diff options
Diffstat (limited to 'library/alloc/src')
| -rw-r--r-- | library/alloc/src/ffi/c_str.rs | 1197 | ||||
| -rw-r--r-- | library/alloc/src/ffi/c_str/tests.rs | 228 | ||||
| -rw-r--r-- | library/alloc/src/ffi/mod.rs | 91 | ||||
| -rw-r--r-- | library/alloc/src/lib.rs | 7 | ||||
| -rw-r--r-- | library/alloc/src/slice.rs | 2 |
5 files changed, 1524 insertions, 1 deletions
diff --git a/library/alloc/src/ffi/c_str.rs b/library/alloc/src/ffi/c_str.rs new file mode 100644 index 00000000000..21433a3baa9 --- /dev/null +++ b/library/alloc/src/ffi/c_str.rs @@ -0,0 +1,1197 @@ +#[cfg(test)] +mod tests; + +use crate::borrow::{Cow, ToOwned}; +use crate::boxed::Box; +use crate::rc::Rc; +use crate::slice::hack::into_vec; +use crate::string::String; +use crate::sync::Arc; +use crate::vec::Vec; +use core::borrow::Borrow; +use core::ffi::{c_char, CStr}; +use core::fmt; +use core::mem; +use core::num::NonZeroU8; +use core::ops; +use core::ptr; +use core::slice; +use core::slice::memchr; +use core::str::{self, Utf8Error}; + +/// A type representing an owned, C-compatible, nul-terminated string with no nul bytes in the +/// middle. +/// +/// This type serves the purpose of being able to safely generate a +/// C-compatible string from a Rust byte slice or vector. An instance of this +/// type is a static guarantee that the underlying bytes contain no interior 0 +/// bytes ("nul characters") and that the final byte is 0 ("nul terminator"). +/// +/// `CString` is to <code>&[CStr]</code> as [`String`] is to <code>&[str]</code>: the former +/// in each pair are owned strings; the latter are borrowed +/// references. +/// +/// # Creating a `CString` +/// +/// A `CString` is created from either a byte slice or a byte vector, +/// or anything that implements <code>[Into]<[Vec]<[u8]>></code> (for +/// example, you can build a `CString` straight out of a [`String`] or +/// a <code>&[str]</code>, since both implement that trait). +/// +/// The [`CString::new`] method will actually check that the provided <code>&[[u8]]</code> +/// does not have 0 bytes in the middle, and return an error if it +/// finds one. +/// +/// # Extracting a raw pointer to the whole C string +/// +/// `CString` implements an [`as_ptr`][`CStr::as_ptr`] method through the [`Deref`] +/// trait. This method will give you a `*const c_char` which you can +/// feed directly to extern functions that expect a nul-terminated +/// string, like C's `strdup()`. Notice that [`as_ptr`][`CStr::as_ptr`] returns a +/// read-only pointer; if the C code writes to it, that causes +/// undefined behavior. +/// +/// # Extracting a slice of the whole C string +/// +/// Alternatively, you can obtain a <code>&[[u8]]</code> slice from a +/// `CString` with the [`CString::as_bytes`] method. Slices produced in this +/// way do *not* contain the trailing nul terminator. This is useful +/// when you will be calling an extern function that takes a `*const +/// u8` argument which is not necessarily nul-terminated, plus another +/// argument with the length of the string — like C's `strndup()`. +/// You can of course get the slice's length with its +/// [`len`][slice::len] method. +/// +/// If you need a <code>&[[u8]]</code> slice *with* the nul terminator, you +/// can use [`CString::as_bytes_with_nul`] instead. +/// +/// Once you have the kind of slice you need (with or without a nul +/// terminator), you can call the slice's own +/// [`as_ptr`][slice::as_ptr] method to get a read-only raw pointer to pass to +/// extern functions. See the documentation for that function for a +/// discussion on ensuring the lifetime of the raw pointer. +/// +/// [str]: prim@str "str" +/// [`Deref`]: ops::Deref +/// +/// # Examples +/// +/// ```ignore (extern-declaration) +/// # fn main() { +/// use std::ffi::CString; +/// use std::os::raw::c_char; +/// +/// extern "C" { +/// fn my_printer(s: *const c_char); +/// } +/// +/// // We are certain that our string doesn't have 0 bytes in the middle, +/// // so we can .expect() +/// let c_to_print = CString::new("Hello, world!").expect("CString::new failed"); +/// unsafe { +/// my_printer(c_to_print.as_ptr()); +/// } +/// # } +/// ``` +/// +/// # Safety +/// +/// `CString` is intended for working with traditional C-style strings +/// (a sequence of non-nul bytes terminated by a single nul byte); the +/// primary use case for these kinds of strings is interoperating with C-like +/// code. Often you will need to transfer ownership to/from that external +/// code. It is strongly recommended that you thoroughly read through the +/// documentation of `CString` before use, as improper ownership management +/// of `CString` instances can lead to invalid memory accesses, memory leaks, +/// and other memory errors. +#[derive(PartialEq, PartialOrd, Eq, Ord, Hash, Clone)] +#[cfg_attr(not(test), rustc_diagnostic_item = "cstring_type")] +#[stable(feature = "rust1", since = "1.0.0")] +pub struct CString { + // Invariant 1: the slice ends with a zero byte and has a length of at least one. + // Invariant 2: the slice contains only one zero byte. + // Improper usage of unsafe function can break Invariant 2, but not Invariant 1. + inner: Box<[u8]>, +} + +/// An error indicating that an interior nul byte was found. +/// +/// While Rust strings may contain nul bytes in the middle, C strings +/// can't, as that byte would effectively truncate the string. +/// +/// This error is created by the [`new`][`CString::new`] method on +/// [`CString`]. See its documentation for more. +/// +/// # Examples +/// +/// ``` +/// use std::ffi::{CString, NulError}; +/// +/// let _: NulError = CString::new(b"f\0oo".to_vec()).unwrap_err(); +/// ``` +#[derive(Clone, PartialEq, Eq, Debug)] +#[stable(feature = "rust1", since = "1.0.0")] +pub struct NulError(usize, Vec<u8>); + +#[derive(Clone, PartialEq, Eq, Debug)] +enum FromBytesWithNulErrorKind { + InteriorNul(usize), + NotNulTerminated, +} + +/// An error indicating that a nul byte was not in the expected position. +/// +/// The vector used to create a [`CString`] must have one and only one nul byte, +/// positioned at the end. +/// +/// This error is created by the [`CString::from_vec_with_nul`] method. +/// See its documentation for more. +/// +/// # Examples +/// +/// ``` +/// use std::ffi::{CString, FromVecWithNulError}; +/// +/// let _: FromVecWithNulError = CString::from_vec_with_nul(b"f\0oo".to_vec()).unwrap_err(); +/// ``` +#[derive(Clone, PartialEq, Eq, Debug)] +#[stable(feature = "cstring_from_vec_with_nul", since = "1.58.0")] +pub struct FromVecWithNulError { + error_kind: FromBytesWithNulErrorKind, + bytes: Vec<u8>, +} + +#[stable(feature = "cstring_from_vec_with_nul", since = "1.58.0")] +impl FromVecWithNulError { + /// Returns a slice of [`u8`]s bytes that were attempted to convert to a [`CString`]. + /// + /// # Examples + /// + /// Basic usage: + /// + /// ``` + /// use std::ffi::CString; + /// + /// // Some invalid bytes in a vector + /// let bytes = b"f\0oo".to_vec(); + /// + /// let value = CString::from_vec_with_nul(bytes.clone()); + /// + /// assert_eq!