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
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
#![cfg_attr(test, allow(unused))]

#[cfg(test)]
mod tests;

use crate::cell::{Cell, RefCell};
use crate::fmt;
use crate::fs::File;
use crate::io::prelude::*;
use crate::io::{
    self, BorrowedCursor, BufReader, IoSlice, IoSliceMut, LineWriter, Lines, SpecReadByte,
};
use crate::panic::{RefUnwindSafe, UnwindSafe};
use crate::sync::atomic::{AtomicBool, Ordering};
use crate::sync::{Arc, Mutex, MutexGuard, OnceLock, ReentrantLock, ReentrantLockGuard};
use crate::sys::stdio;
use crate::thread::AccessError;

type LocalStream = Arc<Mutex<Vec<u8>>>;

thread_local! {
    /// Used by the test crate to capture the output of the print macros and panics.
    static OUTPUT_CAPTURE: Cell<Option<LocalStream>> = {
        Cell::new(None)
    }
}

/// Flag to indicate OUTPUT_CAPTURE is used.
///
/// If it is None and was never set on any thread, this flag is set to false,
/// and OUTPUT_CAPTURE can be safely ignored on all threads, saving some time
/// and memory registering an unused thread local.
///
/// Note about memory ordering: This contains information about whether a
/// thread local variable might be in use. Although this is a global flag, the
/// memory ordering between threads does not matter: we only want this flag to
/// have a consistent order between set_output_capture and print_to *within
/// the same thread*. Within the same thread, things always have a perfectly
/// consistent order. So Ordering::Relaxed is fine.
static OUTPUT_CAPTURE_USED: AtomicBool = AtomicBool::new(false);

/// A handle to a raw instance of the standard input stream of this process.
///
/// This handle is not synchronized or buffered in any fashion. Constructed via
/// the `std::io::stdio::stdin_raw` function.
struct StdinRaw(stdio::Stdin);

/// A handle to a raw instance of the standard output stream of this process.
///
/// This handle is not synchronized or buffered in any fashion. Constructed via
/// the `std::io::stdio::stdout_raw` function.
struct StdoutRaw(stdio::Stdout);

/// A handle to a raw instance of the standard output stream of this process.
///
/// This handle is not synchronized or buffered in any fashion. Constructed via
/// the `std::io::stdio::stderr_raw` function.
struct StderrRaw(stdio::Stderr);

/// Constructs a new raw handle to the standard input of this process.
///
/// The returned handle does not interact with any other handles created nor
/// handles returned by `std::io::stdin`. Data buffered by the `std::io::stdin`
/// handles is **not** available to raw handles returned from this function.
///
/// The returned handle has no external synchronization or buffering.
#[unstable(feature = "libstd_sys_internals", issue = "none")]
const fn stdin_raw() -> StdinRaw {
    StdinRaw(stdio::Stdin::new())
}

/// Constructs a new raw handle to the standard output stream of this process.
///
/// The returned handle does not interact with any other handles created nor
/// handles returned by `std::io::stdout`. Note that data is buffered by the
/// `std::io::stdout` handles so writes which happen via this raw handle may
/// appear before previous writes.
///
/// The returned handle has no external synchronization or buffering layered on
/// top.
#[unstable(feature = "libstd_sys_internals", issue = "none")]
const fn stdout_raw() -> StdoutRaw {
    StdoutRaw(stdio::Stdout::new())
}

/// Constructs a new raw handle to the standard error stream of this process.
///
/// The returned handle does not interact with any other handles created nor
/// handles returned by `std::io::stderr`.
///
/// The returned handle has no external synchronization or buffering layered on
/// top.
#[unstable(feature = "libstd_sys_internals", issue = "none")]
const fn stderr_raw() -> StderrRaw {
    StderrRaw(stdio::Stderr::new())
}

impl Read for StdinRaw {
    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
        handle_ebadf(self.0.read(buf), 0)
    }

    fn read_buf(&mut self, buf: BorrowedCursor<'_>) -> io::Result<()> {
        handle_ebadf(self.0.read_buf(buf), ())
    }

    fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
        handle_ebadf(self.0.read_vectored(bufs), 0)
    }

    #[inline]
    fn is_read_vectored(&self) -> bool {
        self.0.is_read_vectored()
    }

    fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
        handle_ebadf(self.0.read_to_end(buf), 0)
    }

    fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
        handle_ebadf(self.0.read_to_string(buf), 0)
    }
}

impl Write for StdoutRaw {
    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
        handle_ebadf(self.0.write(buf), buf.len())
    }

    fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
        let total = || bufs.iter().map(|b| b.len()).sum();
        handle_ebadf_lazy(self.0.write_vectored(bufs), total)
    }

    #[inline]
    fn is_write_vectored(&self) -> bool {
        self.0.is_write_vectored()
    }

    fn flush(&mut self) -> io::Result<()> {
        handle_ebadf(self.0.flush(), ())
    }

