1 // SPDX-License-Identifier: GPL-2.0 1 // SPDX-License-Identifier: GPL-2.0
2 2
3 //! String representations. 3 //! String representations.
4 4
5 use crate::alloc::{flags::*, vec_ext::VecExt, !! 5 use alloc::alloc::AllocError;
6 use alloc::vec::Vec; 6 use alloc::vec::Vec;
7 use core::fmt::{self, Write}; 7 use core::fmt::{self, Write};
8 use core::ops::{self, Deref, DerefMut, Index}; !! 8 use core::ops::{self, Deref, Index};
9 9
10 use crate::error::{code::*, Error}; !! 10 use crate::{
>> 11 bindings,
>> 12 error::{code::*, Error},
>> 13 };
11 14
12 /// Byte string without UTF-8 validity guarant 15 /// Byte string without UTF-8 validity guarantee.
13 #[repr(transparent)] 16 #[repr(transparent)]
14 pub struct BStr([u8]); 17 pub struct BStr([u8]);
15 18
16 impl BStr { 19 impl BStr {
17 /// Returns the length of this string. 20 /// Returns the length of this string.
18 #[inline] 21 #[inline]
19 pub const fn len(&self) -> usize { 22 pub const fn len(&self) -> usize {
20 self.0.len() 23 self.0.len()
21 } 24 }
22 25
23 /// Returns `true` if the string is empty. 26 /// Returns `true` if the string is empty.
24 #[inline] 27 #[inline]
25 pub const fn is_empty(&self) -> bool { 28 pub const fn is_empty(&self) -> bool {
26 self.len() == 0 29 self.len() == 0
27 } 30 }
28 31
29 /// Creates a [`BStr`] from a `[u8]`. 32 /// Creates a [`BStr`] from a `[u8]`.
30 #[inline] 33 #[inline]
31 pub const fn from_bytes(bytes: &[u8]) -> & 34 pub const fn from_bytes(bytes: &[u8]) -> &Self {
32 // SAFETY: `BStr` is transparent to `[ 35 // SAFETY: `BStr` is transparent to `[u8]`.
33 unsafe { &*(bytes as *const [u8] as *c 36 unsafe { &*(bytes as *const [u8] as *const BStr) }
34 } 37 }
35 } 38 }
36 39
37 impl fmt::Display for BStr { 40 impl fmt::Display for BStr {
38 /// Formats printable ASCII characters, es 41 /// Formats printable ASCII characters, escaping the rest.
39 /// 42 ///
40 /// ``` 43 /// ```
41 /// # use kernel::{fmt, b_str, str::{BStr, 44 /// # use kernel::{fmt, b_str, str::{BStr, CString}};
42 /// let ascii = b_str!("Hello, BStr!"); 45 /// let ascii = b_str!("Hello, BStr!");
43 /// let s = CString::try_from_fmt(fmt!("{} 46 /// let s = CString::try_from_fmt(fmt!("{}", ascii)).unwrap();
44 /// assert_eq!(s.as_bytes(), "Hello, BStr! 47 /// assert_eq!(s.as_bytes(), "Hello, BStr!".as_bytes());
45 /// 48 ///
46 /// let non_ascii = b_str!("🦀"); 49 /// let non_ascii = b_str!("🦀");
47 /// let s = CString::try_from_fmt(fmt!("{} 50 /// let s = CString::try_from_fmt(fmt!("{}", non_ascii)).unwrap();
48 /// assert_eq!(s.as_bytes(), "\\xf0\\x9f\\ 51 /// assert_eq!(s.as_bytes(), "\\xf0\\x9f\\xa6\\x80".as_bytes());
49 /// ``` 52 /// ```
50 fn fmt(&self, f: &mut fmt::Formatter<'_>) 53 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
51 for &b in &self.0 { 54 for &b in &self.0 {
52 match b { 55 match b {
53 // Common escape codes. 56 // Common escape codes.
54 b'\t' => f.write_str("\\t")?, 57 b'\t' => f.write_str("\\t")?,
55 b'\n' => f.write_str("\\n")?, 58 b'\n' => f.write_str("\\n")?,
56 b'\r' => f.write_str("\\r")?, 59 b'\r' => f.write_str("\\r")?,
57 // Printable characters. 60 // Printable characters.
58 0x20..=0x7e => f.write_char(b 61 0x20..=0x7e => f.write_char(b as char)?,
59 _ => write!(f, "\\x{:02x}", b) 62 _ => write!(f, "\\x{:02x}", b)?,
60 } 63 }
61 } 64 }
62 Ok(()) 65 Ok(())
63 } 66 }
64 } 67 }
65 68
66 impl fmt::Debug for BStr { 69 impl fmt::Debug for BStr {
67 /// Formats printable ASCII characters wit 70 /// Formats printable ASCII characters with a double quote on either end,
68 /// escaping the rest. 71 /// escaping the rest.
69 /// 72 ///
70 /// ``` 73 /// ```
71 /// # use kernel::{fmt, b_str, str::{BStr, 74 /// # use kernel::{fmt, b_str, str::{BStr, CString}};
72 /// // Embedded double quotes are escaped. 75 /// // Embedded double quotes are escaped.
73 /// let ascii = b_str!("Hello, \"BStr\"!") 76 /// let ascii = b_str!("Hello, \"BStr\"!");
74 /// let s = CString::try_from_fmt(fmt!("{: 77 /// let s = CString::try_from_fmt(fmt!("{:?}", ascii)).unwrap();
75 /// assert_eq!(s.as_bytes(), "\"Hello, \\\ 78 /// assert_eq!(s.as_bytes(), "\"Hello, \\\"BStr\\\"!\"".as_bytes());
76 /// 79 ///
77 /// let non_ascii = b_str!("😺"); 80 /// let non_ascii = b_str!("😺");
78 /// let s = CString::try_from_fmt(fmt!("{: 81 /// let s = CString::try_from_fmt(fmt!("{:?}", non_ascii)).unwrap();
79 /// assert_eq!(s.as_bytes(), "\"\\xf0\\x9f 82 /// assert_eq!(s.as_bytes(), "\"\\xf0\\x9f\\x98\\xba\"".as_bytes());
80 /// ``` 83 /// ```
81 fn fmt(&self, f: &mut fmt::Formatter<'_>) 84 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
82 f.write_char('"')?; 85 f.write_char('"')?;
83 for &b in &self.0 { 86 for &b in &self.0 {
84 match b { 87 match b {
85 // Common escape codes. 88 // Common escape codes.
86 b'\t' => f.write_str("\\t")?, 89 b'\t' => f.write_str("\\t")?,
87 b'\n' => f.write_str("\\n")?, 90 b'\n' => f.write_str("\\n")?,
88 b'\r' => f.write_str("\\r")?, 91 b'\r' => f.write_str("\\r")?,
89 // String escape characters. 92 // String escape characters.
90 b'\"' => f.write_str("\\\"")?, 93 b'\"' => f.write_str("\\\"")?,
91 b'\\' => f.write_str("\\\\")?, 94 b'\\' => f.write_str("\\\\")?,
92 // Printable characters. 95 // Printable characters.
93 0x20..=0x7e => f.write_char(b 96 0x20..=0x7e => f.write_char(b as char)?,
94 _ => write!(f, "\\x{:02x}", b) 97 _ => write!(f, "\\x{:02x}", b)?,
95 } 98 }
96 } 99 }
97 f.write_char('"') 100 f.write_char('"')
98 } 101 }
99 } 102 }
100 103
101 impl Deref for BStr { 104 impl Deref for BStr {
102 type Target = [u8]; 105 type Target = [u8];
103 106
104 #[inline] 107 #[inline]
105 fn deref(&self) -> &Self::Target { 108 fn deref(&self) -> &Self::Target {
106 &self.0 109 &self.0
107 } 110 }
108 } 111 }
109 112
110 /// Creates a new [`BStr`] from a string liter 113 /// Creates a new [`BStr`] from a string literal.
