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Sun, 02 Feb 2025 04:20:57 -0800 (PST) From: Tamir Duberstein Date: Sun, 02 Feb 2025 07:20:47 -0500 Subject: [PATCH v6 2/4] rust: replace `CStr` with `core::ffi::CStr` Precedence: bulk X-Mailing-List: rust-for-linux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Message-Id: <20250202-cstr-core-v6-2-8469cd6d29fd@gmail.com> References: <20250202-cstr-core-v6-0-8469cd6d29fd@gmail.com> In-Reply-To: <20250202-cstr-core-v6-0-8469cd6d29fd@gmail.com> To: Michal Rostecki , Miguel Ojeda , Alex Gaynor , Boqun Feng , Gary Guo , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross Cc: rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, Tamir Duberstein X-Mailer: b4 0.15-dev `std::ffi::CStr` was moved to `core::ffi::CStr` in Rust 1.64. Replace `kernel::str::CStr` with `core::ffi::CStr` now that we can. `kernel::str::CStr::{from,as}_char_ptr` live on as free functions in `kernel::str` to paper over the difference between `core::ffi::c_char` and `kernel::ffi::char`; see the code comment on the latter type for details. C-String literals were added in Rust 1.77. Opportunistically replace instances of `kernel::c_str!` with C-String literals where other code changes were already necessary; the rest will be done in a later commit. Signed-off-by: Tamir Duberstein --- drivers/gpu/drm/drm_panic_qr.rs | 2 +- rust/kernel/device.rs | 5 +- rust/kernel/error.rs | 4 +- rust/kernel/firmware.rs | 2 +- rust/kernel/kunit.rs | 4 +- rust/kernel/miscdevice.rs | 2 +- rust/kernel/net/phy.rs | 2 +- rust/kernel/prelude.rs | 5 +- rust/kernel/seq_file.rs | 4 +- rust/kernel/str.rs | 449 ++++++---------------------------------- rust/kernel/sync/condvar.rs | 2 +- rust/kernel/sync/lock.rs | 2 +- rust/kernel/sync/lock/global.rs | 2 +- rust/kernel/workqueue.rs | 2 +- 14 files changed, 88 insertions(+), 399 deletions(-) diff --git a/drivers/gpu/drm/drm_panic_qr.rs b/drivers/gpu/drm/drm_panic_qr.rs index bcf248f69252..ef294017888e 100644 --- a/drivers/gpu/drm/drm_panic_qr.rs +++ b/drivers/gpu/drm/drm_panic_qr.rs @@ -958,7 +958,7 @@ fn draw_all(&mut self, data: impl Iterator) { } else { // SAFETY: The caller ensures that `url` is a valid pointer to a // nul-terminated string. - let url_cstr: &CStr = unsafe { CStr::from_char_ptr(url) }; + let url_cstr: &CStr = unsafe { kernel::str::from_char_ptr(url) }; let segments = &[ &Segment::Binary(url_cstr.as_bytes()), &Segment::Numeric(&data_slice[0..data_len]), diff --git a/rust/kernel/device.rs b/rust/kernel/device.rs index d5e6a19ff6b7..f97c409aaba9 100644 --- a/rust/kernel/device.rs +++ b/rust/kernel/device.rs @@ -10,9 +10,6 @@ }; use core::{fmt, ptr}; -#[cfg(CONFIG_PRINTK)] -use crate::c_str; - /// A reference-counted device. /// /// This structure represents the Rust abstraction for a C `struct device`. This implementation @@ -175,7 +172,7 @@ unsafe fn printk(&self, klevel: &[u8], msg: fmt::Arguments<'_>) { bindings::_dev_printk( klevel as *const _ as *const crate::ffi::c_char, self.as_raw(), - c_str!