]
    pub struct FdFlag: c_int {
        /// The file descriptor will automatically be closed during a successful `execve(2)`.
        FD_CLOEXEC;
    }
);

feature! {
#![feature = "fs"]

#[cfg(not(target_os = "redox"))]
#[derive(Debug, Eq, Hash, PartialEq)]
#[non_exhaustive]
pub enum FcntlArg<'a> {
    F_DUPFD(RawFd),
    F_DUPFD_CLOEXEC(RawFd),
    F_GETFD,
    F_SETFD(FdFlag), // FD_FLAGS
    F_GETFL,
    F_SETFL(OFlag), // O_NONBLOCK
    F_SETLK(&'a libc::flock),
    F_SETLKW(&'a libc::flock),
    F_GETLK(&'a mut libc::flock),
    #[cfg(any(target_os = "linux", target_os = "android"))]
    F_OFD_SETLK(&'a libc::flock),
    #[cfg(any(target_os = "linux", target_os = "android"))]
    F_OFD_SETLKW(&'a libc::flock),
    #[cfg(any(target_os = "linux", target_os = "android"))]
    F_OFD_GETLK(&'a mut libc::flock),
    #[cfg(any(
        target_os = "android",
        target_os = "linux",
        target_os = "freebsd"
    ))]
    F_ADD_SEALS(SealFlag),
    #[cfg(any(
        target_os = "android",
        target_os = "linux",
        target_os = "freebsd"
    ))]
    F_GET_SEALS,
    #[cfg(any(target_os = "macos", target_os = "ios"))]
    F_FULLFSYNC,
    #[cfg(any(target_os = "linux", target_os = "android"))]
    F_GETPIPE_SZ,
    #[cfg(any(target_os = "linux", target_os = "android"))]
    F_SETPIPE_SZ(c_int),
    // TODO: Rest of flags
}

#[cfg(target_os = "redox")]
#[derive(Debug, Clone, Copy, Eq, Hash, PartialEq)]
#[non_exhaustive]
pub enum FcntlArg {
    F_DUPFD(RawFd),
    F_DUPFD_CLOEXEC(RawFd),
    F_GETFD,
    F_SETFD(FdFlag), // FD_FLAGS
    F_GETFL,
    F_SETFL(OFlag), // O_NONBLOCK
}
pub use self::FcntlArg::*;

// TODO: Figure out how to handle value fcntl returns
pub fn fcntl(fd: RawFd, arg: FcntlArg) -> Result<c_int> {
    let res = unsafe {
        match arg {
            F_DUPFD(rawfd) => libc::fcntl(fd, libc::F_DUPFD, rawfd),
            F_DUPFD_CLOEXEC(rawfd) => {
                libc::fcntl(fd, libc::F_DUPFD_CLOEXEC, rawfd)
            }
            F_GETFD => libc::fcntl(fd, libc::F_GETFD),
            F_SETFD(flag) => libc::fcntl(fd, libc::F_SETFD, flag.bits()),
            F_GETFL => libc::fcntl(fd, libc::F_GETFL),
            F_SETFL(flag) => libc::fcntl(fd, libc::F_SETFL, flag.bits()),
            #[cfg(not(target_os = "redox"))]
            F_SETLK(flock) => libc::fcntl(fd, libc::F_SETLK, flock),
            #[cfg(not(target_os = "redox"))]
            F_SETLKW(flock) => libc::fcntl(fd, libc::F_SETLKW, flock),
            #[cfg(not(target_os = "redox"))]
            F_GETLK(flock) => libc::fcntl(fd, libc::F_GETLK, flock),
            #[cfg(any(target_os = "android", target_os = "linux"))]
            F_OFD_SETLK(flock) => libc::fcntl(fd, libc::F_OFD_SETLK, flock),
            #[cfg(any(target_os = "android", target_os = "linux"))]
            F_OFD_SETLKW(flock) => libc::fcntl(fd, libc::F_OFD_SETLKW, flock),
            #[cfg(any(target_os = "android", target_os = "linux"))]
            F_OFD_GETLK(flock) => libc::fcntl(fd, libc::F_OFD_GETLK, flock),
            #[cfg(any(
                target_os = "android",
                target_os = "linux",
                target_os = "freebsd"
            ))]
            F_ADD_SEALS(flag) => {
                libc::fcntl(fd, libc::F_ADD_SEALS, flag.bits())
            }
            #[cfg(any(
                target_os = "android",
                target_os = "linux",
                target_os = "freebsd"
            ))]
            F_GET_SEALS => libc::fcntl(fd, libc::F_GET_SEALS),
            #[cfg(any(target_os = "macos", target_os = "ios"))]
            F_FULLFSYNC => libc::fcntl(fd, libc::F_FULLFSYNC),
            #[cfg(any(target_os = "linux", target_os = "android"))]
            F_GETPIPE_SZ => libc::fcntl(fd, libc::F_GETPIPE_SZ),
            #[cfg(any(target_os = "linux", target_os = "android"))]
            F_SETPIPE_SZ(size) => libc::fcntl(fd, libc::F_SETPIPE_SZ, size),
        }
    };