111 /// 114 ///
112 /// `b_str!` converts the supplied string lite 115 /// `b_str!` converts the supplied string literal to byte string, so non-ASCII
113 /// characters can be included. 116 /// characters can be included.
114 /// 117 ///
115 /// # Examples 118 /// # Examples
116 /// 119 ///
117 /// ``` 120 /// ```
118 /// # use kernel::b_str; 121 /// # use kernel::b_str;
119 /// # use kernel::str::BStr; 122 /// # use kernel::str::BStr;
120 /// const MY_BSTR: &BStr = b_str!("My awesome 123 /// const MY_BSTR: &BStr = b_str!("My awesome BStr!");
121 /// ``` 124 /// ```
122 #[macro_export] 125 #[macro_export]
123 macro_rules! b_str { 126 macro_rules! b_str {
124 ($str:literal) => {{ 127 ($str:literal) => {{
125 const S: &'static str = $str; 128 const S: &'static str = $str;
126 const C: &'static $crate::str::BStr = 129 const C: &'static $crate::str::BStr = $crate::str::BStr::from_bytes(S.as_bytes());
127 C 130 C
128 }}; 131 }};
129 } 132 }
130 133
131 /// Possible errors when using conversion func 134 /// Possible errors when using conversion functions in [`CStr`].
132 #[derive(Debug, Clone, Copy)] 135 #[derive(Debug, Clone, Copy)]
133 pub enum CStrConvertError { 136 pub enum CStrConvertError {
134 /// Supplied bytes contain an interior `NU 137 /// Supplied bytes contain an interior `NUL`.
135 InteriorNul, 138 InteriorNul,
136 139
137 /// Supplied bytes are not terminated by ` 140 /// Supplied bytes are not terminated by `NUL`.
138 NotNulTerminated, 141 NotNulTerminated,
139 } 142 }
140 143
141 impl From<CStrConvertError> for Error { 144 impl From<CStrConvertError> for Error {
142 #[inline] 145 #[inline]
143 fn from(_: CStrConvertError) -> Error { 146 fn from(_: CStrConvertError) -> Error {
144 EINVAL 147 EINVAL
145 } 148 }
146 } 149 }
147 150
148 /// A string that is guaranteed to have exactl 151 /// A string that is guaranteed to have exactly one `NUL` byte, which is at the
149 /// end. 152 /// end.
150 /// 153 ///
151 /// Used for interoperability with kernel APIs 154 /// Used for interoperability with kernel APIs that take C strings.
152 #[repr(transparent)] 155 #[repr(transparent)]
153 pub struct CStr([u8]); 156 pub struct CStr([u8]);
154 157
155 impl CStr { 158 impl CStr {
156 /// Returns the length of this string excl 159 /// Returns the length of this string excluding `NUL`.
157 #[inline] 160 #[inline]
158 pub const fn len(&self) -> usize { 161 pub const fn len(&self) -> usize {
159 self.len_with_nul() - 1 162 self.len_with_nul() - 1
160 } 163 }
161 164
162 /// Returns the length of this string with 165 /// Returns the length of this string with `NUL`.
163 #[inline] 166 #[inline]
164 pub const fn len_with_nul(&self) -> usize 167 pub const fn len_with_nul(&self) -> usize {
165 // SAFETY: This is one of the invarian 168 // SAFETY: This is one of the invariant of `CStr`.
166 // We add a `unreachable_unchecked` he 169 // We add a `unreachable_unchecked` here to hint the optimizer that
167 // the value returned from this functi 170 // the value returned from this function is non-zero.
168 if self.0.is_empty() { 171 if self.0.is_empty() {
169 unsafe { core::hint::unreachable_u 172 unsafe { core::hint::unreachable_unchecked() };
170 } 173 }
171 self.0.len() 174 self.0.len()
172 } 175 }
173 176
174 /// Returns `true` if the string only incl 177 /// Returns `true` if the string only includes `NUL`.
175 #[inline] 178 #[inline]
176 pub const fn is_empty(&self) -> bool { 179 pub const fn is_empty(&self) -> bool {
177 self.len() == 0 180 self.len() == 0
178 } 181 }
179 182
180 /// Wraps a raw C string pointer. 183 /// Wraps a raw C string pointer.
181 /// 184 ///
182 /// # Safety 185 /// # Safety
183 /// 186 ///
184 /// `ptr` must be a valid pointer to a `NU 187 /// `ptr` must be a valid pointer to a `NUL`-terminated C string, and it must
185 /// last at least `'a`. When `CStr` is ali 188 /// last at least `'a`. When `CStr` is alive, the memory pointed by `ptr`
186 /// must not be mutated. 189 /// must not be mutated.
187 #[inline] 190 #[inline]
188 pub unsafe fn from_char_ptr<'a>(ptr: *cons 191 pub unsafe fn from_char_ptr<'a>(ptr: *const core::ffi::c_char) -> &'a Self {
189 // SAFETY: The safety precondition gua 192 // SAFETY: The safety precondition guarantees `ptr` is a valid pointer
190 // to a `NUL`-terminated C string. 193 // to a `NUL`-terminated C string.
191 let len = unsafe { bindings::strlen(pt 194 let len = unsafe { bindings::strlen(ptr) } + 1;
192 // SAFETY: Lifetime guaranteed by the 195 // SAFETY: Lifetime guaranteed by the safety precondition.
193 let bytes = unsafe { core::slice::from 196 let bytes = unsafe { core::slice::from_raw_parts(ptr as _, len as _) };
194 // SAFETY: As `len` is returned by `st 197 // SAFETY: As `len` is returned by `strlen`, `bytes` does not contain interior `NUL`.
195 // As we have added 1 to `len`, the la 198 // As we have added 1 to `len`, the last byte is known to be `NUL`.
196 unsafe { Self::from_bytes_with_nul_unc 199 unsafe { Self::from_bytes_with_nul_unchecked(bytes) }
197 } 200 }
198 201
199 /// Creates a [`CStr`] from a `[u8]`. 202 /// Creates a [`CStr`] from a `[u8]`.
200 /// 203 ///
201 /// The provided slice must be `NUL`-termi 204 /// The provided slice must be `NUL`-terminated, does not contain any
202 /// interior `NUL` bytes. 205 /// interior `NUL` bytes.
203 pub const fn from_bytes_with_nul(bytes: &[ 206 pub const fn from_bytes_with_nul(bytes: &[u8]) -> Result<&Self, CStrConvertError> {
204 if bytes.is_empty() { 207 if bytes.is_empty() {
205 return Err(CStrConvertError::NotNu 208 return Err(CStrConvertError::NotNulTerminated);
206 } 209 }
207 if bytes[bytes.len() - 1] != 0 { 210 if bytes[bytes.len() - 1] != 0 {
208 return Err(CStrConvertError::NotNu 211 return Err(CStrConvertError::NotNulTerminated);
209 } 212 }
210 let mut i = 0; 213 let mut i = 0;
211 // `i + 1 < bytes.len()` allows LLVM t 214 // `i + 1 < bytes.len()` allows LLVM to optimize away bounds checking,
212 // while it couldn't optimize away bou 215 // while it couldn't optimize away bounds checks for `i < bytes.len() - 1`.
213 while i + 1 < bytes.len() { 216 while i + 1 < bytes.len() {
214 if bytes[i] == 0 { 217 if bytes[i] == 0 {
215 return Err(CStrConvertError::I 218 return Err(CStrConvertError::InteriorNul);
216 } 219 }
217 i += 1; 220 i += 1;
218 } 221 }
219 // SAFETY: We just checked that all pr 222 // SAFETY: We just checked that all properties hold.
