fs.rs.html -- source
Description: Source to the Rust file `src/libstd/sys/unix/fs.rs`.
Keywords: rust, rustlang, rust-lang

      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

    use os::unix::prelude::*;

    use ffi::{CString, CStr, OsString, OsStr};
    use fmt;
    use io::{self, Error, ErrorKind, SeekFrom};
    use libc::{self, c_int, mode_t};
    use mem;
    use path::{Path, PathBuf};
    use ptr;
    use sync::Arc;
    use sys::fd::FileDesc;
    use sys::time::SystemTime;
    use sys::{cvt, cvt_r};
    use sys_common::{AsInner, FromInner};

    #[cfg(any(target_os = "linux", target_os = "emscripten", target_os = "l4re"))]
    use libc::{stat64, fstat64, lstat64, off64_t, ftruncate64, lseek64, dirent64, readdir64_r, open64};
    #[cfg(any(target_os = "linux", target_os = "emscripten"))]
    use libc::fstatat64;
    #[cfg(any(target_os = "linux", target_os = "emscripten", target_os = "android"))]
    use libc::dirfd;
    #[cfg(target_os = "android")]
    use libc::{stat as stat64, fstat as fstat64, fstatat as fstatat64, lstat as lstat64, lseek64,
               dirent as dirent64, open as open64};
    #[cfg(not(any(target_os = "linux",
                  target_os = "emscripten",
                  target_os = "l4re",
                  target_os = "android")))]
    use libc::{stat as stat64, fstat as fstat64, lstat as lstat64, off_t as off64_t,
               ftruncate as ftruncate64, lseek as lseek64, dirent as dirent64, open as open64};
    #[cfg(not(any(target_os = "linux",
                  target_os = "emscripten",
                  target_os = "solaris",
                  target_os = "l4re",
                  target_os = "fuchsia")))]
    use libc::{readdir_r as readdir64_r};

    pub struct File(FileDesc);

    #[derive(Clone)]
    pub struct FileAttr {
        stat: stat64,
    }

    // all DirEntry's will have a reference to this struct
    struct InnerReadDir {
        dirp: Dir,
        root: PathBuf,
    }

    #[derive(Clone)]
    pub struct ReadDir {
        inner: Arc<InnerReadDir>,
        end_of_stream: bool,
    }

    struct Dir(*mut libc::DIR);

    unsafe impl Send for Dir {}
    unsafe impl Sync for Dir {}

    pub struct DirEntry {
        entry: dirent64,
        dir: ReadDir,
        // We need to store an owned copy of the entry name
        // on Solaris and Fuchsia because a) it uses a zero-length
        // array to store the name, b) its lifetime between readdir
        // calls is not guaranteed.
        #[cfg(any(target_os = "solaris", target_os = "fuchsia"))]
        name: Box<[u8]>
    }

    #[derive(Clone, Debug)]
    pub struct OpenOptions {
        // generic
        read: bool,
        write: bool,
        append: bool,
        truncate: bool,
        create: bool,
        create_new: bool,
        // system-specific
        custom_flags: i32,
        mode: mode_t,
    }

    #[derive(Clone, PartialEq, Eq, Debug)]
    pub struct FilePermissions { mode: mode_t }

    #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
    pub struct FileType { mode: mode_t }

    #[derive(Debug)]
    pub struct DirBuilder { mode: mode_t }

    impl FileAttr {
        pub fn size(&self) -> u64 { self.stat.st_size as u64 }
        pub fn perm(&self) -> FilePermissions {
            FilePermissions { mode: (self.stat.st_mode as mode_t) }
        }

        pub fn file_type(&self) -> FileType {
            FileType { mode: self.stat.st_mode as mode_t }
        }
    }

    #[cfg(target_os = "netbsd")]
    impl FileAttr {
        pub fn modified(&self) -> io::Result<SystemTime> {
            Ok(SystemTime::from(libc::timespec {
                tv_sec: self.stat.st_mtime as libc::time_t,
                tv_nsec: self.stat.st_mtimensec as libc::c_long,
            }))
        }

        pub fn accessed(&self) -> io::Result<SystemTime> {
            Ok(SystemTime::from(libc::timespec {
                tv_sec: self.stat.st_atime as libc::time_t,
                tv_nsec: self.stat.st_atimensec as libc::c_long,
            }))
        }

        pub fn created(&self) -> io::Result<SystemTime> {
            Ok(SystemTime::from(libc::timespec {
                tv_sec: self.stat.st_birthtime as libc::time_t,
                tv_nsec: self.stat.st_birthtimensec as libc::c_long,
            }))
        }
    }

