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 /// use std::ffi::{CString, FromVecWithNulError};
256 /// let _: FromVecWithNulError = CString::from_vec_with_nul(b"f\0oo".to_vec()).unwrap_err();
258 #[derive(Clone, PartialEq, Eq, Debug)]
259 #[stable(feature = "cstring_from_vec_with_nul", since = "1.58.0")]
260 pub struct FromVecWithNulError {
261 error_kind: FromBytesWithNulErrorKind,
265 #[derive(Clone, PartialEq, Eq, Debug)]
266 enum FromBytesWithNulErrorKind {
271 impl FromBytesWithNulError {
272 fn interior_nul(pos: usize) -> FromBytesWithNulError {
273 FromBytesWithNulError { kind: FromBytesWithNulErrorKind::InteriorNul(pos) }
275 fn not_nul_terminated() -> FromBytesWithNulError {
276 FromBytesWithNulError { kind: FromBytesWithNulErrorKind::NotNulTerminated }
280 #[stable(feature = "cstring_from_vec_with_nul", since = "1.58.0")]
281 impl FromVecWithNulError {
282 /// Returns a slice of [`u8`]s bytes that were attempted to convert to a [`CString`].
289 /// use std::ffi::CString;
291 /// // Some invalid bytes in a vector
292 /// let bytes = b"f\0oo".to_vec();
294 /// let value = CString::from_vec_with_nul(bytes.clone());
296 /// assert_eq!(&bytes[..], value.unwrap_err().as_bytes());
299 #[stable(feature = "cstring_from_vec_with_nul", since = "1.58.0")]
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 /// use std::ffi::CString;
317 /// // Some invalid bytes in a vector
318 /// let bytes = b"f\0oo".to_vec();
320 /// let value = CString::from_vec_with_nul(bytes.clone());
322 /// assert_eq!(bytes, value.unwrap_err().into_bytes());
324 #[must_use = "`self` will be dropped if the result is not used"]
325 #[stable(feature = "cstring_from_vec_with_nul", since = "1.58.0")]
326 pub fn into_bytes(self) -> Vec<u8> {
331 /// An error indicating invalid UTF-8 when converting a [`CString`] into a [`String`].
333 /// `CString` is just a wrapper over a buffer of bytes with a nul terminator;
334 /// [`CString::into_string`] performs UTF-8 validation on those bytes and may
335 /// return this error.
337 /// This `struct` is created by [`CString::into_string()`]. See
338 /// its documentation for more.
339 #[derive(Clone, PartialEq, Eq, Debug)]
340 #[stable(feature = "cstring_into", since = "1.7.0")]
341 pub struct IntoStringError {
347 /// Creates a new C-compatible string from a container of bytes.
349 /// This function will consume the provided data and use the
350 /// underlying bytes to construct a new string, ensuring that
351 /// there is a trailing 0 byte. This trailing 0 byte will be
352 /// appended by this function; the provided data should *not*
353 /// contain any 0 bytes in it.
357 /// ```ignore (extern-declaration)
358 /// use std::ffi::CString;
359 /// use std::os::raw::c_char;
361 /// extern "C" { fn puts(s: *const c_char); }
363 /// let to_print = CString::new("Hello!").expect("CString::new failed");
365 /// puts(to_print.as_ptr());
371 /// This function will return an error if the supplied bytes contain an
372 /// internal 0 byte. The [`NulError`] returned will contain the bytes as well as
373 /// the position of the nul byte.
374 #[stable(feature = "rust1", since = "1.0.0")]
375 pub fn new<T: Into<Vec<u8>>>(t: T) -> Result<CString, NulError> {
377 fn into_vec(self) -> Vec<u8>;
379 impl<T: Into<Vec<u8>>> SpecIntoVec for T {
380 default fn into_vec(self) -> Vec<u8> {
384 // Specialization for avoiding reallocation.
385 impl SpecIntoVec for &'_ [u8] {
386 fn into_vec(self) -> Vec<u8> {
387 let mut v = Vec::with_capacity(self.len() + 1);
392 impl SpecIntoVec for &'_ str {
393 fn into_vec(self) -> Vec<u8> {
394 let mut v = Vec::with_capacity(self.len() + 1);
395 v.extend(self.as_bytes());
400 Self::_new(SpecIntoVec::into_vec(t))
403 fn _new(bytes: Vec<u8>) -> Result<CString, NulError> {
404 match memchr::memchr(0, &bytes) {
405 Some(i) => Err(NulError(i, bytes)),
406 None => Ok(unsafe { CString::from_vec_unchecked(bytes) }),
410 /// Creates a C-compatible string by consuming a byte vector,
411 /// without checking for interior 0 bytes.
413 /// Trailing 0 byte will be appended by this function.
415 /// This method is equivalent to [`CString::new`] except that no runtime
416 /// assertion is made that `v` contains no 0 bytes, and it requires an
417 /// actual byte vector, not anything that can be converted to one with Into.
422 /// use std::ffi::CString;
424 /// let raw = b"foo".to_vec();
426 /// let c_string = CString::from_vec_unchecked(raw);
430 #[stable(feature = "rust1", since = "1.0.0")]
431 pub unsafe fn from_vec_unchecked(mut v: Vec<u8>) -> CString {
434 CString { inner: v.into_boxed_slice() }
437 /// Retakes ownership of a `CString` that was transferred to C via
438 /// [`CString::into_raw`].
440 /// Additionally, the length of the string will be recalculated from the pointer.
