// SPDX-License-Identifier: GPL-2.0 //! String representations. use crate::alloc::{flags::*, AllocError, KVec};use crate::fmt::{self, Write};use core::ops::{self, Deref, DerefMut, Index}; use crate::prelude::*; /// Byte string without UTF-8 validity guarantee.#[repr(transparent)]pub struct BStr([u8]); impl BStr { /// Returns the length of this string. #[inline] pub const fn len(&self) -> usize { self.0.len() } /// Returns `true` if the string is empty. #[inline] pub const fn is_empty(&self) -> bool { self.len() == 0 } /// Creates a [`BStr`] from a `[u8]`. #[inline] pub const fn from_bytes(bytes: &[u8]) -> &Self { // SAFETY: `BStr` is transparent to `[u8]`. unsafe { &*(core::ptr::from_ref(bytes) as *const BStr) } } /// Strip a prefix from `self`. Delegates to [`slice::strip_prefix`]. /// /// # Examples /// /// ``` /// # use kernel::b_str; /// assert_eq!(Some(b_str!("bar")), b_str!("foobar").strip_prefix(b_str!("foo"))); /// assert_eq!(None, b_str!("foobar").strip_prefix(b_str!("bar"))); /// assert_eq!(Some(b_str!("foobar")), b_str!("foobar").strip_prefix(b_str!(""))); /// assert_eq!(Some(b_str!("")), b_str!("foobar").strip_prefix(b_str!("foobar"))); /// ``` pub fn strip_prefix(&self, pattern: impl AsRef<Self>) -> Option<&BStr> { self.deref() .strip_prefix(pattern.as_ref().deref()) .map(Self::from_bytes) }} impl fmt::Display for BStr { /// Formats printable ASCII characters, escaping the rest. /// /// ``` /// # use kernel::{prelude::fmt, b_str, str::{BStr, CString}}; /// let ascii = b_str!("Hello, BStr!"); /// let s = CString::try_from_fmt(fmt!("{ascii}"))?; /// assert_eq!(s.to_bytes(), "Hello, BStr!".as_bytes()); /// /// let non_ascii = b_str!("π¦"); /// let s = CString::try_from_fmt(fmt!("{non_ascii}"))?; /// assert_eq!(s.to_bytes(), "\\xf0\\x9f\\xa6\\x80".as_bytes()); /// # Ok::<(), kernel::error::Error>(()) /// ``` fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { for &b in &self.0 { match b { // Common escape codes. b'\t' => f.write_str("\\t")?, b'\n' => f.write_str("\\n")?, b'\r' => f.write_str("\\r")?, // Printable characters. 0x20..=0x7e => f.write_char(b as char)?, _ => write!(f, "\\x{b:02x}")?, } } Ok(()) }} impl fmt::Debug for BStr { /// Formats printable ASCII characters with a double quote on either end, /// escaping the rest. /// /// ``` /// # use kernel::{prelude::fmt, b_str, str::{BStr, CString}}; /// // Embedded double quotes are escaped. /// let ascii = b_str!("Hello, \"BStr\"!"); /// let s = CString::try_from_fmt(fmt!("{ascii:?}"))?; /// assert_eq!(s.to_bytes(), "\"Hello, \\\"BStr\\\"!\"".as_bytes()); /// /// let non_ascii = b_str!("πΊ"); /// let s = CString::try_from_fmt(fmt!("{non_ascii:?}"))?; /// assert_eq!(s.to_bytes(), "\"\\xf0\\x9f\\x98\\xba\"".as_bytes()); /// # Ok::<(), kernel::error::Error>(()) /// ``` fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { f.write_char('"')?; for &b in &self.0 { match b { // Common escape codes. b'\t' => f.write_str("\\t")?, b'\n' => f.write_str("\\n")?, b'\r' => f.write_str("\\r")?, // String escape characters. b'\"' => f.write_str("\\\"")?, b'\\' => f.write_str("\\\\")?, // Printable characters. 0x20..=0x7e => f.write_char(b as char)?, _ => write!