    #[cfg(not(target_os = "netbsd"))]
    impl FileAttr {
        pub fn modified(&self) -> io::Result<SystemTime> {
            Ok(SystemTime::from(libc::timespec {
                tv_sec: self.stat.st_mtime as libc::time_t,
                tv_nsec: self.stat.st_mtime_nsec as _,
            }))
        }

        pub fn accessed(&self) -> io::Result<SystemTime> {
            Ok(SystemTime::from(libc::timespec {
                tv_sec: self.stat.st_atime as libc::time_t,
                tv_nsec: self.stat.st_atime_nsec as _,
            }))
        }

        #[cfg(any(target_os = "bitrig",
                  target_os = "freebsd",
                  target_os = "openbsd",
                  target_os = "macos",
                  target_os = "ios"))]
        pub fn created(&self) -> io::Result<SystemTime> {
            Ok(SystemTime::from(libc::timespec {
                tv_sec: self.stat.st_birthtime as libc::time_t,
                tv_nsec: self.stat.st_birthtime_nsec as libc::c_long,
            }))
        }

        #[cfg(not(any(target_os = "bitrig",
                      target_os = "freebsd",
                      target_os = "openbsd",
                      target_os = "macos",
                      target_os = "ios")))]
        pub fn created(&self) -> io::Result<SystemTime> {
            Err(io::Error::new(io::ErrorKind::Other,
                               "creation time is not available on this platform \
                                currently"))
        }
    }

    impl AsInner<stat64> for FileAttr {
        fn as_inner(&self) -> &stat64 { &self.stat }
    }

    impl FilePermissions {
        pub fn readonly(&self) -> bool {
            // check if any class (owner, group, others) has write permission
            self.mode & 0o222 == 0
        }

        pub fn set_readonly(&mut self, readonly: bool) {
            if readonly {
                // remove write permission for all classes; equivalent to `chmod a-w <file>`
                self.mode &= !0o222;
            } else {
                // add write permission for all classes; equivalent to `chmod a+w <file>`
                self.mode |= 0o222;
            }
        }
        pub fn mode(&self) -> u32 { self.mode as u32 }
    }

    impl FileType {
        pub fn is_dir(&self) -> bool { self.is(libc::S_IFDIR) }
        pub fn is_file(&self) -> bool { self.is(libc::S_IFREG) }
        pub fn is_symlink(&self) -> bool { self.is(libc::S_IFLNK) }

        pub fn is(&self, mode: mode_t) -> bool { self.mode & libc::S_IFMT == mode }
    }

    impl FromInner<u32> for FilePermissions {
        fn from_inner(mode: u32) -> FilePermissions {
            FilePermissions { mode: mode as mode_t }
        }
    }

    impl fmt::Debug for ReadDir {
        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
            // This will only be called from std::fs::ReadDir, which will add a "ReadDir()" frame.
            // Thus the result will be e g 'ReadDir("/home")'
            fmt::Debug::fmt(&*self.inner.root, f)
        }
    }

    impl Iterator for ReadDir {
        type Item = io::Result<DirEntry>;

        #[cfg(any(target_os = "solaris", target_os = "fuchsia"))]
        fn next(&mut self) -> Option<io::Result<DirEntry>> {
            unsafe {
                loop {
                    // Although readdir_r(3) would be a correct function to use here because
                    // of the thread safety, on Illumos and Fuchsia the readdir(3C) function
                    // is safe to use in threaded applications and it is generally preferred
                    // over the readdir_r(3C) function.
                    super::os::set_errno(0);
                    let entry_ptr = libc::readdir(self.inner.dirp.0);
                    if entry_ptr.is_null() {
                        // NULL can mean either the end is reached or an error occurred.
                        // So we had to clear errno beforehand to check for an error now.
                        return match super::os::errno() {
                            0 => None,
                            e => Some(Err(Error::from_raw_os_error(e))),
                        }
                    }

                    let name = (*entry_ptr).d_name.as_ptr();
                    let namelen = libc::strlen(name) as usize;

                    let ret = DirEntry {
                        entry: *entry_ptr,
                        name: ::slice::from_raw_parts(name as *const u8,
                                                      namelen as usize).to_owned().into_boxed_slice(),
                        dir: self.clone()
                    };
                    if ret.name_bytes() != b"." && ret.name_bytes() != b".." {
                        return Some(Ok(ret))
                    }
                }
            }
        }

