// SPDX-License-Identifier: GPL-2.0 //! String representations. use crate::{ alloc::{ AllocError, KVec, // }, error::{ to_result, Result, // }, fmt::{ self, Write, // }, prelude::*, //};use core::{ marker::PhantomData, ops::{ Deref, DerefMut, Index, // }, //}; pub use crate::prelude::CStr; pub mod parse_int; /// 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!("🦀"); /// 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!("😺"); /// 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]#[expect(clippy::disallowed_methods, reason = "internal implementation")]pub const fn as_char_ptr_in_const_context(c_str: &CStr) -> *const c_char { c_str.as_ptr().cast()} mod private { pub trait Sealed {} impl Sealed for super::CStr {}} /// Extensions to [`CStr`].pub trait CStrExt: private::Sealed { /// 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. // This function exists to paper over the fact that `CStr::from_ptr` takes a `*const // core::ffi::c_char` rather than a `*const crate::ffi::c_char`. unsafe fn from_char_ptr<'a>(ptr: *const c_char) -> &'a Self; /// 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). unsafe fn from_bytes_with_nul_unchecked_mut(bytes: &mut [u8]) -> &mut Self; /// Returns a C pointer to the string. // This function exists to paper over the fact that `CStr::as_ptr` returns a `*const // core::ffi::c_char` rather than a `*const crate::ffi::c_char`. fn as_char_ptr(&self) -> *const c_char; /// Convert this [`CStr`] into a [`CString`] by allocating memory and /// copying over the string data. fn to_cstring(&self) -> Result<CString, AllocError>; /// 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 fn make_ascii_lowercase(&mut self); /// 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 fn make_ascii_uppercase(&mut self); /// 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 fn to_ascii_lowercase(&self) -> Result<CString, AllocError>; /// 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 fn to_ascii_uppercase(&self) -> Result<CString, AllocError>;} impl fmt::Display for CStr { /// Formats printable ASCII characters, escaping the rest. /// /// ``` /// # use kernel::prelude::fmt; /// # use kernel::str::CStr; /// # use kernel::str::CString; /// let penguin = c"🐧"; /// 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"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(()) }} /// Converts a mutable C string to a mutable byte slice.////// # Safety////// The caller must ensure that the slice ends in a NUL byte and contains no other NUL bytes before/// the borrow ends and the underlying [`CStr`] is used.unsafe fn to_bytes_mut(s: &mut CStr) -> &mut [u8] { // SAFETY: the cast from `&CStr` to `&[u8]` is safe since `CStr` has the same layout as `&[u8]` // (this is technically not guaranteed, but we rely on it here). The pointer dereference is // safe since it comes from a mutable reference which is guaranteed to be valid for writes. unsafe { &mut *(core::ptr::from_mut(s) as *mut [u8]) }} impl CStrExt for CStr { #[inline] #[expect(clippy::disallowed_methods, reason = "internal implementation")] unsafe fn from_char_ptr<'a>(ptr: *const c_char) -> &'a Self { // SAFETY: The safety preconditions are the same as for `CStr::from_ptr`. unsafe { CStr::from_ptr(ptr.cast()) } } #[inline] unsafe fn