    Errno::result(res)
}

// TODO: convert to libc_enum
#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
#[non_exhaustive]
pub enum FlockArg {
    LockShared,
    LockExclusive,
    Unlock,
    LockSharedNonblock,
    LockExclusiveNonblock,
    UnlockNonblock,
}

#[cfg(not(any(target_os = "redox", target_os = "solaris")))]
pub fn flock(fd: RawFd, arg: FlockArg) -> Result<()> {
    use self::FlockArg::*;

    let res = unsafe {
        match arg {
            LockShared => libc::flock(fd, libc::LOCK_SH),
            LockExclusive => libc::flock(fd, libc::LOCK_EX),
            Unlock => libc::flock(fd, libc::LOCK_UN),
            LockSharedNonblock => {
                libc::flock(fd, libc::LOCK_SH | libc::LOCK_NB)
            }
            LockExclusiveNonblock => {
                libc::flock(fd, libc::LOCK_EX | libc::LOCK_NB)
            }
            UnlockNonblock => libc::flock(fd, libc::LOCK_UN | libc::LOCK_NB),
        }
    };

    Errno::result(res).map(drop)
}
}

#[cfg(any(target_os = "android", target_os = "linux"))]
#[cfg(feature = "zerocopy")]
libc_bitflags! {
    /// Additional flags to `splice` and friends.
    #[cfg_attr(docsrs, doc(cfg(feature = "zerocopy")))]
    pub struct SpliceFFlags: c_uint {
        /// Request that pages be moved instead of copied.
        ///
        /// Not applicable to `vmsplice`.
        SPLICE_F_MOVE;
        /// Do not block on I/O.
        SPLICE_F_NONBLOCK;
        /// Hint that more data will be coming in a subsequent splice.
        ///
        /// Not applicable to `vmsplice`.
        SPLICE_F_MORE;
        /// Gift the user pages to the kernel.
        ///
        /// Not applicable to `splice`.
        SPLICE_F_GIFT;
    }
}

feature! {
#![feature = "zerocopy"]