        #[cfg(not(any(target_os = "solaris", target_os = "fuchsia")))]
        fn next(&mut self) -> Option<io::Result<DirEntry>> {
            if self.end_of_stream {
                return None;
            }

            unsafe {
                let mut ret = DirEntry {
                    entry: mem::zeroed(),
                    dir: self.clone(),
                };
                let mut entry_ptr = ptr::null_mut();
                loop {
                    if readdir64_r(self.inner.dirp.0, &mut ret.entry, &mut entry_ptr) != 0 {
                        if entry_ptr.is_null() {
                            // We encountered an error (which will be returned in this iteration), but
                            // we also reached the end of the directory stream. The `end_of_stream`
                            // flag is enabled to make sure that we return `None` in the next iteration
                            // (instead of looping forever)
                            self.end_of_stream = true;
                        }
                        return Some(Err(Error::last_os_error()))
                    }
                    if entry_ptr.is_null() {
                        return None
                    }
                    if ret.name_bytes() != b"." && ret.name_bytes() != b".." {
                        return Some(Ok(ret))
                    }
                }
            }
        }
    }

    impl Drop for Dir {
        fn drop(&mut self) {
            let r = unsafe { libc::closedir(self.0) };
            debug_assert_eq!(r, 0);
        }
    }

    impl DirEntry {
        pub fn path(&self) -> PathBuf {
            self.dir.inner.root.join(OsStr::from_bytes(self.name_bytes()))
        }

        pub fn file_name(&self) -> OsString {
            OsStr::from_bytes(self.name_bytes()).to_os_string()
        }

        #[cfg(any(target_os = "linux", target_os = "emscripten", target_os = "android"))]
        pub fn metadata(&self) -> io::Result<FileAttr> {
            let fd = cvt(unsafe {dirfd(self.dir.inner.dirp.0)})?;
            let mut stat: stat64 = unsafe { mem::zeroed() };
            cvt(unsafe {
                fstatat64(fd, self.entry.d_name.as_ptr(), &mut stat, libc::AT_SYMLINK_NOFOLLOW)
            })?;
            Ok(FileAttr { stat })
        }

        #[cfg(not(any(target_os = "linux", target_os = "emscripten", target_os = "android")))]
        pub fn metadata(&self) -> io::Result<FileAttr> {
            lstat(&self.path())
        }

        #[cfg(any(target_os = "solaris", target_os = "haiku", target_os = "hermit"))]
        pub fn file_type(&self) -> io::Result<FileType> {
            lstat(&self.path()).map(|m| m.file_type())
        }

        #[cfg(not(any(target_os = "solaris", target_os = "haiku", target_os = "hermit")))]
        pub fn file_type(&self) -> io::Result<FileType> {
            match self.entry.d_type {
                libc::DT_CHR => Ok(FileType { mode: libc::S_IFCHR }),
                libc::DT_FIFO => Ok(FileType { mode: libc::S_IFIFO }),
                libc::DT_LNK => Ok(FileType { mode: libc::S_IFLNK }),
                libc::DT_REG => Ok(FileType { mode: libc::S_IFREG }),
                libc::DT_SOCK => Ok(FileType { mode: libc::S_IFSOCK }),
                libc::DT_DIR => Ok(FileType { mode: libc::S_IFDIR }),
                libc::DT_BLK => Ok(FileType { mode: libc::S_IFBLK }),
                _ => lstat(&self.path()).map(|m| m.file_type()),
            }
        }

        #[cfg(any(target_os = "macos",
                  target_os = "ios",
                  target_os = "linux",
                  target_os = "emscripten",
                  target_os = "android",
                  target_os = "solaris",
                  target_os = "haiku",
                  target_os = "l4re",
                  target_os = "fuchsia",
                  target_os = "hermit"))]
        pub fn ino(&self) -> u64 {
            self.entry.d_ino as u64
        }