444 /// This should only ever be called with a pointer that was earlier
445 /// obtained by calling [`CString::into_raw`]. Other usage (e.g., trying to take
446 /// ownership of a string that was allocated by foreign code) is likely to lead
447 /// to undefined behavior or allocator corruption.
449 /// It should be noted that the length isn't just "recomputed," but that
450 /// the recomputed length must match the original length from the
451 /// [`CString::into_raw`] call. This means the [`CString::into_raw`]/`from_raw`
452 /// methods should not be used when passing the string to C functions that can
453 /// modify the string's length.
455 /// > **Note:** If you need to borrow a string that was allocated by
456 /// > foreign code, use [`CStr`]. If you need to take ownership of
457 /// > a string that was allocated by foreign code, you will need to
458 /// > make your own provisions for freeing it appropriately, likely
459 /// > with the foreign code's API to do that.
463 /// Creates a `CString`, pass ownership to an `extern` function (via raw pointer), then retake
464 /// ownership with `from_raw`:
466 /// ```ignore (extern-declaration)
467 /// use std::ffi::CString;
468 /// use std::os::raw::c_char;
471 /// fn some_extern_function(s: *mut c_char);
474 /// let c_string = CString::new("Hello!").expect("CString::new failed");
475 /// let raw = c_string.into_raw();
477 /// some_extern_function(raw);
478 /// let c_string = CString::from_raw(raw);
481 #[must_use = "call `drop(from_raw(ptr))` if you intend to drop the `CString`"]
482 #[stable(feature = "cstr_memory", since = "1.4.0")]
483 pub unsafe fn from_raw(ptr: *mut c_char) -> CString {
484 // SAFETY: This is called with a pointer that was obtained from a call
485 // to `CString::into_raw` and the length has not been modified. As such,
486 // we know there is a NUL byte (and only one) at the end and that the
487 // information about the size of the allocation is correct on Rust's
490 let len = sys::strlen(ptr) + 1; // Including the NUL byte
491 let slice = slice::from_raw_parts_mut(ptr, len as usize);
492 CString { inner: Box::from_raw(slice as *mut [c_char] as *mut [u8]) }
496 /// Consumes the `CString` and transfers ownership of the string to a C caller.
498 /// The pointer which this function returns must be returned to Rust and reconstituted using
499 /// [`CString::from_raw`] to be properly deallocated. Specifically, one
500 /// should *not* use the standard C `free()` function to deallocate
503 /// Failure to call [`CString::from_raw`] will lead to a memory leak.
505 /// The C side must **not** modify the length of the string (by writing a
506 /// `null` somewhere inside the string or removing the final one) before
507 /// it makes it back into Rust using [`CString::from_raw`]. See the safety section
508 /// in [`CString::from_raw`].
513 /// use std::ffi::CString;
515 /// let c_string = CString::new("foo").expect("CString::new failed");
517 /// let ptr = c_string.into_raw();
520 /// assert_eq!(b'f', *ptr as u8);
521 /// assert_eq!(b'o', *ptr.offset(1) as u8);
522 /// assert_eq!(b'o', *ptr.offset(2) as u8);
523 /// assert_eq!(b'\0', *ptr.offset(3) as u8);
525 /// // retake pointer to free memory
526 /// let _ = CString::from_raw(ptr);
530 #[must_use = "`self` will be dropped if the result is not used"]
531 #[stable(feature = "cstr_memory", since = "1.4.0")]
532 pub fn into_raw(self) -> *mut c_char {
533 Box::into_raw(self.into_inner()) as *mut c_char
536 /// Converts the `CString` into a [`String`] if it contains valid UTF-8 data.
538 /// On failure, ownership of the original `CString` is returned.
543 /// use std::ffi::CString;
545 /// let valid_utf8 = vec![b'f', b'o', b'o'];
546 /// let cstring = CString::new(valid_utf8).expect("CString::new failed");
547 /// assert_eq!(cstring.into_string().expect("into_string() call failed"), "foo");
549 /// let invalid_utf8 = vec![b'f', 0xff, b'o', b'o'];
550 /// let cstring = CString::new(invalid_utf8).expect("CString::new failed");
551 /// let err = cstring.into_string().err().expect("into_string().err() failed");
552 /// assert_eq!(err.utf8_error().valid_up_to(), 1);
554 #[stable(feature = "cstring_into", since = "1.7.0")]
555 pub fn into_string(self) -> Result<String, IntoStringError> {
556 String::from_utf8(self.into_bytes()).map_err(|e| IntoStringError {
557 error: e.utf8_error(),
558 inner: unsafe { CString::from_vec_unchecked(e.into_bytes()) },
562 /// Consumes the `CString` and returns the underlying byte buffer.
564 /// The returned buffer does **not** contain the trailing nul
565 /// terminator, and it is guaranteed to not have any interior nul
571 /// use std::ffi::CString;
573 /// let c_string = CString::new("foo").expect("CString::new failed");
574 /// let bytes = c_string.into_bytes();
575 /// assert_eq!(bytes, vec![b'f', b'o', b'o']);
577 #[must_use = "`self` will be dropped if the result is not used"]
578 #[stable(feature = "cstring_into", since = "1.7.0")]
579 pub fn into_bytes(self) -> Vec<u8> {
580 let mut vec = self.into_inner().into_vec();
581 let _nul = vec.pop();
582 debug_assert_eq!(_nul, Some(0u8));
586 /// Equivalent to [`CString::into_bytes()`] except that the
587 /// returned vector includes the trailing nul terminator.
