cstring 0.1.0

A super simple cstring library for web assembly
Documentation
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
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
// This code comes from the unupdated project https://github.com/Amanieu/cstr_core

// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

#[cfg(test)]
#[macro_use]
extern crate std;

#[cfg(feature = "alloc")]
extern crate alloc;
extern crate cty;
extern crate memchr;

#[cfg(feature = "alloc")]
use alloc::borrow::{Borrow, Cow, ToOwned};
#[cfg(feature = "alloc")]
use alloc::boxed::Box;
#[cfg(feature = "alloc")]
use alloc::rc::Rc;
#[cfg(feature = "alloc")]
use alloc::string::String;
#[cfg(feature = "alloc")]
use alloc::sync::Arc;
#[cfg(feature = "alloc")]
use alloc::vec::Vec;
#[cfg(feature = "alloc")]
use core::{mem, ops, ptr};

use core::cmp::Ordering;
use core::fmt::{self, Write};
use core::slice;
use core::str::{self, Utf8Error};

/// Re-export c_char
pub use cty::c_char;

#[inline]
unsafe fn strlen(p: *const c_char) -> usize {
    let mut n = 0;
    while *p.offset(n as isize) != 0 {
        n += 1;
    }
    n
}

mod ascii {
    use core::ops::Range;

    /// An iterator over the escaped version of a byte.
    ///
    /// This `struct` is created by the [`escape_default`] function. See its
    /// documentation for more.
    ///
    /// [`escape_default`]: fn.escape_default.html
    pub struct EscapeDefault {
        range: Range<usize>,
        data: [u8; 4],
    }

    /// Returns an iterator that produces an escaped version of a `u8`.
    ///
    /// The default is chosen with a bias toward producing literals that are
    /// legal in a variety of languages, including C++11 and similar C-family
    /// languages. The exact rules are:
    ///
    /// - Tab, CR and LF are escaped as '\t', '\r' and '\n' respectively.
    /// - Single-quote, double-quote and backslash chars are backslash-escaped.
    /// - Any other chars in the range [0x20,0x7e] are not escaped.
    /// - Any other chars are given hex escapes of the form '\xNN'.
    /// - Unicode escapes are never generated by this function.
    ///
    /// # Examples
    ///
    /// ```
    /// use std::ascii;
    ///
    /// let escaped = ascii::escape_default(b'0').next().unwrap();
    /// assert_eq!(b'0', escaped);
    ///
    /// let mut escaped = ascii::escape_default(b'\t');
    ///
    /// assert_eq!(b'\\', escaped.next().unwrap());
    /// assert_eq!(b't', escaped.next().unwrap());
    ///
    /// let mut escaped = ascii::escape_default(b'\r');
    ///
    /// assert_eq!(b'\\', escaped.next().unwrap());
    /// assert_eq!(b'r', escaped.next().unwrap());
    ///
    /// let mut escaped = ascii::escape_default(b'\n');
    ///
    /// assert_eq!(b'\\', escaped.next().unwrap());
    /// assert_eq!(b'n', escaped.next().unwrap());
    ///
    /// let mut escaped = ascii::escape_default(b'\'');
    ///
    /// assert_eq!(b'\\', escaped.next().unwrap());
    /// assert_eq!(b'\'', escaped.next().unwrap());
    ///
    /// let mut escaped = ascii::escape_default(b'"');
    ///
    /// assert_eq!(b'\\', escaped.next().unwrap());
    /// assert_eq!(b'"', escaped.next().unwrap());
    ///
    /// let mut escaped = ascii::escape_default(b'\\');
    ///
    /// assert_eq!(b'\\', escaped.next().unwrap());
    /// assert_eq!(b'\\', escaped.next().unwrap());
    ///
    /// let mut escaped = ascii::escape_default(b'\x9d');
    ///
    /// assert_eq!(b'\\', escaped.next().unwrap());
    /// assert_eq!(b'x', escaped.next().unwrap());
    /// assert_eq!(b'9', escaped.next().unwrap());
    /// assert_eq!(b'd', escaped.next().unwrap());
    /// ```
    pub fn escape_default(c: u8) -> EscapeDefault {
        let (data, len) = match c {
            b'\t' => ([b'\\', b't', 0, 0], 2),
            b'\r' => ([b'\\', b'r', 0, 0], 2),
            b'\n' => ([b'\\', b'n', 0, 0], 2),
            b'\\' => ([b'\\', b'\\', 0, 0], 2),
            b'\'' => ([b'\\', b'\'', 0, 0], 2),
            b'"' => ([b'\\', b'"', 0, 0], 2),
            b'\x20'..=b'\x7e' => ([c, 0, 0, 0], 1),
            _ => ([b'\\', b'x', hexify(c >> 4), hexify(c & 0xf)], 4),
        };

        return EscapeDefault {
            range: (0..len),
            data: data,
        };

        fn hexify(b: u8) -> u8 {
            match b {
                0..=9 => b'0' + b,
                _ => b'a' + b - 10,
            }
        }
    }

    impl Iterator for EscapeDefault {
        type Item = u8;
        fn next(&mut self) -> Option<u8> {
            self.range.next().map(|i| self.data[i])
        }
        fn size_hint(&self) -> (usize, Option<usize>) {
            self.range.size_hint()
        }
    }
    impl DoubleEndedIterator for EscapeDefault {
        fn next_back(&mut self) -> Option<u8> {
            self.range.next_back().map(|i| self.data[i])
        }
    }
    impl ExactSizeIterator for EscapeDefault {}
}