        #[cfg(any(target_os = "freebsd",
                  target_os = "openbsd",
                  target_os = "bitrig",
                  target_os = "netbsd",
                  target_os = "dragonfly"))]
        pub fn ino(&self) -> u64 {
            self.entry.d_fileno as u64
        }

        #[cfg(any(target_os = "macos",
                  target_os = "ios",
                  target_os = "netbsd",
                  target_os = "openbsd",
                  target_os = "freebsd",
                  target_os = "dragonfly",
                  target_os = "bitrig"))]
        fn name_bytes(&self) -> &[u8] {
            unsafe {
                ::slice::from_raw_parts(self.entry.d_name.as_ptr() as *const u8,
                                        self.entry.d_namlen as usize)
            }
        }
        #[cfg(any(target_os = "android",
                  target_os = "linux",
                  target_os = "emscripten",
                  target_os = "l4re",
                  target_os = "haiku",
                  target_os = "hermit"))]
        fn name_bytes(&self) -> &[u8] {
            unsafe {
                CStr::from_ptr(self.entry.d_name.as_ptr()).to_bytes()
            }
        }
        #[cfg(any(target_os = "solaris",
                  target_os = "fuchsia"))]
        fn name_bytes(&self) -> &[u8] {
            &*self.name
        }
    }

    impl OpenOptions {
        pub fn new() -> OpenOptions {
            OpenOptions {
                // generic
                read: false,
                write: false,
                append: false,
                truncate: false,
                create: false,
                create_new: false,
                // system-specific
                custom_flags: 0,
                mode: 0o666,
            }
        }

        pub fn read(&mut self, read: bool) { self.read = read; }
        pub fn write(&mut self, write: bool) { self.write = write; }
        pub fn append(&mut self, append: bool) { self.append = append; }
        pub fn truncate(&mut self, truncate: bool) { self.truncate = truncate; }
        pub fn create(&mut self, create: bool) { self.create = create; }
        pub fn create_new(&mut self, create_new: bool) { self.create_new = create_new; }

        pub fn custom_flags(&mut self, flags: i32) { self.custom_flags = flags; }
        pub fn mode(&mut self, mode: u32) { self.mode = mode as mode_t; }

        fn get_access_mode(&self) -> io::Result<c_int> {
            match (self.read, self.write, self.append) {
                (true,  false, false) => Ok(libc::O_RDONLY),
                (false, true,  false) => Ok(libc::O_WRONLY),
                (true,  true,  false) => Ok(libc::O_RDWR),
                (false, _,     true)  => Ok(libc::O_WRONLY | libc::O_APPEND),
                (true,  _,     true)  => Ok(libc::O_RDWR | libc::O_APPEND),
                (false, false, false) => Err(Error::from_raw_os_error(libc::EINVAL)),
            }
        }

        fn get_creation_mode(&self) -> io::Result<c_int> {
            match (self.write, self.append) {
                (true, false) => {}
                (false, false) =>
                    if self.truncate || self.create || self.create_new {
                        return Err(Error::from_raw_os_error(libc::EINVAL));
                    },
                (_, true) =>
                    if self.truncate && !self.create_new {
                        return Err(Error::from_raw_os_error(libc::EINVAL));
                    },
            }

            Ok(match (self.create, self.truncate, self.create_new) {
                    (false, false, false) => 0,
                    (true,  false, false) => libc::O_CREAT,
                    (false, true,  false) => libc::O_TRUNC,
                    (true,  true,  false) => libc::O_CREAT | libc::O_TRUNC,
                    (_,      _,    true)  => libc::O_CREAT | libc::O_EXCL,
               })
        }
    }

    impl File {
        pub fn open(path: &Path, opts: &OpenOptions) -> io::Result<File> {
            let path = cstr(path)?;
            File::open_c(&path, opts)
        }

        pub fn open_c(path: &CStr, opts: &OpenOptions) -> io::Result<File> {
            let flags = libc::O_CLOEXEC |
                        opts.get_access_mode()? |
                        opts.get_creation_mode()? |
                        (opts.custom_flags as c_int & !libc::O_ACCMODE);
            let fd = cvt_r(|| unsafe {
                open64(path.as_ptr(), flags, opts.mode as c_int)
            })?;
            let fd = FileDesc::new(fd);

