diff options
author | Gary Guo <gary@garyguo.net> | 2022-11-10 17:41:29 +0100 |
---|---|---|
committer | Miguel Ojeda <ojeda@kernel.org> | 2022-12-04 01:59:15 +0100 |
commit | c07e67bd2daf99de923b6fd927ab8c18e0f57b05 (patch) | |
tree | a00b2bf56e96c9ce0598287b2c4142bcb978bc2e /rust | |
parent | d126d2380131dfbc880f5b5f0e3015e9bef6fa1c (diff) | |
download | linux-stable-c07e67bd2daf99de923b6fd927ab8c18e0f57b05.tar.gz linux-stable-c07e67bd2daf99de923b6fd927ab8c18e0f57b05.tar.bz2 linux-stable-c07e67bd2daf99de923b6fd927ab8c18e0f57b05.zip |
rust: str: implement several traits for `CStr`
Implement `Debug`, `Display`, `Deref` (into `BStr`), `AsRef<BStr>`
and a set of `Index<...>` traits.
This makes it `CStr` more convenient to use (and closer to `str`).
Co-developed-by: Alex Gaynor <alex.gaynor@gmail.com>
Signed-off-by: Alex Gaynor <alex.gaynor@gmail.com>
Co-developed-by: Morgan Bartlett <mjmouse9999@gmail.com>
Signed-off-by: Morgan Bartlett <mjmouse9999@gmail.com>
Signed-off-by: Gary Guo <gary@garyguo.net>
[Reworded, adapted for upstream and applied latest changes]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Diffstat (limited to 'rust')
-rw-r--r-- | rust/kernel/str.rs | 124 |
1 files changed, 123 insertions, 1 deletions
diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs index d66565f92f71..11d297c1a61c 100644 --- a/rust/kernel/str.rs +++ b/rust/kernel/str.rs @@ -2,7 +2,8 @@ //! String representations. -use core::fmt; +use core::fmt::{self, Write}; +use core::ops::{self, Deref, Index}; use crate::{ bindings, @@ -199,6 +200,127 @@ impl CStr { } } +impl fmt::Display for CStr { + /// Formats printable ASCII characters, escaping the rest. + /// + /// ``` + /// # use kernel::c_str; + /// # use kernel::str::CStr; + /// # use kernel::str::CString; + /// let penguin = c_str!("🐧"); + /// let s = CString::try_from_fmt(fmt!("{}", penguin)).unwrap(); + /// assert_eq!(s.as_bytes_with_nul(), "\\xf0\\x9f\\x90\\xa7\0".as_bytes()); + /// + /// let ascii = c_str!("so \"cool\""); + /// let s = CString::try_from_fmt(fmt!("{}", ascii)).unwrap(); + /// assert_eq!(s.as_bytes_with_nul(), "so \"cool\"\0".as_bytes()); + /// ``` + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + for &c in self.as_bytes() { + if (0x20..0x7f).contains(&c) { + // Printable character. + f.write_char(c as char)?; + } else { + write!(f, "\\x{:02x}", c)?; + } + } + 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::str::CStr; + /// # use kernel::str::CString; + /// let penguin = c_str!("🐧"); + /// let s = CString::try_from_fmt(fmt!("{:?}", penguin)).unwrap(); + /// 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)).unwrap(); + /// assert_eq!(s.as_bytes_with_nul(), "\"so \\\"cool\\\"\"\0".as_bytes()); + /// ``` + 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<BStr> for CStr { + #[inline] + fn as_ref(&self) -> &BStr { + self.as_bytes() + } +} + +impl Deref for CStr { + type Target = BStr; + + #[inline] + fn deref(&self) -> &Self::Target { + self.as_bytes() + } +} + +impl Index<ops::RangeFrom<usize>> for CStr { + type Output = CStr; + + #[inline] + fn index(&self, index: ops::RangeFrom<usize>) -> &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<ops::RangeFull> 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<usize> {} + impl CStrIndex for ops::RangeInclusive<usize> {} + impl CStrIndex for ops::RangeToInclusive<usize> {} +} + +impl<Idx> Index<Idx> for CStr +where + Idx: private::CStrIndex, + BStr: Index<Idx>, +{ + type Output = <BStr as Index<Idx>>::Output; + + #[inline] + fn index(&self, index: Idx) -> &Self::Output { + &self.as_bytes()[index] + } +} + /// Allows formatting of [`fmt::Arguments`] into a raw buffer. /// /// It does not fail if callers write past the end of the buffer so that they can calculate the |