rust: str: implement `Display` and `Debug` for `BStr`
Currently, `BStr` is just a type alias of `[u8]`, limiting its representation to a byte list rather than a character list, which is not ideal for printing and debugging. Implement `Display` and `Debug` traits for `BStr` to facilitate easier printing and debugging. Also, for this purpose, change `BStr` from a type alias of `[u8]` to a struct wrapper of `[u8]`. Co-developed-by: Virgile Andreani <armavica@ulminfo.fr> Signed-off-by: Virgile Andreani <armavica@ulminfo.fr> Signed-off-by: Yutaro Ohno <yutaro.ono.418@gmail.com> Reviewed-by: Alice Ryhl <aliceryhl@google.com> Link: https://lore.kernel.org/r/ZcSlGMGP-e9HqybA@ohnotp [ Formatted code comment. ] Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
This commit is contained in:
Yutaro Ohno
Miguel Ojeda
parent
1b6170ff7a
commit
4951ddd51b
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@ -13,9 +13,102 @@ use crate::{
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};
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/// Byte string without UTF-8 validity guarantee.
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///
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/// `BStr` is simply an alias to `[u8]`, but has a more evident semantical meaning.
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pub type BStr = [u8];
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#[repr(transparent)]
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pub struct BStr([u8]);
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impl BStr {
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/// Returns the length of this string.
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#[inline]
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pub const fn len(&self) -> usize {
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self.0.len()
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}
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/// Returns `true` if the string is empty.
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#[inline]
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pub const fn is_empty(&self) -> bool {
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self.len() == 0
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}
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/// Creates a [`BStr`] from a `[u8]`.
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#[inline]
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pub const fn from_bytes(bytes: &[u8]) -> &Self {
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// SAFETY: `BStr` is transparent to `[u8]`.
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unsafe { &*(bytes as *const [u8] as *const BStr) }
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}
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}
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impl fmt::Display for BStr {
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/// Formats printable ASCII characters, escaping the rest.
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///
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/// ```
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/// # use kernel::{fmt, b_str, str::{BStr, CString}};
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/// let ascii = b_str!("Hello, BStr!");
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/// let s = CString::try_from_fmt(fmt!("{}", ascii)).unwrap();
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/// assert_eq!(s.as_bytes(), "Hello, BStr!".as_bytes());
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///
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/// let non_ascii = b_str!("🦀");
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/// let s = CString::try_from_fmt(fmt!("{}", non_ascii)).unwrap();
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/// assert_eq!(s.as_bytes(), "\\xf0\\x9f\\xa6\\x80".as_bytes());
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/// ```
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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for &b in &self.0 {
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match b {
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// Common escape codes.
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b'\t' => f.write_str("\\t")?,
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b'\n' => f.write_str("\\n")?,
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b'\r' => f.write_str("\\r")?,
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// Printable characters.
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0x20..=0x7e => f.write_char(b as char)?,
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_ => write!(f, "\\x{:02x}", b)?,
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}
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}
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Ok(())
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}
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}
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impl fmt::Debug for BStr {
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/// Formats printable ASCII characters with a double quote on either end,
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/// escaping the rest.
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///
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/// ```
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/// # use kernel::{fmt, b_str, str::{BStr, CString}};
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/// // Embedded double quotes are escaped.
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/// let ascii = b_str!("Hello, \"BStr\"!");
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/// let s = CString::try_from_fmt(fmt!("{:?}", ascii)).unwrap();
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/// assert_eq!(s.as_bytes(), "\"Hello, \\\"BStr\\\"!\"".as_bytes());
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///
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/// let non_ascii = b_str!("😺");
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/// let s = CString::try_from_fmt(fmt!("{:?}", non_ascii)).unwrap();
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/// assert_eq!(s.as_bytes(), "\"\\xf0\\x9f\\x98\\xba\"".as_bytes());
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/// ```
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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f.write_char('"')?;
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for &b in &self.0 {
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match b {
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// Common escape codes.
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b'\t' => f.write_str("\\t")?,
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b'\n' => f.write_str("\\n")?,
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b'\r' => f.write_str("\\r")?,
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// String escape characters.