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

    fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> io::Result<()> {
        handle_ebadf(self.0.write_all_vectored(bufs), ())
    }

    fn write_fmt(&mut self, fmt: fmt::Arguments<'_>) -> io::Result<()> {
        handle_ebadf(self.0.write_fmt(fmt), ())
    }
}

impl Write for StderrRaw {
    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
        handle_ebadf(self.0.write(buf), buf.len())
    }

    fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
        let total = || bufs.iter().map(|b| b.len()).sum();
        handle_ebadf_lazy(self.0.write_vectored(bufs), total)
    }

    #[inline]
    fn is_write_vectored(&self) -> bool {
        self.0.is_write_vectored()
    }

    fn flush(&mut self) -> io::Result<()> {
        handle_ebadf(self.0.flush(), ())
    }

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

    fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> io::Result<()> {
        handle_ebadf(self.0.write_all_vectored(bufs), ())
    }

    fn write_fmt(&mut self, fmt: fmt::Arguments<'_>) -> io::Result<()> {
        handle_ebadf(self.0.write_fmt(fmt), ())
    }
}

fn handle_ebadf<T>(r: io::Result<T>, default: T) -> io::Result<T> {
    match r {
        Err(ref e) if stdio::is_ebadf(e) => Ok(default),
        r => r,
    }
}

fn handle_ebadf_lazy<T>(r: io::Result<T>, default: impl FnOnce() -> T) -> io::Result<T> {
    match r {
        Err(ref e) if stdio::is_ebadf(e) => Ok(default()),
        r => r,
    }
}

/// A handle to the standard input stream of a process.
///
/// Each handle is a shared reference to a global buffer of input data to this
/// process. A handle can be `lock`'d to gain full access to [`BufRead`] methods
/// (e.g., `.lines()`). Reads to this handle are otherwise locked with respect
/// to other reads.
///
/// This handle implements the `Read` trait, but beware that concurrent reads
/// of `Stdin` must be executed with care.
///
/// Created by the [`io::stdin`] method.
///
/// [`io::stdin`]: stdin
///
/// ### Note: Windows Portability Considerations
///
/// When operating in a console, the Windows implementation of this stream does not support
/// non-UTF-8 byte sequences. Attempting to read bytes that are not valid UTF-8 will return
/// an error.
///
/// In a process with a detached console, such as one using
/// `#![windows_subsystem = "windows"]`, or in a child process spawned from such a process,
/// the contained handle will be null. In such cases, the standard library's `Read` and
/// `Write` will do nothing and silently succeed. All other I/O operations, via the
/// standard library or via raw Windows API calls, will fail.
///
/// # Examples
///
/// ```no_run
/// use std::io;
///
/// fn main() -> io::Result<()> {
///     let mut buffer = String::new();
///     let stdin = io::stdin(); // We get `Stdin` here.
///     stdin.read_line(&mut buffer)?;
///     Ok(())
/// }
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub struct Stdin {
    inner: &'static Mutex<BufReader<StdinRaw>>,
}

/// A locked reference to the [`Stdin`] handle.
///
/// This handle implements both the [`Read`] and [`BufRead`] traits, and
/// is constructed via the [`Stdin::lock`] method.
///
/// ### Note: Windows Portability Considerations
///
/// When operating in a console, the Windows implementation of this stream does not support
/// non-UTF-8 byte sequences. Attempting to read bytes that are not valid UTF-8 will return
/// an error.
///
/// In a process with a detached console, such as one using
/// `#![windows_subsystem = "windows"]`, or in a child process spawned from such a process,
/// the contained handle will be null. In such cases, the standard library's `Read` and
/// `Write` will do nothing and silently succeed. All other I/O operations, via the
/// standard library or via raw Windows API calls, will fail.
///
/// # Examples
///
/// ```no_run
/// use std::io::{self, BufRead};
///
/// fn main() -> io::Result<()> {
///     let mut buffer = String::new();
///     let stdin = io::stdin(); // We get `Stdin` here.
///     {
///         let mut handle = stdin.lock(); // We get `StdinLock` here.
///         handle.read_line(&mut buffer)?;
///     } // `StdinLock` is dropped here.
///     Ok(())
/// }
/// ```
#[must_use = "if unused stdin will immediately unlock"]
#[stable(feature = "rust1", since = "1.0.0")]
pub struct StdinLock<'a> {
    inner: MutexGuard<'a, BufReader<StdinRaw>>,
}