/// Copy a range of data from one file to another
///
/// The `copy_file_range` system call performs an in-kernel copy between
/// file descriptors `fd_in` and `fd_out` without the additional cost of
/// transferring data from the kernel to user space and back again. There may be
/// additional optimizations for specific file systems.  It copies up to `len`
/// bytes of data from file descriptor `fd_in` to file descriptor `fd_out`,
/// overwriting any data that exists within the requested range of the target
/// file.
///
/// If the `off_in` and/or `off_out` arguments are used, the values
/// will be mutated to reflect the new position within the file after
/// copying. If they are not used, the relevant file descriptors will be seeked
/// to the new position.
///
/// On successful completion the number of bytes actually copied will be
/// returned.
// Note: FreeBSD defines the offset argument as "off_t".  Linux and Android
// define it as "loff_t".  But on both OSes, on all supported platforms, those
// are 64 bits.  So Nix uses i64 to make the docs simple and consistent.
#[cfg(any(target_os = "android", target_os = "freebsd", target_os = "linux"))]
pub fn copy_file_range<Fd1: AsFd, Fd2: AsFd>(
    fd_in: Fd1,
    off_in: Option<&mut i64>,
    fd_out: Fd2,
    off_out: Option<&mut i64>,
    len: usize,
) -> Result<usize> {
    let off_in = off_in
        .map(|offset| offset as *mut i64)
        .unwrap_or(ptr::null_mut());
    let off_out = off_out
        .map(|offset| offset as *mut i64)
        .unwrap_or(ptr::null_mut());

    cfg_if::cfg_if! {
        if #[cfg(target_os = "freebsd")] {
            let ret = unsafe {
                libc::copy_file_range(
                    fd_in.as_fd().as_raw_fd(),
                    off_in,
                    fd_out.as_fd().as_raw_fd(),
                    off_out,
                    len,
                    0,
                )
            };
        } else {
            // May Linux distros still don't include copy_file_range in their
            // libc implementations, so we need to make a direct syscall.
            let ret = unsafe {
                libc::syscall(
                    libc::SYS_copy_file_range,
                    fd_in,
                    off_in,
                    fd_out.as_fd().as_raw_fd(),
                    off_out,
                    len,
                    0,
                )
            };
        }
    }
    Errno::result(ret).map(|r| r as usize)
}

#[cfg(any(target_os = "linux", target_os = "android"))]
pub fn splice(
    fd_in: RawFd,
    off_in: Option<&mut libc::loff_t>,
    fd_out: RawFd,
    off_out: Option<&mut libc::loff_t>,
    len: usize,
    flags: SpliceFFlags,
) -> Result<usize> {
    let off_in = off_in
        .map(|offset| offset as *mut libc::loff_t)
        .unwrap_or(ptr::null_mut());
    let off_out = off_out
        .map(|offset| offset as *mut libc::loff_t)
        .unwrap_or(ptr::null_mut());

    let ret = unsafe {
        libc::splice(fd_in, off_in, fd_out, off_out, len, flags.bits())
    };
    Errno::result(ret).map(|r| r as usize)
}

#[cfg(any(target_os = "linux", target_os = "android"))]
pub fn tee(
    fd_in: RawFd,
    fd_out: RawFd,
    len: usize,
    flags: SpliceFFlags,
) -> Result<usize> {
    let ret = unsafe { libc::tee(fd_in, fd_out, len, flags.bits()) };
    Errno::result(ret).map(|r| r as usize)
}

#[cfg(any(target_os = "linux", target_os = "android"))]
pub fn vmsplice(
    fd: RawFd,
    iov: &[std::io::IoSlice<'_>],
    flags: SpliceFFlags,
) -> Result<usize> {
    let ret = unsafe {
        libc::vmsplice(
            fd,
            iov.as_ptr() as *const libc::iovec,
            iov.len(),
            flags.bits(),
        )
    };
    Errno::result(ret).map(|r| r as usize)
}
}