("%pA").as_char_ptr(), + crate::str::as_char_ptr(c"%pA"), &msg as *const _ as *const crate::ffi::c_void, ) }; diff --git a/rust/kernel/error.rs b/rust/kernel/error.rs index f6ecf09cb65f..51c5e0f0a0bc 100644 --- a/rust/kernel/error.rs +++ b/rust/kernel/error.rs @@ -164,7 +164,7 @@ pub fn name(&self) -> Option<&'static CStr> { None } else { // SAFETY: The string returned by `errname` is static and `NUL`-terminated. - Some(unsafe { CStr::from_char_ptr(ptr) }) + Some(unsafe { crate::str::from_char_ptr(ptr) }) } } @@ -187,7 +187,7 @@ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { Some(name) => f .debug_tuple( // SAFETY: These strings are ASCII-only. - unsafe { core::str::from_utf8_unchecked(name) }, + unsafe { core::str::from_utf8_unchecked(name.to_bytes()) }, ) .finish(), } diff --git a/rust/kernel/firmware.rs b/rust/kernel/firmware.rs index c5162fdc95ff..e75db4d825ce 100644 --- a/rust/kernel/firmware.rs +++ b/rust/kernel/firmware.rs @@ -61,7 +61,7 @@ fn request_internal(name: &CStr, dev: &Device, func: FwFunc) -> Result { // SAFETY: `pfw` is a valid pointer to a NULL initialized `bindings::firmware` pointer. // `name` and `dev` are valid as by their type invariants. - let ret = unsafe { func.0(pfw as _, name.as_char_ptr(), dev.as_raw()) }; + let ret = unsafe { func.0(pfw as _, crate::str::as_char_ptr(name), dev.as_raw()) }; if ret != 0 { return Err(Error::from_errno(ret)); } diff --git a/rust/kernel/kunit.rs b/rust/kernel/kunit.rs index 630b947c708c..9f40ea744fc2 100644 --- a/rust/kernel/kunit.rs +++ b/rust/kernel/kunit.rs @@ -101,12 +101,12 @@ unsafe impl Sync for Location {} unsafe impl Sync for UnaryAssert {} static LOCATION: Location = Location($crate::bindings::kunit_loc { - file: FILE.as_char_ptr(), + file: $crate::str::as_char_ptr(FILE), line: LINE, }); static ASSERTION: UnaryAssert = UnaryAssert($crate::bindings::kunit_unary_assert { assert: $crate::bindings::kunit_assert {}, - condition: CONDITION.as_char_ptr(), + condition: $crate::str::as_char_ptr(CONDITION), expected_true: true, }); diff --git a/rust/kernel/miscdevice.rs b/rust/kernel/miscdevice.rs index b3a6cc50b240..2dd20e981e9b 100644 --- a/rust/kernel/miscdevice.rs +++ b/rust/kernel/miscdevice.rs @@ -31,7 +31,7 @@ pub const fn into_raw(self) -> bindings::miscdevice { // SAFETY: All zeros is valid for this C type. let mut result: bindings::miscdevice = unsafe { MaybeUninit::zeroed().assume_init() }; result.minor = bindings::MISC_DYNAMIC_MINOR as _; - result.name = self.name.as_char_ptr(); + result.name = crate::str::as_char_ptr(self.name); result.fops = create_vtable::(); result } diff --git a/rust/kernel/net/phy.rs b/rust/kernel/net/phy.rs index d7da29f95e43..9e410de3c3a3 100644 --- a/rust/kernel/net/phy.rs +++ b/rust/kernel/net/phy.rs @@ -504,7 +504,7 @@ unsafe impl Sync for DriverVTable {} pub const fn create_phy_driver() -> DriverVTable { // INVARIANT: All the fields of `struct phy_driver` are initialized properly. DriverVTable(Opaque::new(bindings::phy_driver { - name: T::NAME.as_char_ptr().cast_mut(), + name: crate::str::as_char_ptr(T::NAME), flags: T::FLAGS, phy_id: T::PHY_DEVICE_ID.id, phy_id_mask: T::PHY_DEVICE_ID.mask_as_int(), diff --git a/rust/kernel/prelude.rs b/rust/kernel/prelude.rs index dde2e0649790..96e7029c27da 100644 --- a/rust/kernel/prelude.rs +++ b/rust/kernel/prelude.rs @@ -34,7 +34,10 @@ pub use super::error::{code::*, Error, Result}; -pub use super::{str::CStr, ThisModule}; +pub use super::{ + str::{CStr, CStrExt as _}, + ThisModule, +}; pub use super::init::{InPlaceInit, InPlaceWrite, Init, PinInit}; diff --git a/rust/kernel/seq_file.rs b/rust/kernel/seq_file.rs index 04947c672979..bb3c49fd4ef3 100644 --- a/rust/kernel/seq_file.rs +++ b/rust/kernel/seq_file.rs @@ -4,7 +4,7 @@ //! //! C header: [`include/linux/seq_file.h`](srctree/include/linux/seq_file.h) -use crate::{bindings, c_str, types::NotThreadSafe, types::Opaque}; +use crate::{bindings, types::NotThreadSafe, types::Opaque}; /// A utility for generating the contents of a seq file. #[repr(transparent)] @@ -35,7 +35,7 @@ pub fn call_printf(&self, args: core::fmt::Arguments<'_>) { unsafe { bindings::seq_printf( self.inner.get(), - c_str!