/// Constructs a new handle to the standard input of the current process.
///
/// Each handle returned is a reference to a shared global buffer whose access
/// is synchronized via a mutex. If you need more explicit control over
/// locking, see the [`Stdin::lock`] method.
///
/// ### Note: Windows Portability Considerations
///
/// When operating in a console, the Windows implementation of this stream does not support
/// non-UTF-8 byte sequences. Attempting to read bytes that are not valid UTF-8 will return
/// an error.
///
/// In a process with a detached console, such as one using
/// `#![windows_subsystem = "windows"]`, or in a child process spawned from such a process,
/// the contained handle will be null. In such cases, the standard library's `Read` and
/// `Write` will do nothing and silently succeed. All other I/O operations, via the
/// standard library or via raw Windows API calls, will fail.
///
/// # Examples
///
/// Using implicit synchronization:
///
/// ```no_run
/// use std::io;
///
/// fn main() -> io::Result<()> {
///     let mut buffer = String::new();
///     io::stdin().read_line(&mut buffer)?;
///     Ok(())
/// }
/// ```
///
/// Using explicit synchronization:
///
/// ```no_run
/// use std::io::{self, BufRead};
///
/// fn main() -> io::Result<()> {
///     let mut buffer = String::new();
///     let stdin = io::stdin();
///     let mut handle = stdin.lock();
///
///     handle.read_line(&mut buffer)?;
///     Ok(())
/// }
/// ```
#[must_use]
#[stable(feature = "rust1", since = "1.0.0")]
pub fn stdin() -> Stdin {
    static INSTANCE: OnceLock<Mutex<BufReader<StdinRaw>>> = OnceLock::new();
    Stdin {
        inner: INSTANCE.get_or_init(|| {
            Mutex::new(BufReader::with_capacity(stdio::STDIN_BUF_SIZE, stdin_raw()))
        }),
    }
}

impl Stdin {
    /// Locks this handle to the standard input stream, returning a readable
    /// guard.
    ///
    /// The lock is released when the returned lock goes out of scope. The
    /// returned guard also implements the [`Read`] and [`BufRead`] traits for
    /// accessing the underlying data.
    ///
    /// # Examples
    ///
    /// ```no_run
    /// use std::io::{self, BufRead};
    ///
    /// fn main() -> io::Result<()> {
    ///     let mut buffer = String::new();
    ///     let stdin = io::stdin();
    ///     let mut handle = stdin.lock();
    ///
    ///     handle.read_line(&mut buffer)?;
    ///     Ok(())
    /// }
    /// ```
    #[stable(feature = "rust1", since = "1.0.0")]
    pub fn lock(&self) -> StdinLock<'static> {
        // Locks this handle with 'static lifetime. This depends on the
        // implementation detail that the underlying `Mutex` is static.
        StdinLock { inner: self.inner.lock().unwrap_or_else(|e| e.into_inner()) }
    }

    /// Locks this handle and reads a line of input, appending it to the specified buffer.
    ///
    /// For detailed semantics of this method, see the documentation on
    /// [`BufRead::read_line`].
    ///
    /// # Examples
    ///
    /// ```no_run
    /// use std::io;
    ///
    /// let mut input = String::new();
    /// match io::stdin().read_line(&mut input) {
    ///     Ok(n) => {
    ///         println!("{n} bytes read");
    ///         println!("{input}");
    ///     }
    ///     Err(error) => println!("error: {error}"),
    /// }
    /// ```
    ///
    /// You can run the example one of two ways:
    ///
    /// - Pipe some text to it, e.g., `printf foo | path/to/executable`
    /// - Give it text interactively by running the executable directly,
    ///   in which case it will wait for the Enter key to be pressed before
    ///   continuing
    #[stable(feature = "rust1", since = "1.0.0")]
    pub fn read_line(&self, buf: &mut String) -> io::Result<usize> {
        self.lock().read_line(buf)
    }

    /// Consumes this handle and returns an iterator over input lines.
    ///
    /// For detailed semantics of this method, see the documentation on
    /// [`BufRead::lines`].
    ///
    /// # Examples
    ///
    /// ```no_run
    /// use std::io;
    ///
    /// let lines = io::stdin().lines();
    /// for line in lines {
    ///     println!("got a line: {}", line.unwrap());
    /// }
    /// ```
    #[must_use = "`self` will be dropped if the result is not used"]
    #[stable(feature = "stdin_forwarders", since = "1.62.0")]
    pub fn lines(self) -> Lines<StdinLock<'static>> {
        self.lock().lines()
    }
}

#[stable(feature = "std_debug", since = "1.16.0")]
impl fmt::Debug for Stdin {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("Stdin").finish_non_exhaustive()
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl Read for Stdin {
    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
        self.lock().read(buf)
    }
    fn read_buf(&mut self, buf: BorrowedCursor<'_>) -> io::Result<()> {
        self.lock().read_buf(buf)
    }
    fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
        self.lock().read_vectored(bufs)
    }
    #[inline]
    fn is_read_vectored(&self) -> bool {
        self.lock().is_read_vectored()
    }
    fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
        self.lock().read_to_end(buf)
    }
    fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
        self.lock().read_to_string(buf)
    }
    fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
        self.lock().read_exact(buf)
    }
    fn read_buf_exact(&mut self, cursor: BorrowedCursor<'_>) -> io::Result<()> {
        self.lock().read_buf_exact(cursor)
    }
}