/// A type representing an owned C-compatible string.
///
/// This type serves the primary purpose of being able to safely generate a
/// C-compatible string from a Rust byte slice or vector. An instance of this
/// type is a static guarantee that the underlying bytes contain no interior 0
/// bytes and the final byte is 0.
///
/// A `CString` is created from either a byte slice or a byte vector. A [`u8`]
/// slice can be obtained with the `as_bytes` method. Slices produced from a
/// `CString` do *not* contain the trailing nul terminator unless otherwise
/// specified.
///
/// [`u8`]: ../primitive.u8.html
///
/// # Examples
///
/// ```ignore (extern-declaration)
/// # fn main() {
/// use cstr_core::CString;
/// use cstr_core::c_char;
///
/// extern {
///     fn my_printer(s: *const c_char);
/// }
///
/// let c_to_print = CString::new("Hello, world!").unwrap();
/// unsafe {
///     my_printer(c_to_print.as_ptr());
/// }
/// # }
/// ```
///
/// # Safety
///
/// `CString` is intended for working with traditional C-style strings
/// (a sequence of non-null bytes terminated by a single null byte); the
/// primary use case for these kinds of strings is interoperating with C-like
/// code. Often you will need to transfer ownership to/from that external
/// code. It is strongly recommended that you thoroughly read through the
/// documentation of `CString` before use, as improper ownership management
/// of `CString` instances can lead to invalid memory accesses, memory leaks,
/// and other memory errors.

#[cfg(feature = "alloc")]
#[derive(PartialEq, PartialOrd, Eq, Ord, Hash, Clone)]
pub struct CString {
    // Invariant 1: the slice ends with a zero byte and has a length of at least one.
    // Invariant 2: the slice contains only one zero byte.
    // Improper usage of unsafe function can break Invariant 2, but not Invariant 1.
    inner: Box<[u8]>,
}

/// Representation of a borrowed C string.
///
/// This dynamically sized type is only safely constructed via a borrowed
/// version of an instance of `CString`. This type can be constructed from a raw
/// C string as well and represents a C string borrowed from another location.
///
/// Note that this structure is **not** `repr(C)` and is not recommended to be
/// placed in the signatures of FFI functions. Instead safe wrappers of FFI
/// functions may leverage the unsafe [`from_ptr`] constructor to provide a safe
/// interface to other consumers.
///
/// [`from_ptr`]: #method.from_ptr
///
/// # Examples
///
/// Inspecting a foreign C string:
///
/// ```ignore (extern-declaration)
/// use cstr_core::CStr;
/// use cstr_core::c_char;
///
/// extern { fn my_string() -> *const c_char; }
///
/// unsafe {
///     let slice = CStr::from_ptr(my_string());
///     println!("string length: {}", slice.to_bytes().len());
/// }
/// ```
///
/// Passing a Rust-originating C string:
///
/// ```ignore (extern-declaration)
/// use cstr_core::{CString, CStr};
/// use cstr_core::c_char;
///
/// fn work(data: &CStr) {
///     extern { fn work_with(data: *const c_char); }
///
///     unsafe { work_with(data.as_ptr()) }
/// }
///
/// let s = CString::new("data data data data").unwrap();
/// work(&s);
/// ```
///
/// Converting a foreign C string into a Rust [`String`]:
///
/// [`String`]: ../string/struct.String.html
///
/// ```ignore (extern-declaration)
/// use cstr_core::CStr;
/// use cstr_core::c_char;
///
/// extern { fn my_string() -> *const c_char; }
///
/// fn my_string_safe() -> String {
///     unsafe {
///         CStr::from_ptr(my_string()).to_string_lossy().into_owned()
///     }
/// }
///
/// println!("string: {}", my_string_safe());
/// ```
#[derive(Hash)]
pub struct CStr {
    // FIXME: this should not be represented with a DST slice but rather with
    //        just a raw `c_char` along with some form of marker to make
    //        this an unsized type. Essentially `sizeof(&CStr)` should be the
    //        same as `sizeof(&c_char)` but `CStr` should be an unsized type.
    inner: [c_char],
}

/// An error returned from [`CString::new`] to indicate that a nul byte was found
/// in the vector provided.
///
/// [`CString::new`]: struct.CString.html#method.new
///
/// # Examples
///
/// ```
/// use cstr_core::{CString, NulError};
///
/// let _: NulError = CString::new(b"f\0oo".to_vec()).unwrap_err();
/// ```
#[cfg(feature = "alloc")]
#[derive(Clone, PartialEq, Eq, Debug)]
pub struct NulError(usize, Vec<u8>);

/// An error returned from [`CStr::from_bytes_with_nul`] to indicate that a nul
/// byte was found too early in the slice provided or one wasn't found at all.
///
/// [`CStr::from_bytes_with_nul`]: struct.CStr.html#method.from_bytes_with_nul
///
/// # Examples
///
/// ```
/// use cstr_core::{CStr, FromBytesWithNulError};
///
/// let _: FromBytesWithNulError = CStr::from_bytes_with_nul(b"f\0oo").unwrap_err();
/// ```
#[derive(Clone, PartialEq, Eq, Debug)]
pub struct FromBytesWithNulError {
    kind: FromBytesWithNulErrorKind,
}

#[derive(Clone, PartialEq, Eq, Debug)]
enum FromBytesWithNulErrorKind {
    InteriorNul(usize),
    NotNulTerminated,
}

impl FromBytesWithNulError {
    fn interior_nul(pos: usize) -> FromBytesWithNulError {
        FromBytesWithNulError {
            kind: FromBytesWithNulErrorKind::InteriorNul(pos),
        }
    }
    fn not_nul_terminated() -> FromBytesWithNulError {
        FromBytesWithNulError {
            kind: FromBytesWithNulErrorKind::NotNulTerminated,
        }
    }
}