#[cfg(target_os = "linux")]
#[cfg(feature = "fs")]
libc_bitflags!(
    /// Mode argument flags for fallocate determining operation performed on a given range.
    #[cfg_attr(docsrs, doc(cfg(feature = "fs")))]
    pub struct FallocateFlags: c_int {
        /// File size is not changed.
        ///
        /// offset + len can be greater than file size.
        FALLOC_FL_KEEP_SIZE;
        /// Deallocates space by creating a hole.
        ///
        /// Must be ORed with FALLOC_FL_KEEP_SIZE. Byte range starts at offset and continues for len bytes.
        FALLOC_FL_PUNCH_HOLE;
        /// Removes byte range from a file without leaving a hole.
        ///
        /// Byte range to collapse starts at offset and continues for len bytes.
        FALLOC_FL_COLLAPSE_RANGE;
        /// Zeroes space in specified byte range.
        ///
        /// Byte range starts at offset and continues for len bytes.
        FALLOC_FL_ZERO_RANGE;
        /// Increases file space by inserting a hole within the file size.
        ///
        /// Does not overwrite existing data. Hole starts at offset and continues for len bytes.
        FALLOC_FL_INSERT_RANGE;
        /// Shared file data extants are made private to the file.
        ///
        /// Gaurantees that a subsequent write will not fail due to lack of space.
        FALLOC_FL_UNSHARE_RANGE;
    }
);

feature! {
#![feature = "fs"]

/// Manipulates file space.
///
/// Allows the caller to directly manipulate the allocated disk space for the
/// file referred to by fd.
#[cfg(target_os = "linux")]
#[cfg(feature = "fs")]
pub fn fallocate(
    fd: RawFd,
    mode: FallocateFlags,
    offset: libc::off_t,
    len: libc::off_t,
) -> Result<()> {
    let res = unsafe { libc::fallocate(fd, mode.bits(), offset, len) };
    Errno::result(res).map(drop)
}

/// Argument to [`fspacectl`] describing the range to zero.  The first member is
/// the file offset, and the second is the length of the region.
#[cfg(any(target_os = "freebsd"))]
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub struct SpacectlRange(pub libc::off_t, pub libc::off_t);

#[cfg(any(target_os = "freebsd"))]
impl SpacectlRange {
    #[inline]
    pub fn is_empty(&self) -> bool {
        self.1 == 0
    }

    #[inline]
    pub fn len(&self) -> libc::off_t {
        self.1
    }

    #[inline]
    pub fn offset(&self) -> libc::off_t {
        self.0
    }
}

/// Punch holes in a file.
///
/// `fspacectl` instructs the file system to deallocate a portion of a file.
/// After a successful operation, this region of the file will return all zeroes
/// if read.  If the file system supports deallocation, then it may free the
/// underlying storage, too.
///
/// # Arguments
///
/// - `fd`      -   File to operate on
/// - `range.0` -   File offset at which to begin deallocation
/// - `range.1` -   Length of the region to deallocate
///
/// # Returns
///
/// The operation may deallocate less than the entire requested region.  On
/// success, it returns the region that still remains to be deallocated.  The
/// caller should loop until the returned region is empty.
///
/// # Example
///
#[cfg_attr(fbsd14, doc = " ```")]
#[cfg_attr(not(fbsd14), doc = " ```no_run")]
/// # use std::io::Write;
/// # use std::os::unix::fs::FileExt;
/// # use std::os::unix::io::AsRawFd;
/// # use nix::fcntl::*;
/// # use tempfile::tempfile;
/// const INITIAL: &[u8] = b"0123456789abcdef";
/// let mut f = tempfile().unwrap();
/// f.write_all(INITIAL).unwrap();
/// let mut range = SpacectlRange(3, 6);
/// while (!range.is_empty()) {
///     range = fspacectl(f.as_raw_fd(), range).unwrap();
/// }
/// let mut buf = vec![0; INITIAL.len()];
/// f.read_exact_at(&mut buf, 0).unwrap();
/// assert_eq!(buf, b"012\0\0\0\0\0\09abcdef");
/// ```
#[cfg(target_os = "freebsd")]
pub fn fspacectl(fd: RawFd, range: SpacectlRange) -> Result<SpacectlRange> {
    let mut rqsr = libc::spacectl_range {
        r_offset: range.0,
        r_len: range.1,
    };
    let res = unsafe {
        libc::fspacectl(
            fd,
            libc::SPACECTL_DEALLOC, // Only one command is supported ATM
            &rqsr,
            0, // No flags are currently supported
            &mut rqsr,
        )
    };
    Errno::result(res).map(|_| SpacectlRange(rqsr.r_offset, rqsr.r_len))
}

