zvariant/
signature.rs

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1use core::{
2    convert::TryFrom,
3    fmt::{self, Debug, Display, Formatter},
4    panic, str,
5};
6use serde::{
7    de::{Deserialize, Deserializer, Visitor},
8    ser::{Serialize, Serializer},
9};
10use static_assertions::assert_impl_all;
11use std::{
12    ops::{Bound, RangeBounds},
13    sync::Arc,
14};
15
16use crate::{signature_parser::SignatureParser, Basic, EncodingFormat, Error, Result, Type};
17
18// A data type similar to Cow and [`bytes::Bytes`] but unlike the former won't allow us to only keep
19// the owned bytes in Arc and latter doesn't have a notion of borrowed data and would require API
20// breakage.
21//
22// [`bytes::Bytes`]: https://docs.rs/bytes/0.5.6/bytes/struct.Bytes.html
23#[derive(PartialEq, Eq, Hash, Clone)]
24enum Bytes<'b> {
25    Borrowed(&'b [u8]),
26    Static(&'static [u8]),
27    Owned(Arc<[u8]>),
28}
29
30impl<'b> Bytes<'b> {
31    const fn borrowed<'s: 'b>(bytes: &'s [u8]) -> Self {
32        Self::Borrowed(bytes)
33    }
34
35    fn owned(bytes: Vec<u8>) -> Self {
36        Self::Owned(bytes.into())
37    }
38}
39
40impl<'b> std::ops::Deref for Bytes<'b> {
41    type Target = [u8];
42
43    fn deref(&self) -> &[u8] {
44        match self {
45            Bytes::Borrowed(borrowed) => borrowed,
46            Bytes::Static(borrowed) => borrowed,
47            Bytes::Owned(owned) => owned,
48        }
49    }
50}
51
52/// String that [identifies] the type of an encoded value.
53///
54/// # Examples
55///
56/// ```
57/// use core::convert::TryFrom;
58/// use zvariant::Signature;
59///
60/// // Valid signatures
61/// let s = Signature::try_from("").unwrap();
62/// assert_eq!(s, "");
63/// let s = Signature::try_from("y").unwrap();
64/// assert_eq!(s, "y");
65/// let s = Signature::try_from("xs").unwrap();
66/// assert_eq!(s, "xs");
67/// let s = Signature::try_from("(ysa{sd})").unwrap();
68/// assert_eq!(s, "(ysa{sd})");
69/// let s = Signature::try_from("a{sd}").unwrap();
70/// assert_eq!(s, "a{sd}");
71///
72/// // Invalid signatures
73/// Signature::try_from("z").unwrap_err();
74/// Signature::try_from("(xs").unwrap_err();
75/// Signature::try_from("xs)").unwrap_err();
76/// Signature::try_from("s/").unwrap_err();
77/// Signature::try_from("a").unwrap_err();
78/// Signature::try_from("a{yz}").unwrap_err();
79/// ```
80///
81/// This is implemented so that multiple instances can share the same underlying signature string.
82/// Use [`slice`] method to create new signature that represents a portion of a signature
83///
84/// [identifies]: https://dbus.freedesktop.org/doc/dbus-specification.html#type-system
85/// [`slice`]: #method.slice
86#[derive(Eq, Hash, Clone)]
87pub struct Signature<'a> {
88    bytes: Bytes<'a>,
89    pos: usize,
90    end: usize,
91}
92
93assert_impl_all!(Signature<'_>: Send, Sync, Unpin);
94
95impl<'a> Signature<'a> {
96    /// The signature as a string.
97    pub fn as_str(&self) -> &str {
98        // SAFETY: non-UTF8 characters in Signature are rejected by safe constructors
99        unsafe { str::from_utf8_unchecked(self.as_bytes()) }
100    }
101
102    /// The signature bytes.
103    pub fn as_bytes(&self) -> &[u8] {
104        &self.bytes[self.pos..self.end]
105    }
106
107    /// Create a new Signature from given bytes.
108    ///
109    /// Since the passed bytes are not checked for correctness, it's provided for ease of
110    /// `Type` implementations.
111    ///
112    /// # Safety
113    ///
114    /// This method is unsafe as it allows creating a `str` that is not valid UTF-8.
115    pub unsafe fn from_bytes_unchecked<'s: 'a>(bytes: &'s [u8]) -> Self {
116        Self {
117            bytes: Bytes::borrowed(bytes),
118            pos: 0,
119            end: bytes.len(),
120        }
121    }
122
123    /// Same as `from_bytes_unchecked`, except it takes a static reference.
124    ///
125    /// # Safety
126    ///
127    /// This method is unsafe as it allows creating a `str` that is not valid UTF-8.