592 /// use std::ffi::CString;
594 /// let c_string = CString::new("foo").expect("CString::new failed");
595 /// let bytes = c_string.into_bytes_with_nul();
596 /// assert_eq!(bytes, vec![b'f', b'o', b'o', b'\0']);
598 #[must_use = "`self` will be dropped if the result is not used"]
599 #[stable(feature = "cstring_into", since = "1.7.0")]
600 pub fn into_bytes_with_nul(self) -> Vec<u8> {
601 self.into_inner().into_vec()
604 /// Returns the contents of this `CString` as a slice of bytes.
606 /// The returned slice does **not** contain the trailing nul
607 /// terminator, and it is guaranteed to not have any interior nul
608 /// bytes. If you need the nul terminator, use
609 /// [`CString::as_bytes_with_nul`] instead.
614 /// use std::ffi::CString;
616 /// let c_string = CString::new("foo").expect("CString::new failed");
617 /// let bytes = c_string.as_bytes();
618 /// assert_eq!(bytes, &[b'f', b'o', b'o']);
622 #[stable(feature = "rust1", since = "1.0.0")]
623 pub fn as_bytes(&self) -> &[u8] {
624 // SAFETY: CString has a length at least 1
625 unsafe { self.inner.get_unchecked(..self.inner.len() - 1) }
628 /// Equivalent to [`CString::as_bytes()`] except that the
629 /// returned slice includes the trailing nul terminator.
634 /// use std::ffi::CString;
636 /// let c_string = CString::new("foo").expect("CString::new failed");
637 /// let bytes = c_string.as_bytes_with_nul();
638 /// assert_eq!(bytes, &[b'f', b'o', b'o', b'\0']);
642 #[stable(feature = "rust1", since = "1.0.0")]
643 pub fn as_bytes_with_nul(&self) -> &[u8] {
647 /// Extracts a [`CStr`] slice containing the entire string.
652 /// use std::ffi::{CString, CStr};
654 /// let c_string = CString::new(b"foo".to_vec()).expect("CString::new failed");
655 /// let cstr = c_string.as_c_str();
657 /// CStr::from_bytes_with_nul(b"foo\0").expect("CStr::from_bytes_with_nul failed"));
661 #[stable(feature = "as_c_str", since = "1.20.0")]
662 pub fn as_c_str(&self) -> &CStr {
666 /// Converts this `CString` into a boxed [`CStr`].
671 /// use std::ffi::{CString, CStr};
673 /// let c_string = CString::new(b"foo".to_vec()).expect("CString::new failed");
674 /// let boxed = c_string.into_boxed_c_str();
675 /// assert_eq!(&*boxed,
676 /// CStr::from_bytes_with_nul(b"foo\0").expect("CStr::from_bytes_with_nul failed"));
678 #[must_use = "`self` will be dropped if the result is not used"]
679 #[stable(feature = "into_boxed_c_str", since = "1.20.0")]
680 pub fn into_boxed_c_str(self) -> Box<CStr> {
681 unsafe { Box::from_raw(Box::into_raw(self.into_inner()) as *mut CStr) }
684 /// Bypass "move out of struct which implements [`Drop`] trait" restriction.
686 fn into_inner(self) -> Box<[u8]> {
687 // Rationale: `mem::forget(self)` invalidates the previous call to `ptr::read(&self.inner)`
688 // so we use `ManuallyDrop` to ensure `self` is not dropped.
689 // Then we can return the box directly without invalidating it.
690 // See https://github.com/rust-lang/rust/issues/62553.
691 let this = mem::ManuallyDrop::new(self);
692 unsafe { ptr::read(&this.inner) }
695 /// Converts a <code>[Vec]<[u8]></code> to a [`CString`] without checking the
696 /// invariants on the given [`Vec`].
700 /// The given [`Vec`] **must** have one nul byte as its last element.
701 /// This means it cannot be empty nor have any other nul byte anywhere else.
706 /// use std::ffi::CString;
708 /// unsafe { CString::from_vec_with_nul_unchecked(b"abc\0".to_vec()) },
709 /// unsafe { CString::from_vec_unchecked(b"abc".to_vec()) }
713 #[stable(feature = "cstring_from_vec_with_nul", since = "1.58.0")]
714 pub unsafe fn from_vec_with_nul_unchecked(v: Vec<u8>) -> Self {
715 Self { inner: v.into_boxed_slice() }
718 /// Attempts to converts a <code>[Vec]<[u8]></code> to a [`CString`].
720 /// Runtime checks are present to ensure there is only one nul byte in the
721 /// [`Vec`], its last element.
725 /// If a nul byte is present and not the last element or no nul bytes
726 /// is present, an error will be returned.
730 /// A successful conversion will produce the same result as [`CString::new`]
731 /// when called without the ending nul byte.
734 /// use std::ffi::CString;
736 /// CString::from_vec_with_nul(b"abc\0".to_vec())
737 /// .expect("CString::from_vec_with_nul failed"),
738 /// CString::new(b"abc".to_vec()).expect("CString::new failed")
742 /// An incorrectly formatted [`Vec`] will produce an error.