from_bytes_with_nul_unchecked_mut(bytes: &mut [u8]) -> &mut Self { // SAFETY: the cast from `&[u8]` to `&CStr` is safe since the properties of `bytes` are // guaranteed by the safety precondition and `CStr` has the same layout as `&[u8]` (this is // technically not guaranteed, but we rely on it here). The pointer dereference is safe // since it comes from a mutable reference which is guaranteed to be valid for writes. unsafe { &mut *(core::ptr::from_mut(bytes) as *mut CStr) } } #[inline] #[expect(clippy::disallowed_methods, reason = "internal implementation")] fn as_char_ptr(&self) -> *const c_char { self.as_ptr().cast() } fn to_cstring(&self) -> Result<CString, AllocError> { CString::try_from(self) } fn make_ascii_lowercase(&mut self) { // SAFETY: This doesn't introduce or remove NUL bytes in the C string. unsafe { to_bytes_mut(self) }.make_ascii_lowercase(); } fn make_ascii_uppercase(&mut self) { // SAFETY: This doesn't introduce or remove NUL bytes in the C string. unsafe { to_bytes_mut(self) }.make_ascii_uppercase(); } fn to_ascii_lowercase(&self) -> Result<CString, AllocError> { let mut s = self.to_cstring()?; s.make_ascii_lowercase(); Ok(s) } fn to_ascii_uppercase(&self) -> Result<CString, AllocError> { let mut s = self.to_cstring()?; s.make_ascii_uppercase(); Ok(s) }} impl AsRef<BStr> for CStr { #[inline] fn as_ref(&self) -> &BStr { BStr::from_bytes(self.to_bytes()) }} /// Creates a new [`CStr`] at compile time.////// Rust supports C string literals since Rust 1.77, and they should be used instead of this macro/// where possible. This macro exists to allow static *non-literal* C strings to be created at/// compile time. This is most often used in other macros.////// # Panics////// This macro panics if the operand contains an interior `NUL` byte.////// # Examples////// ```/// # use kernel::c_str;/// # use kernel::str::CStr;/// // This is allowed, but `c"literal"` should be preferred for literals./// const BAD: &CStr = c_str!("literal");////// // `c_str!` is still needed for static non-literal C strings./// const GOOD: &CStr = c_str!(concat!(file!(), ":", line!(), ": My CStr!"));/// ```#[macro_export]macro_rules! c_str { // NB: We could write `($str:lit) => compile_error!("use a C string literal instead");` here but // that would trigger when the literal is at the top of several macro expansions. That would be // too limiting to macro authors. ($str:expr) => {{ const S: &str = concat!($str, "\0"); const C: &$crate::str::CStr = match $crate::str::CStr::from_bytes_with_nul(S.as_bytes()) { Ok(v) => v, Err(_) => panic!("string contains interior NUL"), }; C }};} #[cfg(CONFIG_RUST_STR_KUNIT_TEST)]#[kunit_tests(rust_kernel_str)]mod tests { use super::*; impl From<core::ffi::FromBytesWithNulError> for Error { #[inline] fn from(_: core::ffi::FromBytesWithNulError) -> Error { EINVAL } } macro_rules! format { ($($f:tt)*) => ({ CString::try_from_fmt(fmt!($($f)*))?.to_str()? }) } const ALL_ASCII_CHARS: &str = "\\x01\\x02\\x03\\x04\\x05\\x06\\x07\\x08\\x09\\x0a\\x0b\\x0c\\x0d\\x0e\\x0f\ \\x10\\x11\\x12\\x13\\x14\\x15\\x16\\x17\\x18\\x19\\x1a\\x1b\\x1c\\x1d\\x1e\\x1f \ !\"#$%&'()*+,-./0123456789:;<=>?