/// An error returned from [`CString::into_string`] to indicate that a UTF-8 error
/// was encountered during the conversion.
///
/// [`CString::into_string`]: struct.CString.html#method.into_string
#[cfg(feature = "alloc")]
#[derive(Clone, PartialEq, Eq, Debug)]
pub struct IntoStringError {
    inner: CString,
    error: Utf8Error,
}

#[cfg(feature = "alloc")]
impl CString {
    /// Creates a new C-compatible string from a container of bytes.
    ///
    /// This method will consume the provided data and use the underlying bytes
    /// to construct a new string, ensuring that there is a trailing 0 byte.
    ///
    /// # Examples
    ///
    /// ```ignore (extern-declaration)
    /// use cstr_core::CString;
    /// use cstr_core::c_char;
    ///
    /// extern { fn puts(s: *const c_char); }
    ///
    /// let to_print = CString::new("Hello!").unwrap();
    /// unsafe {
    ///     puts(to_print.as_ptr());
    /// }
    /// ```
    ///
    /// # Errors
    ///
    /// This function will return an error if the bytes yielded contain an
    /// internal 0 byte. The error returned will contain the bytes as well as
    /// the position of the nul byte.
    pub fn new<T: Into<Vec<u8>>>(t: T) -> Result<CString, NulError> {
        Self::_new(t.into())
    }

    fn _new(bytes: Vec<u8>) -> Result<CString, NulError> {
        match memchr::memchr(0, &bytes) {
            Some(i) => Err(NulError(i, bytes)),
            None => Ok(unsafe { CString::from_vec_unchecked(bytes) }),
        }
    }

    /// Creates a C-compatible string from a byte vector without checking for
    /// interior 0 bytes.
    ///
    /// This method is equivalent to [`new`] except that no runtime assertion
    /// is made that `v` contains no 0 bytes, and it requires an actual
    /// byte vector, not anything that can be converted to one with Into.
    ///
    /// [`new`]: #method.new
    ///
    /// # Examples
    ///
    /// ```
    /// use cstr_core::CString;
    ///
    /// let raw = b"foo".to_vec();
    /// unsafe {
    ///     let c_string = CString::from_vec_unchecked(raw);
    /// }
    /// ```
    pub unsafe fn from_vec_unchecked(mut v: Vec<u8>) -> CString {
        v.reserve_exact(1);
        v.push(0);
        CString {
            inner: v.into_boxed_slice(),
        }
    }

    /// Retakes ownership of a `CString` that was transferred to C.
    ///
    /// Additionally, the length of the string will be recalculated from the pointer.
    ///
    /// # Safety
    ///
    /// This should only ever be called with a pointer that was earlier
    /// obtained by calling [`into_raw`] on a `CString`. Other usage (e.g. trying to take
    /// ownership of a string that was allocated by foreign code) is likely to lead
    /// to undefined behavior or allocator corruption.
    ///
    /// [`into_raw`]: #method.into_raw
    ///
    /// # Examples
    ///
    /// Create a `CString`, pass ownership to an `extern` function (via raw pointer), then retake
    /// ownership with `from_raw`:
    ///
    /// ```ignore (extern-declaration)
    /// use cstr_core::CString;
    /// use cstr_core::c_char;
    ///
    /// extern {
    ///     fn some_extern_function(s: *mut c_char);
    /// }
    ///
    /// let c_string = CString::new("Hello!").unwrap();
    /// let raw = c_string.into_raw();
    /// unsafe {
    ///     some_extern_function(raw);
    ///     let c_string = CString::from_raw(raw);
    /// }
    /// ```
    pub unsafe fn from_raw(ptr: *mut c_char) -> CString {
        let len = strlen(ptr) + 1; // Including the NUL byte
        let slice = slice::from_raw_parts_mut(ptr, len as usize);
        CString {
            inner: Box::from_raw(slice as *mut [c_char] as *mut [u8]),
        }
    }

    /// Transfers ownership of the string to a C caller.
    ///
    /// The pointer must be returned to Rust and reconstituted using
    /// [`from_raw`] to be properly deallocated. Specifically, one
    /// should *not* use the standard C `free` function to deallocate
    /// this string.
    ///
    /// Failure to call [`from_raw`] will lead to a memory leak.
    ///
    /// [`from_raw`]: #method.from_raw
    ///
    /// # Examples
    ///
    /// ```
    /// use cstr_core::CString;
    ///
    /// let c_string = CString::new("foo").unwrap();
    ///
    /// let ptr = c_string.into_raw();
    ///
    /// unsafe {
    ///     assert_eq!(b'f', *ptr as u8);
    ///     assert_eq!(b'o', *ptr.offset(1) as u8);
    ///     assert_eq!(b'o', *ptr.offset(2) as u8);
    ///     assert_eq!(b'\0', *ptr.offset(3) as u8);
    ///
    ///     // retake pointer to free memory
    ///     let _ = CString::from_raw(ptr);
    /// }
    /// ```
    #[inline]
    pub fn into_raw(self) -> *mut c_char {
        Box::into_raw(self.into_inner()) as *mut c_char
    }

    /// Converts the `CString` into a [`String`] if it contains valid Unicode data.
    ///
    /// On failure, ownership of the original `CString` is returned.
    ///
    /// [`String`]: ../string/struct.String.html
    pub fn into_string(self) -> Result<String, IntoStringError> {
        String::from_utf8(self.into_bytes()).map_err(|e| IntoStringError {
            error: e.utf8_error(),
            inner: unsafe { CString::from_vec_unchecked(e.into_bytes()) },
        })
    }