(f, "\\x{b:02x}")?, } } f.write_char('"') }} impl Deref for BStr { type Target = [u8]; #[inline] fn deref(&self) -> &Self::Target { &self.0 }} impl PartialEq for BStr { fn eq(&self, other: &Self) -> bool { self.deref().eq(other.deref()) }} impl<Idx> Index<Idx> for BStrwhere [u8]: Index<Idx, Output = [u8]>,{ type Output = Self; fn index(&self, index: Idx) -> &Self::Output { BStr::from_bytes(&self.0[index]) }} impl AsRef<BStr> for [u8] { fn as_ref(&self) -> &BStr { BStr::from_bytes(self) }} impl AsRef<BStr> for BStr { fn as_ref(&self) -> &BStr { self }} /// Creates a new [`BStr`] from a string literal.////// `b_str!` converts the supplied string literal to byte string, so non-ASCII/// characters can be included.////// # Examples////// ```/// # use kernel::b_str;/// # use kernel::str::BStr;/// const MY_BSTR: &BStr = b_str!("My awesome BStr!");/// ```#[macro_export]macro_rules! b_str { ($str:literal) => {{ const S: &'static str = $str; const C: &'static $crate::str::BStr = $crate::str::BStr::from_bytes(S.as_bytes()); C }};} /// Returns a C pointer to the string.// It is a free function rather than a method on an extension trait because://// - error[E0379]: functions in trait impls cannot be declared const#[inline]pub const fn as_char_ptr_in_const_context(c_str: &CStr) -> *const c_char { c_str.0.as_ptr()} /// Possible errors when using conversion functions in [`CStr`].#[derive(Debug, Clone, Copy)]pub enum CStrConvertError { /// Supplied bytes contain an interior `NUL`. InteriorNul, /// Supplied bytes are not terminated by `NUL`. NotNulTerminated,} impl From<CStrConvertError> for Error { #[inline] fn from(_: CStrConvertError) -> Error { EINVAL }} /// A string that is guaranteed to have exactly one `NUL` byte, which is at the/// end.////// Used for interoperability with kernel APIs that take C strings.#[repr(transparent)]pub struct CStr([u8]); impl CStr { /// Returns the length of this string excluding `NUL`. #[inline] pub const fn len(&self) -> usize { self.len_with_nul() - 1 } /// Returns the length of this string with `NUL`. #[inline] pub const fn len_with_nul(&self) -> usize { if self.0.is_empty() { // SAFETY: This is one of the invariant of `CStr`. // We add a `unreachable_unchecked` here to hint the optimizer that // the value returned from this function is non-zero. unsafe { core::hint::unreachable_unchecked() }; } self.0.len() } /// Returns `true` if the string only includes `NUL`. #[inline] pub const fn is_empty(&self) -> bool { self.len() == 0 } /// Wraps a raw C string pointer. /// /// # Safety /// /// `ptr` must be a valid pointer to a `NUL`-terminated C string, and it must /// last at least `'a`. When `CStr` is alive, the memory pointed by `ptr` /// must not be mutated. #[inline] pub unsafe fn from_char_ptr<'a>(ptr: *const c_char) -> &'a Self { // SAFETY: The safety precondition guarantees `ptr` is a valid pointer // to a `NUL`-terminated C string. let len = unsafe { bindings::strlen(ptr) } + 1; // SAFETY: Lifetime guaranteed by the safety precondition. let bytes = unsafe { core::slice::from_raw_parts(ptr.cast(), len) }; // SAFETY: As `len` is returned by `strlen`, `bytes` does not contain interior `NUL`. // As we have added 1 to `len`, the last byte is known to be `NUL`. unsafe { Self::from_bytes_with_nul_unchecked(bytes) } } /// Creates a [`CStr`] from a `[u8]`. /// /// The provided slice must be `NUL`-terminated, does not contain any /// interior `NUL` bytes. pub const fn from_bytes_with_nul(bytes: &[u8]) -> Result<&Self, CStrConvertError> { if bytes.is_empty() { return Err(CStrConvertError::NotNulTerminated); } if bytes[bytes.len() - 1] != 0 { return Err(CStrConvertError::NotNulTerminated); } let mut i = 0; // `i + 1 < bytes.len()` allows LLVM to optimize away bounds checking, // while