@\ ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~\\x7f\ \\x80\\x81\\x82\\x83\\x84\\x85\\x86\\x87\\x88\\x89\\x8a\\x8b\\x8c\\x8d\\x8e\\x8f\ \\x90\\x91\\x92\\x93\\x94\\x95\\x96\\x97\\x98\\x99\\x9a\\x9b\\x9c\\x9d\\x9e\\x9f\ \\xa0\\xa1\\xa2\\xa3\\xa4\\xa5\\xa6\\xa7\\xa8\\xa9\\xaa\\xab\\xac\\xad\\xae\\xaf\ \\xb0\\xb1\\xb2\\xb3\\xb4\\xb5\\xb6\\xb7\\xb8\\xb9\\xba\\xbb\\xbc\\xbd\\xbe\\xbf\ \\xc0\\xc1\\xc2\\xc3\\xc4\\xc5\\xc6\\xc7\\xc8\\xc9\\xca\\xcb\\xcc\\xcd\\xce\\xcf\ \\xd0\\xd1\\xd2\\xd3\\xd4\\xd5\\xd6\\xd7\\xd8\\xd9\\xda\\xdb\\xdc\\xdd\\xde\\xdf\ \\xe0\\xe1\\xe2\\xe3\\xe4\\xe5\\xe6\\xe7\\xe8\\xe9\\xea\\xeb\\xec\\xed\\xee\\xef\ \\xf0\\xf1\\xf2\\xf3\\xf4\\xf5\\xf6\\xf7\\xf8\\xf9\\xfa\\xfb\\xfc\\xfd\\xfe\\xff"; #[test] fn test_cstr_to_str() -> Result { let cstr = c"\xf0\x9f\xa6\x80"; let checked_str = cstr.to_str()?; assert_eq!(checked_str, "🦀"); Ok(()) } #[test] fn test_cstr_to_str_invalid_utf8() -> Result { let cstr = c"\xc3\x28"; assert!(cstr.to_str().is_err()); Ok(()) } #[test] fn test_cstr_display() -> Result { let hello_world = c"hello, world!"; assert_eq!(format!("{hello_world}"), "hello, world!"); let non_printables = c"\x01\x09\x0a"; assert_eq!(format!("{non_printables}"), "\\x01\\x09\\x0a"); let non_ascii = c"d\xe9j\xe0 vu"; assert_eq!(format!("{non_ascii}"), "d\\xe9j\\xe0 vu"); let good_bytes = c"\xf0\x9f\xa6\x80"; assert_eq!(format!("{good_bytes}"), "\\xf0\\x9f\\xa6\\x80"); Ok(()) } #[test] fn test_cstr_display_all_bytes() -> Result { let mut bytes: [u8; 256] = [0; 256]; // fill `bytes` with [1..=255] + [0] for i in u8::MIN..=u8::MAX { bytes[i as usize] = i.wrapping_add(1); } let cstr = CStr::from_bytes_with_nul(&bytes)?; assert_eq!(format!("{cstr}"), ALL_ASCII_CHARS); Ok(())Lines 1–500 of 918. 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// SPDX-License-Identifier: GPL-2.0 //! String representations. use crate::{ alloc::{ AllocError, KVec, // }, error::{ to_result, Result, // }, fmt::{ self, Write, // }, prelude::*, // }; use core::{ marker::PhantomData, ops::{ Deref, DerefMut, Index, // }, // }; pub use crate::prelude::CStr; pub mod parse_int; /// 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!("🦀"); /// 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!("😺"); /// 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] #[expect(clippy::disallowed_methods, reason = "internal implementation")] pub const fn as_char_ptr_in_const_context(c_str: &CStr) -> *const c_char { c_str.as_ptr().cast() } mod private { pub trait Sealed {} impl Sealed for super::CStr {} } /// Extensions to [`CStr`]. pub trait CStrExt: private::Sealed { /// 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. // This function exists to paper over the fact that `CStr::from_ptr` takes a `*const // core::ffi::c_char` rather than a `*const crate::ffi::c_char`. unsafe fn from_char_ptr<'a>(ptr: *const c_char) -> &'a Self; /// 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). unsafe fn from_bytes_with_nul_unchecked_mut(bytes: &mut [u8]) -> &mut Self; /// Returns a C pointer to the string. // This function exists to paper over the fact that `CStr::as_ptr` returns a `*const // core::ffi::c_char` rather than a `*const crate::ffi::c_char`. fn as_char_ptr(&self) -> *const c_char; /// Convert this [`CStr`] into a [`CString`] by allocating memory and /// copying over the string data. fn to_cstring(&self) -> Result<CString, AllocError>; /// 