            // Currently the standard library supports Linux 2.6.18 which did not
            // have the O_CLOEXEC flag (passed above). If we're running on an older
            // Linux kernel then the flag is just ignored by the OS. After we open
            // the first file, we check whether it has CLOEXEC set. If it doesn't,
            // we will explicitly ask for a CLOEXEC fd for every further file we
            // open, if it does, we will skip that step.
            //
            // The CLOEXEC flag, however, is supported on versions of macOS/BSD/etc
            // that we support, so we only do this on Linux currently.
            #[cfg(target_os = "linux")]
            fn ensure_cloexec(fd: &FileDesc) -> io::Result<()> {
                use sync::atomic::{AtomicUsize, Ordering};

                const OPEN_CLOEXEC_UNKNOWN: usize = 0;
                const OPEN_CLOEXEC_SUPPORTED: usize = 1;
                const OPEN_CLOEXEC_NOTSUPPORTED: usize = 2;
                static OPEN_CLOEXEC: AtomicUsize = AtomicUsize::new(OPEN_CLOEXEC_UNKNOWN);

                let need_to_set;
                match OPEN_CLOEXEC.load(Ordering::Relaxed) {
                    OPEN_CLOEXEC_UNKNOWN => {
                        need_to_set = !fd.get_cloexec()?;
                        OPEN_CLOEXEC.store(if need_to_set {
                            OPEN_CLOEXEC_NOTSUPPORTED
                        } else {
                            OPEN_CLOEXEC_SUPPORTED
                        }, Ordering::Relaxed);
                    },
                    OPEN_CLOEXEC_SUPPORTED => need_to_set = false,
                    OPEN_CLOEXEC_NOTSUPPORTED => need_to_set = true,
                    _ => unreachable!(),
                }
                if need_to_set {
                    fd.set_cloexec()?;
                }
                Ok(())
            }

            #[cfg(not(target_os = "linux"))]
            fn ensure_cloexec(_: &FileDesc) -> io::Result<()> {
                Ok(())
            }

            ensure_cloexec(&fd)?;
            Ok(File(fd))
        }

        pub fn file_attr(&self) -> io::Result<FileAttr> {
            let mut stat: stat64 = unsafe { mem::zeroed() };
            cvt(unsafe {
                fstat64(self.0.raw(), &mut stat)
            })?;
            Ok(FileAttr { stat })
        }

        pub fn fsync(&self) -> io::Result<()> {
            cvt_r(|| unsafe { libc::fsync(self.0.raw()) })?;
            Ok(())
        }

        pub fn datasync(&self) -> io::Result<()> {
            cvt_r(|| unsafe { os_datasync(self.0.raw()) })?;
            return Ok(());

            #[cfg(any(target_os = "macos", target_os = "ios"))]
            unsafe fn os_datasync(fd: c_int) -> c_int {
                libc::fcntl(fd, libc::F_FULLFSYNC)
            }
            #[cfg(target_os = "linux")]
            unsafe fn os_datasync(fd: c_int) -> c_int { libc::fdatasync(fd) }
            #[cfg(not(any(target_os = "macos",
                          target_os = "ios",
                          target_os = "linux")))]
            unsafe fn os_datasync(fd: c_int) -> c_int { libc::fsync(fd) }
        }

        pub fn truncate(&self, size: u64) -> io::Result<()> {
            #[cfg(target_os = "android")]
            return ::sys::android::ftruncate64(self.0.raw(), size);

            #[cfg(not(target_os = "android"))]
            return cvt_r(|| unsafe {
                ftruncate64(self.0.raw(), size as off64_t)
            }).map(|_| ());
        }

        pub fn read(&self, buf: &mut [u8]) -> io::Result<usize> {
            self.0.read(buf)
        }

        pub fn read_at(&self, buf: &mut [u8], offset: u64) -> io::Result<usize> {
            self.0.read_at(buf, offset)
        }

        pub fn write(&self, buf: &[u8]) -> io::Result<usize> {
            self.0.write(buf)
        }

        pub fn write_at(&self, buf: &[u8], offset: u64) -> io::Result<usize> {
            self.0.write_at(buf, offset)
        }