#[stable(feature = "read_shared_stdin", since = "1.78.0")]
impl Read for &Stdin {
    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
        self.lock().read(buf)
    }
    fn read_buf(&mut self, buf: BorrowedCursor<'_>) -> io::Result<()> {
        self.lock().read_buf(buf)
    }
    fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
        self.lock().read_vectored(bufs)
    }
    #[inline]
    fn is_read_vectored(&self) -> bool {
        self.lock().is_read_vectored()
    }
    fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
        self.lock().read_to_end(buf)
    }
    fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
        self.lock().read_to_string(buf)
    }
    fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
        self.lock().read_exact(buf)
    }
    fn read_buf_exact(&mut self, cursor: BorrowedCursor<'_>) -> io::Result<()> {
        self.lock().read_buf_exact(cursor)
    }
}

// only used by platform-dependent io::copy specializations, i.e. unused on some platforms
#[cfg(any(target_os = "linux", target_os = "android"))]
impl StdinLock<'_> {
    pub(crate) fn as_mut_buf(&mut self) -> &mut BufReader<impl Read> {
        &mut self.inner
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl Read for StdinLock<'_> {
    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
        self.inner.read(buf)
    }

    fn read_buf(&mut self, buf: BorrowedCursor<'_>) -> io::Result<()> {
        self.inner.read_buf(buf)
    }

    fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
        self.inner.read_vectored(bufs)
    }

    #[inline]
    fn is_read_vectored(&self) -> bool {
        self.inner.is_read_vectored()
    }

    fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
        self.inner.read_to_end(buf)
    }

    fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
        self.inner.read_to_string(buf)
    }

    fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
        self.inner.read_exact(buf)
    }

    fn read_buf_exact(&mut self, cursor: BorrowedCursor<'_>) -> io::Result<()> {
        self.inner.read_buf_exact(cursor)
    }
}

impl SpecReadByte for StdinLock<'_> {
    #[inline]
    fn spec_read_byte(&mut self) -> Option<io::Result<u8>> {
        BufReader::spec_read_byte(&mut *self.inner)
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl BufRead for StdinLock<'_> {
    fn fill_buf(&mut self) -> io::Result<&[u8]> {
        self.inner.fill_buf()
    }

    fn consume(&mut self, n: usize) {
        self.inner.consume(n)
    }

    fn read_until(&mut self, byte: u8, buf: &mut Vec<u8>) -> io::Result<usize> {
        self.inner.read_until(byte, buf)
    }

    fn read_line(&mut self, buf: &mut String) -> io::Result<usize> {
        self.inner.read_line(buf)
    }
}

#[stable(feature = "std_debug", since = "1.16.0")]
impl fmt::Debug for StdinLock<'_> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("StdinLock").finish_non_exhaustive()
    }
}

/// A handle to the global standard output stream of the current process.
///
/// Each handle shares a global buffer of data to be written to the standard
/// output stream. Access is also synchronized via a lock and explicit control
/// over locking is available via the [`lock`] method.
///
/// Created by the [`io::stdout`] method.
///
/// ### Note: Windows Portability Considerations
///
/// When operating in a console, the Windows implementation of this stream does not support
/// non-UTF-8 byte sequences. Attempting to write bytes that are not valid UTF-8 will return
/// an error.
///
/// In a process with a detached console, such as one using
/// `#![windows_subsystem = "windows"]`, or in a child process spawned from such a process,
/// the contained handle will be null. In such cases, the standard library's `Read` and
/// `Write` will do nothing and silently succeed. All other I/O operations, via the
/// standard library or via raw Windows API calls, will fail.
///
/// [`lock`]: Stdout::lock
/// [`io::stdout`]: stdout
#[stable(feature = "rust1", since = "1.0.0")]
pub struct Stdout {
    // FIXME: this should be LineWriter or BufWriter depending on the state of
    //        stdout (tty or not). Note that if this is not line buffered it
    //        should also flush-on-panic or some form of flush-on-abort.
    inner: &'static ReentrantLock<RefCell<LineWriter<StdoutRaw>>>,
}

/// A locked reference to the [`Stdout`] handle.
///
/// This handle implements the [`Write`] trait, and is constructed via
/// the [`Stdout::lock`] method. See its documentation for more.
///
/// ### Note: Windows Portability Considerations
///
/// When operating in a console, the Windows implementation of this stream does not support
/// non-UTF-8 byte sequences. Attempting to write bytes that are not valid UTF-8 will return
/// an error.
///
/// In a process with a detached console, such as one using
/// `#![windows_subsystem = "windows"]`, or in a child process spawned from such a process,
/// the contained handle will be null. In such cases, the standard library's `Read` and
/// `Write` will do nothing and silently succeed. All other I/O operations, via the
/// standard library or via raw Windows API calls, will fail.
#[must_use = "if unused stdout will immediately unlock"]
#[stable(feature = "rust1", since = "1.0.0")]
pub struct StdoutLock<'a> {
    inner: ReentrantLockGuard<'a, RefCell<LineWriter<StdoutRaw>>>,
}

static STDOUT: OnceLock<ReentrantLock<RefCell<LineWriter<StdoutRaw>>>> = OnceLock::new();

