| use crate::cmp::Ordering; |
| use crate::ffi::c_char; |
| use crate::fmt; |
| use crate::intrinsics; |
| use crate::ops; |
| use crate::slice; |
| use crate::slice::memchr; |
| use crate::str; |
| |
| /// Representation of a borrowed C string. |
| /// |
| /// This type represents a borrowed reference to a nul-terminated |
| /// array of bytes. It can be constructed safely from a <code>&[[u8]]</code> |
| /// slice, or unsafely from a raw `*const c_char`. It can then be |
| /// converted to a Rust <code>&[str]</code> by performing UTF-8 validation, or |
| /// into an owned [`CString`]. |
| /// |
| /// `&CStr` is to [`CString`] as <code>&[str]</code> is to [`String`]: the former |
| /// in each pair are borrowed references; the latter are owned |
| /// strings. |
| /// |
| /// Note that this structure is **not** `repr(C)` and is not recommended to be |
| /// placed in the signatures of FFI functions. Instead, safe wrappers of FFI |
| /// functions may leverage the unsafe [`CStr::from_ptr`] constructor to provide |
| /// a safe interface to other consumers. |
| /// |
| /// [`CString`]: ../../std/ffi/struct.CString.html |
| /// [`String`]: ../../std/string/struct.String.html |
| /// |
| /// # Examples |
| /// |
| /// Inspecting a foreign C string: |
| /// |
| /// ```ignore (extern-declaration) |
| /// use std::ffi::CStr; |
| /// use std::os::raw::c_char; |
| /// |
| /// extern "C" { fn my_string() -> *const c_char; } |
| /// |
| /// unsafe { |
| /// let slice = CStr::from_ptr(my_string()); |
| /// println!("string buffer size without nul terminator: {}", slice.to_bytes().len()); |
| /// } |
| /// ``` |
| /// |
| /// Passing a Rust-originating C string: |
| /// |
| /// ```ignore (extern-declaration) |
| /// use std::ffi::{CString, CStr}; |
| /// use std::os::raw::c_char; |
| /// |
| /// fn work(data: &CStr) { |
| /// extern "C" { fn work_with(data: *const c_char); } |
| /// |
| /// unsafe { work_with(data.as_ptr()) } |
| /// } |
| /// |
| /// let s = CString::new("data data data data").expect("CString::new failed"); |
| /// work(&s); |
| /// ``` |
| /// |
| /// Converting a foreign C string into a Rust `String`: |
| /// |
| /// ```ignore (extern-declaration) |
| /// use std::ffi::CStr; |
| /// use std::os::raw::c_char; |
| /// |
| /// extern "C" { fn my_string() -> *const c_char; } |
| /// |
| /// fn my_string_safe() -> String { |
| /// let cstr = unsafe { CStr::from_ptr(my_string()) }; |
| /// // Get copy-on-write Cow<'_, str>, then guarantee a freshly-owned String allocation |
| /// String::from_utf8_lossy(cstr.to_bytes()).to_string() |
| /// } |
| /// |
| /// println!("string: {}", my_string_safe()); |
| /// ``` |
| /// |
| /// [str]: prim@str "str" |
| #[derive(Hash)] |
| #[cfg_attr(not(test), rustc_diagnostic_item = "CStr")] |
| #[stable(feature = "core_c_str", since = "1.64.0")] |
| #[rustc_has_incoherent_inherent_impls] |
| // FIXME: |
| // `fn from` in `impl From<&CStr> for Box<CStr>` current implementation relies |
| // on `CStr` being layout-compatible with `[u8]`. |
| // When attribute privacy is implemented, `CStr` should be annotated as `#[repr(transparent)]`. |
| // Anyway, `CStr` representation and layout are considered implementation detail, are |
| // not documented and must not be relied upon. |
| pub struct CStr { |
| // FIXME: this should not be represented with a DST slice but rather with |
| // just a raw `c_char` along with some form of marker to make |
