1 #![deny(unsafe_op_in_unsafe_fn)]
7 use crate::borrow::{Borrow, Cow};
8 use crate::cmp::Ordering;
9 use crate::error::Error;
10 use crate::fmt::{self, Write};
13 use crate::num::NonZeroU8;
15 use crate::os::raw::c_char;
19 use crate::str::{self, Utf8Error};
22 use crate::sys_common::memchr;
24 /// A type representing an owned, C-compatible, nul-terminated string with no nul bytes in the
27 /// This type serves the purpose of being able to safely generate a
28 /// C-compatible string from a Rust byte slice or vector. An instance of this
29 /// type is a static guarantee that the underlying bytes contain no interior 0
30 /// bytes ("nul characters") and that the final byte is 0 ("nul terminator").
32 /// `CString` is to <code>&[CStr]</code> as [`String`] is to <code>&[str]</code>: the former
33 /// in each pair are owned strings; the latter are borrowed
36 /// # Creating a `CString`
38 /// A `CString` is created from either a byte slice or a byte vector,
39 /// or anything that implements <code>[Into]<[Vec]<[u8]>></code> (for
40 /// example, you can build a `CString` straight out of a [`String`] or
41 /// a <code>&[str]</code>, since both implement that trait).
43 /// The [`CString::new`] method will actually check that the provided <code>&[[u8]]</code>
44 /// does not have 0 bytes in the middle, and return an error if it
47 /// # Extracting a raw pointer to the whole C string
49 /// `CString` implements an [`as_ptr`][`CStr::as_ptr`] method through the [`Deref`]
50 /// trait. This method will give you a `*const c_char` which you can
51 /// feed directly to extern functions that expect a nul-terminated
52 /// string, like C's `strdup()`. Notice that [`as_ptr`][`CStr::as_ptr`] returns a
53 /// read-only pointer; if the C code writes to it, that causes
54 /// undefined behavior.
56 /// # Extracting a slice of the whole C string
58 /// Alternatively, you can obtain a <code>&[[u8]]</code> slice from a
59 /// `CString` with the [`CString::as_bytes`] method. Slices produced in this
60 /// way do *not* contain the trailing nul terminator. This is useful
61 /// when you will be calling an extern function that takes a `*const
62 /// u8` argument which is not necessarily nul-terminated, plus another
63 /// argument with the length of the string — like C's `strndup()`.
64 /// You can of course get the slice's length with its
65 /// [`len`][slice::len] method.
67 /// If you need a <code>&[[u8]]</code> slice *with* the nul terminator, you
68 /// can use [`CString::as_bytes_with_nul`] instead.
70 /// Once you have the kind of slice you need (with or without a nul
71 /// terminator), you can call the slice's own
72 /// [`as_ptr`][slice::as_ptr] method to get a read-only raw pointer to pass to
73 /// extern functions. See the documentation for that function for a
74 /// discussion on ensuring the lifetime of the raw pointer.
76 /// [str]: prim@str "str"
77 /// [`Deref`]: ops::Deref
81 /// ```ignore (extern-declaration)
83 /// use std::ffi::CString;
84 /// use std::os::raw::c_char;
87 /// fn my_printer(s: *const c_char);
90 /// // We are certain that our string doesn't have 0 bytes in the middle,
91 /// // so we can .expect()
92 /// let c_to_print = CString::new("Hello, world!").expect("CString::new failed");
94 /// my_printer(c_to_print.as_ptr());
101 /// `CString` is intended for working with traditional C-style strings
102 /// (a sequence of non-nul bytes terminated by a single nul byte); the
103 /// primary use case for these kinds of strings is interoperating with C-like
104 /// code. Often you will need to transfer ownership to/from that external
105 /// code. It is strongly recommended that you thoroughly read through the
106 /// documentation of `CString` before use, as improper ownership management
107 /// of `CString` instances can lead to invalid memory accesses, memory leaks,
108 /// and other memory errors.
109 #[derive(PartialEq, PartialOrd, Eq, Ord, Hash, Clone)]
110 #[cfg_attr(not(test), rustc_diagnostic_item = "cstring_type")]
111 #[stable(feature = "rust1", since = "1.0.0")]
113 // Invariant 1: the slice ends with a zero byte and has a length of at least one.
114 // Invariant 2: the slice contains only one zero byte.
115 // Improper usage of unsafe function can break Invariant 2, but not Invariant 1.
119 /// Representation of a borrowed C string.
121 /// This type represents a borrowed reference to a nul-terminated
122 /// array of bytes. It can be constructed safely from a <code>&[[u8]]</code>
123 /// slice, or unsafely from a raw `*const c_char`. It can then be
124 /// converted to a Rust <code>&[str]</code> by performing UTF-8 validation, or
125 /// into an owned [`CString`].
127 /// `&CStr` is to [`CString`] as <code>&[str]</code> is to [`String`]: the former
128 /// in each pair are borrowed references; the latter are owned
131 /// Note that this structure is **not** `repr(C)` and is not recommended to be
132 /// placed in the signatures of FFI functions. Instead, safe wrappers of FFI
133 /// functions may leverage the unsafe [`CStr::from_ptr`] constructor to provide
134 /// a safe interface to other consumers.
138 /// Inspecting a foreign C string:
140 /// ```ignore (extern-declaration)
141 /// use std::ffi::CStr;
142 /// use std::os::raw::c_char;
144 /// extern "C" { fn my_string() -> *const c_char; }
147 /// let slice = CStr::from_ptr(my_string());
148 /// println!("string buffer size without nul terminator: {}", slice.to_bytes().len());
152 /// Passing a Rust-originating C string:
154 /// ```ignore (extern-declaration)
155 /// use std::ffi::{CString, CStr};
156 /// use std::os::raw::c_char;
158 /// fn work(data: &CStr) {
159 /// extern "C" { fn work_with(data: *const c_char); }
161 /// unsafe { work_with(data.as_ptr()) }
164 /// let s = CString::new("data data data data").expect("CString::new failed");
168 /// Converting a foreign C string into a Rust [`String`]:
170 /// ```ignore (extern-declaration)
171 /// use std::ffi::CStr;
172 /// use std::os::raw::c_char;
174 /// extern "C" { fn my_string() -> *const c_char; }
176 /// fn my_string_safe() -> String {
178 /// CStr::from_ptr(my_string()).to_string_lossy().into_owned()
182 /// println!("string: {}", my_string_safe());
185 /// [str]: prim@str "str"
187 #[cfg_attr(not(test), rustc_diagnostic_item = "CStr")]
188 #[stable(feature = "rust1", since = "1.0.0")]
190 // `fn from` in `impl From<&CStr> for Box<CStr>` current implementation relies
191 // on `CStr` being layout-compatible with `[u8]`.