    /// Returns the underlying byte buffer.
    ///
    /// The returned buffer does **not** contain the trailing nul separator and
    /// it is guaranteed to not have any interior nul bytes.
    ///
    /// # Examples
    ///
    /// ```
    /// use cstr_core::CString;
    ///
    /// let c_string = CString::new("foo").unwrap();
    /// let bytes = c_string.into_bytes();
    /// assert_eq!(bytes, vec![b'f', b'o', b'o']);
    /// ```
    pub fn into_bytes(self) -> Vec<u8> {
        let mut vec = self.into_inner().into_vec();
        let _nul = vec.pop();
        debug_assert_eq!(_nul, Some(0u8));
        vec
    }

    /// Equivalent to the [`into_bytes`] function except that the returned vector
    /// includes the trailing nul byte.
    ///
    /// [`into_bytes`]: #method.into_bytes
    ///
    /// # Examples
    ///
    /// ```
    /// use cstr_core::CString;
    ///
    /// let c_string = CString::new("foo").unwrap();
    /// let bytes = c_string.into_bytes_with_nul();
    /// assert_eq!(bytes, vec![b'f', b'o', b'o', b'\0']);
    /// ```
    pub fn into_bytes_with_nul(self) -> Vec<u8> {
        self.into_inner().into_vec()
    }

    /// Returns the contents of this `CString` as a slice of bytes.
    ///
    /// The returned slice does **not** contain the trailing nul separator and
    /// it is guaranteed to not have any interior nul bytes.
    ///
    /// # Examples
    ///
    /// ```
    /// use cstr_core::CString;
    ///
    /// let c_string = CString::new("foo").unwrap();
    /// let bytes = c_string.as_bytes();
    /// assert_eq!(bytes, &[b'f', b'o', b'o']);
    /// ```
    #[inline]
    pub fn as_bytes(&self) -> &[u8] {
        &self.inner[..self.inner.len() - 1]
    }

    /// Equivalent to the [`as_bytes`] function except that the returned slice
    /// includes the trailing nul byte.
    ///
    /// [`as_bytes`]: #method.as_bytes
    ///
    /// # Examples
    ///
    /// ```
    /// use cstr_core::CString;
    ///
    /// let c_string = CString::new("foo").unwrap();
    /// let bytes = c_string.as_bytes_with_nul();
    /// assert_eq!(bytes, &[b'f', b'o', b'o', b'\0']);
    /// ```
    #[inline]
    pub fn as_bytes_with_nul(&self) -> &[u8] {
        &self.inner
    }

    /// Extracts a [`CStr`] slice containing the entire string.
    ///
    /// [`CStr`]: struct.CStr.html
    ///
    /// # Examples
    ///
    /// ```
    /// use cstr_core::{CString, CStr};
    ///
    /// let c_string = CString::new(b"foo".to_vec()).unwrap();
    /// let c_str = c_string.as_c_str();
    /// assert_eq!(c_str, CStr::from_bytes_with_nul(b"foo\0").unwrap());
    /// ```
    #[inline]
    pub fn as_c_str(&self) -> &CStr {
        &*self
    }

    /// Converts this `CString` into a boxed [`CStr`].
    ///
    /// [`CStr`]: struct.CStr.html
    ///
    /// # Examples
    ///
    /// ```
    /// use cstr_core::{CString, CStr};
    ///
    /// let c_string = CString::new(b"foo".to_vec()).unwrap();
    /// let boxed = c_string.into_boxed_c_str();
    /// assert_eq!(&*boxed, CStr::from_bytes_with_nul(b"foo\0").unwrap());
    /// ```
    pub fn into_boxed_c_str(self) -> Box<CStr> {
        unsafe { Box::from_raw(Box::into_raw(self.into_inner()) as *mut CStr) }
    }

    // Bypass "move out of struct which implements [`Drop`] trait" restriction.
    ///
    /// [`Drop`]: ../ops/trait.Drop.html
    fn into_inner(self) -> Box<[u8]> {
        unsafe {
            let result = ptr::read(&self.inner);
            mem::forget(self);
            result
        }
    }
}

// Turns this `CString` into an empty string to prevent
// memory unsafe code from working by accident. Inline
// to prevent LLVM from optimizing it away in debug builds.
#[cfg(feature = "alloc")]
impl Drop for CString {
    #[inline]
    fn drop(&mut self) {
        unsafe {
            *self.inner.get_unchecked_mut(0) = 0;
        }
    }
}

#[cfg(feature = "alloc")]
impl ops::Deref for CString {
    type Target = CStr;

    #[inline]
    fn deref(&self) -> &CStr {
        unsafe { CStr::from_bytes_with_nul_unchecked(self.as_bytes_with_nul()) }
    }
}

#[cfg(feature = "alloc")]
impl fmt::Debug for CString {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        fmt::Debug::fmt(&**self, f)
    }
}

#[cfg(feature = "alloc")]
impl From<CString> for Vec<u8> {
    #[inline]
    fn from(s: CString) -> Vec<u8> {
        s.into_bytes()
    }
}

impl fmt::Debug for CStr {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "\"")?;
        for byte in self
            .to_bytes()
            .iter()
            .flat_map(|&b| ascii::escape_default(b))
        {
            f.write_char(byte as char)?;
        }
        write!(f, "\"")
    }
}

impl<'a> Default for &'a CStr {
    fn default() -> &'a CStr {
        const SLICE: &'static [c_char] = &[0];
        unsafe { CStr::from_ptr(SLICE.as_ptr()) }
    }
}

#[cfg(feature = "alloc")]
impl Default for CString {
    /// Creates an empty `CString`.
    fn default() -> CString {
        let a: &CStr = Default::default();
        a.to_owned()
    }
}

#[cfg(feature = "alloc")]
impl Borrow<CStr> for CString {
    #[inline]
    fn borrow(&self) -> &CStr {
        self
    }
}