745 /// use std::ffi::{CString, FromVecWithNulError};
746 /// // Interior nul byte
747 /// let _: FromVecWithNulError = CString::from_vec_with_nul(b"a\0bc".to_vec()).unwrap_err();
749 /// let _: FromVecWithNulError = CString::from_vec_with_nul(b"abc".to_vec()).unwrap_err();
751 #[stable(feature = "cstring_from_vec_with_nul", since = "1.58.0")]
752 pub fn from_vec_with_nul(v: Vec<u8>) -> Result<Self, FromVecWithNulError> {
753 let nul_pos = memchr::memchr(0, &v);
755 Some(nul_pos) if nul_pos + 1 == v.len() => {
756 // SAFETY: We know there is only one nul byte, at the end
758 Ok(unsafe { Self::from_vec_with_nul_unchecked(v) })
760 Some(nul_pos) => Err(FromVecWithNulError {
761 error_kind: FromBytesWithNulErrorKind::InteriorNul(nul_pos),
764 None => Err(FromVecWithNulError {
765 error_kind: FromBytesWithNulErrorKind::NotNulTerminated,
772 // Turns this `CString` into an empty string to prevent
773 // memory-unsafe code from working by accident. Inline
774 // to prevent LLVM from optimizing it away in debug builds.
775 #[stable(feature = "cstring_drop", since = "1.13.0")]
776 impl Drop for CString {
780 *self.inner.get_unchecked_mut(0) = 0;
785 #[stable(feature = "rust1", since = "1.0.0")]
786 impl ops::Deref for CString {
790 fn deref(&self) -> &CStr {
791 unsafe { CStr::from_bytes_with_nul_unchecked(self.as_bytes_with_nul()) }
795 #[stable(feature = "rust1", since = "1.0.0")]
796 impl fmt::Debug for CString {
797 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
798 fmt::Debug::fmt(&**self, f)
802 #[stable(feature = "cstring_into", since = "1.7.0")]
803 impl From<CString> for Vec<u8> {
804 /// Converts a [`CString`] into a <code>[Vec]<[u8]></code>.
806 /// The conversion consumes the [`CString`], and removes the terminating NUL byte.
808 fn from(s: CString) -> Vec<u8> {
813 #[stable(feature = "cstr_debug", since = "1.3.0")]
814 impl fmt::Debug for CStr {
815 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
817 for byte in self.to_bytes().iter().flat_map(|&b| ascii::escape_default(b)) {
818 f.write_char(byte as char)?;
824 #[stable(feature = "cstr_default", since = "1.10.0")]
825 impl Default for &CStr {
826 fn default() -> Self {
827 const SLICE: &[c_char] = &[0];
828 unsafe { CStr::from_ptr(SLICE.as_ptr()) }
832 #[stable(feature = "cstr_default", since = "1.10.0")]
833 impl Default for CString {
834 /// Creates an empty `CString`.
835 fn default() -> CString {
836 let a: &CStr = Default::default();
841 #[stable(feature = "cstr_borrow", since = "1.3.0")]
842 impl Borrow<CStr> for CString {
844 fn borrow(&self) -> &CStr {
849 #[stable(feature = "cstring_from_cow_cstr", since = "1.28.0")]
850 impl<'a> From<Cow<'a, CStr>> for CString {
852 fn from(s: Cow<'a, CStr>) -> Self {
857 #[stable(feature = "box_from_c_str", since = "1.17.0")]
858 impl From<&CStr> for Box<CStr> {
859 fn from(s: &CStr) -> Box<CStr> {
860 let boxed: Box<[u8]> = Box::from(s.to_bytes_with_nul());
861 unsafe { Box::from_raw(Box::into_raw(boxed) as *mut CStr) }
865 #[stable(feature = "box_from_cow", since = "1.45.0")]
866 impl From<Cow<'_, CStr>> for Box<CStr> {
868 fn from(cow: Cow<'_, CStr>) -> Box<CStr> {
870 Cow::Borrowed(s) => Box::from(s),
871 Cow::Owned(s) => Box::from(s),
876 #[stable(feature = "c_string_from_box", since = "1.18.0")]
877 impl From<Box<CStr>> for CString {
878 /// Converts a <code>[Box]<[CStr]></code> into a [`CString`] without copying or allocating.
880 fn from(s: Box<CStr>) -> CString {
885 #[stable(feature = "cstring_from_vec_of_nonzerou8", since = "1.43.0")]
886 impl From<Vec<NonZeroU8>> for CString {
887 /// Converts a <code>[Vec]<[NonZeroU8]></code> into a [`CString`] without
888 /// copying nor checking for inner null bytes.
890 fn from(v: Vec<NonZeroU8>) -> CString {
892 // Transmute `Vec<NonZeroU8>` to `Vec<u8>`.
895 // - transmuting between `NonZeroU8` and `u8` is sound;
896 // - `alloc::Layout<NonZeroU8> == alloc::Layout<u8>`.
897 let (ptr, len, cap): (*mut NonZeroU8, _, _) = Vec::into_raw_parts(v);
898 Vec::from_raw_parts(ptr.cast::<u8>(), len, cap)
900 // SAFETY: `v` cannot contain null bytes, given the type-level
901 // invariant of `NonZeroU8`.
902 CString::from_vec_unchecked(v)
907 #[stable(feature = "more_box_slice_clone", since = "1.29.0")]
908 impl Clone for Box<CStr> {
910 fn clone(&self) -> Self {
915 #[stable(feature = "box_from_c_string", since = "1.20.0")]
916 impl From<CString> for Box<CStr> {
917 /// Converts a [`CString`] into a <code>[Box]<[CStr]></code> without copying or allocating.
919 fn from(s: CString) -> Box<CStr> {
924 #[stable(feature = "cow_from_cstr", since = "1.28.0")]
925 impl<'a> From<CString> for Cow<'a, CStr> {
926 /// Converts a [`CString`] into an owned [`Cow`] without copying or allocating.