192 // When attribute privacy is implemented, `CStr` should be annotated as `#[repr(transparent)]`.
193 // Anyway, `CStr` representation and layout are considered implementation detail, are
194 // not documented and must not be relied upon.
196 // FIXME: this should not be represented with a DST slice but rather with
197 // just a raw `c_char` along with some form of marker to make
198 // this an unsized type. Essentially `sizeof(&CStr)` should be the
199 // same as `sizeof(&c_char)` but `CStr` should be an unsized type.
203 /// An error indicating that an interior nul byte was found.
205 /// While Rust strings may contain nul bytes in the middle, C strings
206 /// can't, as that byte would effectively truncate the string.
208 /// This error is created by the [`new`][`CString::new`] method on
209 /// [`CString`]. See its documentation for more.
214 /// use std::ffi::{CString, NulError};
216 /// let _: NulError = CString::new(b"f\0oo".to_vec()).unwrap_err();
218 #[derive(Clone, PartialEq, Eq, Debug)]
219 #[stable(feature = "rust1", since = "1.0.0")]
220 pub struct NulError(usize, Vec<u8>);
222 /// An error indicating that a nul byte was not in the expected position.
224 /// The slice used to create a [`CStr`] must have one and only one nul byte,
225 /// positioned at the end.
227 /// This error is created by the [`CStr::from_bytes_with_nul`] method.
228 /// See its documentation for more.
233 /// use std::ffi::{CStr, FromBytesWithNulError};
235 /// let _: FromBytesWithNulError = CStr::from_bytes_with_nul(b"f\0oo").unwrap_err();
237 #[derive(Clone, PartialEq, Eq, Debug)]
238 #[stable(feature = "cstr_from_bytes", since = "1.10.0")]
239 pub struct FromBytesWithNulError {
240 kind: FromBytesWithNulErrorKind,
243 /// An error indicating that a nul byte was not in the expected position.
245 /// The vector used to create a [`CString`] must have one and only one nul byte,
246 /// positioned at the end.
248 /// This error is created by the [`CString::from_vec_with_nul`] method.
249 /// See its documentation for more.
254 /// #![feature(cstring_from_vec_with_nul)]
255 /// use std::ffi::{CString, FromVecWithNulError};
257 /// let _: FromVecWithNulError = CString::from_vec_with_nul(b"f\0oo".to_vec()).unwrap_err();
259 #[derive(Clone, PartialEq, Eq, Debug)]
260 #[unstable(feature = "cstring_from_vec_with_nul", issue = "73179")]
261 pub struct FromVecWithNulError {
262 error_kind: FromBytesWithNulErrorKind,
266 #[derive(Clone, PartialEq, Eq, Debug)]
267 enum FromBytesWithNulErrorKind {
272 impl FromBytesWithNulError {
273 fn interior_nul(pos: usize) -> FromBytesWithNulError {
274 FromBytesWithNulError { kind: FromBytesWithNulErrorKind::InteriorNul(pos) }
276 fn not_nul_terminated() -> FromBytesWithNulError {
277 FromBytesWithNulError { kind: FromBytesWithNulErrorKind::NotNulTerminated }
281 #[unstable(feature = "cstring_from_vec_with_nul", issue = "73179")]
282 impl FromVecWithNulError {
283 /// Returns a slice of [`u8`]s bytes that were attempted to convert to a [`CString`].
290 /// #![feature(cstring_from_vec_with_nul)]
291 /// use std::ffi::CString;
293 /// // Some invalid bytes in a vector
294 /// let bytes = b"f\0oo".to_vec();
296 /// let value = CString::from_vec_with_nul(bytes.clone());
298 /// assert_eq!(&bytes[..], value.unwrap_err().as_bytes());
300 pub fn as_bytes(&self) -> &[u8] {
304 /// Returns the bytes that were attempted to convert to a [`CString`].
306 /// This method is carefully constructed to avoid allocation. It will
307 /// consume the error, moving out the bytes, so that a copy of the bytes
308 /// does not need to be made.
315 /// #![feature(cstring_from_vec_with_nul)]
316 /// use std::ffi::CString;
318 /// // Some invalid bytes in a vector
319 /// let bytes = b"f\0oo".to_vec();
321 /// let value = CString::from_vec_with_nul(bytes.clone());
323 /// assert_eq!(bytes, value.unwrap_err().into_bytes());
325 pub fn into_bytes(self) -> Vec<u8> {
330 /// An error indicating invalid UTF-8 when converting a [`CString`] into a [`String`].
332 /// `CString` is just a wrapper over a buffer of bytes with a nul terminator;
333 /// [`CString::into_string`] performs UTF-8 validation on those bytes and may
334 /// return this error.
336 /// This `struct` is created by [`CString::into_string()`]. See
337 /// its documentation for more.
338 #[derive(Clone, PartialEq, Eq, Debug)]
339 #[stable(feature = "cstring_into", since = "1.7.0")]
340 pub struct IntoStringError {
346 /// Creates a new C-compatible string from a container of bytes.
348 /// This function will consume the provided data and use the
349 /// underlying bytes to construct a new string, ensuring that
350 /// there is a trailing 0 byte. This trailing 0 byte will be
351 /// appended by this function; the provided data should *not*
352 /// contain any 0 bytes in it.
356 /// ```ignore (extern-declaration)
357 /// use std::ffi::CString;
358 /// use std::os::raw::c_char;
360 /// extern "C" { fn puts(s: *const c_char); }
362 /// let to_print = CString::new("Hello!").expect("CString::new failed");
364 /// puts(to_print.as_ptr());
370 /// This function will return an error if the supplied bytes contain an
371 /// internal 0 byte. The [`NulError`] returned will contain the bytes as well as
372 /// the position of the nul byte.
373 #[stable(feature = "rust1", since = "1.0.0")]
374 pub fn new<T: Into<Vec<u8>>>(t: T) -> Result<CString, NulError> {
376 fn into_vec(self) -> Vec<u8>;
378 impl<T: Into<Vec<u8>>> SpecIntoVec for T {
379 default fn into_vec(self) -> Vec<u8> {
383 // Specialization for avoiding reallocation.