| // this an unsized type. Essentially `sizeof(&CStr)` should be the |
| // same as `sizeof(&c_char)` but `CStr` should be an unsized type. |
| inner: [c_char], |
| } |
| |
| /// An error indicating that a nul byte was not in the expected position. |
| /// |
| /// The slice used to create a [`CStr`] must have one and only one nul byte, |
| /// positioned at the end. |
| /// |
| /// This error is created by the [`CStr::from_bytes_with_nul`] method. |
| /// See its documentation for more. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::ffi::{CStr, FromBytesWithNulError}; |
| /// |
| /// let _: FromBytesWithNulError = CStr::from_bytes_with_nul(b"f\0oo").unwrap_err(); |
| /// ``` |
| #[derive(Clone, PartialEq, Eq, Debug)] |
| #[stable(feature = "core_c_str", since = "1.64.0")] |
| pub struct FromBytesWithNulError { |
| kind: FromBytesWithNulErrorKind, |
| } |
| |
| #[derive(Clone, PartialEq, Eq, Debug)] |
| enum FromBytesWithNulErrorKind { |
| InteriorNul(usize), |
| NotNulTerminated, |
| } |
| |
| impl FromBytesWithNulError { |
| const fn interior_nul(pos: usize) -> FromBytesWithNulError { |
| FromBytesWithNulError { kind: FromBytesWithNulErrorKind::InteriorNul(pos) } |
| } |
| const fn not_nul_terminated() -> FromBytesWithNulError { |
| FromBytesWithNulError { kind: FromBytesWithNulErrorKind::NotNulTerminated } |
| } |
| |
| #[doc(hidden)] |
| #[unstable(feature = "cstr_internals", issue = "none")] |
| pub fn __description(&self) -> &str { |
| match self.kind { |
| FromBytesWithNulErrorKind::InteriorNul(..) => { |
| "data provided contains an interior nul byte" |
| } |
| FromBytesWithNulErrorKind::NotNulTerminated => "data provided is not nul terminated", |
| } |
| } |
| } |
| |
| /// An error indicating that no nul byte was present. |
| /// |
| /// A slice used to create a [`CStr`] must contain a nul byte somewhere |
| /// within the slice. |
| /// |
| /// This error is created by the [`CStr::from_bytes_until_nul`] method. |
| /// |
| #[derive(Clone, PartialEq, Eq, Debug)] |
| #[unstable(feature = "cstr_from_bytes_until_nul", issue = "95027")] |
| pub struct FromBytesUntilNulError(()); |
| |
| #[unstable(feature = "cstr_from_bytes_until_nul", issue = "95027")] |
| impl fmt::Display for FromBytesUntilNulError { |
| fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| write!(f, "data provided does not contain a nul") |
| } |
| } |
| |
| #[stable(feature = "cstr_debug", since = "1.3.0")] |
| impl fmt::Debug for CStr { |
| fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| write!(f, "\"{}\"", self.to_bytes().escape_ascii()) |
| } |
| } |
| |
| #[stable(feature = "cstr_default", since = "1.10.0")] |
| impl Default for &CStr { |
| fn default() -> Self { |
| const SLICE: &[c_char] = &[0]; |
| // SAFETY: `SLICE` is indeed pointing to a valid nul-terminated string. |
| unsafe { CStr::from_ptr(SLICE.as_ptr()) } |
| } |
| } |
| |
| #[stable(feature = "frombyteswithnulerror_impls", since = "1.17.0")] |
| impl fmt::Display for FromBytesWithNulError { |
| #[allow(deprecated, deprecated_in_future)] |
| fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| f.write_str(self.__description())?; |
| if let FromBytesWithNulErrorKind::InteriorNul(pos) = self.kind { |
| write!(f, " at byte pos {pos}")?; |
| } |
| Ok(()) |
| } |
| } |
| |
| impl CStr { |
| /// Wraps a raw C string with a safe C string wrapper. |
| /// |
| /// This function will wrap the provided `ptr` with a `CStr` wrapper, which |