(&bytes[..], value.unwrap_err().as_bytes()); + /// ``` + #[must_use] + #[stable(feature = "cstring_from_vec_with_nul", since = "1.58.0")] + pub fn as_bytes(&self) -> &[u8] { + &self.bytes[..] + } + + /// Returns the bytes that were attempted to convert to a [`CString`]. + /// + /// This method is carefully constructed to avoid allocation. It will + /// consume the error, moving out the bytes, so that a copy of the bytes + /// does not need to be made. + /// + /// # Examples + /// + /// Basic usage: + /// + /// ``` + /// use std::ffi::CString; + /// + /// // Some invalid bytes in a vector + /// let bytes = b"f\0oo".to_vec(); + /// + /// let value = CString::from_vec_with_nul(bytes.clone()); + /// + /// assert_eq!(bytes, value.unwrap_err().into_bytes()); + /// ``` + #[must_use = "`self` will be dropped if the result is not used"] + #[stable(feature = "cstring_from_vec_with_nul", since = "1.58.0")] + pub fn into_bytes(self) -> Vec<u8> { + self.bytes + } +} + +/// An error indicating invalid UTF-8 when converting a [`CString`] into a [`String`]. +/// +/// `CString` is just a wrapper over a buffer of bytes with a nul terminator; +/// [`CString::into_string`] performs UTF-8 validation on those bytes and may +/// return this error. +/// +/// This `struct` is created by [`CString::into_string()`]. See +/// its documentation for more. +#[derive(Clone, PartialEq, Eq, Debug)] +#[stable(feature = "cstring_into", since = "1.7.0")] +pub struct IntoStringError { + inner: CString, + error: Utf8Error, +} + +impl CString { + /// Creates a new C-compatible string from a container of bytes. + /// + /// This function will consume the provided data and use the + /// underlying bytes to construct a new string, ensuring that + /// there is a trailing 0 byte. This trailing 0 byte will be + /// appended by this function; the provided data should *not* + /// contain any 0 bytes in it. + /// + /// # Examples + /// + /// ```ignore (extern-declaration) + /// use std::ffi::CString; + /// use std::os::raw::c_char; + /// + /// extern "C" { fn puts(s: *const c_char); } + /// + /// let to_print = CString::new("Hello!").expect("CString::new failed"); + /// unsafe { + /// puts(to_print.as_ptr()); + /// } + /// ``` + /// + /// # Errors + /// + /// This function will return an error if the supplied bytes contain an + /// internal 0 byte. The [`NulError`] returned will contain the bytes as well as + /// the position of the nul byte. + #[stable(feature = "rust1", since = "1.0.0")] + pub fn new<T: Into<Vec<u8>>>(t: T) -> Result<CString, NulError> { + trait SpecNewImpl { + fn spec_new_impl(self) -> Result<CString, NulError>; + } + + impl<T: Into<Vec<u8>>> SpecNewImpl for T { + default fn spec_new_impl(self) -> Result<CString, NulError> { + let bytes: Vec<u8> = self.into(); + match memchr::memchr(0, &bytes) { + Some(i) => Err(NulError(i, bytes)), + None => Ok(unsafe { CString::_from_vec_unchecked(bytes) }), + } + } + } + + // Specialization for avoiding reallocation + #[inline(always)] // Without that it is not inlined into specializations + fn spec_new_impl_bytes(bytes: &[u8]) -> Result<CString, NulError> { + // We cannot have such large slice that we would overflow here + // but using `checked_add` allows LLVM to assume that capacity never overflows + // and generate twice shorter code. + // `saturating_add` doesn't help for some reason. + let capacity = bytes.len().checked_add(1).unwrap(); + + // Allocate before validation to avoid duplication of allocation code. + // We still need to allocate and copy memory even if we get an error. + let mut buffer = Vec::with_capacity(capacity); + buffer.extend(bytes); + + // Check memory of self instead of new buffer. + // This allows better optimizations if lto enabled. + match memchr::memchr(0, bytes) { + Some(i) => Err(NulError(i, buffer)), + None => Ok(unsafe { CString::_from_vec_unchecked(buffer) }), + } + } + + impl SpecNewImpl for &'_ [u8] { + fn spec_new_impl(self) -> Result<CString, NulError> { + spec_new_impl_bytes(self) + } + } + + impl SpecNewImpl for &'_ str { + fn spec_new_impl(self) -> Result<CString, NulError> { + spec_new_impl_bytes(self.as_bytes()) + } + } + + impl SpecNewImpl for &'_ mut [u8] { + fn spec_new_impl(self) -> Result<CString, NulError> { + spec_new_impl_bytes(self) + } + } + + t.spec_new_impl() + } + + /// Creates a C-compatible string by consuming a byte vector, + /// without checking for interior 0 bytes. + /// + /// Trailing 0 byte will be appended by this function. + /// + /// This method is equivalent to [`CString::new`] except that no runtime + /// assertion is made that `v` contains no 0 bytes, and it requires an + /// actual byte vector, not anything that can be converted to one with Into. + /// + /// # Examples + /// + /// ``` + /// use std::ffi::CString; + /// + /// let raw = b"foo".to_vec(); + /// unsafe { + /// let c_string = CString::from_vec_unchecked(raw); + /// } + /// ``` + #[must_use] + #[stable(feature = "rust1", since = "1.0.0")] + pub unsafe fn from_vec_unchecked(v: Vec<u8>) -> Self { + debug_assert!