220 Ok(unsafe { Self::from_bytes_with_nul_ 223 Ok(unsafe { Self::from_bytes_with_nul_unchecked(bytes) })
221 } 224 }
222 225
223 /// Creates a [`CStr`] from a `[u8]` witho 226 /// Creates a [`CStr`] from a `[u8]` without performing any additional
224 /// checks. 227 /// checks.
225 /// 228 ///
226 /// # Safety 229 /// # Safety
227 /// 230 ///
228 /// `bytes` *must* end with a `NUL` byte, 231 /// `bytes` *must* end with a `NUL` byte, and should only have a single
229 /// `NUL` byte (or the string will be trun 232 /// `NUL` byte (or the string will be truncated).
230 #[inline] 233 #[inline]
231 pub const unsafe fn from_bytes_with_nul_un 234 pub const unsafe fn from_bytes_with_nul_unchecked(bytes: &[u8]) -> &CStr {
232 // SAFETY: Properties of `bytes` guara 235 // SAFETY: Properties of `bytes` guaranteed by the safety precondition.
233 unsafe { core::mem::transmute(bytes) } 236 unsafe { core::mem::transmute(bytes) }
234 } 237 }
235 238
236 /// Creates a mutable [`CStr`] from a `[u8 <<
237 /// additional checks. <<
238 /// <<
239 /// # Safety <<
240 /// <<
241 /// `bytes` *must* end with a `NUL` byte, <<
242 /// `NUL` byte (or the string will be trun <<
243 #[inline] <<
244 pub unsafe fn from_bytes_with_nul_unchecke <<
245 // SAFETY: Properties of `bytes` guara <<
246 unsafe { &mut *(bytes as *mut [u8] as <<
247 } <<
248 <<
249 /// Returns a C pointer to the string. 239 /// Returns a C pointer to the string.
250 #[inline] 240 #[inline]
251 pub const fn as_char_ptr(&self) -> *const 241 pub const fn as_char_ptr(&self) -> *const core::ffi::c_char {
252 self.0.as_ptr() as _ 242 self.0.as_ptr() as _
253 } 243 }
254 244
255 /// Convert the string to a byte slice wit 245 /// Convert the string to a byte slice without the trailing `NUL` byte.
256 #[inline] 246 #[inline]
257 pub fn as_bytes(&self) -> &[u8] { 247 pub fn as_bytes(&self) -> &[u8] {
258 &self.0[..self.len()] 248 &self.0[..self.len()]
259 } 249 }
260 250
261 /// Convert the string to a byte slice con 251 /// Convert the string to a byte slice containing the trailing `NUL` byte.
262 #[inline] 252 #[inline]
263 pub const fn as_bytes_with_nul(&self) -> & 253 pub const fn as_bytes_with_nul(&self) -> &[u8] {
264 &self.0 254 &self.0
265 } 255 }
266 256
267 /// Yields a [`&str`] slice if the [`CStr` 257 /// Yields a [`&str`] slice if the [`CStr`] contains valid UTF-8.
268 /// 258 ///
269 /// If the contents of the [`CStr`] are va 259 /// If the contents of the [`CStr`] are valid UTF-8 data, this
270 /// function will return the corresponding 260 /// function will return the corresponding [`&str`] slice. Otherwise,
271 /// it will return an error with details o 261 /// it will return an error with details of where UTF-8 validation failed.
272 /// 262 ///
273 /// # Examples 263 /// # Examples
274 /// 264 ///
275 /// ``` 265 /// ```
276 /// # use kernel::str::CStr; 266 /// # use kernel::str::CStr;
277 /// let cstr = CStr::from_bytes_with_nul(b 267 /// let cstr = CStr::from_bytes_with_nul(b"foo\0").unwrap();
278 /// assert_eq!(cstr.to_str(), Ok("foo")); 268 /// assert_eq!(cstr.to_str(), Ok("foo"));
279 /// ``` 269 /// ```
280 #[inline] 270 #[inline]
281 pub fn to_str(&self) -> Result<&str, core: 271 pub fn to_str(&self) -> Result<&str, core::str::Utf8Error> {
282 core::str::from_utf8(self.as_bytes()) 272 core::str::from_utf8(self.as_bytes())
283 } 273 }
284 274
285 /// Unsafely convert this [`CStr`] into a 275 /// Unsafely convert this [`CStr`] into a [`&str`], without checking for
286 /// valid UTF-8. 276 /// valid UTF-8.
287 /// 277 ///
288 /// # Safety 278 /// # Safety
289 /// 279 ///
290 /// The contents must be valid UTF-8. 280 /// The contents must be valid UTF-8.
291 /// 281 ///
292 /// # Examples 282 /// # Examples
293 /// 283 ///
294 /// ``` 284 /// ```
295 /// # use kernel::c_str; 285 /// # use kernel::c_str;
296 /// # use kernel::str::CStr; 286 /// # use kernel::str::CStr;
297 /// let bar = c_str!("ツ"); 287 /// let bar = c_str!("ツ");
298 /// // SAFETY: String literals are guarant 288 /// // SAFETY: String literals are guaranteed to be valid UTF-8
299 /// // by the Rust compiler. 289 /// // by the Rust compiler.
300 /// assert_eq!(unsafe { bar.as_str_uncheck 290 /// assert_eq!(unsafe { bar.as_str_unchecked() }, "ツ");
301 /// ``` 291 /// ```
302 #[inline] 292 #[inline]
303 pub unsafe fn as_str_unchecked(&self) -> & 293 pub unsafe fn as_str_unchecked(&self) -> &str {
304 unsafe { core::str::from_utf8_unchecke 294 unsafe { core::str::from_utf8_unchecked(self.as_bytes()) }
305 } 295 }
306 296
307 /// Convert this [`CStr`] into a [`CString 297 /// Convert this [`CStr`] into a [`CString`] by allocating memory and
308 /// copying over the string data. 298 /// copying over the string data.
309 pub fn to_cstring(&self) -> Result<CString 299 pub fn to_cstring(&self) -> Result<CString, AllocError> {
310 CString::try_from(self) 300 CString::try_from(self)
311 } 301 }
312 <<
313 /// Converts this [`CStr`] to its ASCII lo <<
314 /// <<
315 /// ASCII letters 'A' to 'Z' are mapped to <<
316 /// but non-ASCII letters are unchanged. <<
317 /// <<
318 /// To return a new lowercased value witho <<
319 /// [`to_ascii_lowercase()`]. <<
320 /// <<
321 /// [`to_ascii_lowercase()`]: #method.to_a <<
322 pub fn make_ascii_lowercase(&mut self) { <<
323 // INVARIANT: This doesn't introduce o <<
324 // string. <<
325 self.0.make_ascii_lowercase(); <<
326 } <<
327 <<
328 /// Converts this [`CStr`] to its ASCII up <<
329 /// <<
330 /// ASCII letters 'a' to 'z' are mapped to <<
331 /// but non-ASCII letters are unchanged. <<
332 /// <<
333 /// To return a new uppercased value witho <<
334 /// [`to_ascii_uppercase()`]. <<
335 /// <<
336 /// [`to_ascii_uppercase()`]: #method.to_a <<
337 pub fn make_ascii_uppercase(&mut self) { <<
338 // INVARIANT: This doesn't introduce o <<
339 // string. <<
340 self.0.make_ascii_uppercase(); <<
341 } <<
342 <<
343 /// Returns a copy of this [`CString`] whe <<
344 /// ASCII lower case equivalent. <<
345 /// <<
346 /// ASCII letters 'A' to 'Z' are mapped to <<
347 /// but non-ASCII letters are unchanged. <<
348 /// <<
349 /// To lowercase the value in-place, use [ <<
350 /// <<
351 /// [`make_ascii_lowercase`]: str::make_as <<
352 pub fn to_ascii_lowercase(&self) -> Result <<
353 let mut s = self.to_cstring()?; <<
354 <<
355 s.make_ascii_lowercase(); <<
356 <<
357 Ok(s) <<
358 } <<
359 <<
360 /// Returns a copy of this [`CString`] whe <<
361 /// ASCII upper case equivalent. <<
362 /// <<
363 /// ASCII letters 'a' to 'z' are mapped to <<
364 /// but non-ASCII letters are unchanged. <<
365 /// <<
366 /// To uppercase the value in-place, use [ <<
367 /// <<
368 /// [`make_ascii_uppercase`]: str::make_as <<
369 pub fn to_ascii_uppercase(&self) -> Result <<
370 let mut s = self.to_cstring()?; <<
371 <<
372 s.make_ascii_uppercase(); <<
373 <<
374 Ok(s) <<
375 } <<
376 } 302 }
377 303
378 impl fmt::Display for CStr { 304 impl fmt::Display for CStr {
379 /// Formats printable ASCII characters, es 305 /// Formats printable ASCII characters, escaping the rest.