| /// allows inspection and interoperation of non-owned C strings. The total |
| /// size of the raw C string must be smaller than `isize::MAX` **bytes** |
| /// in memory due to calling the `slice::from_raw_parts` function. |
| /// |
| /// # Safety |
| /// |
| /// * The memory pointed to by `ptr` must contain a valid nul terminator at the |
| /// end of the string. |
| /// |
| /// * `ptr` must be [valid] for reads of bytes up to and including the null terminator. |
| /// This means in particular: |
| /// |
| /// * The entire memory range of this `CStr` must be contained within a single allocated object! |
| /// * `ptr` must be non-null even for a zero-length cstr. |
| /// |
| /// * The memory referenced by the returned `CStr` must not be mutated for |
| /// the duration of lifetime `'a`. |
| /// |
| /// > **Note**: This operation is intended to be a 0-cost cast but it is |
| /// > currently implemented with an up-front calculation of the length of |
| /// > the string. This is not guaranteed to always be the case. |
| /// |
| /// # Caveat |
| /// |
| /// The lifetime for the returned slice is inferred from its usage. To prevent accidental misuse, |
| /// it's suggested to tie the lifetime to whichever source lifetime is safe in the context, |
| /// such as by providing a helper function taking the lifetime of a host value for the slice, |
| /// or by explicit annotation. |
| /// |
| /// # Examples |
| /// |
| /// ```ignore (extern-declaration) |
| /// use std::ffi::{c_char, CStr}; |
| /// |
| /// extern "C" { |
| /// fn my_string() -> *const c_char; |
| /// } |
| /// |
| /// unsafe { |
| /// let slice = CStr::from_ptr(my_string()); |
| /// println!("string returned: {}", slice.to_str().unwrap()); |
| /// } |
| /// ``` |
| /// |
| /// ``` |
| /// #![feature(const_cstr_methods)] |
| /// |
| /// use std::ffi::{c_char, CStr}; |
| /// |
| /// const HELLO_PTR: *const c_char = { |
| /// const BYTES: &[u8] = b"Hello, world!\0"; |
| /// BYTES.as_ptr().cast() |
| /// }; |
| /// const HELLO: &CStr = unsafe { CStr::from_ptr(HELLO_PTR) }; |
| /// ``` |
| /// |
| /// [valid]: core::ptr#safety |
| #[inline] |
| #[must_use] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[rustc_const_unstable(feature = "const_cstr_methods", issue = "101719")] |
| pub const unsafe fn from_ptr<'a>(ptr: *const c_char) -> &'a CStr { |
| // SAFETY: The caller has provided a pointer that points to a valid C |
| // string with a NUL terminator of size less than `isize::MAX`, whose |
| // content remain valid and doesn't change for the lifetime of the |
| // returned `CStr`. |
| // |
| // Thus computing the length is fine (a NUL byte exists), the call to |
| // from_raw_parts is safe because we know the length is at most `isize::MAX`, meaning |
| // the call to `from_bytes_with_nul_unchecked` is correct. |
| // |
| // The cast from c_char to u8 is ok because a c_char is always one byte. |
| unsafe { |
| const fn strlen_ct(s: *const c_char) -> usize { |
| let mut len = 0; |
| |
| // SAFETY: Outer caller has provided a pointer to a valid C string. |
| while unsafe { *s.add(len) } != 0 { |
| len += 1; |
| } |
| |
| len |
| } |
| |
| fn strlen_rt(s: *const c_char) -> usize { |
| extern "C" { |
| /// Provided by libc or compiler_builtins. |
| fn strlen(s: *const c_char) -> usize; |
| } |
| |
| // SAFETY: Outer caller has provided a pointer to a valid C string. |
| unsafe { strlen(s) } |