(memchr::memchr(0, &v).is_none()); + unsafe { Self::_from_vec_unchecked(v) } + } + + unsafe fn _from_vec_unchecked(mut v: Vec<u8>) -> Self { + v.reserve_exact(1); + v.push(0); + Self { inner: v.into_boxed_slice() } + } + + /// Retakes ownership of a `CString` that was transferred to C via + /// [`CString::into_raw`]. + /// + /// Additionally, the length of the string will be recalculated from the pointer. + /// + /// # Safety + /// + /// This should only ever be called with a pointer that was earlier + /// obtained by calling [`CString::into_raw`]. Other usage (e.g., trying to take + /// ownership of a string that was allocated by foreign code) is likely to lead + /// to undefined behavior or allocator corruption. + /// + /// It should be noted that the length isn't just "recomputed," but that + /// the recomputed length must match the original length from the + /// [`CString::into_raw`] call. This means the [`CString::into_raw`]/`from_raw` + /// methods should not be used when passing the string to C functions that can + /// modify the string's length. + /// + /// > **Note:** If you need to borrow a string that was allocated by + /// > foreign code, use [`CStr`]. If you need to take ownership of + /// > a string that was allocated by foreign code, you will need to + /// > make your own provisions for freeing it appropriately, likely + /// > with the foreign code's API to do that. + /// + /// # Examples + /// + /// Creates a `CString`, pass ownership to an `extern` function (via raw pointer), then retake + /// ownership with `from_raw`: + /// + /// ```ignore (extern-declaration) + /// use std::ffi::CString; + /// use std::os::raw::c_char; + /// + /// extern "C" { + /// fn some_extern_function(s: *mut c_char); + /// } + /// + /// let c_string = CString::new("Hello!").expect("CString::new failed"); + /// let raw = c_string.into_raw(); + /// unsafe { + /// some_extern_function(raw); + /// let c_string = CString::from_raw(raw); + /// } + /// ``` + #[must_use = "call `drop(from_raw(ptr))` if you intend to drop the `CString`"] + #[stable(feature = "cstr_memory", since = "1.4.0")] + pub unsafe fn from_raw(ptr: *mut c_char) -> CString { + // SAFETY: This is called with a pointer that was obtained from a call + // to `CString::into_raw` and the length has not been modified. As such, + // we know there is a NUL byte (and only one) at the end and that the + // information about the size of the allocation is correct on Rust's + // side. + unsafe { + extern "C" { + /// Provided by libc or compiler_builtins. + fn strlen(s: *const c_char) -> usize; + } + let len = strlen(ptr) + 1; // Including the NUL byte + let slice = slice::from_raw_parts_mut(ptr, len as usize); + CString { inner: Box::from_raw(slice as *mut [c_char] as *mut [u8]) } + } + } + + /// Consumes the `CString` and transfers ownership of the string to a C caller. + /// + /// The pointer which this function returns must be returned to Rust and reconstituted using + /// [`CString::from_raw`] to be properly deallocated. Specifically, one + /// should *not* use the standard C `free()` function to deallocate + /// this string. + /// + /// Failure to call [`CString::from_raw`] will lead to a memory leak. + /// + /// The C side must **not** modify the length of the string (by writing a + /// `null` somewhere inside the string or removing the final one) before + /// it makes it back into Rust using [`CString::from_raw`]. See the safety section + /// in [`CString::from_raw`]. + /// + /// # Examples + /// + /// ``` + /// use std::ffi::CString; + /// + /// let c_string = CString::new("foo").expect("CString::new failed"); + /// + /// let ptr = c_string.into_raw(); + /// + /// unsafe { + /// assert_eq!(b'f', *ptr as u8); + /// assert_eq!(b'o', *ptr.offset(1) as u8); + /// assert_eq!(b'o', *ptr.offset(2) as u8); + /// assert_eq!(b'\0', *ptr.offset(3) as u8); + /// + /// // retake pointer to free memory + /// let _ = CString::from_raw(ptr); + /// } + /// ``` + #[inline] + #[must_use = "`self` will be dropped if the result is not used"] + #[stable(feature = "cstr_memory", since = "1.4.0")] + pub fn into_raw(self) -> *mut c_char { + Box::into_raw(self.into_inner()) as *mut c_char + } + + /// Converts the `CString` into a [`String`] if it contains valid UTF-8 data. + /// + /// On failure, ownership of the original `CString` is returned. + /// + /// # Examples + /// + /// ``` + /// use std::ffi::CString; + /// + /// let valid_utf8 = vec![b'f', b'o', b'o']; + /// let cstring = CString::new(valid_utf8).expect("CString::new failed"); + /// assert_eq!(cstring.into_string().expect("into_string() call failed"), "foo"); + /// + /// let invalid_utf8 = vec![b'f', 0xff, b'o', b'o']; + /// let cstring = CString::new(invalid_utf8).expect("CString::new failed"); + /// let err = cstring.into_string().err().expect("into_string().err() failed"); + /// assert_eq!(err.utf8_error().valid_up_to(), 1); + /// ``` + #[stable(feature = "cstring_into", since = "1.7.0")] + pub fn into_string(self) -> Result<String, IntoStringError> { + String::from_utf8(self.into_bytes()).map_err(|e| IntoStringError { + error: e.utf8_error(), + inner: unsafe { Self::_from_vec_unchecked(e.into_bytes()) }, + }) + } + + /// Consumes the `CString` and returns the underlying byte buffer. + /// + /// The returned buffer does **not** contain the trailing nul + /// terminator, and it is guaranteed to not have any interior nul + /// bytes. + /// + /// # Examples + /// + /// ``` + /// use std::ffi::CString; + /// + /// let c_string = CString::new("foo").expect("CString::new failed"); + /// let bytes = c_string.into_bytes(); + /// assert_eq!(bytes, vec![b'f', b'o', b'o']); + /// ``` + #[must_use = "`self` will be dropped if the result is not used"] + #[stable(feature = "cstring_into", since = "1.7.0")] + pub fn into_bytes(self) -> Vec<u8> { + let mut vec = into_vec(self.into_inner()); + let _nul = vec.pop(); + debug_assert_eq!(_nul, Some(0u8)); + vec + } + + /// Equivalent to [`CString::into_bytes()`] except that the + /// returned vector includes the trailing nul terminator. + /// + /// # Examples + /// + /// ``` + /// use std::ffi::CString; + /// + /// let c_string = CString::new("foo").expect("CString::new failed"); + /// let bytes = c_string.into_bytes_with_nul(); + /// assert_eq!(bytes, vec![b'f', b'o', b'o', b'\0']); + /// ``` + #[must_use = "`self` will be dropped if the result is not used"] + #[stable(feature = "cstring_into", since = "1.7.0")] + pub fn into_bytes_with_nul(self) -> Vec<u8> { + into_vec(self.into_inner()) + } + + /// Returns the contents of this `CString` as a slice of bytes. + /// + /// The returned slice does **not** contain the trailing nul + /// terminator, and it is guaranteed to not have any interior nul + /// bytes. If you need the nul terminator, use + /// [`CString::as_bytes_with_nul`] instead. + /// + /// # Examples + /// + /// ``` + /// use std::ffi::CString; + /// + /// let c_string = CString::new("foo").expect("CString::new failed"); + /// let bytes = c_string.as_bytes(); + /// assert_eq!(bytes, &[b'f', b'o', b'o']); + /// ``` + #[inline] + #[must_use] + #[stable(feature = "rust1", since = "1.0.0")] + pub fn as_bytes(&self) -> &[u8] { + // SAFETY: CString has a length at least 1 + unsafe { self.inner.get_unchecked(..self.inner.len() - 1) } + } + + /// Equivalent to [`CString::as_bytes()`] except that the + /// returned slice includes the trailing nul terminator. + /// + /// # Examples + /// + /// ``` + /// use std::ffi::CString; + /// + /// let c_string = CString::new("foo").expect("CString::new failed"); + /// let bytes = c_string.as_bytes_with_nul(); + /// assert_eq!