/
c_str.rs
648 lines (595 loc) · 21.6 KB
/
c_str.rs
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
// 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.
use ascii;
use borrow::{Cow, ToOwned, Borrow};
use boxed::Box;
use convert::{Into, From};
use cmp::{PartialEq, Eq, PartialOrd, Ord, Ordering};
use error::Error;
use fmt::{self, Write};
use io;
use iter::Iterator;
use libc;
use mem;
use ops::Deref;
use option::Option::{self, Some, None};
use os::raw::c_char;
use result::Result::{self, Ok, Err};
use slice;
use str::{self, Utf8Error};
use string::String;
use vec::Vec;
/// 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. After
/// being created, a `CString` predominately inherits all of its methods from
/// the `Deref` implementation to `[c_char]`. Note that the underlying array
/// is represented as an array of `c_char` as opposed to `u8`. 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.
///
/// # Examples
///
/// ```no_run
/// # fn main() {
/// use std::ffi::CString;
/// use std::os::raw::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());
/// }
/// # }
/// ```
#[derive(PartialEq, PartialOrd, Eq, Ord, Hash, Clone)]
#[stable(feature = "rust1", since = "1.0.0")]
pub struct CString {
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.
///
/// # Examples
///
/// Inspecting a foreign C string
///
/// ```no_run
/// use std::ffi::CStr;
/// use std::os::raw::c_char;
///
/// extern { fn my_string() -> *const c_char; }
///
/// fn main() {
/// unsafe {
/// let slice = CStr::from_ptr(my_string());
/// println!("string length: {}", slice.to_bytes().len());
/// }
/// }
/// ```
///
/// Passing a Rust-originating C string
///
/// ```no_run
/// use std::ffi::{CString, CStr};
/// use std::os::raw::c_char;
///
/// fn work(data: &CStr) {
/// extern { fn work_with(data: *const c_char); }
///
/// unsafe { work_with(data.as_ptr()) }
/// }
///
/// fn main() {
/// let s = CString::new("data data data data").unwrap();
/// work(&s);
/// }
/// ```
///
/// Converting a foreign C string into a Rust `String`
///
/// ```no_run
/// use std::ffi::CStr;
/// use std::os::raw::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()
/// }
/// }
///
/// fn main() {
/// println!("string: {}", my_string_safe());
/// }
/// ```
#[derive(Hash)]
#[stable(feature = "rust1", since = "1.0.0")]
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.
#[derive(Clone, PartialEq, Debug)]
#[stable(feature = "rust1", since = "1.0.0")]
pub struct NulError(usize, Vec<u8>);
/// An error returned from `CString::into_string` to indicate that a UTF-8 error
/// was encountered during the conversion.
#[derive(Clone, PartialEq, Debug)]
#[unstable(feature = "cstring_into", reason = "recently added", issue = "29157")]
pub struct IntoStringError {
inner: CString,
error: Utf8Error,
}
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
///
/// ```no_run
/// use std::ffi::CString;
/// use std::os::raw::c_char;
///
/// extern { fn puts(s: *const c_char); }
///
/// fn main() {
/// 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.
#[stable(feature = "rust1", since = "1.0.0")]
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 bytes.iter().position(|x| *x == 0) {
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.
#[stable(feature = "rust1", since = "1.0.0")]
pub unsafe fn from_vec_unchecked(mut v: Vec<u8>) -> CString {
v.push(0);
CString { inner: v.into_boxed_slice() }
}
/// Retakes ownership of a CString that was transferred to C.
///
/// The only appropriate argument is a pointer obtained by calling
/// `into_raw`. The length of the string will be recalculated
/// using the pointer.
#[unstable(feature = "cstr_memory2", reason = "recently added",
issue = "27769")]
#[deprecated(since = "1.4.0", reason = "renamed to from_raw")]
pub unsafe fn from_ptr(ptr: *const c_char) -> CString {
CString::from_raw(ptr as *mut _)
}
/// Retakes ownership of a CString that was transferred to C.
///
/// The only appropriate argument is a pointer obtained by calling
/// `into_raw`. The length of the string will be recalculated
/// using the pointer.
#[stable(feature = "cstr_memory", since = "1.4.0")]
pub unsafe fn from_raw(ptr: *mut c_char) -> CString {
let len = libc::strlen(ptr) + 1; // Including the NUL byte
let slice = slice::from_raw_parts(ptr, len as usize);
CString { inner: mem::transmute(slice) }
}
/// 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.
#[unstable(feature = "cstr_memory2", reason = "recently added",
issue = "27769")]
#[deprecated(since = "1.4.0", reason = "renamed to into_raw")]
pub fn into_ptr(self) -> *const c_char {
self.into_raw() as *const _
}
/// 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.
#[stable(feature = "cstr_memory", since = "1.4.0")]
pub fn into_raw(self) -> *mut c_char {
Box::into_raw(self.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.
#[unstable(feature = "cstring_into", reason = "recently added", issue = "29157")]
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.
#[unstable(feature = "cstring_into", reason = "recently added", issue = "29157")]
pub fn into_bytes(self) -> Vec<u8> {
// FIXME: Once this method becomes stable, add an `impl Into<Vec<u8>> for CString`
let mut vec = self.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.
#[unstable(feature = "cstring_into", reason = "recently added", issue = "29157")]
pub fn into_bytes_with_nul(self) -> Vec<u8> {
self.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.