| } |
| |
| let len = intrinsics::const_eval_select((ptr,), strlen_ct, strlen_rt); |
| Self::from_bytes_with_nul_unchecked(slice::from_raw_parts(ptr.cast(), len + 1)) |
| } |
| } |
| |
| /// Creates a C string wrapper from a byte slice. |
| /// |
| /// This method will create a `CStr` from any byte slice that contains at |
| /// least one nul byte. The caller does not need to know or specify where |
| /// the nul byte is located. |
| /// |
| /// If the first byte is a nul character, this method will return an |
| /// empty `CStr`. If multiple nul characters are present, the `CStr` will |
| /// end at the first one. |
| /// |
| /// If the slice only has a single nul byte at the end, this method is |
| /// equivalent to [`CStr::from_bytes_with_nul`]. |
| /// |
| /// # Examples |
| /// ``` |
| /// #![feature(cstr_from_bytes_until_nul)] |
| /// |
| /// use std::ffi::CStr; |
| /// |
| /// let mut buffer = [0u8; 16]; |
| /// unsafe { |
| /// // Here we might call an unsafe C function that writes a string |
| /// // into the buffer. |
| /// let buf_ptr = buffer.as_mut_ptr(); |
| /// buf_ptr.write_bytes(b'A', 8); |
| /// } |
| /// // Attempt to extract a C nul-terminated string from the buffer. |
| /// let c_str = CStr::from_bytes_until_nul(&buffer[..]).unwrap(); |
| /// assert_eq!(c_str.to_str().unwrap(), "AAAAAAAA"); |
| /// ``` |
| /// |
| #[unstable(feature = "cstr_from_bytes_until_nul", issue = "95027")] |
| #[rustc_const_unstable(feature = "cstr_from_bytes_until_nul", issue = "95027")] |
| pub const fn from_bytes_until_nul(bytes: &[u8]) -> Result<&CStr, FromBytesUntilNulError> { |
| let nul_pos = memchr::memchr(0, bytes); |
| match nul_pos { |
| Some(nul_pos) => { |
| let subslice = &bytes[..nul_pos + 1]; |
| // SAFETY: We know there is a nul byte at nul_pos, so this slice |
| // (ending at the nul byte) is a well-formed C string. |
| Ok(unsafe { CStr::from_bytes_with_nul_unchecked(subslice) }) |
| } |
| None => Err(FromBytesUntilNulError(())), |
| } |
| } |
| |
| /// Creates a C string wrapper from a byte slice. |
| /// |
| /// This function will cast the provided `bytes` to a `CStr` |
| /// wrapper after ensuring that the byte slice is nul-terminated |
| /// and does not contain any interior nul bytes. |
| /// |
| /// If the nul byte may not be at the end, |
| /// [`CStr::from_bytes_until_nul`] can be used instead. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::ffi::CStr; |
| /// |
| /// let cstr = CStr::from_bytes_with_nul(b"hello\0"); |
| /// assert!(cstr.is_ok()); |
| /// ``` |
| /// |
| /// Creating a `CStr` without a trailing nul terminator is an error: |
| /// |
| /// ``` |
| /// use std::ffi::CStr; |
| /// |
| /// let cstr = CStr::from_bytes_with_nul(b"hello"); |
| /// assert!(cstr.is_err()); |
| /// ``` |
| /// |
| /// Creating a `CStr` with an interior nul byte is an error: |
| /// |
| /// ``` |
| /// use std::ffi::CStr; |
| /// |
| /// let cstr = CStr::from_bytes_with_nul(b"he\0llo\0"); |
| /// assert!(cstr.is_err()); |
| /// ``` |
| #[stable(feature = "cstr_from_bytes", since = "1.10.0")] |
| #[rustc_const_unstable(feature = "const_cstr_methods", issue = "101719")] |
| pub const fn from_bytes_with_nul(bytes: &[u8]) -> Result<&Self, FromBytesWithNulError> { |
| let nul_pos = memchr::memchr(0, bytes); |
| match nul_pos { |
| Some(nul_pos) if nul_pos + 1 == bytes.len() => { |
| // SAFETY: We know there is only one nul byte, at the end |
| // of the byte slice. |