380 /// 306 ///
381 /// ``` 307 /// ```
382 /// # use kernel::c_str; 308 /// # use kernel::c_str;
383 /// # use kernel::fmt; 309 /// # use kernel::fmt;
384 /// # use kernel::str::CStr; 310 /// # use kernel::str::CStr;
385 /// # use kernel::str::CString; 311 /// # use kernel::str::CString;
386 /// let penguin = c_str!("🐧"); 312 /// let penguin = c_str!("🐧");
387 /// let s = CString::try_from_fmt(fmt!("{} 313 /// let s = CString::try_from_fmt(fmt!("{}", penguin)).unwrap();
388 /// assert_eq!(s.as_bytes_with_nul(), "\\x 314 /// assert_eq!(s.as_bytes_with_nul(), "\\xf0\\x9f\\x90\\xa7\0".as_bytes());
389 /// 315 ///
390 /// let ascii = c_str!("so \"cool\""); 316 /// let ascii = c_str!("so \"cool\"");
391 /// let s = CString::try_from_fmt(fmt!("{} 317 /// let s = CString::try_from_fmt(fmt!("{}", ascii)).unwrap();
392 /// assert_eq!(s.as_bytes_with_nul(), "so 318 /// assert_eq!(s.as_bytes_with_nul(), "so \"cool\"\0".as_bytes());
393 /// ``` 319 /// ```
394 fn fmt(&self, f: &mut fmt::Formatter<'_>) 320 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
395 for &c in self.as_bytes() { 321 for &c in self.as_bytes() {
396 if (0x20..0x7f).contains(&c) { 322 if (0x20..0x7f).contains(&c) {
397 // Printable character. 323 // Printable character.
398 f.write_char(c as char)?; 324 f.write_char(c as char)?;
399 } else { 325 } else {
400 write!(f, "\\x{:02x}", c)?; 326 write!(f, "\\x{:02x}", c)?;
401 } 327 }
402 } 328 }
403 Ok(()) 329 Ok(())
404 } 330 }
405 } 331 }
406 332
407 impl fmt::Debug for CStr { 333 impl fmt::Debug for CStr {
408 /// Formats printable ASCII characters wit 334 /// Formats printable ASCII characters with a double quote on either end, escaping the rest.
409 /// 335 ///
410 /// ``` 336 /// ```
411 /// # use kernel::c_str; 337 /// # use kernel::c_str;
412 /// # use kernel::fmt; 338 /// # use kernel::fmt;
413 /// # use kernel::str::CStr; 339 /// # use kernel::str::CStr;
414 /// # use kernel::str::CString; 340 /// # use kernel::str::CString;
415 /// let penguin = c_str!("🐧"); 341 /// let penguin = c_str!("🐧");
416 /// let s = CString::try_from_fmt(fmt!("{: 342 /// let s = CString::try_from_fmt(fmt!("{:?}", penguin)).unwrap();
417 /// assert_eq!(s.as_bytes_with_nul(), "\"\ 343 /// assert_eq!(s.as_bytes_with_nul(), "\"\\xf0\\x9f\\x90\\xa7\"\0".as_bytes());
418 /// 344 ///
419 /// // Embedded double quotes are escaped. 345 /// // Embedded double quotes are escaped.
420 /// let ascii = c_str!("so \"cool\""); 346 /// let ascii = c_str!("so \"cool\"");
421 /// let s = CString::try_from_fmt(fmt!("{: 347 /// let s = CString::try_from_fmt(fmt!("{:?}", ascii)).unwrap();
422 /// assert_eq!(s.as_bytes_with_nul(), "\"s 348 /// assert_eq!(s.as_bytes_with_nul(), "\"so \\\"cool\\\"\"\0".as_bytes());
423 /// ``` 349 /// ```
424 fn fmt(&self, f: &mut fmt::Formatter<'_>) 350 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
425 f.write_str("\"")?; 351 f.write_str("\"")?;
426 for &c in self.as_bytes() { 352 for &c in self.as_bytes() {
427 match c { 353 match c {
428 // Printable characters. 354 // Printable characters.
429 b'\"' => f.write_str("\\\"")?, 355 b'\"' => f.write_str("\\\"")?,
430 0x20..=0x7e => f.write_char(c 356 0x20..=0x7e => f.write_char(c as char)?,
431 _ => write!(f, "\\x{:02x}", c) 357 _ => write!(f, "\\x{:02x}", c)?,
432 } 358 }
433 } 359 }
434 f.write_str("\"") 360 f.write_str("\"")
435 } 361 }
436 } 362 }
437 363
438 impl AsRef<BStr> for CStr { 364 impl AsRef<BStr> for CStr {
439 #[inline] 365 #[inline]
440 fn as_ref(&self) -> &BStr { 366 fn as_ref(&self) -> &BStr {
441 BStr::from_bytes(self.as_bytes()) 367 BStr::from_bytes(self.as_bytes())
442 } 368 }
443 } 369 }
444 370
445 impl Deref for CStr { 371 impl Deref for CStr {
446 type Target = BStr; 372 type Target = BStr;
447 373
448 #[inline] 374 #[inline]
449 fn deref(&self) -> &Self::Target { 375 fn deref(&self) -> &Self::Target {
450 self.as_ref() 376 self.as_ref()
451 } 377 }
452 } 378 }
453 379
454 impl Index<ops::RangeFrom<usize>> for CStr { 380 impl Index<ops::RangeFrom<usize>> for CStr {
455 type Output = CStr; 381 type Output = CStr;
456 382
457 #[inline] 383 #[inline]
458 fn index(&self, index: ops::RangeFrom<usiz 384 fn index(&self, index: ops::RangeFrom<usize>) -> &Self::Output {
459 // Delegate bounds checking to slice. 385 // Delegate bounds checking to slice.
460 // Assign to _ to mute clippy's unnece 386 // Assign to _ to mute clippy's unnecessary operation warning.
461 let _ = &self.as_bytes()[index.start.. 387 let _ = &self.as_bytes()[index.start..];
462 // SAFETY: We just checked the bounds. 388 // SAFETY: We just checked the bounds.
463 unsafe { Self::from_bytes_with_nul_unc 389 unsafe { Self::from_bytes_with_nul_unchecked(&self.0[index.start..]) }
464 } 390 }
465 } 391 }
466 392
467 impl Index<ops::RangeFull> for CStr { 393 impl Index<ops::RangeFull> for CStr {
468 type Output = CStr; 394 type Output = CStr;
469 395
470 #[inline] 396 #[inline]
471 fn index(&self, _index: ops::RangeFull) -> 397 fn index(&self, _index: ops::RangeFull) -> &Self::Output {
472 self 398 self
473 } 399 }
474 } 400 }
475 401
476 mod private { 402 mod private {
477 use core::ops; 403 use core::ops;
478 404
479 // Marker trait for index types that can b 405 // Marker trait for index types that can be forward to `BStr`.