#[cfg(feature = "alloc")]
impl<'a> From<&'a CStr> for Box<CStr> {
    fn from(s: &'a CStr) -> Box<CStr> {
        let boxed: Box<[u8]> = Box::from(s.to_bytes_with_nul());
        unsafe { Box::from_raw(Box::into_raw(boxed) as *mut CStr) }
    }
}

#[cfg(feature = "alloc")]
impl From<Box<CStr>> for CString {
    #[inline]
    fn from(s: Box<CStr>) -> CString {
        s.into_c_string()
    }
}

#[cfg(feature = "alloc")]
impl From<CString> for Box<CStr> {
    #[inline]
    fn from(s: CString) -> Box<CStr> {
        s.into_boxed_c_str()
    }
}

#[cfg(feature = "alloc")]
impl From<CString> for Arc<CStr> {
    #[inline]
    fn from(s: CString) -> Arc<CStr> {
        let arc: Arc<[u8]> = Arc::from(s.into_inner());
        unsafe { Arc::from_raw(Arc::into_raw(arc) as *const CStr) }
    }
}

#[cfg(feature = "alloc")]
impl<'a> From<&'a CStr> for Arc<CStr> {
    #[inline]
    fn from(s: &CStr) -> Arc<CStr> {
        let arc: Arc<[u8]> = Arc::from(s.to_bytes_with_nul());
        unsafe { Arc::from_raw(Arc::into_raw(arc) as *const CStr) }
    }
}

#[cfg(feature = "alloc")]
impl From<CString> for Rc<CStr> {
    #[inline]
    fn from(s: CString) -> Rc<CStr> {
        let rc: Rc<[u8]> = Rc::from(s.into_inner());
        unsafe { Rc::from_raw(Rc::into_raw(rc) as *const CStr) }
    }
}

#[cfg(feature = "alloc")]
impl<'a> From<&'a CStr> for Rc<CStr> {
    #[inline]
    fn from(s: &CStr) -> Rc<CStr> {
        let rc: Rc<[u8]> = Rc::from(s.to_bytes_with_nul());
        unsafe { Rc::from_raw(Rc::into_raw(rc) as *const CStr) }
    }
}

#[cfg(feature = "alloc")]
impl Default for Box<CStr> {
    fn default() -> Box<CStr> {
        let boxed: Box<[u8]> = Box::from([0]);
        unsafe { Box::from_raw(Box::into_raw(boxed) as *mut CStr) }
    }
}

#[cfg(feature = "alloc")]
impl NulError {
    /// Returns the position of the nul byte in the slice that was provided to
    /// [`CString::new`].
    ///
    /// [`CString::new`]: struct.CString.html#method.new
    ///
    /// # Examples
    ///
    /// ```
    /// use cstr_core::CString;
    ///
    /// let nul_error = CString::new("foo\0bar").unwrap_err();
    /// assert_eq!(nul_error.nul_position(), 3);
    ///
    /// let nul_error = CString::new("foo bar\0").unwrap_err();
    /// assert_eq!(nul_error.nul_position(), 7);
    /// ```
    pub fn nul_position(&self) -> usize {
        self.0
    }

    /// Consumes this error, returning the underlying vector of bytes which
    /// generated the error in the first place.
    ///
    /// # Examples
    ///
    /// ```
    /// use cstr_core::CString;
    ///
    /// let nul_error = CString::new("foo\0bar").unwrap_err();
    /// assert_eq!(nul_error.into_vec(), b"foo\0bar");
    /// ```
    pub fn into_vec(self) -> Vec<u8> {
        self.1
    }
}

#[cfg(feature = "alloc")]
impl fmt::Display for NulError {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "nul byte found in provided data at position: {}", self.0)
    }
}

impl fmt::Display for FromBytesWithNulError {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match self.kind {
            FromBytesWithNulErrorKind::InteriorNul(..) => {
                f.write_str("data provided contains an interior nul byte")?
            }
            FromBytesWithNulErrorKind::NotNulTerminated => {
                f.write_str("data provided is not nul terminated")?
            }
        }
        if let FromBytesWithNulErrorKind::InteriorNul(pos) = self.kind {
            write!(f, " at byte pos {}", pos)?;
        }
        Ok(())
    }
}

#[cfg(feature = "alloc")]
impl IntoStringError {
    /// Consumes this error, returning original [`CString`] which generated the
    /// error.
    ///
    /// [`CString`]: struct.CString.html
    pub fn into_cstring(self) -> CString {
        self.inner
    }

    /// Access the underlying UTF-8 error that was the cause of this error.
    pub fn utf8_error(&self) -> Utf8Error {
        self.error
    }
}

#[cfg(feature = "alloc")]
impl fmt::Display for IntoStringError {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "C string contained non-utf8 bytes")
    }
}

impl CStr {
    /// Casts a raw C string to a safe C string wrapper.
    ///
    /// This function will cast the provided `ptr` to the `CStr` wrapper which
    /// allows inspection and interoperation of non-owned C strings. This method
    /// is unsafe for a number of reasons:
    ///
    /// * There is no guarantee to the validity of `ptr`.
    /// * The returned lifetime is not guaranteed to be the actual lifetime of
    ///   `ptr`.
    /// * There is no guarantee that the memory pointed to by `ptr` contains a
    ///   valid nul terminator byte at the end of the string.
    /// * It is not guaranteed that the memory pointed by `ptr` won't change
    ///   before the `CStr` has been destroyed.
    ///
    /// > **Note**: This operation is intended to be a 0-cost cast but it is
    /// > currently implemented with an up-front calculation of the length of
    /// > the string. This is not guaranteed to always be the case.
    ///
    /// # Examples
    ///
    /// ```ignore (extern-declaration)
    /// # fn main() {
    /// use cstr_core::CStr;
    /// use cstr_core::c_char;
    ///
    /// extern {
    ///     fn my_string() -> *const c_char;
    /// }
    ///
    /// unsafe {
    ///     let slice = CStr::from_ptr(my_string());
    ///     println!("string returned: {}", slice.to_str().unwrap());
    /// }
    /// # }
    /// ```
    pub unsafe fn from_ptr<'a>(ptr: *const c_char) -> &'a CStr {
        let len = strlen(ptr);
        let ptr = ptr as *const u8;
        CStr::from_bytes_with_nul_unchecked(slice::from_raw_parts(ptr, len as usize + 1))
    }