| Ok(unsafe { Self::from_bytes_with_nul_unchecked(bytes) }) |
| } |
| Some(nul_pos) => Err(FromBytesWithNulError::interior_nul(nul_pos)), |
| None => Err(FromBytesWithNulError::not_nul_terminated()), |
| } |
| } |
| |
| /// Unsafely creates a C string wrapper from a byte slice. |
| /// |
| /// This function will cast the provided `bytes` to a `CStr` wrapper without |
| /// performing any sanity checks. |
| /// |
| /// # Safety |
| /// The provided slice **must** be nul-terminated and not contain any interior |
| /// nul bytes. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::ffi::{CStr, CString}; |
| /// |
| /// unsafe { |
| /// let cstring = CString::new("hello").expect("CString::new failed"); |
| /// let cstr = CStr::from_bytes_with_nul_unchecked(cstring.to_bytes_with_nul()); |
| /// assert_eq!(cstr, &*cstring); |
| /// } |
| /// ``` |
| #[inline] |
| #[must_use] |
| #[stable(feature = "cstr_from_bytes", since = "1.10.0")] |
| #[rustc_const_stable(feature = "const_cstr_unchecked", since = "1.59.0")] |
| #[rustc_allow_const_fn_unstable(const_eval_select)] |
| pub const unsafe fn from_bytes_with_nul_unchecked(bytes: &[u8]) -> &CStr { |
| #[inline] |
| fn rt_impl(bytes: &[u8]) -> &CStr { |
| // Chance at catching some UB at runtime with debug builds. |
| debug_assert!(!bytes.is_empty() && bytes[bytes.len() - 1] == 0); |
| |
| // SAFETY: Casting to CStr is safe because its internal representation |
| // is a [u8] too (safe only inside std). |
| // Dereferencing the obtained pointer is safe because it comes from a |
| // reference. Making a reference is then safe because its lifetime |
| // is bound by the lifetime of the given `bytes`. |
| unsafe { &*(bytes as *const [u8] as *const CStr) } |
| } |
| |
| const fn const_impl(bytes: &[u8]) -> &CStr { |
| // Saturating so that an empty slice panics in the assert with a good |
| // message, not here due to underflow. |
| let mut i = bytes.len().saturating_sub(1); |
| assert!(!bytes.is_empty() && bytes[i] == 0, "input was not nul-terminated"); |
| |
| // Ending null byte exists, skip to the rest. |
| while i != 0 { |
| i -= 1; |
| let byte = bytes[i]; |
| assert!(byte != 0, "input contained interior nul"); |
| } |
| |
| // SAFETY: See `rt_impl` cast. |
| unsafe { &*(bytes as *const [u8] as *const CStr) } |
| } |
| |
| // SAFETY: The const and runtime versions have identical behavior |
| // unless the safety contract of `from_bytes_with_nul_unchecked` is |
| // violated, which is UB. |
| unsafe { intrinsics::const_eval_select((bytes,), const_impl, rt_impl) } |
| } |
| |
| /// Returns the inner pointer to this C string. |
| /// |
| /// The returned pointer will be valid for as long as `self` is, and points |
| /// to a contiguous region of memory terminated with a 0 byte to represent |
| /// the end of the string. |
| /// |
| /// **WARNING** |
| /// |
| /// The returned pointer is read-only; writing to it (including passing it |
| /// to C code that writes to it) causes undefined behavior. |
| /// |
| /// It is your responsibility to make sure that the underlying memory is not |
| /// freed too early. For example, the following code will cause undefined |
| /// behavior when `ptr` is used inside the `unsafe` block: |
| /// |
| /// ```no_run |
| /// # #![allow(unused_must_use)] #![allow(temporary_cstring_as_ptr)] |
| /// use std::ffi::CString; |
| /// |
| /// let ptr = CString::new("Hello").expect("CString::new failed").as_ptr(); |