480 pub trait CStrIndex {} 406 pub trait CStrIndex {}
481 407
482 impl CStrIndex for usize {} 408 impl CStrIndex for usize {}
483 impl CStrIndex for ops::Range<usize> {} 409 impl CStrIndex for ops::Range<usize> {}
484 impl CStrIndex for ops::RangeInclusive<usi 410 impl CStrIndex for ops::RangeInclusive<usize> {}
485 impl CStrIndex for ops::RangeToInclusive<u 411 impl CStrIndex for ops::RangeToInclusive<usize> {}
486 } 412 }
487 413
488 impl<Idx> Index<Idx> for CStr 414 impl<Idx> Index<Idx> for CStr
489 where 415 where
490 Idx: private::CStrIndex, 416 Idx: private::CStrIndex,
491 BStr: Index<Idx>, 417 BStr: Index<Idx>,
492 { 418 {
493 type Output = <BStr as Index<Idx>>::Output 419 type Output = <BStr as Index<Idx>>::Output;
494 420
495 #[inline] 421 #[inline]
496 fn index(&self, index: Idx) -> &Self::Outp 422 fn index(&self, index: Idx) -> &Self::Output {
497 &self.as_ref()[index] 423 &self.as_ref()[index]
498 } 424 }
499 } 425 }
500 426
501 /// Creates a new [`CStr`] from a string liter 427 /// Creates a new [`CStr`] from a string literal.
502 /// 428 ///
503 /// The string literal should not contain any 429 /// The string literal should not contain any `NUL` bytes.
504 /// 430 ///
505 /// # Examples 431 /// # Examples
506 /// 432 ///
507 /// ``` 433 /// ```
508 /// # use kernel::c_str; 434 /// # use kernel::c_str;
509 /// # use kernel::str::CStr; 435 /// # use kernel::str::CStr;
510 /// const MY_CSTR: &CStr = c_str!("My awesome 436 /// const MY_CSTR: &CStr = c_str!("My awesome CStr!");
511 /// ``` 437 /// ```
512 #[macro_export] 438 #[macro_export]
513 macro_rules! c_str { 439 macro_rules! c_str {
514 ($str:expr) => {{ 440 ($str:expr) => {{
515 const S: &str = concat!($str, "\0"); 441 const S: &str = concat!($str, "\0");
516 const C: &$crate::str::CStr = match $c 442 const C: &$crate::str::CStr = match $crate::str::CStr::from_bytes_with_nul(S.as_bytes()) {
517 Ok(v) => v, 443 Ok(v) => v,
518 Err(_) => panic!("string contains 444 Err(_) => panic!("string contains interior NUL"),
519 }; 445 };
520 C 446 C
521 }}; 447 }};
522 } 448 }
523 449
524 #[cfg(test)] 450 #[cfg(test)]
525 mod tests { 451 mod tests {
526 use super::*; 452 use super::*;
527 use alloc::format; 453 use alloc::format;
528 454
529 const ALL_ASCII_CHARS: &'static str = 455 const ALL_ASCII_CHARS: &'static str =
530 "\\x01\\x02\\x03\\x04\\x05\\x06\\x07\\ 456 "\\x01\\x02\\x03\\x04\\x05\\x06\\x07\\x08\\x09\\x0a\\x0b\\x0c\\x0d\\x0e\\x0f\
531 \\x10\\x11\\x12\\x13\\x14\\x15\\x16\\x 457 \\x10\\x11\\x12\\x13\\x14\\x15\\x16\\x17\\x18\\x19\\x1a\\x1b\\x1c\\x1d\\x1e\\x1f \
532 !\"#$%&'()*+,-./0123456789:;<=>?@\ 458 !\"#$%&'()*+,-./0123456789:;<=>?@\
533 ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcde 459 ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~\\x7f\
534 \\x80\\x81\\x82\\x83\\x84\\x85\\x86\\x 460 \\x80\\x81\\x82\\x83\\x84\\x85\\x86\\x87\\x88\\x89\\x8a\\x8b\\x8c\\x8d\\x8e\\x8f\
535 \\x90\\x91\\x92\\x93\\x94\\x95\\x96\\x 461 \\x90\\x91\\x92\\x93\\x94\\x95\\x96\\x97\\x98\\x99\\x9a\\x9b\\x9c\\x9d\\x9e\\x9f\
536 \\xa0\\xa1\\xa2\\xa3\\xa4\\xa5\\xa6\\x 462 \\xa0\\xa1\\xa2\\xa3\\xa4\\xa5\\xa6\\xa7\\xa8\\xa9\\xaa\\xab\\xac\\xad\\xae\\xaf\
537 \\xb0\\xb1\\xb2\\xb3\\xb4\\xb5\\xb6\\x 463 \\xb0\\xb1\\xb2\\xb3\\xb4\\xb5\\xb6\\xb7\\xb8\\xb9\\xba\\xbb\\xbc\\xbd\\xbe\\xbf\
538 \\xc0\\xc1\\xc2\\xc3\\xc4\\xc5\\xc6\\x 464 \\xc0\\xc1\\xc2\\xc3\\xc4\\xc5\\xc6\\xc7\\xc8\\xc9\\xca\\xcb\\xcc\\xcd\\xce\\xcf\
539 \\xd0\\xd1\\xd2\\xd3\\xd4\\xd5\\xd6\\x 465 \\xd0\\xd1\\xd2\\xd3\\xd4\\xd5\\xd6\\xd7\\xd8\\xd9\\xda\\xdb\\xdc\\xdd\\xde\\xdf\
540 \\xe0\\xe1\\xe2\\xe3\\xe4\\xe5\\xe6\\x 466 \\xe0\\xe1\\xe2\\xe3\\xe4\\xe5\\xe6\\xe7\\xe8\\xe9\\xea\\xeb\\xec\\xed\\xee\\xef\
541 \\xf0\\xf1\\xf2\\xf3\\xf4\\xf5\\xf6\\x 467 \\xf0\\xf1\\xf2\\xf3\\xf4\\xf5\\xf6\\xf7\\xf8\\xf9\\xfa\\xfb\\xfc\\xfd\\xfe\\xff";
542 468
543 #[test] 469 #[test]
544 fn test_cstr_to_str() { 470 fn test_cstr_to_str() {
545 let good_bytes = b"\xf0\x9f\xa6\x80\0" 471 let good_bytes = b"\xf0\x9f\xa6\x80\0";
546 let checked_cstr = CStr::from_bytes_wi 472 let checked_cstr = CStr::from_bytes_with_nul(good_bytes).unwrap();
547 let checked_str = checked_cstr.to_str( 473 let checked_str = checked_cstr.to_str().unwrap();
548 assert_eq!(checked_str, "🦀"); 474 assert_eq!(checked_str, "🦀");
549 } 475 }
550 476
551 #[test] 477 #[test]
552 #[should_panic] 478 #[should_panic]
553 fn test_cstr_to_str_panic() { 479 fn test_cstr_to_str_panic() {
554 let bad_bytes = b"\xc3\x28\0"; 480 let bad_bytes = b"\xc3\x28\0";
555 let checked_cstr = CStr::from_bytes_wi 481 let checked_cstr = CStr::from_bytes_with_nul(bad_bytes).unwrap();
556 checked_cstr.to_str().unwrap(); 482 checked_cstr.to_str().unwrap();
557 } 483 }
558 484
559 #[test] 485 #[test]
560 fn test_cstr_as_str_unchecked() { 486 fn test_cstr_as_str_unchecked() {
561 let good_bytes = b"\xf0\x9f\x90\xA7\0" 487 let good_bytes = b"\xf0\x9f\x90\xA7\0";
562 let checked_cstr = CStr::from_bytes_wi 488 let checked_cstr = CStr::from_bytes_with_nul(good_bytes).unwrap();
563 let unchecked_str = unsafe { checked_c 489 let unchecked_str = unsafe { checked_cstr.as_str_unchecked() };
564 assert_eq!(unchecked_str, "🐧"); 490 assert_eq!(unchecked_str, "🐧");
565 } 491 }
566 492
567 #[test] 493 #[test]
568 fn test_cstr_display() { 494 fn test_cstr_display() {
569 let hello_world = CStr::from_bytes_wit 495 let hello_world = CStr::from_bytes_with_nul(b"hello, world!\0").unwrap();
570 assert_eq!(format!("{}", hello_world), 496 assert_eq!(format!("{}", hello_world), "hello, world!");