("%pA").as_char_ptr(), + crate::str::as_char_ptr(c"%pA"), &args as *const _ as *const crate::ffi::c_void, ); } diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs index 53450c956a6a..2b63cfaaa981 100644 --- a/rust/kernel/str.rs +++ b/rust/kernel/str.rs @@ -4,7 +4,7 @@ use crate::alloc::{flags::*, AllocError, KVec}; use core::fmt::{self, Write}; -use core::ops::{self, Deref, DerefMut, Index}; +use core::ops::{Deref, DerefMut}; use crate::error::{code::*, Error}; @@ -45,11 +45,11 @@ pub const fn from_bytes(bytes: &[u8]) -> &Self { /// # use kernel::{fmt, b_str, str::CString}; /// let ascii = b_str!("Hello, BStr!"); /// let s = CString::try_from_fmt(fmt!("{}", ascii.display()))?; - /// assert_eq!(s.as_bytes(), "Hello, BStr!".as_bytes()); + /// assert_eq!(s.to_bytes(), "Hello, BStr!".as_bytes()); /// /// let non_ascii = b_str!("🦀"); /// let s = CString::try_from_fmt(fmt!("{}", non_ascii.display()))?; - /// assert_eq!(s.as_bytes(), "\\xf0\\x9f\\xa6\\x80".as_bytes()); + /// assert_eq!(s.to_bytes(), "\\xf0\\x9f\\xa6\\x80".as_bytes()); /// # Ok::<(), kernel::error::Error>(()) /// ``` #[inline] @@ -74,11 +74,11 @@ pub fn display(&self) -> Display<'_> { /// # use kernel::{fmt, b_str, str::CString}; /// let ascii = b_str!("Hello, BStr!"); /// let s = CString::try_from_fmt(fmt!("{}", ascii.display()))?; -/// assert_eq!(s.as_bytes(), "Hello, BStr!".as_bytes()); +/// assert_eq!(s.to_bytes(), "Hello, BStr!".as_bytes()); /// /// let non_ascii = b_str!("🦀"); /// let s = CString::try_from_fmt(fmt!("{}", non_ascii.display()))?; -/// assert_eq!(s.as_bytes(), "\\xf0\\x9f\\xa6\\x80".as_bytes()); +/// assert_eq!(s.to_bytes(), "\\xf0\\x9f\\xa6\\x80".as_bytes()); /// # Ok::<(), kernel::error::Error>(()) /// ``` /// @@ -119,11 +119,11 @@ impl fmt::Debug for BStr { /// // Embedded double quotes are escaped. /// let ascii = b_str!("Hello, \"BStr\"!"); /// let s = CString::try_from_fmt(fmt!("{:?}", ascii))?; - /// assert_eq!(s.as_bytes(), "\"Hello, \\\"BStr\\\"!\"".as_bytes()); + /// 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.as_bytes(), "\"\\xf0\\x9f\\x98\\xba\"".as_bytes()); + /// assert_eq!(s.to_bytes(), "\"\\xf0\\x9f\\x98\\xba\"".as_bytes()); /// # Ok::<(), kernel::error::Error>(()) /// ``` fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { @@ -176,254 +176,10 @@ macro_rules! b_str { }}; } -/// 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 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 crate::ffi::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 as _, 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 *(bytes as *mut [u8] as *mut CStr) } - } - - /// Returns a C pointer to the string. - #[inline] - pub const fn as_char_ptr(&self) -> *const crate::ffi::c_char { - self.0.as_ptr() - } - - /// Convert the string to a byte slice without the trailing `NUL` byte. - #[inline] - pub fn as_bytes(&self) -> &[u8] { - &self.0[..self.len()] - } - - /// Convert the string to a byte slice containing the trailing `NUL` byte. - #[inline] - pub const fn as_bytes_with_nul(&self) -> &[u8] { - &self.0 - } - - /// 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!