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 fn make_ascii_lowercase(&mut self); /// 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 fn make_ascii_uppercase(&mut self); /// 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 fn to_ascii_lowercase(&self) -> Result<CString, AllocError>; /// 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 fn to_ascii_uppercase(&self) -> Result<CString, AllocError>; } impl fmt::Display for CStr { /// Formats printable ASCII characters, escaping the rest. /// /// ``` /// # use kernel::prelude::fmt; /// # use kernel::str::CStr; /// # use kernel::str::CString; /// let penguin = c"🐧"; /// 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"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(()) } } /// Converts a mutable C string to a mutable byte slice. /// /// # Safety /// /// The caller must ensure that the slice ends in a NUL byte and contains no other NUL bytes before /// the borrow ends and the underlying [`CStr`] is used. unsafe fn to_bytes_mut(s: &mut CStr) -> &mut [u8] { // SAFETY: the cast from `&CStr` to `&[u8]` is safe since `CStr` has the same layout as `&[u8]` // (this is technically not guaranteed, but we rely on it here). The pointer dereference is // safe since it comes from a mutable reference which is guaranteed to be valid for writes. unsafe { &mut *(core::ptr::from_mut(s) as *mut [u8]) } } impl CStrExt for CStr { #[inline] #[expect(clippy::disallowed_methods, reason = "internal implementation")] unsafe fn from_char_ptr<'a>(ptr: *const c_char) -> &'a Self { // SAFETY: The safety preconditions are the same as for `CStr::from_ptr`. unsafe { CStr::from_ptr(ptr.cast()) } } #[inline] unsafe fn from_bytes_with_nul_unchecked_mut(bytes: &mut [u8]) -> &mut Self { // SAFETY: the cast from `&[u8]` to `&CStr` is safe since the properties of `bytes` are // guaranteed by the safety precondition and `CStr` has the same layout as `&[u8]` (this is // technically not guaranteed, but we rely on it here). The pointer dereference is safe // since it comes from a mutable reference which is guaranteed to be valid for writes. unsafe { &mut *(core::ptr::from_mut(bytes) as *mut CStr) } } #[inline] #[expect(clippy::disallowed_methods, reason = "internal implementation")] fn as_char_ptr(&self) -> *const c_char { self.as_ptr().cast() } fn to_cstring(&self) -> Result<CString, AllocError> { CString::try_from(self) } fn make_ascii_lowercase(&mut self) { // SAFETY: This doesn't introduce or remove NUL bytes in the C string. unsafe { to_bytes_mut(self) }.make_ascii_lowercase(); } fn make_ascii_uppercase(&mut self) { // SAFETY: This doesn't introduce or remove NUL bytes in the C string. unsafe { to_bytes_mut(self) }.make_ascii_uppercase(); } fn to_ascii_lowercase(&self) -> Result<CString, AllocError> { let mut s = self.to_cstring()?; s.make_ascii_lowercase(); Ok(s) } fn to_ascii_uppercase(&self) -> Result<CString, AllocError> { let mut s = self.to_cstring()?; s.make_ascii_uppercase(); Ok(s) } } impl AsRef<BStr> for CStr { #[inline] fn as_ref(&self) -> &BStr { BStr::from_bytes(self.to_bytes()) } } /// Creates a new [`CStr`] at compile time. /// /// Rust supports C string literals since Rust 1.77, and they should be used instead of this macro /// where possible. This macro exists to allow static *non-literal* C strings to be created at /// compile time. This is most often used in other macros. /// /// # Panics /// /// This macro panics if the operand contains an interior `NUL` byte. /// /// # Examples /// /// ``` /// # use kernel::c_str; /// # use kernel::str::CStr; /// // This is allowed, but `c"literal"` should be preferred for literals. /// const BAD: &CStr = c_str!