571 let non_printables = CStr::from_bytes_ 497 let non_printables = CStr::from_bytes_with_nul(b"\x01\x09\x0a\0").unwrap();
572 assert_eq!(format!("{}", non_printable 498 assert_eq!(format!("{}", non_printables), "\\x01\\x09\\x0a");
573 let non_ascii = CStr::from_bytes_with_ 499 let non_ascii = CStr::from_bytes_with_nul(b"d\xe9j\xe0 vu\0").unwrap();
574 assert_eq!(format!("{}", non_ascii), " 500 assert_eq!(format!("{}", non_ascii), "d\\xe9j\\xe0 vu");
575 let good_bytes = CStr::from_bytes_with 501 let good_bytes = CStr::from_bytes_with_nul(b"\xf0\x9f\xa6\x80\0").unwrap();
576 assert_eq!(format!("{}", good_bytes), 502 assert_eq!(format!("{}", good_bytes), "\\xf0\\x9f\\xa6\\x80");
577 } 503 }
578 504
579 #[test] 505 #[test]
580 fn test_cstr_display_all_bytes() { 506 fn test_cstr_display_all_bytes() {
581 let mut bytes: [u8; 256] = [0; 256]; 507 let mut bytes: [u8; 256] = [0; 256];
582 // fill `bytes` with [1..=255] + [0] 508 // fill `bytes` with [1..=255] + [0]
583 for i in u8::MIN..=u8::MAX { 509 for i in u8::MIN..=u8::MAX {
584 bytes[i as usize] = i.wrapping_add 510 bytes[i as usize] = i.wrapping_add(1);
585 } 511 }
586 let cstr = CStr::from_bytes_with_nul(& 512 let cstr = CStr::from_bytes_with_nul(&bytes).unwrap();
587 assert_eq!(format!("{}", cstr), ALL_AS 513 assert_eq!(format!("{}", cstr), ALL_ASCII_CHARS);
588 } 514 }
589 515
590 #[test] 516 #[test]
591 fn test_cstr_debug() { 517 fn test_cstr_debug() {
592 let hello_world = CStr::from_bytes_wit 518 let hello_world = CStr::from_bytes_with_nul(b"hello, world!\0").unwrap();
593 assert_eq!(format!("{:?}", hello_world 519 assert_eq!(format!("{:?}", hello_world), "\"hello, world!\"");
594 let non_printables = CStr::from_bytes_ 520 let non_printables = CStr::from_bytes_with_nul(b"\x01\x09\x0a\0").unwrap();
595 assert_eq!(format!("{:?}", non_printab 521 assert_eq!(format!("{:?}", non_printables), "\"\\x01\\x09\\x0a\"");
596 let non_ascii = CStr::from_bytes_with_ 522 let non_ascii = CStr::from_bytes_with_nul(b"d\xe9j\xe0 vu\0").unwrap();
597 assert_eq!(format!("{:?}", non_ascii), 523 assert_eq!(format!("{:?}", non_ascii), "\"d\\xe9j\\xe0 vu\"");
598 let good_bytes = CStr::from_bytes_with 524 let good_bytes = CStr::from_bytes_with_nul(b"\xf0\x9f\xa6\x80\0").unwrap();
599 assert_eq!(format!("{:?}", good_bytes) 525 assert_eq!(format!("{:?}", good_bytes), "\"\\xf0\\x9f\\xa6\\x80\"");
600 } 526 }
601 527
602 #[test] 528 #[test]
603 fn test_bstr_display() { 529 fn test_bstr_display() {
604 let hello_world = BStr::from_bytes(b"h 530 let hello_world = BStr::from_bytes(b"hello, world!");
605 assert_eq!(format!("{}", hello_world), 531 assert_eq!(format!("{}", hello_world), "hello, world!");
606 let escapes = BStr::from_bytes(b"_\t_\ 532 let escapes = BStr::from_bytes(b"_\t_\n_\r_\\_\'_\"_");
607 assert_eq!(format!("{}", escapes), "_\ 533 assert_eq!(format!("{}", escapes), "_\\t_\\n_\\r_\\_'_\"_");
608 let others = BStr::from_bytes(b"\x01") 534 let others = BStr::from_bytes(b"\x01");
609 assert_eq!(format!("{}", others), "\\x 535 assert_eq!(format!("{}", others), "\\x01");
610 let non_ascii = BStr::from_bytes(b"d\x 536 let non_ascii = BStr::from_bytes(b"d\xe9j\xe0 vu");
611 assert_eq!(format!("{}", non_ascii), " 537 assert_eq!(format!("{}", non_ascii), "d\\xe9j\\xe0 vu");
612 let good_bytes = BStr::from_bytes(b"\x 538 let good_bytes = BStr::from_bytes(b"\xf0\x9f\xa6\x80");
613 assert_eq!(format!("{}", good_bytes), 539 assert_eq!(format!("{}", good_bytes), "\\xf0\\x9f\\xa6\\x80");
614 } 540 }
615 541
616 #[test] 542 #[test]
617 fn test_bstr_debug() { 543 fn test_bstr_debug() {
618 let hello_world = BStr::from_bytes(b"h 544 let hello_world = BStr::from_bytes(b"hello, world!");
619 assert_eq!(format!("{:?}", hello_world 545 assert_eq!(format!("{:?}", hello_world), "\"hello, world!\"");
620 let escapes = BStr::from_bytes(b"_\t_\ 546 let escapes = BStr::from_bytes(b"_\t_\n_\r_\\_\'_\"_");
621 assert_eq!(format!("{:?}", escapes), " 547 assert_eq!(format!("{:?}", escapes), "\"_\\t_\\n_\\r_\\\\_'_\\\"_\"");
622 let others = BStr::from_bytes(b"\x01") 548 let others = BStr::from_bytes(b"\x01");
623 assert_eq!(format!("{:?}", others), "\ 549 assert_eq!(format!("{:?}", others), "\"\\x01\"");
624 let non_ascii = BStr::from_bytes(b"d\x 550 let non_ascii = BStr::from_bytes(b"d\xe9j\xe0 vu");
625 assert_eq!(format!("{:?}", non_ascii), 551 assert_eq!(format!("{:?}", non_ascii), "\"d\\xe9j\\xe0 vu\"");
626 let good_bytes = BStr::from_bytes(b"\x 552 let good_bytes = BStr::from_bytes(b"\xf0\x9f\xa6\x80");
627 assert_eq!(format!("{:?}", good_bytes) 553 assert_eq!(format!("{:?}", good_bytes), "\"\\xf0\\x9f\\xa6\\x80\"");
628 } 554 }
629 } 555 }
630 556
631 /// Allows formatting of [`fmt::Arguments`] in 557 /// Allows formatting of [`fmt::Arguments`] into a raw buffer.
632 /// 558 ///
633 /// It does not fail if callers write past the 559 /// It does not fail if callers write past the end of the buffer so that they can calculate the
634 /// size required to fit everything. 560 /// size required to fit everything.
635 /// 561 ///
636 /// # Invariants 562 /// # Invariants
637 /// 563 ///
638 /// The memory region between `pos` (inclusive 564 /// The memory region between `pos` (inclusive) and `end` (exclusive) is valid for writes if `pos`
639 /// is less than `end`. 565 /// is less than `end`.
640 pub(crate) struct RawFormatter { 566 pub(crate) struct RawFormatter {
641 // Use `usize` to use `saturating_*` funct 567 // Use `usize` to use `saturating_*` functions.