    /// Creates a C string wrapper from a byte slice.
    ///
    /// This function will cast the provided `bytes` to a `CStr` wrapper after
    /// ensuring that it is null terminated and does not contain any interior
    /// nul bytes.
    ///
    /// # Examples
    ///
    /// ```
    /// use cstr_core::CStr;
    ///
    /// let cstr = CStr::from_bytes_with_nul(b"hello\0");
    /// assert!(cstr.is_ok());
    /// ```
    ///
    /// Creating a `CStr` without a trailing nul byte is an error:
    ///
    /// ```
    /// use cstr_core::CStr;
    ///
    /// let c_str = CStr::from_bytes_with_nul(b"hello");
    /// assert!(c_str.is_err());
    /// ```
    ///
    /// Creating a `CStr` with an interior nul byte is an error:
    ///
    /// ```
    /// use cstr_core::CStr;
    ///
    /// let c_str = CStr::from_bytes_with_nul(b"he\0llo\0");
    /// assert!(c_str.is_err());
    /// ```
    pub fn from_bytes_with_nul(bytes: &[u8]) -> Result<&CStr, FromBytesWithNulError> {
        let nul_pos = memchr::memchr(0, bytes);
        if let Some(nul_pos) = nul_pos {
            if nul_pos + 1 != bytes.len() {
                return Err(FromBytesWithNulError::interior_nul(nul_pos));
            }
            Ok(unsafe { CStr::from_bytes_with_nul_unchecked(bytes) })
        } else {
            Err(FromBytesWithNulError::not_nul_terminated())
        }
    }

    /// Unsafely creates a C string wrapper from a byte slice.
    ///
    /// This function will cast the provided `bytes` to a `CStr` wrapper without
    /// performing any sanity checks. The provided slice must be null terminated
    /// and not contain any interior nul bytes.
    ///
    /// # Examples
    ///
    /// ```
    /// use cstr_core::{CStr, CString};
    ///
    /// unsafe {
    ///     let cstring = CString::new("hello").unwrap();
    ///     let cstr = CStr::from_bytes_with_nul_unchecked(cstring.to_bytes_with_nul());
    ///     assert_eq!(cstr, &*cstring);
    /// }
    /// ```
    #[inline]
    pub unsafe fn from_bytes_with_nul_unchecked(bytes: &[u8]) -> &CStr {
        &*(bytes as *const [u8] as *const CStr)
    }

    /// Returns the inner pointer to this C string.
    ///
    /// The returned pointer will be valid for as long as `self` is and points
    /// to a contiguous region of memory terminated with a 0 byte to represent
    /// the end of the string.
    ///
    /// **WARNING**
    ///
    /// It is your responsibility to make sure that the underlying memory is not
    /// freed too early. For example, the following code will cause undefined
    /// behavior when `ptr` is used inside the `unsafe` block:
    ///
    /// ```no_run
    /// use cstr_core::{CString};
    ///
    /// let ptr = CString::new("Hello").unwrap().as_ptr();
    /// unsafe {
    ///     // `ptr` is dangling
    ///     *ptr;
    /// }
    /// ```
    ///
    /// This happens because the pointer returned by `as_ptr` does not carry any
    /// lifetime information and the string is deallocated immediately after
    /// the `CString::new("Hello").unwrap().as_ptr()` expression is evaluated.
    /// To fix the problem, bind the string to a local variable:
    ///
    /// ```no_run
    /// use cstr_core::{CString};
    ///
    /// let hello = CString::new("Hello").unwrap();
    /// let ptr = hello.as_ptr();
    /// unsafe {
    ///     // `ptr` is valid because `hello` is in scope
    ///     *ptr;
    /// }
    /// ```
    #[inline]
    pub fn as_ptr(&self) -> *const c_char {
        self.inner.as_ptr()
    }

    /// Converts this C string to a byte slice.
    ///
    /// This function will calculate the length of this string (which normally
    /// requires a linear amount of work to be done) and then return the
    /// resulting slice of `u8` elements.
    ///
    /// The returned slice will **not** contain the trailing nul that this C
    /// string has.
    ///
    /// > **Note**: This method is currently implemented as a constant-time
    /// > cast, but it is planned to alter its definition in the future to
    /// > perform the length calculation whenever this method is called.
    ///
    /// # Examples
    ///
    /// ```
    /// use cstr_core::CStr;
    ///
    /// let c_str = CStr::from_bytes_with_nul(b"foo\0").unwrap();
    /// assert_eq!(c_str.to_bytes(), b"foo");
    /// ```
    #[inline]
    pub fn to_bytes(&self) -> &[u8] {
        let bytes = self.to_bytes_with_nul();
        &bytes[..bytes.len() - 1]
    }