384 impl SpecIntoVec for &'_ [u8] {
385 fn into_vec(self) -> Vec<u8> {
386 let mut v = Vec::with_capacity(self.len() + 1);
391 impl SpecIntoVec for &'_ str {
392 fn into_vec(self) -> Vec<u8> {
393 let mut v = Vec::with_capacity(self.len() + 1);
394 v.extend(self.as_bytes());
399 Self::_new(SpecIntoVec::into_vec(t))
402 fn _new(bytes: Vec<u8>) -> Result<CString, NulError> {
403 match memchr::memchr(0, &bytes) {
404 Some(i) => Err(NulError(i, bytes)),
405 None => Ok(unsafe { CString::from_vec_unchecked(bytes) }),
409 /// Creates a C-compatible string by consuming a byte vector,
410 /// without checking for interior 0 bytes.
412 /// This method is equivalent to [`CString::new`] except that no runtime
413 /// assertion is made that `v` contains no 0 bytes, and it requires an
414 /// actual byte vector, not anything that can be converted to one with Into.
419 /// use std::ffi::CString;
421 /// let raw = b"foo".to_vec();
423 /// let c_string = CString::from_vec_unchecked(raw);
426 #[stable(feature = "rust1", since = "1.0.0")]
427 pub unsafe fn from_vec_unchecked(mut v: Vec<u8>) -> CString {
430 CString { inner: v.into_boxed_slice() }
433 /// Retakes ownership of a `CString` that was transferred to C via
434 /// [`CString::into_raw`].
436 /// Additionally, the length of the string will be recalculated from the pointer.
440 /// This should only ever be called with a pointer that was earlier
441 /// obtained by calling [`CString::into_raw`]. Other usage (e.g., trying to take
442 /// ownership of a string that was allocated by foreign code) is likely to lead
443 /// to undefined behavior or allocator corruption.
445 /// It should be noted that the length isn't just "recomputed," but that
446 /// the recomputed length must match the original length from the
447 /// [`CString::into_raw`] call. This means the [`CString::into_raw`]/`from_raw`
448 /// methods should not be used when passing the string to C functions that can
449 /// modify the string's length.
451 /// > **Note:** If you need to borrow a string that was allocated by
452 /// > foreign code, use [`CStr`]. If you need to take ownership of
453 /// > a string that was allocated by foreign code, you will need to
454 /// > make your own provisions for freeing it appropriately, likely
455 /// > with the foreign code's API to do that.
459 /// Creates a `CString`, pass ownership to an `extern` function (via raw pointer), then retake
460 /// ownership with `from_raw`:
462 /// ```ignore (extern-declaration)
463 /// use std::ffi::CString;
464 /// use std::os::raw::c_char;
467 /// fn some_extern_function(s: *mut c_char);
470 /// let c_string = CString::new("Hello!").expect("CString::new failed");
471 /// let raw = c_string.into_raw();
473 /// some_extern_function(raw);
474 /// let c_string = CString::from_raw(raw);
477 #[stable(feature = "cstr_memory", since = "1.4.0")]
478 pub unsafe fn from_raw(ptr: *mut c_char) -> CString {
479 // SAFETY: This is called with a pointer that was obtained from a call
480 // to `CString::into_raw` and the length has not been modified. As such,
481 // we know there is a NUL byte (and only one) at the end and that the
482 // information about the size of the allocation is correct on Rust's
485 let len = sys::strlen(ptr) + 1; // Including the NUL byte
486 let slice = slice::from_raw_parts_mut(ptr, len as usize);
487 CString { inner: Box::from_raw(slice as *mut [c_char] as *mut [u8]) }
491 /// Consumes the `CString` and transfers ownership of the string to a C caller.
493 /// The pointer which this function returns must be returned to Rust and reconstituted using
494 /// [`CString::from_raw`] to be properly deallocated. Specifically, one
495 /// should *not* use the standard C `free()` function to deallocate
498 /// Failure to call [`CString::from_raw`] will lead to a memory leak.
500 /// The C side must **not** modify the length of the string (by writing a
501 /// `null` somewhere inside the string or removing the final one) before
502 /// it makes it back into Rust using [`CString::from_raw`]. See the safety section
503 /// in [`CString::from_raw`].
508 /// use std::ffi::CString;
510 /// let c_string = CString::new("foo").expect("CString::new failed");
512 /// let ptr = c_string.into_raw();
515 /// assert_eq!(b'f', *ptr as u8);
516 /// assert_eq!(b'o', *ptr.offset(1) as u8);
517 /// assert_eq!(b'o', *ptr.offset(2) as u8);
518 /// assert_eq!(b'\0', *ptr.offset(3) as u8);
520 /// // retake pointer to free memory
521 /// let _ = CString::from_raw(ptr);
525 #[stable(feature = "cstr_memory", since = "1.4.0")]
526 pub fn into_raw(self) -> *mut c_char {
527 Box::into_raw(self.into_inner()) as *mut c_char
530 /// Converts the `CString` into a [`String`] if it contains valid UTF-8 data.
532 /// On failure, ownership of the original `CString` is returned.
537 /// use std::ffi::CString;
539 /// let valid_utf8 = vec![b'f', b'o', b'o'];
540 /// let cstring = CString::new(valid_utf8).expect("CString::new failed");
541 /// assert_eq!(cstring.into_string().expect("into_string() call failed"), "foo");
543 /// let invalid_utf8 = vec![b'f', 0xff, b'o', b'o'];
544 /// let cstring = CString::new(invalid_utf8).expect("CString::new failed");
545 /// let err = cstring.into_string().err().expect("into_string().err() failed");
546 /// assert_eq!(err.utf8_error().valid_up_to(), 1);
549 #[stable(feature = "cstring_into", since = "1.7.0")]
550 pub fn into_string(self) -> Result<String, IntoStringError> {
551 String::from_utf8(self.into_bytes()).map_err(|e| IntoStringError {
552 error: e.utf8_error(),
553 inner: unsafe { CString::from_vec_unchecked(e.into_bytes()) },
557 /// Consumes the `CString` and returns the underlying byte buffer.
559 /// The returned buffer does **not** contain the trailing nul
560 /// terminator, and it is guaranteed to not have any interior nul
566 /// use std::ffi::CString;
568 /// let c_string = CString::new("foo").expect("CString::new failed");
569 /// let bytes = c_string.into_bytes();
570 /// assert_eq!(bytes, vec![b'f', b'o', b'o']);
572 #[stable(feature = "cstring_into", since = "1.7.0")]
573 pub fn into_bytes(self) -> Vec<u8> {
574 let mut vec = self.into_inner().into_vec();
575 let _nul = vec.pop();
576 debug_assert_eq!(_nul, Some(0u8));
580 /// Equivalent to [`CString::into_bytes()`] except that the
581 /// returned vector includes the trailing nul terminator.