it couldn't optimize away bounds checks for `i < bytes.len() - 1`. while i + 1 < bytes.len() { if bytes[i] == 0 { return Err(CStrConvertError::InteriorNul); } i += 1; } // SAFETY: We just checked that all properties hold. Ok(unsafe { Self::from_bytes_with_nul_unchecked(bytes) }) } /// Creates a [`CStr`] from a `[u8]` without performing any additional /// checks. /// /// # Safety /// /// `bytes` *must* end with a `NUL` byte, and should only have a single /// `NUL` byte (or the string will be truncated). #[inline] pub const unsafe fn from_bytes_with_nul_unchecked(bytes: &[u8]) -> &CStr { // SAFETY: Properties of `bytes` guaranteed by the safety precondition. unsafe { core::mem::transmute(bytes) } } /// Creates a mutable [`CStr`] from a `[u8]` without performing any /// additional checks. /// /// # Safety /// /// `bytes` *must* end with a `NUL` byte, and should only have a single /// `NUL` byte (or the string will be truncated). #[inline] pub unsafe fn from_bytes_with_nul_unchecked_mut(bytes: &mut [u8]) -> &mut CStr { // SAFETY: Properties of `bytes` guaranteed by the safety precondition. unsafe { &mut *(core::ptr::from_mut(bytes) as *mut CStr) } } /// Returns a C pointer to the string. /// /// Using this function in a const context is deprecated in favor of /// [`as_char_ptr_in_const_context`] in preparation for replacing `CStr` with `core::ffi::CStr` /// which does not have this method. #[inline] pub const fn as_char_ptr(&self) -> *const c_char { as_char_ptr_in_const_context(self) } /// Convert the string to a byte slice without the trailing `NUL` byte. #[inline] pub fn to_bytes(&self) -> &[u8] { &self.0[..self.len()] } /// Convert the string to a byte slice without the trailing `NUL` byte. /// /// This function is deprecated in favor of [`Self::to_bytes`] in preparation for replacing /// `CStr` with `core::ffi::CStr` which does not have this method. #[inline] pub fn as_bytes(&self) -> &[u8] { self.to_bytes() } /// Convert the string to a byte slice containing the trailing `NUL` byte. #[inline] pub const fn to_bytes_with_nul(&self) -> &[u8] { &self.0 } /// Convert the string to a byte slice containing the trailing `NUL` byte. /// /// This function is deprecated in favor of [`Self::to_bytes_with_nul`] in preparation for /// replacing `CStr` with `core::ffi::CStr` which does not have this method. #[inline] pub const fn as_bytes_with_nul(&self) -> &[u8] { self.to_bytes_with_nul() } /// Yields a [`&str`] 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 [`&str`] slice. Otherwise, /// it will return an error with details of where UTF-8 validation failed. /// /// # Examples /// /// ``` /// # use kernel::str::CStr; /// let cstr = CStr::from_bytes_with_nul(b"foo\0")?; /// assert_eq!(cstr.to_str(), Ok("foo")); /// # Ok::<(), kernel::error::Error>(()) /// ``` #[inline] pub fn to_str(&self) -> Result<&str, core::str::Utf8Error> { core::str::from_utf8(self.as_bytes()) } /// Unsafely convert this [`CStr`] into a [`&str`], without checking for /// valid UTF-8. /// /// # Safety /// /// The contents must be valid UTF-8. /// /// # Examples /// /// ``` /// # use kernel::c_str; /// # use kernel::str::CStr; /// let bar = c_str!("γ"); /// // SAFETY: String literals are guaranteed to be valid UTF-8 /// // by the Rust compiler. /// assert_eq!