642 beg: usize, 568 beg: usize,
643 pos: usize, 569 pos: usize,
644 end: usize, 570 end: usize,
645 } 571 }
646 572
647 impl RawFormatter { 573 impl RawFormatter {
648 /// Creates a new instance of [`RawFormatt 574 /// Creates a new instance of [`RawFormatter`] with an empty buffer.
649 fn new() -> Self { 575 fn new() -> Self {
650 // INVARIANT: The buffer is empty, so 576 // INVARIANT: The buffer is empty, so the region that needs to be writable is empty.
651 Self { 577 Self {
652 beg: 0, 578 beg: 0,
653 pos: 0, 579 pos: 0,
654 end: 0, 580 end: 0,
655 } 581 }
656 } 582 }
657 583
658 /// Creates a new instance of [`RawFormatt 584 /// Creates a new instance of [`RawFormatter`] with the given buffer pointers.
659 /// 585 ///
660 /// # Safety 586 /// # Safety
661 /// 587 ///
662 /// If `pos` is less than `end`, then the 588 /// If `pos` is less than `end`, then the region between `pos` (inclusive) and `end`
663 /// (exclusive) must be valid for writes f 589 /// (exclusive) must be valid for writes for the lifetime of the returned [`RawFormatter`].
664 pub(crate) unsafe fn from_ptrs(pos: *mut u 590 pub(crate) unsafe fn from_ptrs(pos: *mut u8, end: *mut u8) -> Self {
665 // INVARIANT: The safety requirements 591 // INVARIANT: The safety requirements guarantee the type invariants.
666 Self { 592 Self {
667 beg: pos as _, 593 beg: pos as _,
668 pos: pos as _, 594 pos: pos as _,
669 end: end as _, 595 end: end as _,
670 } 596 }
671 } 597 }
672 598
673 /// Creates a new instance of [`RawFormatt 599 /// Creates a new instance of [`RawFormatter`] with the given buffer.
674 /// 600 ///
675 /// # Safety 601 /// # Safety
676 /// 602 ///
677 /// The memory region starting at `buf` an 603 /// The memory region starting at `buf` and extending for `len` bytes must be valid for writes
678 /// for the lifetime of the returned [`Raw 604 /// for the lifetime of the returned [`RawFormatter`].
679 pub(crate) unsafe fn from_buffer(buf: *mut 605 pub(crate) unsafe fn from_buffer(buf: *mut u8, len: usize) -> Self {
680 let pos = buf as usize; 606 let pos = buf as usize;
681 // INVARIANT: We ensure that `end` is 607 // INVARIANT: We ensure that `end` is never less then `buf`, and the safety requirements
682 // guarantees that the memory region i 608 // guarantees that the memory region is valid for writes.
683 Self { 609 Self {
684 pos, 610 pos,
685 beg: pos, 611 beg: pos,
686 end: pos.saturating_add(len), 612 end: pos.saturating_add(len),
687 } 613 }
688 } 614 }
689 615
690 /// Returns the current insert position. 616 /// Returns the current insert position.
691 /// 617 ///
692 /// N.B. It may point to invalid memory. 618 /// N.B. It may point to invalid memory.
693 pub(crate) fn pos(&self) -> *mut u8 { 619 pub(crate) fn pos(&self) -> *mut u8 {
694 self.pos as _ 620 self.pos as _
695 } 621 }
696 622
697 /// Returns the number of bytes written to 623 /// Returns the number of bytes written to the formatter.
698 pub(crate) fn bytes_written(&self) -> usiz 624 pub(crate) fn bytes_written(&self) -> usize {
699 self.pos - self.beg 625 self.pos - self.beg
700 } 626 }
701 } 627 }
702 628
703 impl fmt::Write for RawFormatter { 629 impl fmt::Write for RawFormatter {
704 fn write_str(&mut self, s: &str) -> fmt::R 630 fn write_str(&mut self, s: &str) -> fmt::Result {
705 // `pos` value after writing `len` byt 631 // `pos` value after writing `len` bytes. This does not have to be bounded by `end`, but we
706 // don't want it to wrap around to 0. 632 // don't want it to wrap around to 0.
707 let pos_new = self.pos.saturating_add( 633 let pos_new = self.pos.saturating_add(s.len());
708 634
709 // Amount that we can copy. `saturatin 635 // Amount that we can copy. `saturating_sub` ensures we get 0 if `pos` goes past `end`.
710 let len_to_copy = core::cmp::min(pos_n 636 let len_to_copy = core::cmp::min(pos_new, self.end).saturating_sub(self.pos);
711 637
712 if len_to_copy > 0 { 638 if len_to_copy > 0 {
713 // SAFETY: If `len_to_copy` is non 639 // SAFETY: If `len_to_copy` is non-zero, then we know `pos` has not gone past `end`
714 // yet, so it is valid for write p 640 // yet, so it is valid for write per the type invariants.
715 unsafe { 641 unsafe {
716 core::ptr::copy_nonoverlapping 642 core::ptr::copy_nonoverlapping(
717 s.as_bytes().as_ptr(), 643 s.as_bytes().as_ptr(),
718 self.pos as *mut u8, 644 self.pos as *mut u8,
719 len_to_copy, 645 len_to_copy,
720 ) 646 )
721 }; 647 };
722 } 648 }
723 649
724 self.pos = pos_new; 650 self.pos = pos_new;
725 Ok(()) 651 Ok(())
726 } 652 }
727 } 653 }
728 654
729 /// Allows formatting of [`fmt::Arguments`] in 655 /// Allows formatting of [`fmt::Arguments`] into a raw buffer.
730 /// 656 ///
731 /// Fails if callers attempt to write more tha 657 /// Fails if callers attempt to write more than will fit in the buffer.
732 pub(crate) struct Formatter(RawFormatter); 658 pub(crate) struct Formatter(RawFormatter);
733 659
734 impl Formatter { 660 impl Formatter {
735 /// Creates a new instance of [`Formatter` 661 /// Creates a new instance of [`Formatter`] with the given buffer.
736 /// 662 ///
737 /// # Safety 663 /// # Safety
738 /// 664 ///
739 /// The memory region starting at `buf` an 665 /// The memory region starting at `buf` and extending for `len` bytes must be valid for writes
740 /// for the lifetime of the returned [`For 666 /// for the lifetime of the returned [`Formatter`].
741 pub(crate) unsafe fn from_buffer(buf: *mut 667 pub(crate) unsafe fn from_buffer(buf: *mut u8, len: usize) -> Self {
742 // SAFETY: The safety requirements of 668 // SAFETY: The safety requirements of this function satisfy those of the callee.
743 Self(unsafe { RawFormatter::from_buffe 669 Self(unsafe { RawFormatter::from_buffer(buf, len) })
744 } 670 }
745 } 671 }
746 672
747 impl Deref for Formatter { 673 impl Deref for Formatter {
748 type Target = RawFormatter; 674 type Target = RawFormatter;
749 675
750 fn deref(&self) -> &Self::Target { 676 fn deref(&self) -> &Self::Target {
751 &self.0 677 &self.0
752 } 678 }
753 } 679 }
754 680
755 impl fmt::Write for Formatter { 681 impl fmt::Write for Formatter {
756 fn write_str(&mut self, s: &str) -> fmt::R 682 fn write_str(&mut self, s: &str) -> fmt::Result {
757 self.0.write_str(s)?; 683 self.0.write_str(s)?;
758 684
759 // Fail the request if we go past the 685 // Fail the request if we go past the end of the buffer.
760 if self.0.pos > self.0.end { 686 if self.0.pos > self.0.end {
761 Err(fmt::Error) 687 Err(fmt::Error)
762 } else { 688 } else {
763 Ok(()) 689 Ok(())
764 } 690 }
765 } 691 }
766 } 692 }
767 693
768 /// An owned string that is guaranteed to have 694 /// An owned string that is guaranteed to have exactly one `NUL` byte, which is at the end.