/// Constructs a new handle to the standard output of the current process.
///
/// Each handle returned is a reference to a shared global buffer whose access
/// is synchronized via a mutex. If you need more explicit control over
/// locking, see the [`Stdout::lock`] method.
///
/// ### Note: Windows Portability Considerations
///
/// When operating in a console, the Windows implementation of this stream does not support
/// non-UTF-8 byte sequences. Attempting to write bytes that are not valid UTF-8 will return
/// an error.
///
/// In a process with a detached console, such as one using
/// `#![windows_subsystem = "windows"]`, or in a child process spawned from such a process,
/// the contained handle will be null. In such cases, the standard library's `Read` and
/// `Write` will do nothing and silently succeed. All other I/O operations, via the
/// standard library or via raw Windows API calls, will fail.
///
/// # Examples
///
/// Using implicit synchronization:
///
/// ```no_run
/// use std::io::{self, Write};
///
/// fn main() -> io::Result<()> {
///     io::stdout().write_all(b"hello world")?;
///
///     Ok(())
/// }
/// ```
///
/// Using explicit synchronization:
///
/// ```no_run
/// use std::io::{self, Write};
///
/// fn main() -> io::Result<()> {
///     let stdout = io::stdout();
///     let mut handle = stdout.lock();
///
///     handle.write_all(b"hello world")?;
///
///     Ok(())
/// }
/// ```
#[must_use]
#[stable(feature = "rust1", since = "1.0.0")]
#[cfg_attr(not(test), rustc_diagnostic_item = "io_stdout")]
pub fn stdout() -> Stdout {
    Stdout {
        inner: STDOUT
            .get_or_init(|| ReentrantLock::new(RefCell::new(LineWriter::new(stdout_raw())))),
    }
}

// Flush the data and disable buffering during shutdown
// by replacing the line writer by one with zero
// buffering capacity.
pub fn cleanup() {
    let mut initialized = false;
    let stdout = STDOUT.get_or_init(|| {
        initialized = true;
        ReentrantLock::new(RefCell::new(LineWriter::with_capacity(0, stdout_raw())))
    });

    if !initialized {
        // The buffer was previously initialized, overwrite it here.
        // We use try_lock() instead of lock(), because someone
        // might have leaked a StdoutLock, which would
        // otherwise cause a deadlock here.
        if let Some(lock) = stdout.try_lock() {
            *lock.borrow_mut() = LineWriter::with_capacity(0, stdout_raw());
        }
    }
}

impl Stdout {
    /// Locks this handle to the standard output stream, returning a writable
    /// guard.
    ///
    /// The lock is released when the returned lock goes out of scope. The
    /// returned guard also implements the `Write` trait for writing data.
    ///
    /// # Examples
    ///
    /// ```no_run
    /// use std::io::{self, Write};
    ///
    /// fn main() -> io::Result<()> {
    ///     let mut stdout = io::stdout().lock();
    ///
    ///     stdout.write_all(b"hello world")?;
    ///
    ///     Ok(())
    /// }
    /// ```
    #[stable(feature = "rust1", since = "1.0.0")]
    pub fn lock(&self) -> StdoutLock<'static> {
        // Locks this handle with 'static lifetime. This depends on the
        // implementation detail that the underlying `ReentrantMutex` is
        // static.
        StdoutLock { inner: self.inner.lock() }
    }
}

#[stable(feature = "catch_unwind", since = "1.9.0")]
impl UnwindSafe for Stdout {}

#[stable(feature = "catch_unwind", since = "1.9.0")]
impl RefUnwindSafe for Stdout {}

#[stable(feature = "std_debug", since = "1.16.0")]
impl fmt::Debug for Stdout {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("Stdout").finish_non_exhaustive()
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl Write for Stdout {
    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
        (&*self).write(buf)
    }
    fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
        (&*self).write_vectored(bufs)
    }
    #[inline]
    fn is_write_vectored(&self) -> bool {
        io::Write::is_write_vectored(&&*self)
    }
    fn flush(&mut self) -> io::Result<()> {
        (&*self).flush()
    }
    fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
        (&*self).write_all(buf)
    }
    fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> io::Result<()> {
        (&*self).write_all_vectored(bufs)
    }
    fn write_fmt(&mut self, args: fmt::Arguments<'_>) -> io::Result<()> {
        (&*self).write_fmt(args)
    }
}

#[stable(feature = "write_mt", since = "1.48.0")]
impl Write for &Stdout {
    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
        self.lock().write(buf)
    }
    fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
        self.lock().write_vectored(bufs)
    }
    #[inline]
    fn is_write_vectored(&self) -> bool {
        self.lock().is_write_vectored()
    }
    fn flush(&mut self) -> io::Result<()> {
        self.lock().flush()
    }
    fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
        self.lock().write_all(buf)
    }
    fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> io::Result<()> {
        self.lock().write_all_vectored(bufs)
    }
    fn write_fmt(&mut self, args: fmt::Arguments<'_>) -> io::Result<()> {
        self.lock().write_fmt(args)
    }
}

#[stable(feature = "catch_unwind", since = "1.9.0")]
impl UnwindSafe for StdoutLock<'_> {}