928 fn from(s: CString) -> Cow<'a, CStr> {
933 #[stable(feature = "cow_from_cstr", since = "1.28.0")]
934 impl<'a> From<&'a CStr> for Cow<'a, CStr> {
935 /// Converts a [`CStr`] into a borrowed [`Cow`] without copying or allocating.
937 fn from(s: &'a CStr) -> Cow<'a, CStr> {
942 #[stable(feature = "cow_from_cstr", since = "1.28.0")]
943 impl<'a> From<&'a CString> for Cow<'a, CStr> {
944 /// Converts a `&`[`CString`] into a borrowed [`Cow`] without copying or allocating.
946 fn from(s: &'a CString) -> Cow<'a, CStr> {
947 Cow::Borrowed(s.as_c_str())
951 #[stable(feature = "shared_from_slice2", since = "1.24.0")]
952 impl From<CString> for Arc<CStr> {
953 /// Converts a [`CString`] into an <code>[Arc]<[CStr]></code> without copying or allocating.
955 fn from(s: CString) -> Arc<CStr> {
956 let arc: Arc<[u8]> = Arc::from(s.into_inner());
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<&CStr> for Arc<CStr> {
964 fn from(s: &CStr) -> Arc<CStr> {
965 let arc: Arc<[u8]> = Arc::from(s.to_bytes_with_nul());
966 unsafe { Arc::from_raw(Arc::into_raw(arc) as *const CStr) }
970 #[stable(feature = "shared_from_slice2", since = "1.24.0")]
971 impl From<CString> for Rc<CStr> {
972 /// Converts a [`CString`] into an <code>[Rc]<[CStr]></code> without copying or allocating.
974 fn from(s: CString) -> Rc<CStr> {
975 let rc: Rc<[u8]> = Rc::from(s.into_inner());
976 unsafe { Rc::from_raw(Rc::into_raw(rc) as *const CStr) }
980 #[stable(feature = "shared_from_slice2", since = "1.24.0")]
981 impl From<&CStr> for Rc<CStr> {
983 fn from(s: &CStr) -> Rc<CStr> {
984 let rc: Rc<[u8]> = Rc::from(s.to_bytes_with_nul());
985 unsafe { Rc::from_raw(Rc::into_raw(rc) as *const CStr) }
989 #[stable(feature = "default_box_extra", since = "1.17.0")]
990 impl Default for Box<CStr> {
991 fn default() -> Box<CStr> {
992 let boxed: Box<[u8]> = Box::from([0]);
993 unsafe { Box::from_raw(Box::into_raw(boxed) as *mut CStr) }
998 /// Returns the position of the nul byte in the slice that caused
999 /// [`CString::new`] to fail.
1004 /// use std::ffi::CString;
1006 /// let nul_error = CString::new("foo\0bar").unwrap_err();
1007 /// assert_eq!(nul_error.nul_position(), 3);
1009 /// let nul_error = CString::new("foo bar\0").unwrap_err();
1010 /// assert_eq!(nul_error.nul_position(), 7);
1012 #[stable(feature = "rust1", since = "1.0.0")]
1013 pub fn nul_position(&self) -> usize {
1017 /// Consumes this error, returning the underlying vector of bytes which
1018 /// generated the error in the first place.
1023 /// use std::ffi::CString;
1025 /// let nul_error = CString::new("foo\0bar").unwrap_err();
1026 /// assert_eq!(nul_error.into_vec(), b"foo\0bar");
1028 #[must_use = "`self` will be dropped if the result is not used"]
1029 #[stable(feature = "rust1", since = "1.0.0")]
1030 pub fn into_vec(self) -> Vec<u8> {
1035 #[stable(feature = "rust1", since = "1.0.0")]
1036 impl Error for NulError {
1037 #[allow(deprecated)]
1038 fn description(&self) -> &str {
1039 "nul byte found in data"
1043 #[stable(feature = "rust1", since = "1.0.0")]
1044 impl fmt::Display for NulError {
1045 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1046 write!(f, "nul byte found in provided data at position: {}", self.0)
1050 #[stable(feature = "rust1", since = "1.0.0")]
1051 impl From<NulError> for io::Error {
1052 /// Converts a [`NulError`] into a [`io::Error`].
1053 fn from(_: NulError) -> io::Error {
1054 io::Error::new_const(io::ErrorKind::InvalidInput, &"data provided contains a nul byte")
1058 #[stable(feature = "frombyteswithnulerror_impls", since = "1.17.0")]
1059 impl Error for FromBytesWithNulError {
1060 #[allow(deprecated)]
1061 fn description(&self) -> &str {
1063 FromBytesWithNulErrorKind::InteriorNul(..) => {
1064 "data provided contains an interior nul byte"
1066 FromBytesWithNulErrorKind::NotNulTerminated => "data provided is not nul terminated",
1071 #[stable(feature = "frombyteswithnulerror_impls", since = "1.17.0")]
1072 impl fmt::Display for FromBytesWithNulError {
1073 #[allow(deprecated, deprecated_in_future)]
1074 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1075 f.write_str(self.description())?;
1076 if let FromBytesWithNulErrorKind::InteriorNul(pos) = self.kind {
1077 write!(f, " at byte pos {}", pos)?;
1083 #[stable(feature = "cstring_from_vec_with_nul", since = "1.58.0")]
1084 impl Error for FromVecWithNulError {}
1086 #[stable(feature = "cstring_from_vec_with_nul", since = "1.58.0")]
1087 impl fmt::Display for FromVecWithNulError {
1088 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1089 match self.error_kind {
1090 FromBytesWithNulErrorKind::InteriorNul(pos) => {
1091 write!(f, "data provided contains an interior nul byte at pos {}", pos)
1093 FromBytesWithNulErrorKind::NotNulTerminated => {
1094 write!(f, "data provided is not nul terminated")
1100 impl IntoStringError {
1101 /// Consumes this error, returning original [`CString`] which generated the
1103 #[must_use = "`self` will be dropped if the result is not used"]
1104 #[stable(feature = "cstring_into", since = "1.7.0")]
1105 pub fn into_cstring(self) -> CString {
1109 /// Access the underlying UTF-8 error that was the cause of this error.