586 /// use std::ffi::CString;
588 /// let c_string = CString::new("foo").expect("CString::new failed");
589 /// let bytes = c_string.into_bytes_with_nul();
590 /// assert_eq!(bytes, vec![b'f', b'o', b'o', b'\0']);
592 #[stable(feature = "cstring_into", since = "1.7.0")]
593 pub fn into_bytes_with_nul(self) -> Vec<u8> {
594 self.into_inner().into_vec()
597 /// Returns the contents of this `CString` as a slice of bytes.
599 /// The returned slice does **not** contain the trailing nul
600 /// terminator, and it is guaranteed to not have any interior nul
601 /// bytes. If you need the nul terminator, use
602 /// [`CString::as_bytes_with_nul`] instead.
607 /// use std::ffi::CString;
609 /// let c_string = CString::new("foo").expect("CString::new failed");
610 /// let bytes = c_string.as_bytes();
611 /// assert_eq!(bytes, &[b'f', b'o', b'o']);
614 #[stable(feature = "rust1", since = "1.0.0")]
615 pub fn as_bytes(&self) -> &[u8] {
616 // SAFETY: CString has a length at least 1
617 unsafe { self.inner.get_unchecked(..self.inner.len() - 1) }
620 /// Equivalent to [`CString::as_bytes()`] except that the
621 /// returned slice includes the trailing nul terminator.
626 /// use std::ffi::CString;
628 /// let c_string = CString::new("foo").expect("CString::new failed");
629 /// let bytes = c_string.as_bytes_with_nul();
630 /// assert_eq!(bytes, &[b'f', b'o', b'o', b'\0']);
633 #[stable(feature = "rust1", since = "1.0.0")]
634 pub fn as_bytes_with_nul(&self) -> &[u8] {
638 /// Extracts a [`CStr`] slice containing the entire string.
643 /// use std::ffi::{CString, CStr};
645 /// let c_string = CString::new(b"foo".to_vec()).expect("CString::new failed");
646 /// let cstr = c_string.as_c_str();
648 /// CStr::from_bytes_with_nul(b"foo\0").expect("CStr::from_bytes_with_nul failed"));
651 #[stable(feature = "as_c_str", since = "1.20.0")]
652 pub fn as_c_str(&self) -> &CStr {
656 /// Converts this `CString` into a boxed [`CStr`].
661 /// use std::ffi::{CString, CStr};
663 /// let c_string = CString::new(b"foo".to_vec()).expect("CString::new failed");
664 /// let boxed = c_string.into_boxed_c_str();
665 /// assert_eq!(&*boxed,
666 /// CStr::from_bytes_with_nul(b"foo\0").expect("CStr::from_bytes_with_nul failed"));
668 #[stable(feature = "into_boxed_c_str", since = "1.20.0")]
669 pub fn into_boxed_c_str(self) -> Box<CStr> {
670 unsafe { Box::from_raw(Box::into_raw(self.into_inner()) as *mut CStr) }
673 /// Bypass "move out of struct which implements [`Drop`] trait" restriction.
675 fn into_inner(self) -> Box<[u8]> {
676 // Rationale: `mem::forget(self)` invalidates the previous call to `ptr::read(&self.inner)`
677 // so we use `ManuallyDrop` to ensure `self` is not dropped.
678 // Then we can return the box directly without invalidating it.
679 // See https://github.com/rust-lang/rust/issues/62553.
680 let this = mem::ManuallyDrop::new(self);
681 unsafe { ptr::read(&this.inner) }
684 /// Converts a <code>[Vec]<[u8]></code> to a [`CString`] without checking the
685 /// invariants on the given [`Vec`].
689 /// The given [`Vec`] **must** have one nul byte as its last element.
690 /// This means it cannot be empty nor have any other nul byte anywhere else.
695 /// #![feature(cstring_from_vec_with_nul)]
696 /// use std::ffi::CString;
698 /// unsafe { CString::from_vec_with_nul_unchecked(b"abc\0".to_vec()) },
699 /// unsafe { CString::from_vec_unchecked(b"abc".to_vec()) }
702 #[unstable(feature = "cstring_from_vec_with_nul", issue = "73179")]
703 pub unsafe fn from_vec_with_nul_unchecked(v: Vec<u8>) -> Self {
704 Self { inner: v.into_boxed_slice() }
707 /// Attempts to converts a <code>[Vec]<[u8]></code> to a [`CString`].
709 /// Runtime checks are present to ensure there is only one nul byte in the
710 /// [`Vec`], its last element.
714 /// If a nul byte is present and not the last element or no nul bytes
715 /// is present, an error will be returned.
719 /// A successful conversion will produce the same result as [`CString::new`]
720 /// when called without the ending nul byte.
723 /// #![feature(cstring_from_vec_with_nul)]
724 /// use std::ffi::CString;
726 /// CString::from_vec_with_nul(b"abc\0".to_vec())
727 /// .expect("CString::from_vec_with_nul failed"),
728 /// CString::new(b"abc".to_vec()).expect("CString::new failed")
732 /// An incorrectly formatted [`Vec`] will produce an error.
735 /// #![feature(cstring_from_vec_with_nul)]
736 /// use std::ffi::{CString, FromVecWithNulError};
737 /// // Interior nul byte
738 /// let _: FromVecWithNulError = CString::from_vec_with_nul(b"a\0bc".to_vec()).unwrap_err();
740 /// let _: FromVecWithNulError = CString::from_vec_with_nul(b"abc".to_vec()).unwrap_err();
742 #[unstable(feature = "cstring_from_vec_with_nul", issue = "73179")]
743 pub fn from_vec_with_nul(v: Vec<u8>) -> Result<Self, FromVecWithNulError> {
744 let nul_pos = memchr::memchr(0, &v);
746 Some(nul_pos) if nul_pos + 1 == v.len() => {
747 // SAFETY: We know there is only one nul byte, at the end
749 Ok(unsafe { Self::from_vec_with_nul_unchecked(v) })
751 Some(nul_pos) => Err(FromVecWithNulError {
752 error_kind: FromBytesWithNulErrorKind::InteriorNul(nul_pos),
755 None => Err(FromVecWithNulError {
756 error_kind: FromBytesWithNulErrorKind::NotNulTerminated,
763 // Turns this `CString` into an empty string to prevent
764 // memory-unsafe code from working by accident. Inline
765 // to prevent LLVM from optimizing it away in debug builds.