| /// unsafe { |
| /// // `ptr` is dangling |
| /// *ptr; |
| /// } |
| /// ``` |
| /// |
| /// This happens because the pointer returned by `as_ptr` does not carry any |
| /// lifetime information and the `CString` is deallocated immediately after |
| /// the `CString::new("Hello").expect("CString::new failed").as_ptr()` |
| /// expression is evaluated. |
| /// To fix the problem, bind the `CString` to a local variable: |
| /// |
| /// ```no_run |
| /// # #![allow(unused_must_use)] |
| /// use std::ffi::CString; |
| /// |
| /// let hello = CString::new("Hello").expect("CString::new failed"); |
| /// let ptr = hello.as_ptr(); |
| /// unsafe { |
| /// // `ptr` is valid because `hello` is in scope |
| /// *ptr; |
| /// } |
| /// ``` |
| /// |
| /// This way, the lifetime of the `CString` in `hello` encompasses |
| /// the lifetime of `ptr` and the `unsafe` block. |
| #[inline] |
| #[must_use] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[rustc_const_stable(feature = "const_str_as_ptr", since = "1.32.0")] |
| pub const fn as_ptr(&self) -> *const c_char { |
| self.inner.as_ptr() |
| } |
| |
| /// Returns `true` if `self.to_bytes()` has a length of 0. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// #![feature(cstr_is_empty)] |
| /// |
| /// use std::ffi::CStr; |
| /// # use std::ffi::FromBytesWithNulError; |
| /// |
| /// # fn main() { test().unwrap(); } |
| /// # fn test() -> Result<(), FromBytesWithNulError> { |
| /// let cstr = CStr::from_bytes_with_nul(b"foo\0")?; |
| /// assert!(!cstr.is_empty()); |
| /// |
| /// let empty_cstr = CStr::from_bytes_with_nul(b"\0")?; |
| /// assert!(empty_cstr.is_empty()); |
| /// # Ok(()) |
| /// # } |
| /// ``` |
| #[inline] |
| #[unstable(feature = "cstr_is_empty", issue = "102444")] |
| pub const fn is_empty(&self) -> bool { |
| // SAFETY: We know there is at least one byte; for empty strings it |
| // is the NUL terminator. |
| (unsafe { self.inner.get_unchecked(0) }) == &0 |
| } |
| |
| /// Converts this C string to a byte slice. |
| /// |
| /// The returned slice will **not** contain the trailing nul terminator that this C |
| /// string has. |
| /// |
| /// > **Note**: This method is currently implemented as a constant-time |
| /// > cast, but it is planned to alter its definition in the future to |
| /// > perform the length calculation whenever this method is called. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::ffi::CStr; |
| /// |
| /// let cstr = CStr::from_bytes_with_nul(b"foo\0").expect("CStr::from_bytes_with_nul failed"); |
| /// assert_eq!(cstr.to_bytes(), b"foo"); |
| /// ``` |
| #[inline] |
| #[must_use = "this returns the result of the operation, \ |
| without modifying the original"] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[rustc_const_unstable(feature = "const_cstr_methods", issue = "101719")] |
| pub const fn to_bytes(&self) -> &[u8] { |
| let bytes = self.to_bytes_with_nul(); |
| // SAFETY: to_bytes_with_nul returns slice with length at least 1 |
| unsafe { bytes.get_unchecked(..bytes.len() - 1) } |
| } |
| |
| /// Converts this C string to a byte slice containing the trailing 0 byte. |
| /// |
| /// This function is the equivalent of [`CStr::to_bytes`] except that it |
| /// will retain the trailing nul terminator instead of chopping it off. |
| /// |
| /// > **Note**: This method is currently implemented as a 0-cost cast, but |
| /// > it is planned to alter its definition in the future to perform the |