        pub fn flush(&self) -> io::Result<()> { Ok(()) }

        pub fn seek(&self, pos: SeekFrom) -> io::Result<u64> {
            let (whence, pos) = match pos {
                // Casting to `i64` is fine, too large values will end up as
                // negative which will cause an error in `lseek64`.
                SeekFrom::Start(off) => (libc::SEEK_SET, off as i64),
                SeekFrom::End(off) => (libc::SEEK_END, off),
                SeekFrom::Current(off) => (libc::SEEK_CUR, off),
            };
            #[cfg(target_os = "emscripten")]
            let pos = pos as i32;
            let n = cvt(unsafe { lseek64(self.0.raw(), pos, whence) })?;
            Ok(n as u64)
        }

        pub fn duplicate(&self) -> io::Result<File> {
            self.0.duplicate().map(File)
        }

        pub fn fd(&self) -> &FileDesc { &self.0 }

        pub fn into_fd(self) -> FileDesc { self.0 }

        pub fn set_permissions(&self, perm: FilePermissions) -> io::Result<()> {
            cvt_r(|| unsafe { libc::fchmod(self.0.raw(), perm.mode) })?;
            Ok(())
        }
    }

    impl DirBuilder {
        pub fn new() -> DirBuilder {
            DirBuilder { mode: 0o777 }
        }

        pub fn mkdir(&self, p: &Path) -> io::Result<()> {
            let p = cstr(p)?;
            cvt(unsafe { libc::mkdir(p.as_ptr(), self.mode) })?;
            Ok(())
        }

        pub fn set_mode(&mut self, mode: u32) {
            self.mode = mode as mode_t;
        }
    }

    fn cstr(path: &Path) -> io::Result<CString> {
        Ok(CString::new(path.as_os_str().as_bytes())?)
    }

    impl FromInner<c_int> for File {
        fn from_inner(fd: c_int) -> File {
            File(FileDesc::new(fd))
        }
    }

    impl fmt::Debug for File {
        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
            #[cfg(target_os = "linux")]
            fn get_path(fd: c_int) -> Option<PathBuf> {
                let mut p = PathBuf::from("/proc/self/fd");
                p.push(&fd.to_string());
                readlink(&p).ok()
            }

            #[cfg(target_os = "macos")]
            fn get_path(fd: c_int) -> Option<PathBuf> {
                // FIXME: The use of PATH_MAX is generally not encouraged, but it
                // is inevitable in this case because macOS defines `fcntl` with
                // `F_GETPATH` in terms of `MAXPATHLEN`, and there are no
                // alternatives. If a better method is invented, it should be used
                // instead.
                let mut buf = vec![0;libc::PATH_MAX as usize];
                let n = unsafe { libc::fcntl(fd, libc::F_GETPATH, buf.as_ptr()) };
                if n == -1 {
                    return None;
                }
                let l = buf.iter().position(|&c| c == 0).unwrap();
                buf.truncate(l as usize);
                buf.shrink_to_fit();
                Some(PathBuf::from(OsString::from_vec(buf)))
            }

            #[cfg(not(any(target_os = "linux", target_os = "macos")))]
            fn get_path(_fd: c_int) -> Option<PathBuf> {
                // FIXME(#24570): implement this for other Unix platforms
                None
            }

            #[cfg(any(target_os = "linux", target_os = "macos"))]
            fn get_mode(fd: c_int) -> Option<(bool, bool)> {
                let mode = unsafe { libc::fcntl(fd, libc::F_GETFL) };
                if mode == -1 {
                    return None;
                }
                match mode & libc::O_ACCMODE {
                    libc::O_RDONLY => Some((true, false)),
                    libc::O_RDWR => Some((true, true)),
                    libc::O_WRONLY => Some((false, true)),
                    _ => None
                }
            }

            #[cfg(not(any(target_os = "linux", target_os = "macos")))]
            fn get_mode(_fd: c_int) -> Option<(bool, bool)> {
                // FIXME(#24570): implement this for other Unix platforms
                None
            }

            let fd = self.0.raw();
            let mut b = f.debug_struct("File");
            b.field("fd", &fd);
            if let Some(path) = get_path(fd) {
                b.field("path", &path);
            }
            if let Some((read, write)) = get_mode(fd) {
                b.field("read", &read).field("write", &write);
            }
            b.finish()
        }
    }

    pub fn readdir(p: &Path) -> io::Result<ReadDir> {
        let root = p.to_path_buf();
        let p = cstr(p)?;
        unsafe {
            let ptr = libc::opendir(p.as_ptr());
            if ptr.is_null() {
                Err(Error::last_os_error())
            } else {
                let inner = InnerReadDir { dirp: Dir(ptr), root };
                Ok(ReadDir{
                    inner: Arc::new(inner),
                    end_of_stream: false,
                })
            }
        }
    }