#[stable(feature = "catch_unwind", since = "1.9.0")]
impl RefUnwindSafe for StdoutLock<'_> {}

#[stable(feature = "rust1", since = "1.0.0")]
impl Write for StdoutLock<'_> {
    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
        self.inner.borrow_mut().write(buf)
    }
    fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
        self.inner.borrow_mut().write_vectored(bufs)
    }
    #[inline]
    fn is_write_vectored(&self) -> bool {
        self.inner.borrow_mut().is_write_vectored()
    }
    fn flush(&mut self) -> io::Result<()> {
        self.inner.borrow_mut().flush()
    }
    fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
        self.inner.borrow_mut().write_all(buf)
    }
    fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> io::Result<()> {
        self.inner.borrow_mut().write_all_vectored(bufs)
    }
}

#[stable(feature = "std_debug", since = "1.16.0")]
impl fmt::Debug for StdoutLock<'_> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("StdoutLock").finish_non_exhaustive()
    }
}

/// A handle to the standard error stream of a process.
///
/// For more information, see the [`io::stderr`] method.
///
/// [`io::stderr`]: stderr
///
/// ### Note: Windows Portability Considerations
///
/// When operating in a console, the Windows implementation of this stream does not support
/// non-UTF-8 byte sequences. Attempting to write bytes that are not valid UTF-8 will return
/// an error.
///
/// In a process with a detached console, such as one using
/// `#![windows_subsystem = "windows"]`, or in a child process spawned from such a process,
/// the contained handle will be null. In such cases, the standard library's `Read` and
/// `Write` will do nothing and silently succeed. All other I/O operations, via the
/// standard library or via raw Windows API calls, will fail.
#[stable(feature = "rust1", since = "1.0.0")]
pub struct Stderr {
    inner: &'static ReentrantLock<RefCell<StderrRaw>>,
}

/// A locked reference to the [`Stderr`] handle.
///
/// This handle implements the [`Write`] trait and is constructed via
/// the [`Stderr::lock`] method. See its documentation for more.
///
/// ### Note: Windows Portability Considerations
///
/// When operating in a console, the Windows implementation of this stream does not support
/// non-UTF-8 byte sequences. Attempting to write bytes that are not valid UTF-8 will return
/// an error.
///
/// In a process with a detached console, such as one using
/// `#![windows_subsystem = "windows"]`, or in a child process spawned from such a process,
/// the contained handle will be null. In such cases, the standard library's `Read` and
/// `Write` will do nothing and silently succeed. All other I/O operations, via the
/// standard library or via raw Windows API calls, will fail.
#[must_use = "if unused stderr will immediately unlock"]
#[stable(feature = "rust1", since = "1.0.0")]
pub struct StderrLock<'a> {
    inner: ReentrantLockGuard<'a, RefCell<StderrRaw>>,
}

/// Constructs a new handle to the standard error of the current process.
///
/// This handle is not buffered.
///
/// ### Note: Windows Portability Considerations
///
/// When operating in a console, the Windows implementation of this stream does not support
/// non-UTF-8 byte sequences. Attempting to write bytes that are not valid UTF-8 will return
/// an error.
///
/// In a process with a detached console, such as one using
/// `#![windows_subsystem = "windows"]`, or in a child process spawned from such a process,
/// the contained handle will be null. In such cases, the standard library's `Read` and
/// `Write` will do nothing and silently succeed. All other I/O operations, via the
/// standard library or via raw Windows API calls, will fail.
///
/// # Examples
///
/// Using implicit synchronization:
///
/// ```no_run
/// use std::io::{self, Write};
///
/// fn main() -> io::Result<()> {
///     io::stderr().write_all(b"hello world")?;
///
///     Ok(())
/// }
/// ```
///
/// Using explicit synchronization:
///
/// ```no_run
/// use std::io::{self, Write};
///
/// fn main() -> io::Result<()> {
///     let stderr = io::stderr();
///     let mut handle = stderr.lock();
///
///     handle.write_all(b"hello world")?;
///
///     Ok(())
/// }
/// ```
#[must_use]
#[stable(feature = "rust1", since = "1.0.0")]
#[cfg_attr(not(test), rustc_diagnostic_item = "io_stderr")]
pub fn stderr() -> Stderr {
    // Note that unlike `stdout()` we don't use `at_exit` here to register a
    // destructor. Stderr is not buffered, so there's no need to run a
    // destructor for flushing the buffer
    static INSTANCE: ReentrantLock<RefCell<StderrRaw>> =
        ReentrantLock::new(RefCell::new(stderr_raw()));