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b'\"' => f.write_str("\\\"")?,
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b'\\' => f.write_str("\\\\")?,
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// Printable characters.
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0x20..=0x7e => f.write_char(b as char)?,
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_ => write!(f, "\\x{:02x}", b)?,
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}
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}
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f.write_char('"')
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}
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}
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impl Deref for BStr {
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type Target = [u8];
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#[inline]
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fn deref(&self) -> &Self::Target {
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&self.0
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}
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}
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/// Creates a new [`BStr`] from a string literal.
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///
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@ -33,7 +126,7 @@ pub type BStr = [u8];
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macro_rules! b_str {
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($str:literal) => {{
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const S: &'static str = $str;
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const C: &'static $crate::str::BStr = S.as_bytes();
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const C: &'static $crate::str::BStr = $crate::str::BStr::from_bytes(S.as_bytes());
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C
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}};
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}
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@ -271,7 +364,7 @@ impl fmt::Debug for CStr {
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impl AsRef<BStr> for CStr {
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#[inline]
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fn as_ref(&self) -> &BStr {
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self.as_bytes()
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BStr::from_bytes(self.as_bytes())
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}
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}
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@ -280,7 +373,7 @@ impl Deref for CStr {
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#[inline]
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fn deref(&self) -> &Self::Target {
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self.as_bytes()
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self.as_ref()
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}
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}
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@ -327,7 +420,7 @@ where
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#[inline]
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fn index(&self, index: Idx) -> &Self::Output {
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&self.as_bytes()[index]
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&self.as_ref()[index]
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}
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}
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@ -357,6 +450,21 @@ macro_rules! c_str {
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#[cfg(test)]
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mod tests {
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use super::*;
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use alloc::format;
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const ALL_ASCII_CHARS: &'static str =
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"\\x01\\x02\\x03\\x04\\x05\\x06\\x07\\x08\\x09\\x0a\\x0b\\x0c\\x0d\\x0e\\x0f\
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\\x10\\x11\\x12\\x13\\x14\\x15\\x16\\x17\\x18\\x19\\x1a\\x1b\\x1c\\x1d\\x1e\\x1f \
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!\"#$%&'()*+,-./0123456789:;<=>?@\
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ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~\\x7f\
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\\x80\\x81\\x82\\x83\\x84\\x85\\x86\\x87\\x88\\x89\\x8a\\x8b\\x8c\\x8d\\x8e\\x8f\
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\\x90\\x91\\x92\\x93\\x94\\x95\\x96\\x97\\x98\\x99\\x9a\\x9b\\x9c\\x9d\\x9e\\x9f\
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\\xa0\\xa1\\xa2\\xa3\\xa4\\xa5\\xa6\\xa7\\xa8\\xa9\\xaa\\xab\\xac\\xad\\xae\\xaf\
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\\xb0\\xb1\\xb2\\xb3\\xb4\\xb5\\xb6\\xb7\\xb8\\xb9\\xba\\xbb\\xbc\\xbd\\xbe\\xbf\
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\\xc0\\xc1\\xc2\\xc3\\xc4\\xc5\\xc6\\xc7\\xc8\\xc9\\xca\\xcb\\xcc\\xcd\\xce\\xcf\
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\\xd0\\xd1\\xd2\\xd3\\xd4\\xd5\\xd6\\xd7\\xd8\\xd9\\xda\\xdb\\xdc\\xdd\\xde\\xdf\
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\\xe0\\xe1\\xe2\\xe3\\xe4\\xe5\\xe6\\xe7\\xe8\\xe9\\xea\\xeb\\xec\\xed\\xee\\xef\
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\\xf0\\xf1\\xf2\\xf3\\xf4\\xf5\\xf6\\xf7\\xf8\\xf9\\xfa\\xfb\\xfc\\xfd\\xfe\\xff";
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#[test]
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fn test_cstr_to_str() {
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@ -381,6 +489,69 @@ mod tests {
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let unchecked_str = unsafe { checked_cstr.as_str_unchecked() };