(bytes, &[b'f', b'o', b'o', b'\0']); + /// ``` + #[inline] + #[must_use] + #[stable(feature = "rust1", since = "1.0.0")] + pub fn as_bytes_with_nul(&self) -> &[u8] { + &self.inner + } + + /// Extracts a [`CStr`] slice containing the entire string. + /// + /// # Examples + /// + /// ``` + /// use std::ffi::{CString, CStr}; + /// + /// let c_string = CString::new(b"foo".to_vec()).expect("CString::new failed"); + /// let cstr = c_string.as_c_str(); + /// assert_eq!(cstr, + /// CStr::from_bytes_with_nul(b"foo\0").expect("CStr::from_bytes_with_nul failed")); + /// ``` + #[inline] + #[must_use] + #[stable(feature = "as_c_str", since = "1.20.0")] + pub fn as_c_str(&self) -> &CStr { + &*self + } + + /// Converts this `CString` into a boxed [`CStr`]. + /// + /// # Examples + /// + /// ``` + /// use std::ffi::{CString, CStr}; + /// + /// let c_string = CString::new(b"foo".to_vec()).expect("CString::new failed"); + /// let boxed = c_string.into_boxed_c_str(); + /// assert_eq!(&*boxed, + /// CStr::from_bytes_with_nul(b"foo\0").expect("CStr::from_bytes_with_nul failed")); + /// ``` + #[must_use = "`self` will be dropped if the result is not used"] + #[stable(feature = "into_boxed_c_str", since = "1.20.0")] + pub fn into_boxed_c_str(self) -> Box<CStr> { + unsafe { Box::from_raw(Box::into_raw(self.into_inner()) as *mut CStr) } + } + + /// Bypass "move out of struct which implements [`Drop`] trait" restriction. + #[inline] + fn into_inner(self) -> Box<[u8]> { + // Rationale: `mem::forget(self)` invalidates the previous call to `ptr::read(&self.inner)` + // so we use `ManuallyDrop` to ensure `self` is not dropped. + // Then we can return the box directly without invalidating it. + // See https://github.com/rust-lang/rust/issues/62553. + let this = mem::ManuallyDrop::new(self); + unsafe { ptr::read(&this.inner) } + } + + /// Converts a <code>[Vec]<[u8]></code> to a [`CString`] without checking the + /// invariants on the given [`Vec`]. + /// + /// # Safety + /// + /// The given [`Vec`] **must** have one nul byte as its last element. + /// This means it cannot be empty nor have any other nul byte anywhere else. + /// + /// # Example + /// + /// ``` + /// use std::ffi::CString; + /// assert_eq!( + /// unsafe { CString::from_vec_with_nul_unchecked(b"abc\0".to_vec()) }, + /// unsafe { CString::from_vec_unchecked(b"abc".to_vec()) } + /// ); + /// ``` + #[must_use] + #[stable(feature = "cstring_from_vec_with_nul", since = "1.58.0")] + pub unsafe fn from_vec_with_nul_unchecked(v: Vec<u8>) -> Self { + debug_assert!(memchr::memchr(0, &v).unwrap() + 1 == v.len()); + unsafe { Self::_from_vec_with_nul_unchecked(v) } + } + + unsafe fn _from_vec_with_nul_unchecked(v: Vec<u8>) -> Self { + Self { inner: v.into_boxed_slice() } + } + + /// Attempts to converts a <code>[Vec]<[u8]></code> to a [`CString`]. + /// + /// Runtime checks are present to ensure there is only one nul byte in the + /// [`Vec`], its last element. + /// + /// # Errors + /// + /// If a nul byte is present and not the last element or no nul bytes + /// is present, an error will be returned. + /// + /// # Examples + /// + /// A successful conversion will produce the same result as [`CString::new`] + /// when called without the ending nul byte. + /// + /// ``` + /// use std::ffi::CString; + /// assert_eq!( + /// CString::from_vec_with_nul(b"abc\0".to_vec()) + /// .expect("CString::from_vec_with_nul failed"), + /// CString::new(b"abc".to_vec()).expect("CString::new failed") + /// ); + /// ``` + /// + /// An incorrectly formatted [`Vec`] will produce an error. + /// + /// ``` + /// use std::ffi::{CString, FromVecWithNulError}; + /// // Interior nul byte + /// let _: FromVecWithNulError = CString::from_vec_with_nul(b"a\0bc".to_vec()).unwrap_err(); + /// // No nul byte + /// let _: FromVecWithNulError = CString::from_vec_with_nul(b"abc".to_vec()).unwrap_err(); + /// ``` + #[stable(feature = "cstring_from_vec_with_nul", since = "1.58.0")] + pub fn from_vec_with_nul(v: Vec<u8>) -> Result<Self, FromVecWithNulError> { + let nul_pos = memchr::memchr(0, &v); + match nul_pos { + Some(nul_pos) if nul_pos + 1 == v.len() => { + // SAFETY: We know there is only one nul byte, at the end + // of the vec. + Ok(unsafe { Self::_from_vec_with_nul_unchecked(v) }) + } + Some(nul_pos) => Err(FromVecWithNulError { + error_kind: FromBytesWithNulErrorKind::InteriorNul(nul_pos), + bytes: v, + }), + None => Err(FromVecWithNulError { + error_kind: FromBytesWithNulErrorKind::NotNulTerminated, + bytes: v, + }), + } + } +} + +// Turns this `CString` into an empty string to prevent +// memory-unsafe code from working by accident. Inline +// to prevent LLVM from optimizing it away in debug builds. +#[stable(feature = "cstring_drop", since = "1.13.0")] +impl Drop for CString { + #[inline] + fn drop(&mut self) { + unsafe { + *self.inner.get_unchecked_mut(0) = 0; + } + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl ops::Deref for CString { + type Target = CStr; + + #[inline] + fn deref(&self) -> &CStr { + unsafe { CStr::from_bytes_with_nul_unchecked(self.as_bytes_with_nul()) } + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl fmt::Debug for CString { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + fmt::Debug::fmt(&**self, f) + } +} + +#[stable(feature = "cstring_into", since = "1.7.0")] +impl From<CString> for Vec<u8> { + /// Converts a [`CString`] into a <code>[Vec]<[u8]></code>. + /// + /// The conversion consumes the [`CString`], and removes the terminating NUL byte. + #[inline] + fn from(s: CString) -> Vec<u8> { + s.into_bytes() + } +} + +#[stable(feature = "cstr_default", since = "1.10.0")] +impl Default for CString { + /// Creates an empty `CString`. + fn default() -> CString { + let a: &CStr = Default::default(); + a.to_owned() + } +} + +#[stable(feature = "cstr_borrow", since = "1.3.0")] +impl Borrow<CStr> for CString { + #[inline] + fn borrow(&self) -> &CStr { + self + } +} + +#[stable(feature = "cstring_from_cow_cstr", since = "1.28.0")] +impl<'a> From<Cow<'a, CStr>> for CString { + /// Converts a `Cow<'a, CStr>` into a `CString`, by copying the contents if they are + /// borrowed. + #[inline] + fn from(s: Cow<'a, CStr>) -> Self { + s.into_owned() + } +} + +#[cfg(not(test))] +#[stable(feature = "box_from_c_str", since = "1.17.0")] +impl From<&CStr> for Box<CStr> { + /// Converts a `&CStr` into a `Box<CStr>`, + /// by copying