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