    Stderr { inner: &INSTANCE }
}

impl Stderr {
    /// Locks this handle to the standard error stream, returning a writable
    /// guard.
    ///
    /// The lock is released when the returned lock goes out of scope. The
    /// returned guard also implements the [`Write`] trait for writing data.
    ///
    /// # Examples
    ///
    /// ```
    /// use std::io::{self, Write};
    ///
    /// fn foo() -> io::Result<()> {
    ///     let stderr = io::stderr();
    ///     let mut handle = stderr.lock();
    ///
    ///     handle.write_all(b"hello world")?;
    ///
    ///     Ok(())
    /// }
    /// ```
    #[stable(feature = "rust1", since = "1.0.0")]
    pub fn lock(&self) -> StderrLock<'static> {
        // Locks this handle with 'static lifetime. This depends on the
        // implementation detail that the underlying `ReentrantMutex` is
        // static.
        StderrLock { inner: self.inner.lock() }
    }
}

#[stable(feature = "catch_unwind", since = "1.9.0")]
impl UnwindSafe for Stderr {}

#[stable(feature = "catch_unwind", since = "1.9.0")]
impl RefUnwindSafe for Stderr {}

#[stable(feature = "std_debug", since = "1.16.0")]
impl fmt::Debug for Stderr {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("Stderr").finish_non_exhaustive()
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl Write for Stderr {
    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
        (&*self).write(buf)
    }
    fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
        (&*self).write_vectored(bufs)
    }
    #[inline]
    fn is_write_vectored(&self) -> bool {
        io::Write::is_write_vectored(&&*self)
    }
    fn flush(&mut self) -> io::Result<()> {
        (&*self).flush()
    }
    fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
        (&*self).write_all(buf)
    }
    fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> io::Result<()> {
        (&*self).write_all_vectored(bufs)
    }
    fn write_fmt(&mut self, args: fmt::Arguments<'_>) -> io::Result<()> {
        (&*self).write_fmt(args)
    }
}

#[stable(feature = "write_mt", since = "1.48.0")]
impl Write for &Stderr {
    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
        self.lock().write(buf)
    }
    fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
        self.lock().write_vectored(bufs)
    }
    #[inline]
    fn is_write_vectored(&self) -> bool {
        self.lock().is_write_vectored()
    }
    fn flush(&mut self) -> io::Result<()> {
        self.lock().flush()
    }
    fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
        self.lock().write_all(buf)
    }
    fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> io::Result<()> {
        self.lock().write_all_vectored(bufs)
    }
    fn write_fmt(&mut self, args: fmt::Arguments<'_>) -> io::Result<()> {
        self.lock().write_fmt(args)
    }
}

#[stable(feature = "catch_unwind", since = "1.9.0")]
impl UnwindSafe for StderrLock<'_> {}

#[stable(feature = "catch_unwind", since = "1.9.0")]
impl RefUnwindSafe for StderrLock<'_> {}

#[stable(feature = "rust1", since = "1.0.0")]
impl Write for StderrLock<'_> {
    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
        self.inner.borrow_mut().write(buf)
    }
    fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
        self.inner.borrow_mut().write_vectored(bufs)
    }
    #[inline]
    fn is_write_vectored(&self) -> bool {
        self.inner.borrow_mut().is_write_vectored()
    }
    fn flush(&mut self) -> io::Result<()> {
        self.inner.borrow_mut().flush()
    }
    fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
        self.inner.borrow_mut().write_all(buf)
    }
    fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> io::Result<()> {
        self.inner.borrow_mut().write_all_vectored(bufs)
    }
}

#[stable(feature = "std_debug", since = "1.16.0")]
impl fmt::Debug for StderrLock<'_> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("StderrLock").finish_non_exhaustive()
    }
}

/// Sets the thread-local output capture buffer and returns the old one.
#[unstable(
    feature = "internal_output_capture",
    reason = "this function is meant for use in the test crate \
        and may disappear in the future",
    issue = "none"
)]
#[doc(hidden)]
pub fn set_output_capture(sink: Option<LocalStream>) -> Option<LocalStream> {
    try_set_output_capture(sink).expect(
        "cannot access a Thread Local Storage value \
         during or after destruction",
    )
}

/// Tries to set the thread-local output capture buffer and returns the old one.
/// This may fail once thread-local destructors are called. It's used in panic
/// handling instead of `set_output_capture`.
#[unstable(
    feature = "internal_output_capture",
    reason = "this function is meant for use in the test crate \
    and may disappear in the future",
    issue = "none"
)]
#[doc(hidden)]
pub fn try_set_output_capture(
    sink: Option<LocalStream>,
) -> Result<Option<LocalStream>, AccessError> {
    if sink.is_none() && !OUTPUT_CAPTURE_USED.load(Ordering::Relaxed) {
        // OUTPUT_CAPTURE is definitely None since OUTPUT_CAPTURE_USED is false.
        return Ok(None);
    }
    OUTPUT_CAPTURE_USED.store(true, Ordering::Relaxed);
    OUTPUT_CAPTURE.try_with(move |slot| slot.replace(sink))
}