the contents into a newly allocated [`Box`]. + fn from(s: &CStr) -> Box<CStr> { + let boxed: Box<[u8]> = Box::from(s.to_bytes_with_nul()); + unsafe { Box::from_raw(Box::into_raw(boxed) as *mut CStr) } + } +} + +#[stable(feature = "box_from_cow", since = "1.45.0")] +impl From<Cow<'_, CStr>> for Box<CStr> { + /// Converts a `Cow<'a, CStr>` into a `Box<CStr>`, + /// by copying the contents if they are borrowed. + #[inline] + fn from(cow: Cow<'_, CStr>) -> Box<CStr> { + match cow { + Cow::Borrowed(s) => Box::from(s), + Cow::Owned(s) => Box::from(s), + } + } +} + +#[stable(feature = "c_string_from_box", since = "1.18.0")] +impl From<Box<CStr>> for CString { + /// Converts a <code>[Box]<[CStr]></code> into a [`CString`] without copying or allocating. + #[inline] + fn from(s: Box<CStr>) -> CString { + let raw = Box::into_raw(s) as *mut [u8]; + CString { inner: unsafe { Box::from_raw(raw) } } + } +} + +#[stable(feature = "cstring_from_vec_of_nonzerou8", since = "1.43.0")] +impl From<Vec<NonZeroU8>> for CString { + /// Converts a <code>[Vec]<[NonZeroU8]></code> into a [`CString`] without + /// copying nor checking for inner null bytes. + #[inline] + fn from(v: Vec<NonZeroU8>) -> CString { + unsafe { + // Transmute `Vec<NonZeroU8>` to `Vec<u8>`. + let v: Vec<u8> = { + // SAFETY: + // - transmuting between `NonZeroU8` and `u8` is sound; + // - `alloc::Layout<NonZeroU8> == alloc::Layout<u8>`. + let (ptr, len, cap): (*mut NonZeroU8, _, _) = Vec::into_raw_parts(v); + Vec::from_raw_parts(ptr.cast::<u8>(), len, cap) + }; + // SAFETY: `v` cannot contain null bytes, given the type-level + // invariant of `NonZeroU8`. + Self::_from_vec_unchecked(v) + } + } +} + +#[cfg(not(test))] +#[stable(feature = "more_box_slice_clone", since = "1.29.0")] +impl Clone for Box<CStr> { + #[inline] + fn clone(&self) -> Self { + (**self).into() + } +} + +#[stable(feature = "box_from_c_string", since = "1.20.0")] +impl From<CString> for Box<CStr> { + /// Converts a [`CString`] into a <code>[Box]<[CStr]></code> without copying or allocating. + #[inline] + fn from(s: CString) -> Box<CStr> { + s.into_boxed_c_str() + } +} + +#[stable(feature = "cow_from_cstr", since = "1.28.0")] +impl<'a> From<CString> for Cow<'a, CStr> { + /// Converts a [`CString`] into an owned [`Cow`] without copying or allocating. + #[inline] + fn from(s: CString) -> Cow<'a, CStr> { + Cow::Owned(s) + } +} + +#[stable(feature = "cow_from_cstr", since = "1.28.0")] +impl<'a> From<&'a CStr> for Cow<'a, CStr> { + /// Converts a [`CStr`] into a borrowed [`Cow`] without copying or allocating. + #[inline] + fn from(s: &'a CStr) -> Cow<'a, CStr> { + Cow::Borrowed(s) + } +} + +#[stable(feature = "cow_from_cstr", since = "1.28.0")] +impl<'a> From<&'a CString> for Cow<'a, CStr> { + /// Converts a `&`[`CString`] into a borrowed [`Cow`] without copying or allocating. + #[inline] + fn from(s: &'a CString) -> Cow<'a, CStr> { + Cow::Borrowed(s.as_c_str()) + } +} + +#[stable(feature = "shared_from_slice2", since = "1.24.0")] +impl From<CString> for Arc<CStr> { + /// Converts a [`CString`] into an <code>[Arc]<[CStr]></code> by moving the [`CString`] + /// data into a new [`Arc`] buffer. + #[inline] + fn from(s: CString) -> Arc<CStr> { + let arc: Arc<[u8]> = Arc::from(s.into_inner()); + unsafe { Arc::from_raw(Arc::into_raw(arc) as *const CStr) } + } +} + +#[stable(feature = "shared_from_slice2", since = "1.24.0")] +impl From<&CStr> for Arc<CStr> { + /// Converts a `&CStr` into a `Arc<CStr>`, + /// by copying the contents into a newly allocated [`Arc`]. + #[inline] + fn from(s: &CStr) -> Arc<CStr> { + let arc: Arc<[u8]> = Arc::from(s.to_bytes_with_nul()); + unsafe { Arc::from_raw(Arc::into_raw(arc) as *const CStr) } + } +} + +#[stable(feature = "shared_from_slice2", since = "1.24.0")] +impl From<CString> for Rc<CStr> { + /// Converts a [`CString`] into an <code>[Rc]<[CStr]></code> by moving the [`CString`] + /// data into a new [`Arc`] buffer. + #[inline] + fn from(s: CString) -> Rc<CStr> { + let rc: Rc<[u8]> = Rc::from(s.into_inner()); + unsafe { Rc::from_raw(Rc::into_raw(rc) as *const CStr) } + } +} + +#[stable(feature = "shared_from_slice2", since = "1.24.0")] +impl From<&CStr> for Rc<CStr> { + /// Converts a `&CStr` into a `Rc<CStr>`, + /// by copying the contents into a newly allocated [`Rc`]. + #[inline] + fn from(s: &CStr) -> Rc<CStr> { + let rc: Rc<[u8]> = Rc::from(s.to_bytes_with_nul()); + unsafe { Rc::from_raw(Rc::into_raw(rc) as *const CStr) } + } +} + +#[cfg(not(test))] +#[stable(feature = "default_box_extra", since = "1.17.0")] +impl Default for Box<CStr> { + fn default() -> Box<CStr> { + let boxed: Box<[u8]> = Box::from([0]); + unsafe { Box::from_raw(Box::into_raw(boxed) as *mut CStr) } + } +} + +impl NulError { + /// Returns the position of the nul byte in the slice that caused + /// [`CString::new`] to fail. + /// + /// # Examples + /// + /// ``` + /// use std::ffi::CString; + /// + /// let nul_error = CString::new("foo\0bar").unwrap_err(); + /// assert_eq!(nul_error.nul_position(), 3); + /// + /// let nul_error = CString::new("foo bar\0").unwrap_err(); + /// assert_eq!(nul_error.nul_position(), 7); + /// ``` + #[must_use] + #[stable(feature = "rust1", since = "1.0.0")] + pub fn nul_position(&self) -> usize { + self.0 + } + + /// Consumes this error, returning the underlying vector of bytes which + /// generated the error in the first place. + /// + /// # Examples + /// + /// ``` + /// use std::ffi::CString; + /// + /// let nul_error = CString::new("foo\0bar").unwrap_err(); + /// assert_eq!(nul_error.into_vec(), b"foo\0bar"); + /// ``` + #[must_use = "`self` will be dropped if the result is not used"] + #[stable(feature = "rust1", since = "1.0.0")] + pub fn into_vec(self) -> Vec<u8> { + self.1 + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl fmt::Display for NulError { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + write!(f, "nul byte found in provided data at position: {}", self.0) + } +} + +#[stable(feature = "cstring_from_vec_with_nul", since = "1.58.0")] +impl fmt::Display for FromVecWithNulError { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + match self.error_kind { + FromBytesWithNulErrorKind::InteriorNul(pos) => { + write!(f, "data provided contains an interior nul byte at pos {pos}") + } + FromBytesWithNulErrorKind::NotNulTerminated => { + write!