1110 #[stable(feature = "cstring_into", since = "1.7.0")]
1111 pub fn utf8_error(&self) -> Utf8Error {
1116 #[stable(feature = "cstring_into", since = "1.7.0")]
1117 impl Error for IntoStringError {
1118 #[allow(deprecated)]
1119 fn description(&self) -> &str {
1120 "C string contained non-utf8 bytes"
1123 fn source(&self) -> Option<&(dyn Error + 'static)> {
1128 #[stable(feature = "cstring_into", since = "1.7.0")]
1129 impl fmt::Display for IntoStringError {
1130 #[allow(deprecated, deprecated_in_future)]
1131 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1132 self.description().fmt(f)
1137 /// Wraps a raw C string with a safe C string wrapper.
1139 /// This function will wrap the provided `ptr` with a `CStr` wrapper, which
1140 /// allows inspection and interoperation of non-owned C strings. The total
1141 /// size of the raw C string must be smaller than `isize::MAX` **bytes**
1142 /// in memory due to calling the `slice::from_raw_parts` function.
1143 /// This method is unsafe for a number of reasons:
1145 /// * There is no guarantee to the validity of `ptr`.
1146 /// * The returned lifetime is not guaranteed to be the actual lifetime of
1148 /// * There is no guarantee that the memory pointed to by `ptr` contains a
1149 /// valid nul terminator byte at the end of the string.
1150 /// * It is not guaranteed that the memory pointed by `ptr` won't change
1151 /// before the `CStr` has been destroyed.
1153 /// > **Note**: This operation is intended to be a 0-cost cast but it is
1154 /// > currently implemented with an up-front calculation of the length of
1155 /// > the string. This is not guaranteed to always be the case.
1159 /// ```ignore (extern-declaration)
1161 /// use std::ffi::CStr;
1162 /// use std::os::raw::c_char;
1165 /// fn my_string() -> *const c_char;
1169 /// let slice = CStr::from_ptr(my_string());
1170 /// println!("string returned: {}", slice.to_str().unwrap());
1175 #[stable(feature = "rust1", since = "1.0.0")]
1176 pub unsafe fn from_ptr<'a>(ptr: *const c_char) -> &'a CStr {
1177 // SAFETY: The caller has provided a pointer that points to a valid C
1178 // string with a NUL terminator of size less than `isize::MAX`, whose
1179 // content remain valid and doesn't change for the lifetime of the
1182 // Thus computing the length is fine (a NUL byte exists), the call to
1183 // from_raw_parts is safe because we know the length is at most `isize::MAX`, meaning
1184 // the call to `from_bytes_with_nul_unchecked` is correct.
1186 // The cast from c_char to u8 is ok because a c_char is always one byte.
1188 let len = sys::strlen(ptr);
1189 let ptr = ptr as *const u8;
1190 CStr::from_bytes_with_nul_unchecked(slice::from_raw_parts(ptr, len as usize + 1))
1194 /// Creates a C string wrapper from a byte slice.
1196 /// This function will cast the provided `bytes` to a `CStr`
1197 /// wrapper after ensuring that the byte slice is nul-terminated
1198 /// and does not contain any interior nul bytes.
1203 /// use std::ffi::CStr;
1205 /// let cstr = CStr::from_bytes_with_nul(b"hello\0");
1206 /// assert!(cstr.is_ok());
1209 /// Creating a `CStr` without a trailing nul terminator is an error:
1212 /// use std::ffi::CStr;
1214 /// let cstr = CStr::from_bytes_with_nul(b"hello");
1215 /// assert!(cstr.is_err());
1218 /// Creating a `CStr` with an interior nul byte is an error:
1221 /// use std::ffi::CStr;
1223 /// let cstr = CStr::from_bytes_with_nul(b"he\0llo\0");
1224 /// assert!(cstr.is_err());
1226 #[stable(feature = "cstr_from_bytes", since = "1.10.0")]
1227 pub fn from_bytes_with_nul(bytes: &[u8]) -> Result<&CStr, FromBytesWithNulError> {
1228 let nul_pos = memchr::memchr(0, bytes);
1229 if let Some(nul_pos) = nul_pos {
1230 if nul_pos + 1 != bytes.len() {
1231 return Err(FromBytesWithNulError::interior_nul(nul_pos));
1233 Ok(unsafe { CStr::from_bytes_with_nul_unchecked(bytes) })
1235 Err(FromBytesWithNulError::not_nul_terminated())
1239 /// Unsafely creates a C string wrapper from a byte slice.
1241 /// This function will cast the provided `bytes` to a `CStr` wrapper without
1242 /// performing any sanity checks. The provided slice **must** be nul-terminated
1243 /// and not contain any interior nul bytes.