(unsafe { bar.as_str_unchecked() }, "γ"); /// ``` #[inline] pub unsafe fn as_str_unchecked(&self) -> &str { // SAFETY: TODO. unsafe { core::str::from_utf8_unchecked(self.as_bytes()) } } /// Convert this [`CStr`] into a [`CString`] by allocating memory and /// copying over the string data. pub fn to_cstring(&self) -> Result<CString, AllocError> { CString::try_from(self) } /// Converts this [`CStr`] to its ASCII lower case equivalent in-place. /// /// ASCII letters 'A' to 'Z' are mapped to 'a' to 'z', /// but non-ASCII letters are unchanged. /// /// To return a new lowercased value without modifying the existing one, use /// [`to_ascii_lowercase()`]. /// /// [`to_ascii_lowercase()`]: #method.to_ascii_lowercase pub fn make_ascii_lowercase(&mut self) { // INVARIANT: This doesn't introduce or remove NUL bytes in the C // string. self.0.make_ascii_lowercase(); } /// Converts this [`CStr`] to its ASCII upper case equivalent in-place. /// /// ASCII letters 'a' to 'z' are mapped to 'A' to 'Z', /// but non-ASCII letters are unchanged. /// /// To return a new uppercased value without modifying the existing one, use /// [`to_ascii_uppercase()`]. /// /// [`to_ascii_uppercase()`]: #method.to_ascii_uppercase pub fn make_ascii_uppercase(&mut self) { // INVARIANT: This doesn't introduce or remove NUL bytes in the C // string. self.0.make_ascii_uppercase(); } /// Returns a copy of this [`CString`] where each character is mapped to its /// ASCII lower case equivalent. /// /// ASCII letters 'A' to 'Z' are mapped to 'a' to 'z', /// but non-ASCII letters are unchanged. /// /// To lowercase the value in-place, use [`make_ascii_lowercase`]. /// /// [`make_ascii_lowercase`]: str::make_ascii_lowercase pub fn to_ascii_lowercase(&self) -> Result<CString, AllocError> { let mut s = self.to_cstring()?; s.make_ascii_lowercase(); Ok(s) } /// Returns a copy of this [`CString`] where each character is mapped to its /// ASCII upper case equivalent. /// /// ASCII letters 'a' to 'z' are mapped to 'A' to 'Z', /// but non-ASCII letters are unchanged. /// /// To uppercase the value in-place, use [`make_ascii_uppercase`]. /// /// [`make_ascii_uppercase`]: str::make_ascii_uppercase pub fn to_ascii_uppercase(&self) -> Result<CString, AllocError> { let mut s = self.to_cstring()?; s.make_ascii_uppercase(); Ok(s) }} impl fmt::Display for CStr { /// Formats printable ASCII characters, escaping the rest. /// /// ``` /// # use kernel::c_str; /// # use kernel::prelude::fmt; /// # use kernel::str::CStr; /// # use kernel::str::CString; /// let penguin = c_str!("π§"); /// let s = CString::try_from_fmt(fmt!("{penguin}"))?; /// assert_eq!(s.to_bytes_with_nul(), "\\xf0\\x9f\\x90\\xa7\0".as_bytes()); /// /// let ascii = c_str!("so \"cool\""); /// let s = CString::try_from_fmt(fmt!("{ascii}"))?; /// assert_eq!(s.to_bytes_with_nul(), "so \"cool\"\0".as_bytes()); /// # Ok::<(), kernel::error::Error>(()) /// ``` fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { for &c in self.to_bytes() { if (0x20..0x7f).contains(&c) { // Printable character. f.write_char(c as char)?; } else { write!(f, "\\x{c:02x}")?; } } Ok(()) }} impl fmt::Debug for CStr { /// Formats printable ASCII characters with a double quote on either end, escaping the rest. /// /// ``` /// # use kernel::c_str; /// # use kernel::prelude::fmt; /// # use kernel::str::CStr; /// # use kernel::str::CString; /// let penguin = c_str!("π§"); /// let s = CString::try_from_fmt(fmt!("{penguin:?}"))?; /// assert_eq!(s.as_bytes_with_nul(), "\"\\xf0\\x9f\\x90\\xa7\"\0".as_bytes()); /// /// // Embedded double quotes are escaped.Lines 1β500 of 963. 