766 #[stable(feature = "cstring_drop", since = "1.13.0")]
767 impl Drop for CString {
771 *self.inner.get_unchecked_mut(0) = 0;
776 #[stable(feature = "rust1", since = "1.0.0")]
777 impl ops::Deref for CString {
781 fn deref(&self) -> &CStr {
782 unsafe { CStr::from_bytes_with_nul_unchecked(self.as_bytes_with_nul()) }
786 #[stable(feature = "rust1", since = "1.0.0")]
787 impl fmt::Debug for CString {
788 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
789 fmt::Debug::fmt(&**self, f)
793 #[stable(feature = "cstring_into", since = "1.7.0")]
794 impl From<CString> for Vec<u8> {
795 /// Converts a [`CString`] into a <code>[Vec]<[u8]></code>.
797 /// The conversion consumes the [`CString`], and removes the terminating NUL byte.
799 fn from(s: CString) -> Vec<u8> {
804 #[stable(feature = "cstr_debug", since = "1.3.0")]
805 impl fmt::Debug for CStr {
806 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
808 for byte in self.to_bytes().iter().flat_map(|&b| ascii::escape_default(b)) {
809 f.write_char(byte as char)?;
815 #[stable(feature = "cstr_default", since = "1.10.0")]
816 impl Default for &CStr {
817 fn default() -> Self {
818 const SLICE: &[c_char] = &[0];
819 unsafe { CStr::from_ptr(SLICE.as_ptr()) }
823 #[stable(feature = "cstr_default", since = "1.10.0")]
824 impl Default for CString {
825 /// Creates an empty `CString`.
826 fn default() -> CString {
827 let a: &CStr = Default::default();
832 #[stable(feature = "cstr_borrow", since = "1.3.0")]
833 impl Borrow<CStr> for CString {
835 fn borrow(&self) -> &CStr {
840 #[stable(feature = "cstring_from_cow_cstr", since = "1.28.0")]
841 impl<'a> From<Cow<'a, CStr>> for CString {
843 fn from(s: Cow<'a, CStr>) -> Self {
848 #[stable(feature = "box_from_c_str", since = "1.17.0")]
849 impl From<&CStr> for Box<CStr> {
850 fn from(s: &CStr) -> Box<CStr> {
851 let boxed: Box<[u8]> = Box::from(s.to_bytes_with_nul());
852 unsafe { Box::from_raw(Box::into_raw(boxed) as *mut CStr) }
856 #[stable(feature = "box_from_cow", since = "1.45.0")]
857 impl From<Cow<'_, CStr>> for Box<CStr> {
859 fn from(cow: Cow<'_, CStr>) -> Box<CStr> {
861 Cow::Borrowed(s) => Box::from(s),
862 Cow::Owned(s) => Box::from(s),
867 #[stable(feature = "c_string_from_box", since = "1.18.0")]
868 impl From<Box<CStr>> for CString {
869 /// Converts a <code>[Box]<[CStr]></code> into a [`CString`] without copying or allocating.
871 fn from(s: Box<CStr>) -> CString {
876 #[stable(feature = "cstring_from_vec_of_nonzerou8", since = "1.43.0")]
877 impl From<Vec<NonZeroU8>> for CString {
878 /// Converts a <code>[Vec]<[NonZeroU8]></code> into a [`CString`] without
879 /// copying nor checking for inner null bytes.
881 fn from(v: Vec<NonZeroU8>) -> CString {
883 // Transmute `Vec<NonZeroU8>` to `Vec<u8>`.
886 // - transmuting between `NonZeroU8` and `u8` is sound;
887 // - `alloc::Layout<NonZeroU8> == alloc::Layout<u8>`.
888 let (ptr, len, cap): (*mut NonZeroU8, _, _) = Vec::into_raw_parts(v);
889 Vec::from_raw_parts(ptr.cast::<u8>(), len, cap)
891 // SAFETY: `v` cannot contain null bytes, given the type-level
892 // invariant of `NonZeroU8`.
893 CString::from_vec_unchecked(v)
898 #[stable(feature = "more_box_slice_clone", since = "1.29.0")]
899 impl Clone for Box<CStr> {
901 fn clone(&self) -> Self {
906 #[stable(feature = "box_from_c_string", since = "1.20.0")]
907 impl From<CString> for Box<CStr> {
908 /// Converts a [`CString`] into a <code>[Box]<[CStr]></code> without copying or allocating.
910 fn from(s: CString) -> Box<CStr> {
915 #[stable(feature = "cow_from_cstr", since = "1.28.0")]
916 impl<'a> From<CString> for Cow<'a, CStr> {
917 /// Converts a [`CString`] into an owned [`Cow`] without copying or allocating.
919 fn from(s: CString) -> Cow<'a, CStr> {
924 #[stable(feature = "cow_from_cstr", since = "1.28.0")]
925 impl<'a> From<&'a CStr> for Cow<'a, CStr> {
926 /// Converts a [`CStr`] into a borrowed [`Cow`] without copying or allocating.
928 fn from(s: &'a CStr) -> Cow<'a, CStr> {
933 #[stable(feature = "cow_from_cstr", since = "1.28.0")]
934 impl<'a> From<&'a CString> for Cow<'a, CStr> {
935 /// Converts a `&`[`CString`] into a borrowed [`Cow`] without copying or allocating.
937 fn from(s: &'a CString) -> Cow<'a, CStr> {
938 Cow::Borrowed(s.as_c_str())
942 #[stable(feature = "shared_from_slice2", since = "1.24.0")]
943 impl From<CString> for Arc<CStr> {
944 /// Converts a [`CString`] into an <code>[Arc]<[CStr]></code> without copying or allocating.
946 fn from(s: CString) -> Arc<CStr> {
947 let arc: Arc<[u8]> = Arc::from(s.into_inner());
948 unsafe { Arc::from_raw(Arc::into_raw(arc) as *const CStr) }
952 #[stable(feature = "shared_from_slice2", since = "1.24.0")]
953 impl From<&CStr> for Arc<CStr> {
955 fn from(s: &CStr) -> Arc<CStr> {
956 let arc: Arc<[u8]> = Arc::from(s.to_bytes_with_nul());
957 unsafe { Arc::from_raw(Arc::into_raw(arc) as *const CStr) }
961 #[stable(feature = "shared_from_slice2", since = "1.24.0")]
962 impl From<CString> for Rc<CStr> {
963 /// Converts a [`CString`] into an <code>[Rc]<[CStr]></code> without copying or allocating.