1248 /// use std::ffi::{CStr, CString};
1251 /// let cstring = CString::new("hello").expect("CString::new failed");
1252 /// let cstr = CStr::from_bytes_with_nul_unchecked(cstring.to_bytes_with_nul());
1253 /// assert_eq!(cstr, &*cstring);
1258 #[stable(feature = "cstr_from_bytes", since = "1.10.0")]
1259 #[rustc_const_unstable(feature = "const_cstr_unchecked", issue = "none")]
1260 pub const unsafe fn from_bytes_with_nul_unchecked(bytes: &[u8]) -> &CStr {
1261 // SAFETY: Casting to CStr is safe because its internal representation
1262 // is a [u8] too (safe only inside std).
1263 // Dereferencing the obtained pointer is safe because it comes from a
1264 // reference. Making a reference is then safe because its lifetime
1265 // is bound by the lifetime of the given `bytes`.
1266 unsafe { &*(bytes as *const [u8] as *const CStr) }
1269 /// Returns the inner pointer to this C string.
1271 /// The returned pointer will be valid for as long as `self` is, and points
1272 /// to a contiguous region of memory terminated with a 0 byte to represent
1273 /// the end of the string.
1277 /// The returned pointer is read-only; writing to it (including passing it
1278 /// to C code that writes to it) causes undefined behavior.
1280 /// It is your responsibility to make sure that the underlying memory is not
1281 /// freed too early. For example, the following code will cause undefined
1282 /// behavior when `ptr` is used inside the `unsafe` block:
1285 /// # #![allow(unused_must_use)] #![allow(temporary_cstring_as_ptr)]
1286 /// use std::ffi::CString;
1288 /// let ptr = CString::new("Hello").expect("CString::new failed").as_ptr();
1290 /// // `ptr` is dangling
1295 /// This happens because the pointer returned by `as_ptr` does not carry any
1296 /// lifetime information and the [`CString`] is deallocated immediately after
1297 /// the `CString::new("Hello").expect("CString::new failed").as_ptr()`
1298 /// expression is evaluated.
1299 /// To fix the problem, bind the `CString` to a local variable:
1302 /// # #![allow(unused_must_use)]
1303 /// use std::ffi::CString;
1305 /// let hello = CString::new("Hello").expect("CString::new failed");
1306 /// let ptr = hello.as_ptr();
1308 /// // `ptr` is valid because `hello` is in scope
1313 /// This way, the lifetime of the [`CString`] in `hello` encompasses
1314 /// the lifetime of `ptr` and the `unsafe` block.
1317 #[stable(feature = "rust1", since = "1.0.0")]
1318 #[rustc_const_stable(feature = "const_str_as_ptr", since = "1.32.0")]
1319 pub const fn as_ptr(&self) -> *const c_char {
1323 /// Converts this C string to a byte slice.
1325 /// The returned slice will **not** contain the trailing nul terminator that this C
1328 /// > **Note**: This method is currently implemented as a constant-time
1329 /// > cast, but it is planned to alter its definition in the future to
1330 /// > perform the length calculation whenever this method is called.
1335 /// use std::ffi::CStr;
1337 /// let cstr = CStr::from_bytes_with_nul(b"foo\0").expect("CStr::from_bytes_with_nul failed");
1338 /// assert_eq!(cstr.to_bytes(), b"foo");
1341 #[must_use = "this returns the result of the operation, \
1342 without modifying the original"]
1343 #[stable(feature = "rust1", since = "1.0.0")]
1344 pub fn to_bytes(&self) -> &[u8] {
1345 let bytes = self.to_bytes_with_nul();
1346 // SAFETY: to_bytes_with_nul returns slice with length at least 1
1347 unsafe { bytes.get_unchecked(..bytes.len() - 1) }
1350 /// Converts this C string to a byte slice containing the trailing 0 byte.
1352 /// This function is the equivalent of [`CStr::to_bytes`] except that it
1353 /// will retain the trailing nul terminator instead of chopping it off.
1355 /// > **Note**: This method is currently implemented as a 0-cost cast, but
1356 /// > it is planned to alter its definition in the future to perform the
1357 /// > length calculation whenever this method is called.
1362 /// use std::ffi::CStr;
1364 /// let cstr = CStr::from_bytes_with_nul(b"foo\0").expect("CStr::from_bytes_with_nul failed");
1365 /// assert_eq!(cstr.to_bytes_with_nul(), b"foo\0");
1368 #[must_use = "this returns the result of the operation, \
1369 without modifying the original"]
1370 #[stable(feature = "rust1", since = "1.0.0")]
1371 pub fn to_bytes_with_nul(&self) -> &[u8] {
1372 unsafe { &*(&self.inner as *const [c_char] as *const [u8]) }
1375 /// Yields a <code>&[str]</code> slice if the `CStr` contains valid UTF-8.
1377 /// If the contents of the `CStr` are valid UTF-8 data, this
1378 /// function will return the corresponding <code>&[str]</code> slice. Otherwise,
1379 /// it will return an error with details of where UTF-8 validation failed.
1381 /// [str]: prim@str "str"
1386 /// use std::ffi::CStr;
1388 /// let cstr = CStr::from_bytes_with_nul(b"foo\0").expect("CStr::from_bytes_with_nul failed");
1389 /// assert_eq!(cstr.to_str(), Ok("foo"));
1391 #[stable(feature = "cstr_to_str", since = "1.4.0")]
1392 pub fn to_str(&self) -> Result<&str, str::Utf8Error> {
1393 // N.B., when `CStr` is changed to perform the length check in `.to_bytes()`
1394 // instead of in `from_ptr()`, it may be worth considering if this should
1395 // be rewritten to do the UTF-8 check inline with the length calculation
1396 // instead of doing it afterwards.