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assert_eq!(unchecked_str, "🐧");
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}
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#[test]
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fn test_cstr_display() {
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let hello_world = CStr::from_bytes_with_nul(b"hello, world!\0").unwrap();
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assert_eq!(format!("{}", hello_world), "hello, world!");
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let non_printables = CStr::from_bytes_with_nul(b"\x01\x09\x0a\0").unwrap();
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assert_eq!(format!("{}", non_printables), "\\x01\\x09\\x0a");
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let non_ascii = CStr::from_bytes_with_nul(b"d\xe9j\xe0 vu\0").unwrap();
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assert_eq!(format!("{}", non_ascii), "d\\xe9j\\xe0 vu");
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let good_bytes = CStr::from_bytes_with_nul(b"\xf0\x9f\xa6\x80\0").unwrap();
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assert_eq!(format!("{}", good_bytes), "\\xf0\\x9f\\xa6\\x80");
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}
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#[test]
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fn test_cstr_display_all_bytes() {
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let mut bytes: [u8; 256] = [0; 256];
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// fill `bytes` with [1..=255] + [0]
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for i in u8::MIN..=u8::MAX {
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bytes[i as usize] = i.wrapping_add(1);
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}
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let cstr = CStr::from_bytes_with_nul(&bytes).unwrap();
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assert_eq!(format!("{}", cstr), ALL_ASCII_CHARS);
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}
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#[test]
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fn test_cstr_debug() {
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let hello_world = CStr::from_bytes_with_nul(b"hello, world!\0").unwrap();
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assert_eq!(format!("{:?}", hello_world), "\"hello, world!\"");
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let non_printables = CStr::from_bytes_with_nul(b"\x01\x09\x0a\0").unwrap();
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assert_eq!(format!("{:?}", non_printables), "\"\\x01\\x09\\x0a\"");
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let non_ascii = CStr::from_bytes_with_nul(b"d\xe9j\xe0 vu\0").unwrap();
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assert_eq!(format!("{:?}", non_ascii), "\"d\\xe9j\\xe0 vu\"");
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let good_bytes = CStr::from_bytes_with_nul(b"\xf0\x9f\xa6\x80\0").unwrap();
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assert_eq!(format!("{:?}", good_bytes), "\"\\xf0\\x9f\\xa6\\x80\"");
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}
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#[test]
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fn test_bstr_display() {
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let hello_world = BStr::from_bytes(b"hello, world!");
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assert_eq!(format!("{}", hello_world), "hello, world!");
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let escapes = BStr::from_bytes(b"_\t_\n_\r_\\_\'_\"_");
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assert_eq!(format!("{}", escapes), "_\\t_\\n_\\r_\\_'_\"_");
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let others = BStr::from_bytes(b"\x01");
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assert_eq!(format!("{}", others), "\\x01");
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let non_ascii = BStr::from_bytes(b"d\xe9j\xe0 vu");
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assert_eq!(format!("{}", non_ascii), "d\\xe9j\\xe0 vu");
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let good_bytes = BStr::from_bytes(b"\xf0\x9f\xa6\x80");
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assert_eq!(format!("{}", good_bytes), "\\xf0\\x9f\\xa6\\x80");
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}
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#[test]
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fn test_bstr_debug() {
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let hello_world = BStr::from_bytes(b"hello, world!");
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assert_eq!(format!("{:?}", hello_world), "\"hello, world!\"");
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let escapes = BStr::from_bytes(b"_\t_\n_\r_\\_\'_\"_");
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assert_eq!(format!("{:?}", escapes), "\"_\\t_\\n_\\r_\\\\_'_\\\"_\"");
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let others = BStr::from_bytes(b"\x01");
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assert_eq!(format!("{:?}", others), "\"\\x01\"");
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let non_ascii = BStr::from_bytes(b"d\xe9j\xe0 vu");
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assert_eq!(format!("{:?}", non_ascii), "\"d\\xe9j\\xe0 vu\"");
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let good_bytes = BStr::from_bytes(b"\xf0\x9f\xa6\x80");
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assert_eq!(format!("{:?}", good_bytes), "\"\\xf0\\x9f\\xa6\\x80\"");
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}
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}
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/// Allows formatting of [`fmt::Arguments`] into a raw buffer.
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