965 fn from(s: CString) -> Rc<CStr> {
966 let rc: Rc<[u8]> = Rc::from(s.into_inner());
967 unsafe { Rc::from_raw(Rc::into_raw(rc) as *const CStr) }
971 #[stable(feature = "shared_from_slice2", since = "1.24.0")]
972 impl From<&CStr> for Rc<CStr> {
974 fn from(s: &CStr) -> Rc<CStr> {
975 let rc: Rc<[u8]> = Rc::from(s.to_bytes_with_nul());
976 unsafe { Rc::from_raw(Rc::into_raw(rc) as *const CStr) }
980 #[stable(feature = "default_box_extra", since = "1.17.0")]
981 impl Default for Box<CStr> {
982 fn default() -> Box<CStr> {
983 let boxed: Box<[u8]> = Box::from([0]);
984 unsafe { Box::from_raw(Box::into_raw(boxed) as *mut CStr) }
989 /// Returns the position of the nul byte in the slice that caused
990 /// [`CString::new`] to fail.
995 /// use std::ffi::CString;
997 /// let nul_error = CString::new("foo\0bar").unwrap_err();
998 /// assert_eq!(nul_error.nul_position(), 3);
1000 /// let nul_error = CString::new("foo bar\0").unwrap_err();
1001 /// assert_eq!(nul_error.nul_position(), 7);
1003 #[stable(feature = "rust1", since = "1.0.0")]
1004 pub fn nul_position(&self) -> usize {
1008 /// Consumes this error, returning the underlying vector of bytes which
1009 /// generated the error in the first place.
1014 /// use std::ffi::CString;
1016 /// let nul_error = CString::new("foo\0bar").unwrap_err();
1017 /// assert_eq!(nul_error.into_vec(), b"foo\0bar");
1019 #[stable(feature = "rust1", since = "1.0.0")]
1020 pub fn into_vec(self) -> Vec<u8> {
1025 #[stable(feature = "rust1", since = "1.0.0")]
1026 impl Error for NulError {
1027 #[allow(deprecated)]
1028 fn description(&self) -> &str {
1029 "nul byte found in data"
1033 #[stable(feature = "rust1", since = "1.0.0")]
1034 impl fmt::Display for NulError {
1035 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1036 write!(f, "nul byte found in provided data at position: {}", self.0)
1040 #[stable(feature = "rust1", since = "1.0.0")]
1041 impl From<NulError> for io::Error {
1042 /// Converts a [`NulError`] into a [`io::Error`].
1043 fn from(_: NulError) -> io::Error {
1044 io::Error::new_const(io::ErrorKind::InvalidInput, &"data provided contains a nul byte")
1048 #[stable(feature = "frombyteswithnulerror_impls", since = "1.17.0")]
1049 impl Error for FromBytesWithNulError {
1050 #[allow(deprecated)]
1051 fn description(&self) -> &str {
1053 FromBytesWithNulErrorKind::InteriorNul(..) => {
1054 "data provided contains an interior nul byte"
1056 FromBytesWithNulErrorKind::NotNulTerminated => "data provided is not nul terminated",
1061 #[stable(feature = "frombyteswithnulerror_impls", since = "1.17.0")]
1062 impl fmt::Display for FromBytesWithNulError {
1063 #[allow(deprecated, deprecated_in_future)]
1064 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1065 f.write_str(self.description())?;
1066 if let FromBytesWithNulErrorKind::InteriorNul(pos) = self.kind {
1067 write!(f, " at byte pos {}", pos)?;
1073 #[unstable(feature = "cstring_from_vec_with_nul", issue = "73179")]
1074 impl Error for FromVecWithNulError {}
1076 #[unstable(feature = "cstring_from_vec_with_nul", issue = "73179")]
1077 impl fmt::Display for FromVecWithNulError {
1078 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1079 match self.error_kind {
1080 FromBytesWithNulErrorKind::InteriorNul(pos) => {
1081 write!(f, "data provided contains an interior nul byte at pos {}", pos)
1083 FromBytesWithNulErrorKind::NotNulTerminated => {
1084 write!(f, "data provided is not nul terminated")
1090 impl IntoStringError {
1091 /// Consumes this error, returning original [`CString`] which generated the
1093 #[stable(feature = "cstring_into", since = "1.7.0")]
1094 pub fn into_cstring(self) -> CString {
1098 /// Access the underlying UTF-8 error that was the cause of this error.
1099 #[stable(feature = "cstring_into", since = "1.7.0")]
1100 pub fn utf8_error(&self) -> Utf8Error {
1105 #[stable(feature = "cstring_into", since = "1.7.0")]
1106 impl Error for IntoStringError {
1107 #[allow(deprecated)]
1108 fn description(&self) -> &str {
1109 "C string contained non-utf8 bytes"
1112 fn source(&self) -> Option<&(dyn Error + 'static)> {
1117 #[stable(feature = "cstring_into", since = "1.7.0")]
1118 impl fmt::Display for IntoStringError {
1119 #[allow(deprecated, deprecated_in_future)]
1120 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1121 self.description().fmt(f)
1126 /// Wraps a raw C string with a safe C string wrapper.
1128 /// This function will wrap the provided `ptr` with a `CStr` wrapper, which
1129 /// allows inspection and interoperation of non-owned C strings. The total
1130 /// size of the raw C string must be smaller than `isize::MAX` **bytes**
1131 /// in memory due to calling the `slice::from_raw_parts` function.
1132 /// This method is unsafe for a number of reasons:
1134 /// * There is no guarantee to the validity of `ptr`.
1135 /// * The returned lifetime is not guaranteed to be the actual lifetime of
1137 /// * There is no guarantee that the memory pointed to by `ptr` contains a
1138 /// valid nul terminator byte at the end of the string.
1139 /// * It is not guaranteed that the memory pointed by `ptr` won't change
1140 /// before the `CStr` has been destroyed.
1142 /// > **Note**: This operation is intended to be a 0-cost cast but it is
1143 /// > currently implemented with an up-front calculation of the length of
1144 /// > the string. This is not guaranteed to always be the case.
1148 /// ```ignore (extern-declaration)
1150 /// use std::ffi::CStr;
1151 /// use std::os::raw::c_char;
1154 /// fn my_string() -> *const c_char;
1158 /// let slice = CStr::from_ptr(my_string());
1159 /// println!("string returned: {}", slice.to_str().unwrap());
1163 #[stable(feature = "rust1", since = "1.0.0")]
1164 pub unsafe fn from_ptr<'a>(ptr: *const c_char) -> &'a CStr {
1165 // SAFETY: The caller has provided a pointer that points to a valid C
1166 // string with a NUL terminator of size less than `isize::MAX`, whose
1167 // content remain valid and doesn't change for the lifetime of the
1170 // Thus computing the length is fine (a NUL byte exists), the call to
1171 // from_raw_parts is safe because we know the length is at most `isize::MAX`, meaning
1172 // the call to `from_bytes_with_nul_unchecked` is correct.