("ツ"); - /// // SAFETY: String literals are guaranteed to be valid UTF-8 - /// // by the Rust compiler. - /// assert_eq!(unsafe { bar.as_str_unchecked() }, "ツ"); - /// ``` - #[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::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 { - 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 { - let mut s = self.to_cstring()?; - - s.make_ascii_uppercase(); - - Ok(s) - } +pub use core::ffi::CStr; +/// Extensions to [`CStr`]. +pub trait CStrExt { /// Returns an object that implements [`Display`] for safely printing a [`CStr`] that may /// contain non-Unicode data. If you would like an implementation which escapes the [`CStr`] /// please use [`Debug`] instead. @@ -439,114 +195,59 @@ pub fn to_ascii_uppercase(&self) -> Result { /// # use kernel::str::CString; /// let penguin = c_str!("🐧"); /// let s = CString::try_from_fmt(fmt!("{}", penguin.display()))?; - /// assert_eq!(s.as_bytes_with_nul(), "\\xf0\\x9f\\x90\\xa7\0".as_bytes()); + /// 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.display()))?; - /// assert_eq!(s.as_bytes_with_nul(), "so \"cool\"\0".as_bytes()); + /// assert_eq!(s.to_bytes_with_nul(), "so \"cool\"\0".as_bytes()); /// # Ok::<(), kernel::error::Error>(()) /// ``` + fn display(&self) -> Display<'_>; +} + +impl CStrExt for CStr { #[inline] - pub fn display(&self) -> Display<'_> { + fn display(&self) -> Display<'_> { Display { - inner: self, + inner: BStr::from_bytes(self.to_bytes()), escape_common: false, } } } -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::fmt; - /// # use kernel::str::CString; - /// let penguin = c_str!("🐧"); - /// 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. - /// let ascii = c_str!("so \"cool\""); - /// let s = CString::try_from_fmt(fmt!("{:?}", ascii))?; - /// assert_eq!(s.as_bytes_with_nul(), "\"so \\\"cool\\\"\"\0".as_bytes()); - /// # Ok::<(), kernel::error::Error>(()) - /// ``` - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - f.write_str("\"")?; - for &c in self.as_bytes() { - match c { - // Printable characters. - b'\"' => f.write_str("\\\"")?, - 0x20..=0x7e => f.write_char(c as char)?, - _ => write!(f, "\\x{:02x}", c)?, - } - } - f.write_str("\"") - } -} - -impl AsRef for CStr { - #[inline] - fn as_ref(&self) -> &BStr { - BStr::from_bytes(self.as_bytes()) - } -} - -impl Deref for CStr { - type Target = BStr; - - #[inline] - fn deref(&self) -> &Self::Target { - self.as_ref() - } -} - -impl Index> for CStr { - type Output = CStr; - - #[inline] - fn index(&self, index: ops::RangeFrom) -> &Self::Output { - // Delegate bounds checking to slice. - // Assign to _ to mute clippy's unnecessary operation warning. - let _ = &self.as_bytes()[index.start..]; - // SAFETY: We just checked the bounds. - unsafe { Self::from_bytes_with_nul_unchecked(&self.0[index.start..]) } - } -} - -impl Index for CStr { - type Output = CStr; - - #[inline] - fn index(&self, _index: ops::RangeFull) -> &Self::Output { - self - } -} - -mod private { - use core::ops; - - // Marker trait for index types that can be forward