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// SPDX-License-Identifier: GPL-2.0 //! String representations. use crate::alloc::{flags::*, AllocError, KVec}; use crate::fmt::{self, Write}; use core::ops::{self, Deref, DerefMut, Index}; use crate::prelude::*; /// Byte string without UTF-8 validity guarantee. #[repr(transparent)] pub struct BStr([u8]); impl BStr { /// Returns the length of this string. #[inline] pub const fn len(&self) -> usize { self.0.len() } /// Returns `true` if the string is empty. #[inline] pub const fn is_empty(&self) -> bool { self.len() == 0 } /// Creates a [`BStr`] from a `[u8]`. #[inline] pub const fn from_bytes(bytes: &[u8]) -> &Self { // SAFETY: `BStr` is transparent to `[u8]`. unsafe { &*(core::ptr::from_ref(bytes) as *const BStr) } } /// Strip a prefix from `self`. Delegates to [`slice::strip_prefix`]. /// /// # Examples /// /// ``` /// # use kernel::b_str; /// assert_eq!(Some(b_str!("bar")), b_str!("foobar").strip_prefix(b_str!("foo"))); /// assert_eq!(None, b_str!("foobar").strip_prefix(b_str!("bar"))); /// assert_eq!(Some(b_str!("foobar")), b_str!("foobar").strip_prefix(b_str!(""))); /// assert_eq!(Some(b_str!("")), b_str!("foobar").strip_prefix(b_str!("foobar"))); /// ``` pub fn strip_prefix(&self, pattern: impl AsRef<Self>) -> Option<&BStr> { self.deref() .strip_prefix(pattern.as_ref().deref()) .map(Self::from_bytes) } } impl fmt::Display for BStr { /// Formats printable ASCII characters, escaping the rest. /// /// ``` /// # use kernel::{prelude::fmt, b_str, str::{BStr, CString}}; /// let ascii = b_str!("Hello, BStr!"); /// let s = CString::try_from_fmt(fmt!("{ascii}"))?; /// assert_eq!(s.to_bytes(), "Hello, BStr!".as_bytes()); /// /// let non_ascii = b_str!("π¦"); /// let s = CString::try_from_fmt(fmt!("{non_ascii}"))?; /// assert_eq!(s.to_bytes(), "\\xf0\\x9f\\xa6\\x80".as_bytes()); /// # Ok::<(), kernel::error::Error>(()) /// ``` fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { for &b in &self.0 { match b { // Common escape codes. b'\t' => f.write_str("\\t")?, b'\n' => f.write_str("\\n")?, b'\r' => f.write_str("\\r")?, // Printable characters. 0x20..=0x7e => f.write_char(b as char)?, _ => write!(f, "\\x{b:02x}")?, } } Ok(()) } } impl fmt::Debug for BStr { /// Formats printable ASCII characters with a double quote on either end, /// escaping the rest. /// /// ``` /// # use kernel::{prelude::fmt, b_str, str::{BStr, CString}}; /// // Embedded double quotes are escaped. /// let ascii = b_str!("Hello, \"BStr\"!"); /// let s = CString::try_from_fmt(fmt!("{ascii:?}"))?; /// assert_eq!(s.to_bytes(), "\"Hello, \\\"BStr\\\"!\"".as_bytes()); /// /// let non_ascii = b_str!("πΊ"); /// let s = CString::try_from_fmt(fmt!("{non_ascii:?}"))?; /// assert_eq!(s.to_bytes(), "\"\\xf0\\x9f\\x98\\xba\"".as_bytes()); /// # Ok::<(), kernel::error::Error>(()) /// ``` fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { f.write_char('"')?; for &b in &self.0 { match b { // Common escape codes. b'\t' => f.write_str("\\t")?, b'\n' => f.write_str("\\n")?, b'\r' => f.write_str("\\r")?, // String escape characters. b'\"' => f.write_str("\\\"")?, b'\\' => f.write_str("\\\\")?, // Printable characters. 0x20..=0x7e => f.write_char(b as char)?, _ => write!