    pub fn unlink(p: &Path) -> io::Result<()> {
        let p = cstr(p)?;
        cvt(unsafe { libc::unlink(p.as_ptr()) })?;
        Ok(())
    }

    pub fn rename(old: &Path, new: &Path) -> io::Result<()> {
        let old = cstr(old)?;
        let new = cstr(new)?;
        cvt(unsafe { libc::rename(old.as_ptr(), new.as_ptr()) })?;
        Ok(())
    }

    pub fn set_perm(p: &Path, perm: FilePermissions) -> io::Result<()> {
        let p = cstr(p)?;
        cvt_r(|| unsafe { libc::chmod(p.as_ptr(), perm.mode) })?;
        Ok(())
    }

    pub fn rmdir(p: &Path) -> io::Result<()> {
        let p = cstr(p)?;
        cvt(unsafe { libc::rmdir(p.as_ptr()) })?;
        Ok(())
    }

    pub fn remove_dir_all(path: &Path) -> io::Result<()> {
        let filetype = lstat(path)?.file_type();
        if filetype.is_symlink() {
            unlink(path)
        } else {
            remove_dir_all_recursive(path)
        }
    }

    fn remove_dir_all_recursive(path: &Path) -> io::Result<()> {
        for child in readdir(path)? {
            let child = child?;
            if child.file_type()?.is_dir() {
                remove_dir_all_recursive(&child.path())?;
            } else {
                unlink(&child.path())?;
            }
        }
        rmdir(path)
    }

    pub fn readlink(p: &Path) -> io::Result<PathBuf> {
        let c_path = cstr(p)?;
        let p = c_path.as_ptr();

        let mut buf = Vec::with_capacity(256);

        loop {
            let buf_read = cvt(unsafe {
                libc::readlink(p, buf.as_mut_ptr() as *mut _, buf.capacity())
            })? as usize;

            unsafe { buf.set_len(buf_read); }

            if buf_read != buf.capacity() {
                buf.shrink_to_fit();

                return Ok(PathBuf::from(OsString::from_vec(buf)));
            }

            // Trigger the internal buffer resizing logic of `Vec` by requiring
            // more space than the current capacity. The length is guaranteed to be
            // the same as the capacity due to the if statement above.
            buf.reserve(1);
        }
    }

    pub fn symlink(src: &Path, dst: &Path) -> io::Result<()> {
        let src = cstr(src)?;
        let dst = cstr(dst)?;
        cvt(unsafe { libc::symlink(src.as_ptr(), dst.as_ptr()) })?;
        Ok(())
    }

    pub fn link(src: &Path, dst: &Path) -> io::Result<()> {
        let src = cstr(src)?;
        let dst = cstr(dst)?;
        cvt(unsafe { libc::link(src.as_ptr(), dst.as_ptr()) })?;
        Ok(())
    }

    pub fn stat(p: &Path) -> io::Result<FileAttr> {
        let p = cstr(p)?;
        let mut stat: stat64 = unsafe { mem::zeroed() };
        cvt(unsafe {
            stat64(p.as_ptr(), &mut stat)
        })?;
        Ok(FileAttr { stat })
    }

    pub fn lstat(p: &Path) -> io::Result<FileAttr> {
        let p = cstr(p)?;
        let mut stat: stat64 = unsafe { mem::zeroed() };
        cvt(unsafe {
            lstat64(p.as_ptr(), &mut stat)
        })?;
        Ok(FileAttr { stat })
    }

    pub fn canonicalize(p: &Path) -> io::Result<PathBuf> {
        let path = CString::new(p.as_os_str().as_bytes())?;
        let buf;
        unsafe {
            let r = libc::realpath(path.as_ptr(), ptr::null_mut());
            if r.is_null() {
                return Err(io::Error::last_os_error())
            }
            buf = CStr::from_ptr(r).to_bytes().to_vec();
            libc::free(r as *mut _);
        }
        Ok(PathBuf::from(OsString::from_vec(buf)))
    }