to `BStr`. - pub trait CStrIndex {} - - impl CStrIndex for usize {} - impl CStrIndex for ops::Range {} - impl CStrIndex for ops::RangeInclusive {} - impl CStrIndex for ops::RangeToInclusive {} +/// Wraps a raw C string with a safe C string wrapper. +/// +/// # Safety +/// +/// * The memory pointed to by `ptr` must contain a valid nul terminator at the end of the string. +/// +/// * `ptr` must be [valid] for reads of bytes up to and including the nul terminator. This means in +/// particular: +/// +/// * The entire memory range of this `CStr` must be contained within a single allocated object! +/// * `ptr` must be non-null even for a zero-length cstr. +/// +/// * The memory referenced by the returned `CStr` must not be mutated for the duration of lifetime +/// `'a`. +/// +/// * The nul terminator must be within `isize::MAX` from `ptr` +// 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`. +#[inline] +pub unsafe fn from_char_ptr<'a>(ptr: *const crate::ffi::c_char) -> &'a CStr { + // SAFETY: The safety preconditions are the same as for `from_ptr`. + unsafe { CStr::from_ptr(ptr.cast()) } } -impl Index for CStr -where - Idx: private::CStrIndex, - BStr: Index, -{ - type Output = >::Output; - - #[inline] - fn index(&self, index: Idx) -> &Self::Output { - &self.as_ref()[index] - } +/// 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`. 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(c_str: &CStr) -> *const crate::ffi::c_char { + c_str.as_ptr().cast() } /// Creates a new [`CStr`] from a string literal. @@ -629,25 +330,15 @@ fn test_cstr_to_str_panic() { checked_cstr.to_str().unwrap(); } - #[test] - fn test_cstr_as_str_unchecked() { - let good_bytes = b"\xf0\x9f\x90\xA7\0"; - let checked_cstr = CStr::from_bytes_with_nul(good_bytes).unwrap(); - // SAFETY: The contents come from a string literal which contains valid UTF-8. - let unchecked_str = unsafe { checked_cstr.as_str_unchecked() }; - assert_eq!(unchecked_str, "🐧"); - } - #[test] fn test_cstr_display() { - let hello_world = CStr::from_bytes_with_nul(b"hello, world!\0").unwrap(); - assert_eq!(format!("{}", hello_world.display()), "hello, world!"); - let non_printables = CStr::from_bytes_with_nul(b"\x01\x09\x0a\0").unwrap(); - assert_eq!(format!("{}", non_printables.display()), "\\x01\\x09\\x0a"); - let non_ascii = CStr::from_bytes_with_nul(b"d\xe9j\xe0 vu\0").unwrap(); - assert_eq!(format!("{}", non_ascii.display()), "d\\xe9j\\xe0 vu"); - let good_bytes = CStr::from_bytes_with_nul(b"\xf0\x9f\xa6\x80\0").unwrap(); - assert_eq!(format!("{}", good_bytes.display()), "\\xf0\\x9f\\xa6\\x80"); + assert_eq!(format!("{}", c"hello, world!".display()), "hello, world!"); + assert_eq!(format!("{}", c"\x01\x09\x0a".display()), "\\x01\\x09\\x0a"); + assert_eq!(format!("{}", c"d\xe9j\xe0 vu".display()), "d\\xe9j\\xe0 vu"); + assert_eq!( + format!("{}", c"\xf0\x9f\xa6\x80".display()), + "\\xf0\\x9f\\xa6\\x80" + ); } #[test] @@ -663,14 +354,13 @@ fn test_cstr_display_all_bytes() { #[test] fn test_cstr_debug() { - let hello_world = CStr::from_bytes_with_nul(b"hello, world!\0").unwrap(); - assert_eq!(format!("{:?}", hello_world), "\"hello, world!\""); - let non_printables = CStr::from_bytes_with_nul(b"\x01\x09\x0a\0").unwrap(); - assert_eq!(format!("{:?}", non_printables), "\"\\x01\\x09\\x0a\""); - let non_ascii = CStr::from_bytes_with_nul(b"d\xe9j\xe0 vu\0").unwrap(); - assert_eq!