(f, "data provided is not nul terminated") + } + } + } +} + +impl IntoStringError { + /// Consumes this error, returning original [`CString`] which generated the + /// error. + #[must_use = "`self` will be dropped if the result is not used"] + #[stable(feature = "cstring_into", since = "1.7.0")] + pub fn into_cstring(self) -> CString { + self.inner + } + + /// Access the underlying UTF-8 error that was the cause of this error. + #[must_use] + #[stable(feature = "cstring_into", since = "1.7.0")] + pub fn utf8_error(&self) -> Utf8Error { + self.error + } + + #[doc(hidden)] + #[unstable(feature = "cstr_internals", issue = "none")] + pub fn __source(&self) -> &Utf8Error { + &self.error + } +} + +impl IntoStringError { + fn description(&self) -> &str { + "C string contained non-utf8 bytes" + } +} + +#[stable(feature = "cstring_into", since = "1.7.0")] +impl fmt::Display for IntoStringError { + #[allow(deprecated, deprecated_in_future)] + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + self.description().fmt(f) + } +} + +#[stable(feature = "cstr_borrow", since = "1.3.0")] +impl ToOwned for CStr { + type Owned = CString; + + fn to_owned(&self) -> CString { + CString { inner: self.to_bytes_with_nul().into() } + } + + fn clone_into(&self, target: &mut CString) { + let mut b = into_vec(mem::take(&mut target.inner)); + self.to_bytes_with_nul().clone_into(&mut b); + target.inner = b.into_boxed_slice(); + } +} + +#[stable(feature = "cstring_asref", since = "1.7.0")] +impl From<&CStr> for CString { + fn from(s: &CStr) -> CString { + s.to_owned() + } +} + +#[stable(feature = "cstring_asref", since = "1.7.0")] +impl ops::Index<ops::RangeFull> for CString { + type Output = CStr; + + #[inline] + fn index(&self, _index: ops::RangeFull) -> &CStr { + self + } +} + +#[stable(feature = "cstring_asref", since = "1.7.0")] +impl AsRef<CStr> for CString { + #[inline] + fn as_ref(&self) -> &CStr { + self + } +} + +#[cfg(bootstrap)] +#[doc(hidden)] +#[unstable(feature = "cstr_internals", issue = "none")] +pub trait CStrExt { + /// Converts a `CStr` into a <code>[Cow]<[str]></code>. + /// + /// If the contents of the `CStr` are valid UTF-8 data, this + /// function will return a <code>[Cow]::[Borrowed]\(&[str])</code> + /// with the corresponding <code>&[str]</code> slice. Otherwise, it will + /// replace any invalid UTF-8 sequences with + /// [`U+FFFD REPLACEMENT CHARACTER`][U+FFFD] and return a + /// <code>[Cow]::[Owned]\(&[str])</code> with the result. + /// + /// [str]: prim@str "str" + /// [Borrowed]: Cow::Borrowed + /// [Owned]: Cow::Owned + /// [U+FFFD]: crate::char::REPLACEMENT_CHARACTER "std::char::REPLACEMENT_CHARACTER" + /// + /// # Examples + /// + /// Calling `to_string_lossy` on a `CStr` containing valid UTF-8: + /// + /// ``` + /// use std::borrow::Cow; + /// use std::ffi::CStr; + /// + /// let cstr = CStr::from_bytes_with_nul(b"Hello World\0") + /// .expect("CStr::from_bytes_with_nul failed"); + /// assert_eq!(cstr.to_string_lossy(), Cow::Borrowed("Hello World")); + /// ``` + /// + /// Calling `to_string_lossy` on a `CStr` containing invalid UTF-8: + /// + /// ``` + /// use std::borrow::Cow; + /// use std::ffi::CStr; + /// + /// let cstr = CStr::from_bytes_with_nul(b"Hello \xF0\x90\x80World\0") + /// .expect("CStr::from_bytes_with_nul failed"); + /// assert_eq!( + /// cstr.to_string_lossy(), + /// Cow::Owned(String::from("Hello �World")) as Cow<'_, str> + /// ); + /// ``` + #[must_use = "this returns the result of the operation, \ + without modifying the original"] + #[stable(feature = "cstr_to_str", since = "1.4.0")] + fn to_string_lossy(&self) -> Cow<'_, str>; + + /// Converts a <code>[Box]<[CStr]></code> into a [`CString`] without copying or allocating. + /// + /// # Examples + /// + /// ``` + /// use std::ffi::CString; + /// + /// let c_string = CString::new(b"foo".to_vec()).expect("CString::new failed"); + /// let boxed = c_string.into_boxed_c_str(); + /// assert_eq!(boxed.into_c_string(), CString::new("foo").expect("CString::new failed")); + /// ``` + #[must_use = "`self` will be dropped if the result is not used"] + #[stable(feature = "into_boxed_c_str", since = "1.20.0")] + fn into_c_string(self: Box<Self>) -> CString; +} + +#[cfg(bootstrap)] +#[unstable(feature = "cstr_internals", issue = "none")] +impl CStrExt for CStr { + fn to_string_lossy(&self) -> Cow<'_, str> { + String::from_utf8_lossy(self.to_bytes()) + } + + fn into_c_string(self: Box<Self>) -> CString { + CString::from(self) + } +} + +#[cfg(not(bootstrap))] +#[cfg(not(test))] +impl CStr { + /// Converts a `CStr` into a <code>[Cow]<[str]></code>. + /// + /// If the contents of the `CStr` are valid UTF-8 data, this + /// function will return a <code>[Cow]::[Borrowed]\(&[str])</code> + /// with the corresponding <code>&[str]</code> slice. Otherwise, it will + /// replace any invalid UTF-8 sequences with + /// [`U+FFFD REPLACEMENT CHARACTER`][U+FFFD] and return a + /// <code>[Cow]::[Owned]\(&[str])</code> with the result. + /// + /// [str]: prim@str "str" + /// [Borrowed]: Cow::Borrowed + /// [Owned]: Cow::Owned + /// [U+FFFD]: core::char::REPLACEMENT_CHARACTER "std::char::REPLACEMENT_CHARACTER" + /// + /// # Examples + /// + /// Calling `to_string_lossy` on a `CStr` containing valid UTF-8: + /// + /// ``` + /// use std::borrow::Cow; + /// use std::ffi::CStr; + /// + /// let cstr = CStr::from_bytes_with_nul(b"Hello World\0") + /// .expect("CStr::from_bytes_with_nul failed"); + /// assert_eq!(cstr.to_string_lossy(), Cow::Borrowed("Hello World")); + /// ``` + /// + /// Calling `to_string_lossy` on a `CStr` containing invalid UTF-8: + /// + /// ``` + /// use std::borrow::Cow; + /// use std::ffi::CStr; + /// + /// let cstr = CStr::from_bytes_with_nul(b"Hello \xF0\x90\x80World\0") + /// .expect("CStr::from_bytes_with_nul failed"); + /// assert_eq!( + /// cstr.to_string_lossy(), + /// Cow::Owned(String::from("Hello �World")) as Cow<'_, str> + /// ); + /// ``` + #[rustc_allow_incoherent_impl] + #[must_use = "this returns the result of the operation, \ + without modifying the original"] + #[stable(feature = "cstr_to_str", since = "1.4.0")] + pub fn to_string_lossy(&self) -> Cow<'_, str> { + String::from_utf8_lossy(self.to_bytes()) + } + + /// Converts a <code>[Box]<[CStr]></code> into a [`CString`] without copying or allocating. + /// + /// # Examples + /// + /// ``` + /// use std::ffi::CString; + /// + /// let c_string = CString::new(b"foo".to_vec()).expect("CString::new failed"); + /// let boxed = c_string.into_boxed_c_str(); + /// assert_eq!