| /// > length calculation whenever this method is called. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::ffi::CStr; |
| /// |
| /// let cstr = CStr::from_bytes_with_nul(b"foo\0").expect("CStr::from_bytes_with_nul failed"); |
| /// assert_eq!(cstr.to_bytes_with_nul(), b"foo\0"); |
| /// ``` |
| #[inline] |
| #[must_use = "this returns the result of the operation, \ |
| without modifying the original"] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[rustc_const_unstable(feature = "const_cstr_methods", issue = "101719")] |
| pub const fn to_bytes_with_nul(&self) -> &[u8] { |
| // SAFETY: Transmuting a slice of `c_char`s to a slice of `u8`s |
| // is safe on all supported targets. |
| unsafe { &*(&self.inner as *const [c_char] as *const [u8]) } |
| } |
| |
| /// Yields a <code>&[str]</code> slice if the `CStr` contains valid UTF-8. |
| /// |
| /// If the contents of the `CStr` are valid UTF-8 data, this |
| /// function will return the corresponding <code>&[str]</code> slice. Otherwise, |
| /// it will return an error with details of where UTF-8 validation failed. |
| /// |
| /// [str]: prim@str "str" |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::ffi::CStr; |
| /// |
| /// let cstr = CStr::from_bytes_with_nul(b"foo\0").expect("CStr::from_bytes_with_nul failed"); |
| /// assert_eq!(cstr.to_str(), Ok("foo")); |
| /// ``` |
| #[stable(feature = "cstr_to_str", since = "1.4.0")] |
| #[rustc_const_unstable(feature = "const_cstr_methods", issue = "101719")] |
| pub const fn to_str(&self) -> Result<&str, str::Utf8Error> { |
| // N.B., when `CStr` is changed to perform the length check in `.to_bytes()` |
| // instead of in `from_ptr()`, it may be worth considering if this should |
| // be rewritten to do the UTF-8 check inline with the length calculation |
| // instead of doing it afterwards. |
| str::from_utf8(self.to_bytes()) |
| } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl PartialEq for CStr { |
| fn eq(&self, other: &CStr) -> bool { |
| self.to_bytes().eq(other.to_bytes()) |
| } |
| } |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl Eq for CStr {} |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl PartialOrd for CStr { |
| fn partial_cmp(&self, other: &CStr) -> Option<Ordering> { |
| self.to_bytes().partial_cmp(&other.to_bytes()) |
| } |
| } |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl Ord for CStr { |
| fn cmp(&self, other: &CStr) -> Ordering { |
| self.to_bytes().cmp(&other.to_bytes()) |
| } |
| } |
| |
| #[stable(feature = "cstr_range_from", since = "1.47.0")] |
| impl ops::Index<ops::RangeFrom<usize>> for CStr { |
| type Output = CStr; |
| |
| fn index(&self, index: ops::RangeFrom<usize>) -> &CStr { |
| let bytes = self.to_bytes_with_nul(); |
| // we need to manually check the starting index to account for the null |
| // byte, since otherwise we could get an empty string that doesn't end |
| // in a null. |
| if index.start < bytes.len() { |
| // SAFETY: Non-empty tail of a valid `CStr` is still a valid `CStr`. |
| unsafe { CStr::from_bytes_with_nul_unchecked(&bytes[index.start..]) } |
| } else { |
| panic!( |
| "index out of bounds: the len is {} but the index is {}", |
| bytes.len(), |
| index.start |
| ); |
| } |
| } |
| } |
| |
| #[stable(feature = "cstring_asref", since = "1.7.0")] |
| impl AsRef<CStr> for CStr { |
| #[inline] |
| fn as_ref(&self) -> &CStr { |
| self |
| } |
| } |