(format!("{:?}", non_ascii), "\"d\\xe9j\\xe0 vu\""); - let good_bytes = CStr::from_bytes_with_nul(b"\xf0\x9f\xa6\x80\0").unwrap(); - assert_eq!(format!("{:?}", good_bytes), "\"\\xf0\\x9f\\xa6\\x80\""); + assert_eq!(format!("{:?}", c"hello, world!"), "\"hello, world!\""); + assert_eq!(format!("{:?}", c"\x01\x09\x0a"), "\"\\x01\\t\\n\""); + assert_eq!(format!("{:?}", c"d\xe9j\xe0 vu"), "\"d\\xe9j\\xe0 vu\""); + assert_eq!( + format!("{:?}", c"\xf0\x9f\xa6\x80"), + "\"\\xf0\\x9f\\xa6\\x80\"" + ); } #[test] @@ -850,14 +540,14 @@ fn write_str(&mut self, s: &str) -> fmt::Result { /// # Examples /// /// ``` -/// use kernel::{str::CString, fmt}; +/// use kernel::{fmt, str::CString}; /// /// let s = CString::try_from_fmt(fmt!("{}{}{}", "abc", 10, 20))?; -/// assert_eq!(s.as_bytes_with_nul(), "abc1020\0".as_bytes()); +/// assert_eq!(s.to_bytes_with_nul(), "abc1020\0".as_bytes()); /// /// let tmp = "testing"; /// let s = CString::try_from_fmt(fmt!("{tmp}{}", 123))?; -/// assert_eq!(s.as_bytes_with_nul(), "testing123\0".as_bytes()); +/// assert_eq!(s.to_bytes_with_nul(), "testing123\0".as_bytes()); /// /// // This fails because it has an embedded `NUL` byte. /// let s = CString::try_from_fmt(fmt!("a\0b{}", 123)); @@ -915,9 +605,8 @@ fn deref(&self) -> &Self::Target { impl DerefMut for CString { fn deref_mut(&mut self) -> &mut Self::Target { - // SAFETY: A `CString` is always NUL-terminated and contains no other - // NUL bytes. - unsafe { CStr::from_bytes_with_nul_unchecked_mut(self.buf.as_mut_slice()) } + // SAFETY: Properties of `bytes` guaranteed by the safety precondition. + unsafe { &mut *(self.buf.as_mut_slice() as *mut [u8] as *mut CStr) } } } @@ -927,7 +616,7 @@ impl<'a> TryFrom<&'a CStr> for CString { fn try_from(cstr: &'a CStr) -> Result { let mut buf = KVec::new(); - buf.extend_from_slice(cstr.as_bytes_with_nul(), GFP_KERNEL)?; + buf.extend_from_slice(cstr.to_bytes_with_nul(), GFP_KERNEL)?; // INVARIANT: The `CStr` and `CString` types have the same invariants for // the string data, and we copied it over without changes. diff --git a/rust/kernel/sync/condvar.rs b/rust/kernel/sync/condvar.rs index 7df565038d7d..7bf3df980433 100644 --- a/rust/kernel/sync/condvar.rs +++ b/rust/kernel/sync/condvar.rs @@ -107,7 +107,7 @@ pub fn new(name: &'static CStr, key: &'static LockClassKey) -> impl PinInit impl PinIni // SAFETY: `slot` is valid while the closure is called and both `name` and `key` have // static lifetimes so they live indefinitely. state <- Opaque::ffi_init(|slot| unsafe { - B::init(slot, name.as_char_ptr(), key.as_ptr()) + B::init(slot, crate::str::as_char_ptr(name), key.as_ptr()) }), }) } diff --git a/rust/kernel/sync/lock/global.rs b/rust/kernel/sync/lock/global.rs index 480ee724e3cc..4c4d60a51c1f 100644 --- a/rust/kernel/sync/lock/global.rs +++ b/rust/kernel/sync/lock/global.rs @@ -69,7 +69,7 @@ pub unsafe fn init(&'static self) { unsafe { B::Backend::init( self.inner.state.get(), - B::NAME.as_char_ptr(), + crate::str::as_char_ptr(B::NAME), B::get_lock_class().as_ptr(), ) } diff --git a/rust/kernel/workqueue.rs b/rust/kernel/workqueue.rs index 1dcd53478edd..284b9a739c01 100644 --- a/rust/kernel/workqueue.rs +++ b/rust/kernel/workqueue.rs @@ -382,7 +382,7 @@ pub fn new(name: &'static CStr, key: &'static LockClassKey) -> impl PinInit