    /// Converts this C string to a byte slice containing the trailing 0 byte.
    ///
    /// This function is the equivalent of [`to_bytes`] except that it will retain
    /// the trailing nul instead of chopping it off.
    ///
    /// > **Note**: This method is currently implemented as a 0-cost cast, but
    /// > it is planned to alter its definition in the future to perform the
    /// > length calculation whenever this method is called.
    ///
    /// [`to_bytes`]: #method.to_bytes
    ///
    /// # Examples
    ///
    /// ```
    /// use cstr_core::CStr;
    ///
    /// let c_str = CStr::from_bytes_with_nul(b"foo\0").unwrap();
    /// assert_eq!(c_str.to_bytes_with_nul(), b"foo\0");
    /// ```
    #[inline]
    pub fn to_bytes_with_nul(&self) -> &[u8] {
        unsafe { &*(&self.inner as *const [c_char] as *const [u8]) }
    }

    /// Yields a [`&str`] slice if the `CStr` contains valid UTF-8.
    ///
    /// This function will calculate the length of this string and check for
    /// UTF-8 validity, and then return the [`&str`] if it's valid.
    ///
    /// > **Note**: This method is currently implemented to check for validity
    /// > after a constant-time cast, but it is planned to alter its definition
    /// > in the future to perform the length calculation in addition to the
    /// > UTF-8 check whenever this method is called.
    ///
    /// [`&str`]: ../primitive.str.html
    ///
    /// # Examples
    ///
    /// ```
    /// use cstr_core::CStr;
    ///
    /// let c_str = CStr::from_bytes_with_nul(b"foo\0").unwrap();
    /// assert_eq!(c_str.to_str(), Ok("foo"));
    /// ```
    pub fn to_str(&self) -> Result<&str, Utf8Error> {
        // NB: When CStr is changed to perform the length check in .to_bytes()
        // instead of in from_ptr(), it may be worth considering if this should
        // be rewritten to do the UTF-8 check inline with the length calculation
        // instead of doing it afterwards.
        str::from_utf8(self.to_bytes())
    }

    /// Converts a `CStr` into a [`Cow`]`<`[`str`]`>`.
    ///
    /// This function will calculate the length of this string (which normally
    /// requires a linear amount of work to be done) and then return the
    /// resulting slice as a [`Cow`]`<`[`str`]`>`, replacing any invalid UTF-8 sequences
    /// with `U+FFFD REPLACEMENT CHARACTER`.
    ///
    /// > **Note**: This method is currently implemented to check for validity
    /// > after a constant-time cast, but it is planned to alter its definition
    /// > in the future to perform the length calculation in addition to the
    /// > UTF-8 check whenever this method is called.
    ///
    /// [`Cow`]: ../borrow/enum.Cow.html
    /// [`str`]: ../primitive.str.html
    ///
    /// # Examples
    ///
    /// Calling `to_string_lossy` on a `CStr` containing valid UTF-8:
    ///
    /// ```
    /// use std::borrow::Cow;
    /// use cstr_core::CStr;
    ///
    /// let c_str = CStr::from_bytes_with_nul(b"Hello World\0").unwrap();
    /// assert_eq!(c_str.to_string_lossy(), Cow::Borrowed("Hello World"));
    /// ```
    ///
    /// Calling `to_string_lossy` on a `CStr` containing invalid UTF-8:
    ///
    /// ```
    /// use std::borrow::Cow;
    /// use cstr_core::CStr;
    ///
    /// let c_str = CStr::from_bytes_with_nul(b"Hello \xF0\x90\x80World\0").unwrap();
    /// assert_eq!(
    ///     c_str.to_string_lossy(),
    ///     Cow::Owned(String::from("Hello �World")) as Cow<str>
    /// );
    /// ```
    #[cfg(feature = "alloc")]
    pub fn to_string_lossy(&self) -> Cow<str> {
        String::from_utf8_lossy(self.to_bytes())
    }

    /// Converts a [`Box`]`<CStr>` into a [`CString`] without copying or allocating.
    ///
    /// [`Box`]: ../boxed/struct.Box.html
    /// [`CString`]: struct.CString.html
    ///
    /// # Examples
    ///
    /// ```
    /// use cstr_core::CString;
    ///
    /// let c_string = CString::new(b"foo".to_vec()).unwrap();
    /// let boxed = c_string.into_boxed_c_str();
    /// assert_eq!(boxed.into_c_string(), CString::new("foo").unwrap());
    /// ```
    #[cfg(feature = "alloc")]
    pub fn into_c_string(self: Box<CStr>) -> CString {
        let raw = Box::into_raw(self) as *mut [u8];
        CString {
            inner: unsafe { Box::from_raw(raw) },
        }
    }
}

impl PartialEq for CStr {
    fn eq(&self, other: &CStr) -> bool {
        self.to_bytes().eq(other.to_bytes())
    }
}
impl Eq for CStr {}
impl PartialOrd for CStr {
    fn partial_cmp(&self, other: &CStr) -> Option<Ordering> {
        self.to_bytes().partial_cmp(&other.to_bytes())
    }
}
impl Ord for CStr {
    fn cmp(&self, other: &CStr) -> Ordering {
        self.to_bytes().cmp(&other.to_bytes())
    }
}

#[cfg(feature = "alloc")]
impl ToOwned for CStr {
    type Owned = CString;

    fn to_owned(&self) -> CString {
        CString {
            inner: self.to_bytes_with_nul().into(),
        }
    }
}

#[cfg(feature = "alloc")]
impl<'a> From<&'a CStr> for CString {
    fn from(s: &'a CStr) -> CString {
        s.to_owned()
    }
}

#[cfg(feature = "alloc")]
impl ops::Index<ops::RangeFull> for CString {
    type Output = CStr;

    #[inline]
    fn index(&self, _index: ops::RangeFull) -> &CStr {
        self
    }
}

impl AsRef<CStr> for CStr {
    #[inline]
    fn as_ref(&self) -> &CStr {
        self
    }
}