1174 // The cast from c_char to u8 is ok because a c_char is always one byte.
1176 let len = sys::strlen(ptr);
1177 let ptr = ptr as *const u8;
1178 CStr::from_bytes_with_nul_unchecked(slice::from_raw_parts(ptr, len as usize + 1))
1182 /// Creates a C string wrapper from a byte slice.
1184 /// This function will cast the provided `bytes` to a `CStr`
1185 /// wrapper after ensuring that the byte slice is nul-terminated
1186 /// and does not contain any interior nul bytes.
1191 /// use std::ffi::CStr;
1193 /// let cstr = CStr::from_bytes_with_nul(b"hello\0");
1194 /// assert!(cstr.is_ok());
1197 /// Creating a `CStr` without a trailing nul terminator is an error:
1200 /// use std::ffi::CStr;
1202 /// let cstr = CStr::from_bytes_with_nul(b"hello");
1203 /// assert!(cstr.is_err());
1206 /// Creating a `CStr` with an interior nul byte is an error:
1209 /// use std::ffi::CStr;
1211 /// let cstr = CStr::from_bytes_with_nul(b"he\0llo\0");
1212 /// assert!(cstr.is_err());
1214 #[stable(feature = "cstr_from_bytes", since = "1.10.0")]
1215 pub fn from_bytes_with_nul(bytes: &[u8]) -> Result<&CStr, FromBytesWithNulError> {
1216 let nul_pos = memchr::memchr(0, bytes);
1217 if let Some(nul_pos) = nul_pos {
1218 if nul_pos + 1 != bytes.len() {
1219 return Err(FromBytesWithNulError::interior_nul(nul_pos));
1221 Ok(unsafe { CStr::from_bytes_with_nul_unchecked(bytes) })
1223 Err(FromBytesWithNulError::not_nul_terminated())
1227 /// Unsafely creates a C string wrapper from a byte slice.
1229 /// This function will cast the provided `bytes` to a `CStr` wrapper without
1230 /// performing any sanity checks. The provided slice **must** be nul-terminated
1231 /// and not contain any interior nul bytes.
1236 /// use std::ffi::{CStr, CString};
1239 /// let cstring = CString::new("hello").expect("CString::new failed");
1240 /// let cstr = CStr::from_bytes_with_nul_unchecked(cstring.to_bytes_with_nul());
1241 /// assert_eq!(cstr, &*cstring);
1245 #[stable(feature = "cstr_from_bytes", since = "1.10.0")]
1246 #[rustc_const_unstable(feature = "const_cstr_unchecked", issue = "none")]
1247 pub const unsafe fn from_bytes_with_nul_unchecked(bytes: &[u8]) -> &CStr {
1248 // SAFETY: Casting to CStr is safe because its internal representation
1249 // is a [u8] too (safe only inside std).
1250 // Dereferencing the obtained pointer is safe because it comes from a
1251 // reference. Making a reference is then safe because its lifetime
1252 // is bound by the lifetime of the given `bytes`.
1253 unsafe { &*(bytes as *const [u8] as *const CStr) }
1256 /// Returns the inner pointer to this C string.
1258 /// The returned pointer will be valid for as long as `self` is, and points
1259 /// to a contiguous region of memory terminated with a 0 byte to represent
1260 /// the end of the string.
1264 /// The returned pointer is read-only; writing to it (including passing it
1265 /// to C code that writes to it) causes undefined behavior.
1267 /// It is your responsibility to make sure that the underlying memory is not
1268 /// freed too early. For example, the following code will cause undefined
1269 /// behavior when `ptr` is used inside the `unsafe` block:
1272 /// # #![allow(unused_must_use)] #![allow(temporary_cstring_as_ptr)]
1273 /// use std::ffi::CString;
1275 /// let ptr = CString::new("Hello").expect("CString::new failed").as_ptr();
1277 /// // `ptr` is dangling
1282 /// This happens because the pointer returned by `as_ptr` does not carry any
1283 /// lifetime information and the [`CString`] is deallocated immediately after
1284 /// the `CString::new("Hello").expect("CString::new failed").as_ptr()`
1285 /// expression is evaluated.
1286 /// To fix the problem, bind the `CString` to a local variable:
1289 /// # #![allow(unused_must_use)]
1290 /// use std::ffi::CString;
1292 /// let hello = CString::new("Hello").expect("CString::new failed");
1293 /// let ptr = hello.as_ptr();
1295 /// // `ptr` is valid because `hello` is in scope
1300 /// This way, the lifetime of the [`CString`] in `hello` encompasses
1301 /// the lifetime of `ptr` and the `unsafe` block.
1303 #[stable(feature = "rust1", since = "1.0.0")]
1304 #[rustc_const_stable(feature = "const_str_as_ptr", since = "1.32.0")]
1305 pub const fn as_ptr(&self) -> *const c_char {
1309 /// Converts this C string to a byte slice.
1311 /// The returned slice will **not** contain the trailing nul terminator that this C
1314 /// > **Note**: This method is currently implemented as a constant-time
1315 /// > cast, but it is planned to alter its definition in the future to
1316 /// > perform the length calculation whenever this method is called.
1321 /// use std::ffi::CStr;
1323 /// let cstr = CStr::from_bytes_with_nul(b"foo\0").expect("CStr::from_bytes_with_nul failed");
1324 /// assert_eq!(cstr.to_bytes(), b"foo");
1327 #[stable(feature = "rust1", since = "1.0.0")]
1328 pub fn to_bytes(&self) -> &[u8] {
1329 let bytes = self.to_bytes_with_nul();
1330 // SAFETY: to_bytes_with_nul returns slice with length at least 1
1331 unsafe { bytes.get_unchecked(..bytes.len() - 1) }
1334 /// Converts this C string to a byte slice containing the trailing 0 byte.
1336 /// This function is the equivalent of [`CStr::to_bytes`] except that it
1337 /// will retain the trailing nul terminator instead of chopping it off.
1339 /// > **Note**: This method is currently implemented as a 0-cost cast, but
1340 /// > it is planned to alter its definition in the future to perform the
1341 /// > length calculation whenever this method is called.