    #[cfg(not(any(target_os = "linux", target_os = "android")))]
    pub fn copy(from: &Path, to: &Path) -> io::Result<u64> {
        use fs::File;
        if !from.is_file() {
            return Err(Error::new(ErrorKind::InvalidInput,
                                  "the source path is not an existing regular file"))
        }

        let mut reader = File::open(from)?;
        let mut writer = File::create(to)?;
        let perm = reader.metadata()?.permissions();

        let ret = io::copy(&mut reader, &mut writer)?;
        writer.set_permissions(perm)?;
        Ok(ret)
    }

    #[cfg(any(target_os = "linux", target_os = "android"))]
    pub fn copy(from: &Path, to: &Path) -> io::Result<u64> {
        use cmp;
        use fs::File;
        use sync::atomic::{AtomicBool, Ordering};

        // Kernel prior to 4.5 don't have copy_file_range
        // We store the availability in a global to avoid unnecessary syscalls
        static HAS_COPY_FILE_RANGE: AtomicBool = AtomicBool::new(true);

        unsafe fn copy_file_range(
            fd_in: libc::c_int,
            off_in: *mut libc::loff_t,
            fd_out: libc::c_int,
            off_out: *mut libc::loff_t,
            len: libc::size_t,
            flags: libc::c_uint,
        ) -> libc::c_long {
            libc::syscall(
                libc::SYS_copy_file_range,
                fd_in,
                off_in,
                fd_out,
                off_out,
                len,
                flags,
            )
        }

        if !from.is_file() {
            return Err(Error::new(ErrorKind::InvalidInput,
                                  "the source path is not an existing regular file"))
        }

        let mut reader = File::open(from)?;
        let mut writer = File::create(to)?;
        let (perm, len) = {
            let metadata = reader.metadata()?;
            (metadata.permissions(), metadata.size())
        };

        let has_copy_file_range = HAS_COPY_FILE_RANGE.load(Ordering::Relaxed);
        let mut written = 0u64;
        while written < len {
            let copy_result = if has_copy_file_range {
                let bytes_to_copy = cmp::min(len - written, usize::max_value() as u64) as usize;
                let copy_result = unsafe {
                    // We actually don't have to adjust the offsets,
                    // because copy_file_range adjusts the file offset automatically
                    cvt(copy_file_range(reader.as_raw_fd(),
                                        ptr::null_mut(),
                                        writer.as_raw_fd(),
                                        ptr::null_mut(),
                                        bytes_to_copy,
                                        0)
                        )
                };
                if let Err(ref copy_err) = copy_result {
                    match copy_err.raw_os_error() {
                        Some(libc::ENOSYS) | Some(libc::EPERM) => {
                            HAS_COPY_FILE_RANGE.store(false, Ordering::Relaxed);
                        }
                        _ => {}
                    }
                }
                copy_result
            } else {
                Err(io::Error::from_raw_os_error(libc::ENOSYS))
            };
            match copy_result {
                Ok(ret) => written += ret as u64,
                Err(err) => {
                    match err.raw_os_error() {
                        Some(os_err) if os_err == libc::ENOSYS
                                     || os_err == libc::EXDEV
                                     || os_err == libc::EPERM => {
                            // Try fallback io::copy if either:
                            // - Kernel version is < 4.5 (ENOSYS)
                            // - Files are mounted on different fs (EXDEV)
                            // - copy_file_range is disallowed, for example by seccomp (EPERM)
                            assert_eq!(written, 0);
                            let ret = io::copy(&mut reader, &mut writer)?;
                            writer.set_permissions(perm)?;
                            return Ok(ret)
                        },
                        _ => return Err(err),
                    }
                }
            }
        }
        writer.set_permissions(perm)?;
        Ok(written)
    }

# Help

## Keyboard Shortcuts

`?`
  Show this help dialog
`S`
  Focus the search field
`↑`
  Move up in search results
`↓`
  Move down in search results
`↹`
  Switch tab
`⏎`
  Go to active search result
`+`
  Expand all sections
`-`
  Collapse all sections

## Search Tricks

Prefix searches with a type followed by a colon (e.g., `fn:`) to restrict the search to a given type.

Accepted types are: `fn`, `mod`, `struct`, `enum`, `trait`, `type`, `macro`, and `const`.

Search functions by type signature (e.g., `vec -> usize` or `* -> vec`)

Search multiple things at once by splitting your query with comma (e.g., `str,u8` or `String,struct:Vec,test`)