(f, "\\x{b:02x}")?, } } f.write_char('"') } } impl Deref for BStr { type Target = [u8]; #[inline] fn deref(&self) -> &Self::Target { &self.0 } } impl PartialEq for BStr { fn eq(&self, other: &Self) -> bool { self.deref().eq(other.deref()) } } impl<Idx> Index<Idx> for BStr where [u8]: Index<Idx, Output = [u8]>, { type Output = Self; fn index(&self, index: Idx) -> &Self::Output { BStr::from_bytes(&self.0[index]) } } impl AsRef<BStr> for [u8] { fn as_ref(&self) -> &BStr { BStr::from_bytes(self) } } impl AsRef<BStr> for BStr { fn as_ref(&self) -> &BStr { self } } /// Creates a new [`BStr`] from a string literal. /// /// `b_str!` converts the supplied string literal to byte string, so non-ASCII /// characters can be included. /// /// # Examples /// /// ``` /// # use kernel::b_str; /// # use kernel::str::BStr; /// const MY_BSTR: &BStr = b_str!("My awesome BStr!"); /// ``` #[macro_export] macro_rules! b_str { ($str:literal) => {{ const S: &'static str = $str; const C: &'static $crate::str::BStr = $crate::str::BStr::from_bytes(S.as_bytes()); C }}; } /// Returns a C pointer to the string. // It is a free function rather than a method on an extension trait because: // // - error[E0379]: functions in trait impls cannot be declared const #[inline] pub const fn as_char_ptr_in_const_context(c_str: &CStr) -> *const c_char { c_str.0.as_ptr() } /// Possible errors when using conversion functions in [`CStr`]. #[derive(Debug, Clone, Copy)] pub enum CStrConvertError { /// Supplied bytes contain an interior `NUL`. InteriorNul, /// Supplied bytes are not terminated by `NUL`. NotNulTerminated, } impl From<CStrConvertError> for Error { #[inline] fn from(_: CStrConvertError) -> Error { EINVAL } } /// A string that is guaranteed to have exactly one `NUL` byte, which is at the /// end. /// /// Used for interoperability with kernel APIs that take C strings. #[repr(transparent)] pub struct CStr([u8]); impl CStr { /// Returns the length of this string excluding `NUL`. #[inline] pub const fn len(&self) -> usize { self.len_with_nul() - 1 } /// Returns the length of this string with `NUL`. #[inline] pub const fn len_with_nul(&self) -> usize { if self.0.is_empty() { // SAFETY: This is one of the invariant of `CStr`. // We add a `unreachable_unchecked` here to hint the optimizer that // the value returned from this function is non-zero. unsafe { core::hint::unreachable_unchecked() }; } self.0.len() } /// Returns `true` if the string only includes `NUL`. #[inline] pub const fn is_empty(&self) -> bool { self.len() == 0 } /// Wraps a raw C string pointer. /// /// # Safety /// /// `ptr` must be a valid pointer to a `NUL`-terminated C string, and it must /// last at least `'a`. When `CStr` is alive, the memory pointed by `ptr` /// must not be mutated. #[inline] pub unsafe fn from_char_ptr<'a>(ptr: *const c_char) -> &'a Self { // SAFETY: The safety precondition guarantees `ptr` is a valid pointer // to a `NUL`-terminated C string. let len = unsafe { bindings::strlen(ptr) } + 1; // SAFETY: Lifetime guaranteed by the safety precondition. let bytes = unsafe { core::slice::from_raw_parts(ptr.cast(), len) }; // SAFETY: As `len` is returned by `strlen`, `bytes` does not contain interior `NUL`. // As we have added 1 to `len`, the last byte is known to be `NUL`. unsafe { Self::from_bytes_with_nul_unchecked(bytes) } } /// Creates a [`CStr`] from a `[u8]`. /// /// The provided slice must be `NUL`-terminated, does not contain any /// interior `NUL` bytes. pub const fn from_bytes_with_nul(bytes: &[u8]) -> Result<&Self, CStrConvertError> { if bytes.is_empty() { return Err(CStrConvertError::NotNulTerminated); } if bytes[bytes.len() - 1] != 0 { return Err(CStrConvertError::NotNulTerminated); } let mut i = 0; // `i + 1 < bytes.len()` allows LLVM to optimize away bounds checking, // while it couldn't optimize away bounds checks for `i < bytes.len() - 1`. while i + 1 < bytes.len() { if bytes[i] == 0 { return Err(CStrConvertError::InteriorNul); } i += 1; } // SAFETY: We just checked that all properties hold. Ok(unsafe { Self::from_bytes_with_nul_unchecked(bytes) }) } /// Creates a [`CStr`] from a `[u8]` without performing any additional /// checks. /// /// # Safety /// /// `bytes` *must* end with a `NUL` byte, and should only have a single /// `NUL` byte (or the string will be truncated). #[inline] pub const unsafe fn from_bytes_with_nul_unchecked(bytes: &[u8]) -> &CStr { // SAFETY: Properties of `bytes` guaranteed by the safety precondition. unsafe { core::mem::transmute(bytes) } } /// Creates a mutable [`CStr`] from a `[u8]` without performing any /// additional checks. /// /// # Safety /// /// `bytes` *must* end with a `NUL` byte, and should only have a single /// `NUL` byte (or the string will be truncated). #[inline] pub unsafe fn from_bytes_with_nul_unchecked_mut(bytes: &mut [u8]) -> &mut CStr { // SAFETY: Properties of `bytes` guaranteed by the safety precondition. unsafe { &mut *(core::ptr::from_mut(bytes) as *mut CStr) } } /// Returns a C pointer to the string. /// /// Using this function in a const context is deprecated in favor of /// [`as_char_ptr_in_const_context`] in preparation for replacing `CStr` with `core::ffi::CStr` /// which does not have this method. #[inline] pub const fn as_char_ptr(&self) -> *const c_char { as_char_ptr_in_const_context(self) } /// Convert the string to a byte slice without the trailing `NUL` byte. #[inline] pub fn to_bytes(&self) -> &[u8] { &self.0[..self.len()] } /// Convert the string to a byte slice without the trailing `NUL` byte. /// /// This function is deprecated in favor of [`Self::to_bytes`] in preparation for replacing /// `CStr` with `core::ffi::CStr` which does not have this method. #[inline] pub fn as_bytes(&self) -> &[u8] { self.to_bytes() } /// Convert the string to a byte slice containing the trailing `NUL` byte. #[inline] pub const fn to_bytes_with_nul(&self) -> &[u8] { &self.0 } /// Convert the string to a byte slice containing the trailing `NUL` byte. /// /// This function is deprecated in favor of [`Self::to_bytes_with_nul`] in preparation for /// replacing `CStr` with `core::ffi::CStr` which does not have this method. #[inline] pub const fn as_bytes_with_nul(&self) -> &[u8] { self.to_bytes_with_nul() } /// Yields a [`&str`] 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 [`&str`] slice. Otherwise, /// it will return an error with details of where UTF-8 validation failed. /// /// # Examples /// /// ``` /// # use kernel::str::CStr; /// let cstr = CStr::from_bytes_with_nul(b"foo\0")?; /// assert_eq!(cstr.to_str(), Ok("foo")); /// # Ok::<(), kernel::error::Error>(()) /// ``` #[inline] pub fn to_str(&self) -> Result<&str, core::str::Utf8Error> { core::str::from_utf8(self.as_bytes()) } /// Unsafely convert this [`CStr`] into a [`&str`], without checking for /// valid UTF-8. /// /// # Safety /// /// The contents must be valid UTF-8. /// /// # Examples /// /// ``` /// # use kernel::c_str; /// # use kernel::str::CStr; /// let bar = c_str!("γ"); /// // SAFETY: String literals are guaranteed to be valid UTF-8 /// // by the Rust compiler. /// assert_eq!