#[stable(feature = "rust1", since = "1.0.0")]
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.
#[stable(feature = "rust1", since = "1.0.0")]
pub fn as_bytes_with_nul(&self) -> &[u8] {
&self.inner
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl Deref for CString {
type Target = CStr;
fn deref(&self) -> &CStr {
unsafe { mem::transmute(self.as_bytes_with_nul()) }
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl fmt::Debug for CString {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
fmt::Debug::fmt(&**self, f)
}
}
#[stable(feature = "cstr_debug", since = "1.3.0")]
impl fmt::Debug for CStr {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
try!(write!(f, "\""));
for byte in self.to_bytes().iter().flat_map(|&b| ascii::escape_default(b)) {
try!(f.write_char(byte as char));
}
write!(f, "\"")
}
}
#[stable(feature = "cstr_borrow", since = "1.3.0")]
impl Borrow<CStr> for CString {
fn borrow(&self) -> &CStr { self }
}
impl NulError {
/// Returns the position of the nul byte in the slice that was provided to
/// `CString::new`.
#[stable(feature = "rust1", since = "1.0.0")]
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.
#[stable(feature = "rust1", since = "1.0.0")]
pub fn into_vec(self) -> Vec<u8> { self.1 }
}
#[stable(feature = "rust1", since = "1.0.0")]
impl Error for NulError {
fn description(&self) -> &str { "nul byte found in data" }
}
#[stable(feature = "rust1", since = "1.0.0")]
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)
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl From<NulError> for io::Error {
fn from(_: NulError) -> io::Error {
io::Error::new(io::ErrorKind::InvalidInput,
"data provided contains a nul byte")
}
}
impl IntoStringError {
/// Consumes this error, returning original `CString` which generated the
/// error.
#[unstable(feature = "cstring_into", reason = "recently added", issue = "29157")]
pub fn into_cstring(self) -> CString {
self.inner
}
/// Access the underlying UTF-8 error that was the cause of this error.
#[unstable(feature = "cstring_into", reason = "recently added", issue = "29157")]
pub fn utf8_error(&self) -> Utf8Error {
self.error
}
}
#[unstable(feature = "cstring_into", reason = "recently added", issue = "29157")]
impl Error for IntoStringError {
fn description(&self) -> &str {
Error::description(&self.error)
}
}
#[unstable(feature = "cstring_into", reason = "recently added", issue = "29157")]
impl fmt::Display for IntoStringError {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
fmt::Display::fmt(&self.error, f)
}
}
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.
///
/// > **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
///
/// ```no_run
/// # fn main() {
/// use std::ffi::CStr;
/// use std::os::raw::c_char;
/// use std::str;
///
/// extern {
/// fn my_string() -> *const c_char;
/// }
///
/// unsafe {
/// let slice = CStr::from_ptr(my_string());
/// println!("string returned: {}",
/// str::from_utf8(slice.to_bytes()).unwrap());
/// }
/// # }
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub unsafe fn from_ptr<'a>(ptr: *const c_char) -> &'a CStr {
let len = libc::strlen(ptr);
mem::transmute(slice::from_raw_parts(ptr, len as usize + 1))
}
/// 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.
#[stable(feature = "rust1", since = "1.0.0")]
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 0-cost cast, but
/// > it is planned to alter its definition in the future to perform the
/// > length calculation whenever this method is called.
#[stable(feature = "rust1", since = "1.0.0")]
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.
#[stable(feature = "rust1", since = "1.0.0")]
pub fn to_bytes_with_nul(&self) -> &[u8] {
unsafe { mem::transmute(&self.inner) }
}
/// 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 0-cost 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.
#[stable(feature = "cstr_to_str", since = "1.4.0")]
pub fn to_str(&self) -> Result<&str, 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 0-cost 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.
#[stable(feature = "cstr_to_str", since = "1.4.0")]
pub fn to_string_lossy(&self) -> Cow<str> {
String::from_utf8_lossy(self.to_bytes())
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl PartialEq for CStr {
fn eq(&self, other: &CStr) -> bool {
self.to_bytes().eq(other.to_bytes())
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl Eq for CStr {}
#[stable(feature = "rust1", since = "1.0.0")]
impl PartialOrd for CStr {
fn partial_cmp(&self, other: &CStr) -> Option<Ordering> {
self.to_bytes().partial_cmp(&other.to_bytes())
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl Ord for CStr {
fn cmp(&self, other: &CStr) -> Ordering {
self.to_bytes().cmp(&other.to_bytes())
}
}
#[stable(feature = "cstr_borrow", since = "1.3.0")]
impl ToOwned for CStr {
type Owned = CString;
fn to_owned(&self) -> CString {
unsafe { CString::from_vec_unchecked(self.to_bytes().to_vec()) }
}
}
#[cfg(test)]
mod tests {
use prelude::v1::*;
use super::*;
use os::raw::c_char;
use borrow::Cow::{Borrowed, Owned};
use hash::{SipHasher, 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 = SipHasher::new_with_keys(0, 0);
cstr.hash(&mut s);
let cstr_hash = s.finish();
let mut s = SipHasher::new_with_keys(0, 0);
CString::new(&data[..data.len() - 1]).unwrap().hash(&mut s);
let cstring_hash = s.finish();
assert_eq!(cstr_hash, cstring_hash);
}
}