1397 str::from_utf8(self.to_bytes())
1400 /// Converts a `CStr` into a <code>[Cow]<[str]></code>.
1402 /// If the contents of the `CStr` are valid UTF-8 data, this
1403 /// function will return a <code>[Cow]::[Borrowed]\(&[str])</code>
1404 /// with the corresponding <code>&[str]</code> slice. Otherwise, it will
1405 /// replace any invalid UTF-8 sequences with
1406 /// [`U+FFFD REPLACEMENT CHARACTER`][U+FFFD] and return a
1407 /// <code>[Cow]::[Owned]\(&[str])</code> with the result.
1409 /// [str]: prim@str "str"
1410 /// [Borrowed]: Cow::Borrowed
1411 /// [Owned]: Cow::Owned
1412 /// [U+FFFD]: crate::char::REPLACEMENT_CHARACTER "std::char::REPLACEMENT_CHARACTER"
1416 /// Calling `to_string_lossy` on a `CStr` containing valid UTF-8:
1419 /// use std::borrow::Cow;
1420 /// use std::ffi::CStr;
1422 /// let cstr = CStr::from_bytes_with_nul(b"Hello World\0")
1423 /// .expect("CStr::from_bytes_with_nul failed");
1424 /// assert_eq!(cstr.to_string_lossy(), Cow::Borrowed("Hello World"));
1427 /// Calling `to_string_lossy` on a `CStr` containing invalid UTF-8:
1430 /// use std::borrow::Cow;
1431 /// use std::ffi::CStr;
1433 /// let cstr = CStr::from_bytes_with_nul(b"Hello \xF0\x90\x80World\0")
1434 /// .expect("CStr::from_bytes_with_nul failed");
1436 /// cstr.to_string_lossy(),
1437 /// Cow::Owned(String::from("Hello �World")) as Cow<'_, str>
1440 #[must_use = "this returns the result of the operation, \
1441 without modifying the original"]
1442 #[stable(feature = "cstr_to_str", since = "1.4.0")]
1443 pub fn to_string_lossy(&self) -> Cow<'_, str> {
1444 String::from_utf8_lossy(self.to_bytes())
1447 /// Converts a <code>[Box]<[CStr]></code> into a [`CString`] without copying or allocating.
1452 /// use std::ffi::CString;
1454 /// let c_string = CString::new(b"foo".to_vec()).expect("CString::new failed");
1455 /// let boxed = c_string.into_boxed_c_str();
1456 /// assert_eq!(boxed.into_c_string(), CString::new("foo").expect("CString::new failed"));
1458 #[stable(feature = "into_boxed_c_str", since = "1.20.0")]
1459 pub fn into_c_string(self: Box<CStr>) -> CString {
1460 let raw = Box::into_raw(self) as *mut [u8];
1461 CString { inner: unsafe { Box::from_raw(raw) } }
1465 #[stable(feature = "rust1", since = "1.0.0")]
1466 impl PartialEq for CStr {
1467 fn eq(&self, other: &CStr) -> bool {
1468 self.to_bytes().eq(other.to_bytes())
1471 #[stable(feature = "rust1", since = "1.0.0")]
1473 #[stable(feature = "rust1", since = "1.0.0")]
1474 impl PartialOrd for CStr {
1475 fn partial_cmp(&self, other: &CStr) -> Option<Ordering> {
1476 self.to_bytes().partial_cmp(&other.to_bytes())
1479 #[stable(feature = "rust1", since = "1.0.0")]
1481 fn cmp(&self, other: &CStr) -> Ordering {
1482 self.to_bytes().cmp(&other.to_bytes())
1486 #[stable(feature = "cstr_borrow", since = "1.3.0")]
1487 impl ToOwned for CStr {
1488 type Owned = CString;
1490 fn to_owned(&self) -> CString {
1491 CString { inner: self.to_bytes_with_nul().into() }
1494 fn clone_into(&self, target: &mut CString) {
1495 let mut b = Vec::from(mem::take(&mut target.inner));
1496 self.to_bytes_with_nul().clone_into(&mut b);
1497 target.inner = b.into_boxed_slice();
1501 #[stable(feature = "cstring_asref", since = "1.7.0")]
1502 impl From<&CStr> for CString {
1503 fn from(s: &CStr) -> CString {
1508 #[stable(feature = "cstring_asref", since = "1.7.0")]
1509 impl ops::Index<ops::RangeFull> for CString {
1513 fn index(&self, _index: ops::RangeFull) -> &CStr {
1518 #[stable(feature = "cstr_range_from", since = "1.47.0")]
1519 impl ops::Index<ops::RangeFrom<usize>> for CStr {
1522 fn index(&self, index: ops::RangeFrom<usize>) -> &CStr {
1523 let bytes = self.to_bytes_with_nul();
1524 // we need to manually check the starting index to account for the null
1525 // byte, since otherwise we could get an empty string that doesn't end
1527 if index.start < bytes.len() {
1528 unsafe { CStr::from_bytes_with_nul_unchecked(&bytes[index.start..]) }
1531 "index out of bounds: the len is {} but the index is {}",
1539 #[stable(feature = "cstring_asref", since = "1.7.0")]
1540 impl AsRef<CStr> for CStr {
1542 fn as_ref(&self) -> &CStr {
1547 #[stable(feature = "cstring_asref", since = "1.7.0")]
1548 impl AsRef<CStr> for CString {
1550 fn as_ref(&self) -> &CStr {