/// Like [`fspacectl`], but will never return incomplete.
///
/// # Arguments
///
/// - `fd`      -   File to operate on
/// - `offset`  -   File offset at which to begin deallocation
/// - `len`     -   Length of the region to deallocate
///
/// # Returns
///
/// Returns `()` on success.  On failure, the region may or may not be partially
/// deallocated.
///
/// # Example
///
#[cfg_attr(fbsd14, doc = " ```")]
#[cfg_attr(not(fbsd14), doc = " ```no_run")]
/// # use std::io::Write;
/// # use std::os::unix::fs::FileExt;
/// # use std::os::unix::io::AsRawFd;
/// # use nix::fcntl::*;
/// # use tempfile::tempfile;
/// const INITIAL: &[u8] = b"0123456789abcdef";
/// let mut f = tempfile().unwrap();
/// f.write_all(INITIAL).unwrap();
/// fspacectl_all(f.as_raw_fd(), 3, 6).unwrap();
/// let mut buf = vec![0; INITIAL.len()];
/// f.read_exact_at(&mut buf, 0).unwrap();
/// assert_eq!(buf, b"012\0\0\0\0\0\09abcdef");
/// ```
#[cfg(target_os = "freebsd")]
pub fn fspacectl_all(
    fd: RawFd,
    offset: libc::off_t,
    len: libc::off_t,
) -> Result<()> {
    let mut rqsr = libc::spacectl_range {
        r_offset: offset,
        r_len: len,
    };
    while rqsr.r_len > 0 {
        let res = unsafe {
            libc::fspacectl(
                fd,
                libc::SPACECTL_DEALLOC, // Only one command is supported ATM
                &rqsr,
                0, // No flags are currently supported
                &mut rqsr,
            )
        };
        Errno::result(res)?;
    }
    Ok(())
}

#[cfg(any(
    target_os = "linux",
    target_os = "android",
    target_os = "emscripten",
    target_os = "fuchsia",
    target_os = "wasi",
    target_env = "uclibc",
    target_os = "freebsd"
))]
mod posix_fadvise {
    use crate::errno::Errno;
    use crate::Result;
    use std::os::unix::io::RawFd;

    #[cfg(feature = "fs")]
    libc_enum! {
        #[repr(i32)]
        #[non_exhaustive]
        #[cfg_attr(docsrs, doc(cfg(feature = "fs")))]
        pub enum PosixFadviseAdvice {
            POSIX_FADV_NORMAL,
            POSIX_FADV_SEQUENTIAL,
            POSIX_FADV_RANDOM,
            POSIX_FADV_NOREUSE,
            POSIX_FADV_WILLNEED,
            POSIX_FADV_DONTNEED,
        }
    }

    feature! {
    #![feature = "fs"]
    pub fn posix_fadvise(
        fd: RawFd,
        offset: libc::off_t,
        len: libc::off_t,
        advice: PosixFadviseAdvice,
    ) -> Result<()> {
        let res = unsafe { libc::posix_fadvise(fd, offset, len, advice as libc::c_int) };

        if res == 0 {
            Ok(())
        } else {
            Err(Errno::from_i32(res))
        }
    }
    }
}

#[cfg(any(
    target_os = "linux",
    target_os = "android",
    target_os = "dragonfly",
    target_os = "emscripten",
    target_os = "fuchsia",
    target_os = "wasi",
    target_os = "freebsd"
))]
pub fn posix_fallocate(
    fd: RawFd,
    offset: libc::off_t,
    len: libc::off_t,
) -> Result<()> {
    let res = unsafe { libc::posix_fallocate(fd, offset, len) };
    match Errno::result(res) {
        Err(err) => Err(err),
        Ok(0) => Ok(()),
        Ok(errno) => Err(Errno::from_i32(errno)),
    }
}
}