769 /// 695 ///
770 /// Used for interoperability with kernel APIs 696 /// Used for interoperability with kernel APIs that take C strings.
771 /// 697 ///
772 /// # Invariants 698 /// # Invariants
773 /// 699 ///
774 /// The string is always `NUL`-terminated and 700 /// The string is always `NUL`-terminated and contains no other `NUL` bytes.
775 /// 701 ///
776 /// # Examples 702 /// # Examples
777 /// 703 ///
778 /// ``` 704 /// ```
779 /// use kernel::{str::CString, fmt}; 705 /// use kernel::{str::CString, fmt};
780 /// 706 ///
781 /// let s = CString::try_from_fmt(fmt!("{}{}{} 707 /// let s = CString::try_from_fmt(fmt!("{}{}{}", "abc", 10, 20)).unwrap();
782 /// assert_eq!(s.as_bytes_with_nul(), "abc1020 708 /// assert_eq!(s.as_bytes_with_nul(), "abc1020\0".as_bytes());
783 /// 709 ///
784 /// let tmp = "testing"; 710 /// let tmp = "testing";
785 /// let s = CString::try_from_fmt(fmt!("{tmp}{ 711 /// let s = CString::try_from_fmt(fmt!("{tmp}{}", 123)).unwrap();
786 /// assert_eq!(s.as_bytes_with_nul(), "testing 712 /// assert_eq!(s.as_bytes_with_nul(), "testing123\0".as_bytes());
787 /// 713 ///
788 /// // This fails because it has an embedded ` 714 /// // This fails because it has an embedded `NUL` byte.
789 /// let s = CString::try_from_fmt(fmt!("a\0b{} 715 /// let s = CString::try_from_fmt(fmt!("a\0b{}", 123));
790 /// assert_eq!(s.is_ok(), false); 716 /// assert_eq!(s.is_ok(), false);
791 /// ``` 717 /// ```
792 pub struct CString { 718 pub struct CString {
793 buf: Vec<u8>, 719 buf: Vec<u8>,
794 } 720 }
795 721
796 impl CString { 722 impl CString {
797 /// Creates an instance of [`CString`] fro 723 /// Creates an instance of [`CString`] from the given formatted arguments.
798 pub fn try_from_fmt(args: fmt::Arguments<' 724 pub fn try_from_fmt(args: fmt::Arguments<'_>) -> Result<Self, Error> {
799 // Calculate the size needed (formatte 725 // Calculate the size needed (formatted string plus `NUL` terminator).
800 let mut f = RawFormatter::new(); 726 let mut f = RawFormatter::new();
801 f.write_fmt(args)?; 727 f.write_fmt(args)?;
802 f.write_str("\0")?; 728 f.write_str("\0")?;
803 let size = f.bytes_written(); 729 let size = f.bytes_written();
804 730
805 // Allocate a vector with the required 731 // Allocate a vector with the required number of bytes, and write to it.
806 let mut buf = <Vec<_> as VecExt<_>>::w !! 732 let mut buf = Vec::try_with_capacity(size)?;
807 // SAFETY: The buffer stored in `buf` 733 // SAFETY: The buffer stored in `buf` is at least of size `size` and is valid for writes.
808 let mut f = unsafe { Formatter::from_b 734 let mut f = unsafe { Formatter::from_buffer(buf.as_mut_ptr(), size) };
809 f.write_fmt(args)?; 735 f.write_fmt(args)?;
810 f.write_str("\0")?; 736 f.write_str("\0")?;
811 737
812 // SAFETY: The number of bytes that ca 738 // SAFETY: The number of bytes that can be written to `f` is bounded by `size`, which is
813 // `buf`'s capacity. The contents of t 739 // `buf`'s capacity. The contents of the buffer have been initialised by writes to `f`.
814 unsafe { buf.set_len(f.bytes_written() 740 unsafe { buf.set_len(f.bytes_written()) };
815 741
816 // Check that there are no `NUL` bytes 742 // Check that there are no `NUL` bytes before the end.
817 // SAFETY: The buffer is valid for rea 743 // SAFETY: The buffer is valid for read because `f.bytes_written()` is bounded by `size`
818 // (which the minimum buffer size) and 744 // (which the minimum buffer size) and is non-zero (we wrote at least the `NUL` terminator)
819 // so `f.bytes_written() - 1` doesn't 745 // so `f.bytes_written() - 1` doesn't underflow.
820 let ptr = unsafe { bindings::memchr(bu 746 let ptr = unsafe { bindings::memchr(buf.as_ptr().cast(), 0, (f.bytes_written() - 1) as _) };
821 if !ptr.is_null() { 747 if !ptr.is_null() {
822 return Err(EINVAL); 748 return Err(EINVAL);
823 } 749 }
824 750
825 // INVARIANT: We wrote the `NUL` termi 751 // INVARIANT: We wrote the `NUL` terminator and checked above that no other `NUL` bytes
826 // exist in the buffer. 752 // exist in the buffer.
827 Ok(Self { buf }) 753 Ok(Self { buf })
828 } 754 }
829 } 755 }
830 756
831 impl Deref for CString { 757 impl Deref for CString {
832 type Target = CStr; 758 type Target = CStr;
833 759
834 fn deref(&self) -> &Self::Target { 760 fn deref(&self) -> &Self::Target {
835 // SAFETY: The type invariants guarant 761 // SAFETY: The type invariants guarantee that the string is `NUL`-terminated and that no
836 // other `NUL` bytes exist. 762 // other `NUL` bytes exist.
837 unsafe { CStr::from_bytes_with_nul_unc 763 unsafe { CStr::from_bytes_with_nul_unchecked(self.buf.as_slice()) }
838 } 764 }
839 } 765 }
840 766
841 impl DerefMut for CString { <<
842 fn deref_mut(&mut self) -> &mut Self::Targ <<
843 // SAFETY: A `CString` is always NUL-t <<
844 // NUL bytes. <<
845 unsafe { CStr::from_bytes_with_nul_unc <<
846 } <<
847 } <<
848 <<
849 impl<'a> TryFrom<&'a CStr> for CString { 767 impl<'a> TryFrom<&'a CStr> for CString {
850 type Error = AllocError; 768 type Error = AllocError;
851 769
852 fn try_from(cstr: &'a CStr) -> Result<CStr 770 fn try_from(cstr: &'a CStr) -> Result<CString, AllocError> {
853 let mut buf = Vec::new(); 771 let mut buf = Vec::new();
854 772
855 <Vec<_> as VecExt<_>>::extend_from_sli !! 773 buf.try_extend_from_slice(cstr.as_bytes_with_nul())
856 .map_err(|_| AllocError)?; 774 .map_err(|_| AllocError)?;
857 775
858 // INVARIANT: The `CStr` and `CString` 776 // INVARIANT: The `CStr` and `CString` types have the same invariants for
859 // the string data, and we copied it o 777 // the string data, and we copied it over without changes.
860 Ok(CString { buf }) 778 Ok(CString { buf })
861 } 779 }
862 } 780 }
863 781
864 impl fmt::Debug for CString { 782 impl fmt::Debug for CString {
865 fn fmt(&self, f: &mut fmt::Formatter<'_>) 783 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
866 fmt::Debug::fmt(&**self, f) 784 fmt::Debug::fmt(&**self, f)
867 } 785 }
868 } 786 }
869 787
870 /// A convenience alias for [`core::format_arg 788 /// A convenience alias for [`core::format_args`].
871 #[macro_export] 789 #[macro_export]
872 macro_rules! fmt { 790 macro_rules! fmt {
873 ($($f:tt)*) => ( core::format_args!($($f)* 791 ($($f:tt)*) => ( core::format_args!($($f)*) )
874 } 792 }
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