("literal"); /// /// // `c_str!` is still needed for static non-literal C strings. /// const GOOD: &CStr = c_str!(concat!(file!(), ":", line!(), ": My CStr!")); /// ``` #[macro_export] macro_rules! c_str { // NB: We could write `($str:lit) => compile_error!("use a C string literal instead");` here but // that would trigger when the literal is at the top of several macro expansions. That would be // too limiting to macro authors. ($str:expr) => {{ const S: &str = concat!($str, "\0"); const C: &$crate::str::CStr = match $crate::str::CStr::from_bytes_with_nul(S.as_bytes()) { Ok(v) => v, Err(_) => panic!("string contains interior NUL"), }; C }}; } #[cfg(CONFIG_RUST_STR_KUNIT_TEST)] #[kunit_tests(rust_kernel_str)] mod tests { use super::*; impl From<core::ffi::FromBytesWithNulError> for Error { #[inline] fn from(_: core::ffi::FromBytesWithNulError) -> Error { EINVAL } } macro_rules! format { ($($f:tt)*) => ({ CString::try_from_fmt(fmt!($($f)*))?.to_str()? }) } const ALL_ASCII_CHARS: &str = "\\x01\\x02\\x03\\x04\\x05\\x06\\x07\\x08\\x09\\x0a\\x0b\\x0c\\x0d\\x0e\\x0f\ \\x10\\x11\\x12\\x13\\x14\\x15\\x16\\x17\\x18\\x19\\x1a\\x1b\\x1c\\x1d\\x1e\\x1f \ !\"#$%&'()*+,-./0123456789:;<=>?@\ ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~\\x7f\ \\x80\\x81\\x82\\x83\\x84\\x85\\x86\\x87\\x88\\x89\\x8a\\x8b\\x8c\\x8d\\x8e\\x8f\ \\x90\\x91\\x92\\x93\\x94\\x95\\x96\\x97\\x98\\x99\\x9a\\x9b\\x9c\\x9d\\x9e\\x9f\ \\xa0\\xa1\\xa2\\xa3\\xa4\\xa5\\xa6\\xa7\\xa8\\xa9\\xaa\\xab\\xac\\xad\\xae\\xaf\ \\xb0\\xb1\\xb2\\xb3\\xb4\\xb5\\xb6\\xb7\\xb8\\xb9\\xba\\xbb\\xbc\\xbd\\xbe\\xbf\ \\xc0\\xc1\\xc2\\xc3\\xc4\\xc5\\xc6\\xc7\\xc8\\xc9\\xca\\xcb\\xcc\\xcd\\xce\\xcf\ \\xd0\\xd1\\xd2\\xd3\\xd4\\xd5\\xd6\\xd7\\xd8\\xd9\\xda\\xdb\\xdc\\xdd\\xde\\xdf\ \\xe0\\xe1\\xe2\\xe3\\xe4\\xe5\\xe6\\xe7\\xe8\\xe9\\xea\\xeb\\xec\\xed\\xee\\xef\ \\xf0\\xf1\\xf2\\xf3\\xf4\\xf5\\xf6\\xf7\\xf8\\xf9\\xfa\\xfb\\xfc\\xfd\\xfe\\xff"; #[test] fn test_cstr_to_str() -> Result { let cstr = c"\xf0\x9f\xa6\x80"; let checked_str = cstr.to_str()?; assert_eq!(checked_str, "🦀"); Ok(()) } #[test] fn test_cstr_to_str_invalid_utf8() -> Result { let cstr = c"\xc3\x28"; assert!(cstr.to_str().is_err()); Ok(()) } #[test] fn test_cstr_display() -> Result { let hello_world = c"hello, world!"; assert_eq!(format!("{hello_world}"), "hello, world!"); let non_printables = c"\x01\x09\x0a"; assert_eq!(format!("{non_printables}"), "\\x01\\x09\\x0a"); let non_ascii = c"d\xe9j\xe0 vu"; assert_eq!(format!("{non_ascii}"), "d\\xe9j\\xe0 vu"); let good_bytes = c"\xf0\x9f\xa6\x80"; assert_eq!(format!("{good_bytes}"), "\\xf0\\x9f\\xa6\\x80"); Ok(()) } #[test] fn test_cstr_display_all_bytes() -> Result { let mut bytes: [u8; 256] = [0; 256]; // fill `bytes` with [1..=255] + [0] for i in u8::MIN..=u8::MAX { bytes[i as usize] = i.wrapping_add(1); } let cstr = CStr::from_bytes_with_nul(&bytes)?; assert_eq!(format!("{cstr}"), ALL_ASCII_CHARS); Ok(())