1346 /// use std::ffi::CStr;
1348 /// let cstr = CStr::from_bytes_with_nul(b"foo\0").expect("CStr::from_bytes_with_nul failed");
1349 /// assert_eq!(cstr.to_bytes_with_nul(), b"foo\0");
1352 #[stable(feature = "rust1", since = "1.0.0")]
1353 pub fn to_bytes_with_nul(&self) -> &[u8] {
1354 unsafe { &*(&self.inner as *const [c_char] as *const [u8]) }
1357 /// Yields a <code>&[str]</code> slice if the `CStr` contains valid UTF-8.
1359 /// If the contents of the `CStr` are valid UTF-8 data, this
1360 /// function will return the corresponding <code>&[str]</code> slice. Otherwise,
1361 /// it will return an error with details of where UTF-8 validation failed.
1363 /// [str]: prim@str "str"
1368 /// use std::ffi::CStr;
1370 /// let cstr = CStr::from_bytes_with_nul(b"foo\0").expect("CStr::from_bytes_with_nul failed");
1371 /// assert_eq!(cstr.to_str(), Ok("foo"));
1373 #[stable(feature = "cstr_to_str", since = "1.4.0")]
1374 pub fn to_str(&self) -> Result<&str, str::Utf8Error> {
1375 // N.B., when `CStr` is changed to perform the length check in `.to_bytes()`
1376 // instead of in `from_ptr()`, it may be worth considering if this should
1377 // be rewritten to do the UTF-8 check inline with the length calculation
1378 // instead of doing it afterwards.
1379 str::from_utf8(self.to_bytes())
1382 /// Converts a `CStr` into a <code>[Cow]<[str]></code>.
1384 /// If the contents of the `CStr` are valid UTF-8 data, this
1385 /// function will return a <code>[Cow]::[Borrowed]\(&[str])</code>
1386 /// with the corresponding <code>&[str]</code> slice. Otherwise, it will
1387 /// replace any invalid UTF-8 sequences with
1388 /// [`U+FFFD REPLACEMENT CHARACTER`][U+FFFD] and return a
1389 /// <code>[Cow]::[Owned]\(&[str])</code> with the result.
1391 /// [str]: prim@str "str"
1392 /// [Borrowed]: Cow::Borrowed
1393 /// [Owned]: Cow::Owned
1394 /// [U+FFFD]: crate::char::REPLACEMENT_CHARACTER "std::char::REPLACEMENT_CHARACTER"
1398 /// Calling `to_string_lossy` on a `CStr` containing valid UTF-8:
1401 /// use std::borrow::Cow;
1402 /// use std::ffi::CStr;
1404 /// let cstr = CStr::from_bytes_with_nul(b"Hello World\0")
1405 /// .expect("CStr::from_bytes_with_nul failed");
1406 /// assert_eq!(cstr.to_string_lossy(), Cow::Borrowed("Hello World"));
1409 /// Calling `to_string_lossy` on a `CStr` containing invalid UTF-8:
1412 /// use std::borrow::Cow;
1413 /// use std::ffi::CStr;
1415 /// let cstr = CStr::from_bytes_with_nul(b"Hello \xF0\x90\x80World\0")
1416 /// .expect("CStr::from_bytes_with_nul failed");
1418 /// cstr.to_string_lossy(),
1419 /// Cow::Owned(String::from("Hello �World")) as Cow<'_, str>
1422 #[stable(feature = "cstr_to_str", since = "1.4.0")]
1423 pub fn to_string_lossy(&self) -> Cow<'_, str> {
1424 String::from_utf8_lossy(self.to_bytes())
1427 /// Converts a <code>[Box]<[CStr]></code> into a [`CString`] without copying or allocating.
1432 /// use std::ffi::CString;
1434 /// let c_string = CString::new(b"foo".to_vec()).expect("CString::new failed");
1435 /// let boxed = c_string.into_boxed_c_str();
1436 /// assert_eq!(boxed.into_c_string(), CString::new("foo").expect("CString::new failed"));
1438 #[stable(feature = "into_boxed_c_str", since = "1.20.0")]
1439 pub fn into_c_string(self: Box<CStr>) -> CString {
1440 let raw = Box::into_raw(self) as *mut [u8];
1441 CString { inner: unsafe { Box::from_raw(raw) } }
1445 #[stable(feature = "rust1", since = "1.0.0")]
1446 impl PartialEq for CStr {
1447 fn eq(&self, other: &CStr) -> bool {
1448 self.to_bytes().eq(other.to_bytes())
1451 #[stable(feature = "rust1", since = "1.0.0")]
1453 #[stable(feature = "rust1", since = "1.0.0")]
1454 impl PartialOrd for CStr {
1455 fn partial_cmp(&self, other: &CStr) -> Option<Ordering> {
1456 self.to_bytes().partial_cmp(&other.to_bytes())
1459 #[stable(feature = "rust1", since = "1.0.0")]
1461 fn cmp(&self, other: &CStr) -> Ordering {
1462 self.to_bytes().cmp(&other.to_bytes())
1466 #[stable(feature = "cstr_borrow", since = "1.3.0")]
1467 impl ToOwned for CStr {
1468 type Owned = CString;
1470 fn to_owned(&self) -> CString {
1471 CString { inner: self.to_bytes_with_nul().into() }
1474 fn clone_into(&self, target: &mut CString) {
1475 let mut b = Vec::from(mem::take(&mut target.inner));
1476 self.to_bytes_with_nul().clone_into(&mut b);
1477 target.inner = b.into_boxed_slice();
1481 #[stable(feature = "cstring_asref", since = "1.7.0")]
1482 impl From<&CStr> for CString {
1483 fn from(s: &CStr) -> CString {
1488 #[stable(feature = "cstring_asref", since = "1.7.0")]
1489 impl ops::Index<ops::RangeFull> for CString {
1493 fn index(&self, _index: ops::RangeFull) -> &CStr {
1498 #[stable(feature = "cstr_range_from", since = "1.47.0")]
1499 impl ops::Index<ops::RangeFrom<usize>> for CStr {
1502 fn index(&self, index: ops::RangeFrom<usize>) -> &CStr {
1503 let bytes = self.to_bytes_with_nul();
1504 // we need to manually check the starting index to account for the null
1505 // byte, since otherwise we could get an empty string that doesn't end
1507 if index.start < bytes.len() {
1508 unsafe { CStr::from_bytes_with_nul_unchecked(&bytes[index.start..]) }
1511 "index out of bounds: the len is {} but the index is {}",
1519 #[stable(feature = "cstring_asref", since = "1.7.0")]
1520 impl AsRef<CStr> for CStr {
1522 fn as_ref(&self) -> &CStr {
1527 #[stable(feature = "cstring_asref", since = "1.7.0")]
1528 impl AsRef<CStr> for CString {
1530 fn as_ref(&self) -> &CStr {