#[cfg(feature = "alloc")]
impl AsRef<CStr> for CString {
    #[inline]
    fn as_ref(&self) -> &CStr {
        self
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use std::borrow::Cow::{Borrowed, Owned};
    use std::collections::hash_map::DefaultHasher;
    use std::hash::{Hash, Hasher};

    #[test]
    fn c_to_rust() {
        let data = b"123\0";
        let ptr = data.as_ptr() as *const c_char;
        unsafe {
            assert_eq!(CStr::from_ptr(ptr).to_bytes(), b"123");
            assert_eq!(CStr::from_ptr(ptr).to_bytes_with_nul(), b"123\0");
        }
    }

    #[test]
    fn simple() {
        let s = CString::new("1234").unwrap();
        assert_eq!(s.as_bytes(), b"1234");
        assert_eq!(s.as_bytes_with_nul(), b"1234\0");
    }

    #[test]
    fn build_with_zero1() {
        assert!(CString::new(&b"\0"[..]).is_err());
    }
    #[test]
    fn build_with_zero2() {
        assert!(CString::new(vec![0]).is_err());
    }

    #[test]
    fn build_with_zero3() {
        unsafe {
            let s = CString::from_vec_unchecked(vec![0]);
            assert_eq!(s.as_bytes(), b"\0");
        }
    }

    #[test]
    fn formatted() {
        let s = CString::new(&b"abc\x01\x02\n\xE2\x80\xA6\xFF"[..]).unwrap();
        assert_eq!(format!("{:?}", s), r#""abc\x01\x02\n\xe2\x80\xa6\xff""#);
    }

    #[test]
    fn borrowed() {
        unsafe {
            let s = CStr::from_ptr(b"12\0".as_ptr() as *const _);
            assert_eq!(s.to_bytes(), b"12");
            assert_eq!(s.to_bytes_with_nul(), b"12\0");
        }
    }

    #[test]
    fn to_str() {
        let data = b"123\xE2\x80\xA6\0";
        let ptr = data.as_ptr() as *const c_char;
        unsafe {
            assert_eq!(CStr::from_ptr(ptr).to_str(), Ok("123…"));
            assert_eq!(CStr::from_ptr(ptr).to_string_lossy(), Borrowed("123…"));
        }
        let data = b"123\xE2\0";
        let ptr = data.as_ptr() as *const c_char;
        unsafe {
            assert!(CStr::from_ptr(ptr).to_str().is_err());
            assert_eq!(
                CStr::from_ptr(ptr).to_string_lossy(),
                Owned::<str>(format!("123\u{FFFD}"))
            );
        }
    }

    #[test]
    fn to_owned() {
        let data = b"123\0";
        let ptr = data.as_ptr() as *const c_char;

        let owned = unsafe { CStr::from_ptr(ptr).to_owned() };
        assert_eq!(owned.as_bytes_with_nul(), data);
    }

    #[test]
    fn equal_hash() {
        let data = b"123\xE2\xFA\xA6\0";
        let ptr = data.as_ptr() as *const c_char;
        let cstr: &'static CStr = unsafe { CStr::from_ptr(ptr) };

        let mut s = DefaultHasher::new();
        cstr.hash(&mut s);
        let cstr_hash = s.finish();
        let mut s = DefaultHasher::new();
        CString::new(&data[..data.len() - 1]).unwrap().hash(&mut s);
        let cstring_hash = s.finish();

        assert_eq!(cstr_hash, cstring_hash);
    }

    #[test]
    fn from_bytes_with_nul() {
        let data = b"123\0";
        let cstr = CStr::from_bytes_with_nul(data);
        assert_eq!(cstr.map(CStr::to_bytes), Ok(&b"123"[..]));
        let cstr = CStr::from_bytes_with_nul(data);
        assert_eq!(cstr.map(CStr::to_bytes_with_nul), Ok(&b"123\0"[..]));

        unsafe {
            let cstr = CStr::from_bytes_with_nul(data);
            let cstr_unchecked = CStr::from_bytes_with_nul_unchecked(data);
            assert_eq!(cstr, Ok(cstr_unchecked));
        }
    }

    #[test]
    fn from_bytes_with_nul_unterminated() {
        let data = b"123";
        let cstr = CStr::from_bytes_with_nul(data);
        assert!(cstr.is_err());
    }

    #[test]
    fn from_bytes_with_nul_interior() {
        let data = b"1\023\0";
        let cstr = CStr::from_bytes_with_nul(data);
        assert!(cstr.is_err());
    }

    #[test]
    fn into_boxed() {
        let orig: &[u8] = b"Hello, world!\0";
        let cstr = CStr::from_bytes_with_nul(orig).unwrap();
        let boxed: Box<CStr> = Box::from(cstr);
        let cstring = cstr.to_owned().into_boxed_c_str().into_c_string();
        assert_eq!(cstr, &*boxed);
        assert_eq!(&*boxed, &*cstring);
        assert_eq!(&*cstring, cstr);
    }

    #[test]
    fn boxed_default() {
        let boxed = <Box<CStr>>::default();
        assert_eq!(boxed.to_bytes_with_nul(), &[0]);
    }

    #[test]
    fn into_rc() {
        let orig: &[u8] = b"Hello, world!\0";
        let cstr = CStr::from_bytes_with_nul(orig).unwrap();
        let rc: Rc<CStr> = Rc::from(cstr);
        let arc: Arc<CStr> = Arc::from(cstr);

        assert_eq!(&*rc, cstr);
        assert_eq!(&*arc, cstr);

        let rc2: Rc<CStr> = Rc::from(cstr.to_owned());
        let arc2: Arc<CStr> = Arc::from(cstr.to_owned());

        assert_eq!(&*rc2, cstr);
        assert_eq!(&*arc2, cstr);
    }
}