128    pub unsafe fn from_static_bytes_unchecked(bytes: &'static [u8]) -> Self {
129        Self {
130            bytes: Bytes::Static(bytes),
131            pos: 0,
132            end: bytes.len(),
133        }
134    }
135
136    /// Same as `from_bytes_unchecked`, except it takes a string reference.
137    pub const fn from_str_unchecked<'s: 'a>(signature: &'s str) -> Self {
138        Self {
139            bytes: Bytes::borrowed(signature.as_bytes()),
140            pos: 0,
141            end: signature.len(),
142        }
143    }
144
145    /// Same as `from_str_unchecked`, except it takes a static string reference.
146    pub const fn from_static_str_unchecked(signature: &'static str) -> Self {
147        Self {
148            bytes: Bytes::Static(signature.as_bytes()),
149            pos: 0,
150            end: signature.len(),
151        }
152    }
153
154    /// Same as `from_str_unchecked`, except it takes an owned `String`.
155    pub fn from_string_unchecked(signature: String) -> Self {
156        let bytes = signature.into_bytes();
157        let end = bytes.len();
158
159        Self {
160            bytes: Bytes::owned(bytes),
161            pos: 0,
162            end,
163        }
164    }
165
166    /// Same as `from_static_str_unchecked`, except it checks validity of the signature.
167    ///
168    /// It's recommended to use this method instead of `TryFrom<&str>` implementation for
169    /// `&'static str`. The former will ensure that [`Signature::to_owned`] and
170    /// [`Signature::into_owned`] do not clone the underlying bytes.
171    pub fn from_static_str(signature: &'static str) -> Result<Self> {
172        let bytes = signature.as_bytes();
173        ensure_correct_signature_str(bytes)?;
174
175        Ok(Self {
176            bytes: Bytes::Static(bytes),
177            pos: 0,
178            end: signature.len(),
179        })
180    }
181
182    /// Same as `from_static_bytes_unchecked`, except it checks validity of the signature.
183    ///
184    /// It's recommended to use this method instead of the `TryFrom<&[u8]>` implementation for
185    /// `&'static [u8]`. The former will ensure that [`Signature::to_owned`] and
186    /// [`Signature::into_owned`] do not clone the underlying bytes.
187    pub fn from_static_bytes(bytes: &'static [u8]) -> Result<Self> {
188        ensure_correct_signature_str(bytes)?;
189
190        Ok(Self {
191            bytes: Bytes::Static(bytes),
192            pos: 0,
193            end: bytes.len(),
194        })
195    }
196
197    /// the signature's length.
198    pub fn len(&self) -> usize {
199        self.end - self.pos
200    }
201
202    /// if the signature is empty.
203    pub fn is_empty(&self) -> bool {
204        self.as_bytes().is_empty()
205    }
206
207    /// Creates an owned clone of `self`.
208    pub fn to_owned(&self) -> Signature<'static> {
209        match &self.bytes {
210            Bytes::Borrowed(_) => {
211                let bytes = Bytes::owned(self.as_bytes().to_vec());
212                let pos = 0;
213                let end = bytes.len();
214
215                Signature { bytes, pos, end }
216            }
217            Bytes::Static(b) => Signature {
218                bytes: Bytes::Static(b),
219                pos: self.pos,
220                end: self.end,
221            },
222            Bytes::Owned(owned) => Signature {
223                bytes: Bytes::Owned(owned.clone()),
224                pos: self.pos,
225                end: self.end,
226            },
227        }
228    }
229
230    /// Creates an owned clone of `self`.
231    pub fn into_owned(self) -> Signature<'static> {
232        self.to_owned()
233    }
234
235    /// Returns a slice of `self` for the provided range.
236    ///
237    /// # Panics
238    ///
239    /// Requires that begin <= end and end <= self.len(), otherwise slicing will panic.