/// Writes `args` to the capture buffer if enabled and possible, or `global_s`
/// otherwise. `label` identifies the stream in a panic message.
///
/// This function is used to print error messages, so it takes extra
/// care to avoid causing a panic when `OUTPUT_CAPTURE` is unusable.
/// For instance, if the TLS key for output capturing is already destroyed, or
/// if the local stream is in use by another thread, it will just fall back to
/// the global stream.
///
/// However, if the actual I/O causes an error, this function does panic.
///
/// Writing to non-blocking stdout/stderr can cause an error, which will lead
/// this function to panic.
fn print_to<T>(args: fmt::Arguments<'_>, global_s: fn() -> T, label: &str)
where
    T: Write,
{
    if print_to_buffer_if_capture_used(args) {
        // Successfully wrote to capture buffer.
        return;
    }

    if let Err(e) = global_s().write_fmt(args) {
        panic!("failed printing to {label}: {e}");
    }
}

fn print_to_buffer_if_capture_used(args: fmt::Arguments<'_>) -> bool {
    OUTPUT_CAPTURE_USED.load(Ordering::Relaxed)
        && OUTPUT_CAPTURE.try_with(|s| {
            // Note that we completely remove a local sink to write to in case
            // our printing recursively panics/prints, so the recursive
            // panic/print goes to the global sink instead of our local sink.
            s.take().map(|w| {
                let _ = w.lock().unwrap_or_else(|e| e.into_inner()).write_fmt(args);
                s.set(Some(w));
            })
        }) == Ok(Some(()))
}

/// Used by impl Termination for Result to print error after `main` or a test
/// has returned. Should avoid panicking, although we can't help it if one of
/// the Display impls inside args decides to.
pub(crate) fn attempt_print_to_stderr(args: fmt::Arguments<'_>) {
    if print_to_buffer_if_capture_used(args) {
        return;
    }

    // Ignore error if the write fails, for example because stderr is already
    // closed. There is not much point panicking at this point.
    let _ = stderr().write_fmt(args);
}

/// Trait to determine if a descriptor/handle refers to a terminal/tty.
#[stable(feature = "is_terminal", since = "1.70.0")]
pub trait IsTerminal: crate::sealed::Sealed {
    /// Returns `true` if the descriptor/handle refers to a terminal/tty.
    ///
    /// On platforms where Rust does not know how to detect a terminal yet, this will return
    /// `false`. This will also return `false` if an unexpected error occurred, such as from
    /// passing an invalid file descriptor.
    ///
    /// # Platform-specific behavior
    ///
    /// On Windows, in addition to detecting consoles, this currently uses some heuristics to
    /// detect older msys/cygwin/mingw pseudo-terminals based on device name: devices with names
    /// starting with `msys-` or `cygwin-` and ending in `-pty` will be considered terminals.
    /// Note that this [may change in the future][changes].
    ///
    /// # Examples
    ///
    /// An example of a type for which `IsTerminal` is implemented is [`Stdin`]:
    ///
    /// ```no_run
    /// use std::io::{self, IsTerminal, Write};
    ///
    /// fn main() -> io::Result<()> {
    ///     let stdin = io::stdin();
    ///
    ///     // Indicate that the user is prompted for input, if this is a terminal.
    ///     if stdin.is_terminal() {
    ///         print!("> ");
    ///         io::stdout().flush()?;
    ///     }
    ///
    ///     let mut name = String::new();
    ///     let _ = stdin.read_line(&mut name)?;
    ///
    ///     println!("Hello {}", name.trim_end());
    ///
    ///     Ok(())
    /// }
    /// ```
    ///
    /// The example can be run in two ways:
    ///
    /// - If you run this example by piping some text to it, e.g. `echo "foo" | path/to/executable`
    ///   it will print: `Hello foo`.
    /// - If you instead run the example interactively by running `path/to/executable` directly, it will
    ///   prompt for input.
    ///
    /// [changes]: io#platform-specific-behavior
    /// [`Stdin`]: crate::io::Stdin
    #[stable(feature = "is_terminal", since = "1.70.0")]
    fn is_terminal(&self) -> bool;
}

macro_rules! impl_is_terminal {
    ($($t:ty),*$(,)?) => {$(
        #[unstable(feature = "sealed", issue = "none")]
        impl crate::sealed::Sealed for $t {}

        #[stable(feature = "is_terminal", since = "1.70.0")]
        impl IsTerminal for $t {
            #[inline]
            fn is_terminal(&self) -> bool {
                crate::sys::io::is_terminal(self)
            }
        }
    )*}
}

impl_is_terminal!(File, Stdin, StdinLock<'_>, Stdout, StdoutLock<'_>, Stderr, StderrLock<'_>);

#[unstable(
    feature = "print_internals",
    reason = "implementation detail which may disappear or be replaced at any time",
    issue = "none"
)]
#[doc(hidden)]
#[cfg(not(test))]
pub fn _print(args: fmt::Arguments<'_>) {
    print_to(args, stdout, "stdout");
}

#[unstable(
    feature = "print_internals",
    reason = "implementation detail which may disappear or be replaced at any time",
    issue = "none"
)]
#[doc(hidden)]
#[cfg(not(test))]
pub fn _eprint(args: fmt::Arguments<'_>) {
    print_to(args, stderr, "stderr");
}

#[cfg(test)]
pub use realstd::io::{_eprint, _print};