(boxed.into_c_string(), CString::new("foo").expect("CString::new failed")); + /// ``` + #[rustc_allow_incoherent_impl] + #[must_use = "`self` will be dropped if the result is not used"] + #[stable(feature = "into_boxed_c_str", since = "1.20.0")] + pub fn into_c_string(self: Box<Self>) -> CString { + CString::from(self) + } +} diff --git a/library/alloc/src/ffi/c_str/tests.rs b/library/alloc/src/ffi/c_str/tests.rs new file mode 100644 index 00000000000..0b7476d5cc7 --- /dev/null +++ b/library/alloc/src/ffi/c_str/tests.rs @@ -0,0 +1,228 @@ +use super::*; +use crate::rc::Rc; +use crate::sync::Arc; +use core::assert_matches::assert_matches; +use core::ffi::FromBytesUntilNulError; +use core::hash::{Hash, Hasher}; + +#[allow(deprecated)] +use core::hash::SipHasher13 as DefaultHasher; + +#[test] +fn c_to_rust() { + let data = b"123\0"; + let ptr = data.as_ptr() as *const c_char; + unsafe { + assert_eq!(CStr::from_ptr(ptr).to_bytes(), b"123"); + assert_eq!(CStr::from_ptr(ptr).to_bytes_with_nul(), b"123\0"); + } +} + +#[test] +fn simple() { + let s = CString::new("1234").unwrap(); + assert_eq!(s.as_bytes(), b"1234"); + assert_eq!(s.as_bytes_with_nul(), b"1234\0"); +} + +#[test] +fn build_with_zero1() { + assert!(CString::new(&b"\0"[..]).is_err()); +} +#[test] +fn build_with_zero2() { + assert!(CString::new(vec![0]).is_err()); +} + +#[test] +fn formatted() { + let s = CString::new(&b"abc\x01\x02\n\xE2\x80\xA6\xFF"[..]).unwrap(); + assert_eq!(format!("{s:?}"), r#""abc\x01\x02\n\xe2\x80\xa6\xff""#); +} + +#[test] +fn borrowed() { + unsafe { + let s = CStr::from_ptr(b"12\0".as_ptr() as *const _); + assert_eq!(s.to_bytes(), b"12"); + assert_eq!(s.to_bytes_with_nul(), b"12\0"); + } +} + +#[test] +fn to_owned() { + let data = b"123\0"; + let ptr = data.as_ptr() as *const c_char; + + let owned = unsafe { CStr::from_ptr(ptr).to_owned() }; + assert_eq!(owned.as_bytes_with_nul(), data); +} + +#[test] +fn equal_hash() { + let data = b"123\xE2\xFA\xA6\0"; + let ptr = data.as_ptr() as *const c_char; + let cstr: &'static CStr = unsafe { CStr::from_ptr(ptr) }; + + #[allow(deprecated)] + let mut s = DefaultHasher::new(); + cstr.hash(&mut s); + let cstr_hash = s.finish(); + #[allow(deprecated)] + let mut s = DefaultHasher::new(); + CString::new(&data[..data.len() - 1]).unwrap().hash(&mut s); + let cstring_hash = s.finish(); + + assert_eq!(cstr_hash, cstring_hash); +} + +#[test] +fn from_bytes_with_nul() { + let data = b"123\0"; + let cstr = CStr::from_bytes_with_nul(data); + assert_eq!(cstr.map(CStr::to_bytes), Ok(&b"123"[..])); + let cstr = CStr::from_bytes_with_nul(data); + assert_eq!(cstr.map(CStr::to_bytes_with_nul), Ok(&b"123\0"[..])); + + unsafe { + let cstr = CStr::from_bytes_with_nul(data); + let cstr_unchecked = CStr::from_bytes_with_nul_unchecked(data); + assert_eq!(cstr, Ok(cstr_unchecked)); + } +} + +#[test] +fn from_bytes_with_nul_unterminated() { + let data = b"123"; + let cstr = CStr::from_bytes_with_nul(data); + assert!(cstr.is_err()); +} + +#[test] +fn from_bytes_with_nul_interior() { + let data = b"1\023\0"; + let cstr = CStr::from_bytes_with_nul(data); + assert!(cstr.is_err()); +} + +#[test] +fn cstr_from_bytes_until_nul() { + // Test an empty slice. This should fail because it + // does not contain a nul byte. + let b = b""; + assert_matches!(CStr::from_bytes_until_nul(&b[..]), Err(FromBytesUntilNulError { .. })); + + // Test a non-empty slice, that does not contain a nul byte. + let b = b"hello"; + assert_matches!(CStr::from_bytes_until_nul(&b[..]), Err(FromBytesUntilNulError { .. })); + + // Test an empty nul-terminated string + let b = b"\0"; + let r = CStr::from_bytes_until_nul(&b[..]).unwrap(); + assert_eq!(r.to_bytes(), b""); + + // Test a slice with the nul byte in the middle + let b = b"hello\0world!"; + let r = CStr::from_bytes_until_nul(&b[..]).unwrap(); + assert_eq!(r.to_bytes(), b"hello"); + + // Test a slice with the nul byte at the end + let b = b"hello\0"; + let r = CStr::from_bytes_until_nul(&b[..]).unwrap(); + assert_eq!(r.to_bytes(), b"hello"); + + // Test a slice with two nul bytes at the end + let b = b"hello\0\0"; + let r = CStr::from_bytes_until_nul(&b[..]).unwrap(); + assert_eq!(r.to_bytes(), b"hello"); + + // Test a slice containing lots of nul bytes + let b = b"\0\0\0\0"; + let r = CStr::from_bytes_until_nul(&b[..]).unwrap(); + assert_eq!(r.to_bytes(), b""); +} + +#[test] +fn into_boxed() { + let orig: &[u8] = b"Hello, world!\0"; + let cstr = CStr::from_bytes_with_nul(orig).unwrap(); + let boxed: Box<CStr> = Box::from(cstr); + let cstring = cstr.to_owned().into_boxed_c_str().into_c_string(); + assert_eq!(cstr, &*boxed); + assert_eq!(&*boxed, &*cstring); + assert_eq!(&*cstring, cstr); +} + +#[test] +fn boxed_default() { + let boxed = <Box<CStr>>::default(); + assert_eq!(boxed.to_bytes_with_nul(), &[0]); +} + +#[test] +fn test_c_str_clone_into() { + let mut c_string = CString::new("lorem").unwrap(); + let c_ptr = c_string.as_ptr(); + let c_str = CStr::from_bytes_with_nul(b"ipsum\0").unwrap(); + c_str.clone_into(&mut c_string); + assert_eq!(c_str, c_string.as_c_str()); + // The exact same size shouldn't have needed to move its allocation + assert_eq!(c_ptr, c_string.as_ptr()); +} + +#[test] +fn into_rc() { + let orig: &[u8] = b"Hello, world!\0"; + let cstr = CStr::from_bytes_with_nul(orig).unwrap(); + let rc: Rc<CStr> = Rc::from(cstr); + let arc: Arc<CStr> = Arc::from(cstr); + + assert_eq!(&*rc, cstr); + assert_eq!(&*arc, cstr); + + let rc2: Rc<CStr> = Rc::from(cstr.to_owned()); + let arc2: Arc<CStr> = Arc::from(cstr.to_owned()); + + assert_eq!(&*rc2, cstr); + assert_eq!(&*arc2, cstr); +} + +#[test] +fn cstr_const_constructor() { + const CSTR: &CStr = unsafe { CStr::from_bytes_with_nul_unchecked(b"Hello, world!\0") }; + + assert_eq!(CSTR.to_str().unwrap(), "Hello, world!"); +} + +#[test] +fn cstr_index_from() { + let original = b"Hello, world!\0"; + let cstr = CStr::from_bytes_with_nul(original).unwrap(); + let result = CStr::from_bytes_with_nul(&original[7..]).unwrap(); + + assert_eq!(&cstr[7..], result); +} + +#[test] +#[should_panic] +fn cstr_index_from_empty() { + let original = b"Hello, world!\0"; + let cstr = CStr::from_bytes_with_nul(original).unwrap(); + let _ = &cstr[original.len()..]; +} + +#[test] +fn c_string_from_empty_string() { + let original = ""; + let cstring = CString::new(original).unwrap(); + assert_eq!(original.as_bytes(), cstring.as_bytes()); + assert_eq!([b'\0'], cstring.as_bytes_with_nul()); +} + +#[test] +fn c_str_from_empty_string() { + let original = b"\0"; + let cstr = CStr::from_bytes_with_nul(original).unwrap(); + assert_eq!([] as [u8; 0], cstr.to_bytes()); + assert_eq!