(unsafe { bar.as_str_unchecked() }, "γ"); /// ``` #[inline] pub unsafe fn as_str_unchecked(&self) -> &str { // SAFETY: TODO. unsafe { core::str::from_utf8_unchecked(self.as_bytes()) } } /// Convert this [`CStr`] into a [`CString`] by allocating memory and /// copying over the string data. pub fn to_cstring(&self) -> Result<CString, AllocError> { CString::try_from(self) } /// Converts this [`CStr`] to its ASCII lower case equivalent in-place. /// /// ASCII letters 'A' to 'Z' are mapped to 'a' to 'z', /// but non-ASCII letters are unchanged. /// /// To return a new lowercased value without modifying the existing one, use /// [`to_ascii_lowercase()`]. /// /// [`to_ascii_lowercase()`]: #method.to_ascii_lowercase pub fn make_ascii_lowercase(&mut self) { // INVARIANT: This doesn't introduce or remove NUL bytes in the C // string. self.0.make_ascii_lowercase(); } /// Converts this [`CStr`] to its ASCII upper case equivalent in-place. /// /// ASCII letters 'a' to 'z' are mapped to 'A' to 'Z', /// but non-ASCII letters are unchanged. /// /// To return a new uppercased value without modifying the existing one, use /// [`to_ascii_uppercase()`]. /// /// [`to_ascii_uppercase()`]: #method.to_ascii_uppercase pub fn make_ascii_uppercase(&mut self) { // INVARIANT: This doesn't introduce or remove NUL bytes in the C // string. self.0.make_ascii_uppercase(); } /// Returns a copy of this [`CString`] where each character is mapped to its /// ASCII lower case equivalent. /// /// ASCII letters 'A' to 'Z' are mapped to 'a' to 'z', /// but non-ASCII letters are unchanged. /// /// To lowercase the value in-place, use [`make_ascii_lowercase`]. /// /// [`make_ascii_lowercase`]: str::make_ascii_lowercase pub fn to_ascii_lowercase(&self) -> Result<CString, AllocError> { let mut s = self.to_cstring()?; s.make_ascii_lowercase(); Ok(s) } /// Returns a copy of this [`CString`] where each character is mapped to its /// ASCII upper case equivalent. /// /// ASCII letters 'a' to 'z' are mapped to 'A' to 'Z', /// but non-ASCII letters are unchanged. /// /// To uppercase the value in-place, use [`make_ascii_uppercase`]. /// /// [`make_ascii_uppercase`]: str::make_ascii_uppercase pub fn to_ascii_uppercase(&self) -> Result<CString, AllocError> { let mut s = self.to_cstring()?; s.make_ascii_uppercase(); Ok(s) } } impl fmt::Display for CStr { /// Formats printable ASCII characters, escaping the rest. /// /// ``` /// # use kernel::c_str; /// # use kernel::prelude::fmt; /// # use kernel::str::CStr; /// # use kernel::str::CString; /// let penguin = c_str!("π§"); /// let s = CString::try_from_fmt(fmt!("{penguin}"))?; /// assert_eq!(s.to_bytes_with_nul(), "\\xf0\\x9f\\x90\\xa7\0".as_bytes()); /// /// let ascii = c_str!("so \"cool\""); /// let s = CString::try_from_fmt(fmt!("{ascii}"))?; /// assert_eq!(s.to_bytes_with_nul(), "so \"cool\"\0".as_bytes()); /// # Ok::<(), kernel::error::Error>(()) /// ``` fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { for &c in self.to_bytes() { if (0x20..0x7f).contains(&c) { // Printable character. f.write_char(c as char)?; } else { write!(f, "\\x{c:02x}")?; } } Ok(()) } } impl fmt::Debug for CStr { /// Formats printable ASCII characters with a double quote on either end, escaping the rest. /// /// ``` /// # use kernel::c_str; /// # use kernel::prelude::fmt; /// # use kernel::str::CStr; /// # use kernel::str::CString; /// let penguin = c_str!("π§"); /// let s = CString::try_from_fmt(fmt!("{penguin:?}"))?; /// assert_eq!(s.as_bytes_with_nul(), "\"\\xf0\\x9f\\x90\\xa7\"\0".as_bytes()); /// /// // Embedded double quotes are escaped.