([b'\0'], cstr.to_bytes_with_nul()); +} diff --git a/library/alloc/src/ffi/mod.rs b/library/alloc/src/ffi/mod.rs new file mode 100644 index 00000000000..6b2e4af45b2 --- /dev/null +++ b/library/alloc/src/ffi/mod.rs @@ -0,0 +1,91 @@ +//! Utilities related to FFI bindings. +//! +//! This module provides utilities to handle data across non-Rust +//! interfaces, like other programming languages and the underlying +//! operating system. It is mainly of use for FFI (Foreign Function +//! Interface) bindings and code that needs to exchange C-like strings +//! with other languages. +//! +//! # Overview +//! +//! Rust represents owned strings with the [`String`] type, and +//! borrowed slices of strings with the [`str`] primitive. Both are +//! always in UTF-8 encoding, and may contain nul bytes in the middle, +//! i.e., if you look at the bytes that make up the string, there may +//! be a `\0` among them. Both `String` and `str` store their length +//! explicitly; there are no nul terminators at the end of strings +//! like in C. +//! +//! C strings are different from Rust strings: +//! +//! * **Encodings** - Rust strings are UTF-8, but C strings may use +//! other encodings. If you are using a string from C, you should +//! check its encoding explicitly, rather than just assuming that it +//! is UTF-8 like you can do in Rust. +//! +//! * **Character size** - C strings may use `char` or `wchar_t`-sized +//! characters; please **note** that C's `char` is different from Rust's. +//! The C standard leaves the actual sizes of those types open to +//! interpretation, but defines different APIs for strings made up of +//! each character type. Rust strings are always UTF-8, so different +//! Unicode characters will be encoded in a variable number of bytes +//! each. The Rust type [`char`] represents a '[Unicode scalar +//! value]', which is similar to, but not the same as, a '[Unicode +//! code point]'. +//! +//! * **Nul terminators and implicit string lengths** - Often, C +//! strings are nul-terminated, i.e., they have a `\0` character at the +//! end. The length of a string buffer is not stored, but has to be +//! calculated; to compute the length of a string, C code must +//! manually call a function like `strlen()` for `char`-based strings, +//! or `wcslen()` for `wchar_t`-based ones. Those functions return +//! the number of characters in the string excluding the nul +//! terminator, so the buffer length is really `len+1` characters. +//! Rust strings don't have a nul terminator; their length is always +//! stored and does not need to be calculated. While in Rust +//! accessing a string's length is an *O*(1) operation (because the +//! length is stored); in C it is an *O*(*n*) operation because the +//! length needs to be computed by scanning the string for the nul +//! terminator. +//! +//! * **Internal nul characters** - When C strings have a nul +//! terminator character, this usually means that they cannot have nul +//! characters in the middle — a nul character would essentially +//! truncate the string. Rust strings *can* have nul characters in +//! the middle, because nul does not have to mark the end of the +//! string in Rust. +//! +//! # Representations of non-Rust strings +//! +//! [`CString`] and [`CStr`] are useful when you need to transfer +//! UTF-8 strings to and from languages with a C ABI, like Python. +//! +//! * **From Rust to C:** [`CString`] represents an owned, C-friendly +//! string: it is nul-terminated, and has no internal nul characters. +//! Rust code can create a [`CString`] out of a normal string (provided +//! that the string doesn't have nul characters in the middle), and +//! then use a variety of methods to obtain a raw <code>\*mut [u8]</code> that can +//! then be passed as an argument to functions which use the C +//! conventions for strings. +//! +//! * **From C to Rust:** [`CStr`] represents a borrowed C string; it +//! is what you would use to wrap a raw <code>\*const [u8]</code> that you got from +//! a C function. A [`CStr`] is guaranteed to be a nul-terminated array +//! of bytes. Once you have a [`CStr`], you can convert it to a Rust +//! <code>&[str]</code> if it's valid UTF-8, or lossily convert it by adding +//! replacement characters. +//! +//! [`String`]: crate::string::String +//! [`CStr`]: core::ffi::CStr + +#![unstable(feature = "alloc_ffi", issue = "94079")] + +#[cfg(bootstrap)] +#[unstable(feature = "cstr_internals", issue = "none")] +pub use self::c_str::CStrExt; +#[stable(feature = "cstring_from_vec_with_nul", since = "1.58.0")] +pub use self::c_str::FromVecWithNulError; +#[stable(feature = "rust1", since = "1.0.0")] +pub use self::c_str::{CString, IntoStringError, NulError}; + +mod c_str; diff --git a/library/alloc/src/lib.rs b/library/alloc/src/lib.rs index c54001dceea..f577afdce1e 100644 --- a/library/alloc/src/lib.rs +++ b/library/alloc/src/lib.rs @@ -91,6 +91,7 @@ #![feature(array_chunks)] #![feature(array_methods)] #![feature(array_windows)] +#![feature(assert_matches)] #![feature(async_iterator)] #![feature(coerce_unsized)] #![cfg_attr(not(no_global_oom_handling), feature(const_alloc_error))] @@ -105,8 +106,10 @@ #![feature(const_maybe_uninit_as_mut_ptr)] #![feature(const_refs_to_cell)] #![feature(core_intrinsics)] +#![feature(core_ffi_c)] #![feature(const_eval_select)] #![feature(const_pin)] +#![feature(cstr_from_bytes_until_nul)] #![feature(dispatch_from_dyn)] #![feature(exact_size_is_empty)] #![feature(extend_one)] @@ -152,6 +155,7 @@ #![feature(exclusive_range_pattern)] #![feature(fundamental)] #![cfg_attr(not(test), feature(generator_trait))] +#![feature(hashmap_internals)] #![feature(lang_items)] #![feature(let_else)] #![feature(min_specialization)] @@ -160,6 +164,7 @@ #![feature(nll)] // Not necessary, but here to test the `nll` feature. #![feature(rustc_allow_const_fn_unstable)] #![feature(rustc_attrs)] +#![feature(slice_internals)] #![feature(staged_api)] #![cfg_attr(test, feature(test))] #![feature(unboxed_closures)] @@ -205,6 +210,8 @@ mod boxed { } pub mod borrow; pub mod collections; +#[cfg(not(no_global_oom_handling))] +pub mod ffi; pub mod fmt; pub mod rc; pub mod slice; diff --git a/library/alloc/src/slice.rs b/library/alloc/src/slice.rs index 31edbe0c5af..02a47c57b8a 100644 --- a/library/alloc/src/slice.rs +++ b/library/alloc/src/slice.rs @@ -153,7 +153,7 @@ pub use hack::to_vec; // functions are actually methods that are in `impl [T]` but not in // `core::slice::SliceExt` - we need to supply these functions for the // `test_permutations` test -mod hack { +pub(crate) mod hack { use core::alloc::Allocator; use crate::boxed::Box; |