240    #[must_use]
241    pub fn slice(&self, range: impl RangeBounds<usize>) -> Self {
242        let len = self.len();
243
244        let pos = match range.start_bound() {
245            Bound::Included(&n) => n,
246            Bound::Excluded(&n) => n + 1,
247            Bound::Unbounded => 0,
248        };
249
250        let end = match range.end_bound() {
251            Bound::Included(&n) => n + 1,
252            Bound::Excluded(&n) => n,
253            Bound::Unbounded => len,
254        };
255
256        assert!(
257            pos <= end,
258            "range start must not be greater than end: {:?} > {:?}",
259            pos,
260            end,
261        );
262        assert!(end <= len, "range end out of bounds: {:?} > {:?}", end, len,);
263
264        if end == pos {
265            return Self::from_str_unchecked("");
266        }
267
268        let mut clone = self.clone();
269        clone.pos += pos;
270        clone.end = self.pos + end;
271
272        clone
273    }
274}
275
276impl<'a> Debug for Signature<'a> {
277    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
278        f.debug_tuple("Signature").field(&self.as_str()).finish()
279    }
280}
281
282impl<'a> Basic for Signature<'a> {
283    const SIGNATURE_CHAR: char = 'g';
284    const SIGNATURE_STR: &'static str = "g";
285
286    fn alignment(format: EncodingFormat) -> usize {
287        match format {
288            EncodingFormat::DBus => 1,
289            #[cfg(feature = "gvariant")]
290            EncodingFormat::GVariant => 1,
291        }
292    }
293}
294
295impl<'a> Type for Signature<'a> {
296    fn signature() -> Signature<'static> {
297        Signature::from_static_str_unchecked(Self::SIGNATURE_STR)
298    }
299}
300
301impl<'a, 'b> From<&'b Signature<'a>> for Signature<'a> {
302    fn from(signature: &'b Signature<'a>) -> Signature<'a> {
303        signature.clone()
304    }
305}
306
307impl<'a> TryFrom<&'a [u8]> for Signature<'a> {
308    type Error = Error;
309
310    fn try_from(value: &'a [u8]) -> Result<Self> {
311        ensure_correct_signature_str(value)?;
312
313        // SAFETY: ensure_correct_signature_str checks UTF8
314        unsafe { Ok(Self::from_bytes_unchecked(value)) }
315    }
316}
317
318/// Try to create a Signature from a string.
319impl<'a> TryFrom<&'a str> for Signature<'a> {
320    type Error = Error;
321
322    fn try_from(value: &'a str) -> Result<Self> {
323        Self::try_from(value.as_bytes())
324    }
325}
326
327impl<'a> TryFrom<String> for Signature<'a> {
328    type Error = Error;
329
330    fn try_from(value: String) -> Result<Self> {
331        ensure_correct_signature_str(value.as_bytes())?;
332
333        Ok(Self::from_string_unchecked(value))
334    }
335}
336
337impl<'a> From<Signature<'a>> for String {
338    fn from(value: Signature<'a>) -> String {
339        String::from(value.as_str())
340    }
341}
342
343impl<'a> From<&Signature<'a>> for String {
344    fn from(value: &Signature<'a>) -> String {
345        String::from(value.as_str())
346    }
347}
348
349impl<'a> std::ops::Deref for Signature<'a> {
350    type Target = str;
351
352    fn deref(&self) -> &Self::Target {
353        self.as_str()
354    }
355}
356
357impl<'a, 'b> PartialEq<Signature<'a>> for Signature<'b> {
358    fn eq(&self, other: &Signature<'_>) -> bool {
359        self.as_bytes() == other.as_bytes()
360    }
361}
362
363impl<'a> PartialEq<str> for Signature<'a> {
364    fn eq(&self, other: &str) -> bool {
365        self.as_bytes() == other.as_bytes()
366    }
367}
368
369impl<'a> PartialEq<&str> for Signature<'a> {
370    fn eq(&self, other: &&str) -> bool {
371        self.as_bytes() == other.as_bytes()
372    }
373}
374
375impl<'a> Display for Signature<'a> {
376    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
377        std::fmt::Display::fmt(&self.as_str(), f)
378    }
379}
380
381impl<'a> Serialize for Signature<'a> {
382    fn serialize<S>(&self, serializer: S) -> core::result::Result<S::Ok, S::Error>
383    where
384        S: Serializer,
385    {
386        serializer.serialize_str(self.as_str())
387    }
388}
389
390impl<'de: 'a, 'a> Deserialize<'de> for Signature<'a> {
391    fn deserialize<D>(deserializer: D) -> core::result::Result<Self, D::Error>
392    where
393        D: Deserializer<'de>,
394    {
395        let visitor = SignatureVisitor;
396
397        deserializer.deserialize_str(visitor)
398    }
399}
400
401struct SignatureVisitor;
402
403impl<'de> Visitor<'de> for SignatureVisitor {
404    type Value = Signature<'de>;
405
406    fn expecting(&self, formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
407        formatter.write_str("a Signature")
408    }
409
410    #[inline]
411    fn visit_borrowed_str<E>(self, value: &'de str) -> core::result::Result<Signature<'de>, E>
412    where
413        E: serde::de::Error,
414    {
415        Signature::try_from(value).map_err(serde::de::Error::custom)
416    }
417}
418
419fn ensure_correct_signature_str(signature: &[u8]) -> Result<()> {
420    if signature.len() > 255 {
421        return Err(serde::de::Error::invalid_length(
422            signature.len(),
423            &"<= 255 characters",
424        ));
425    }
426
427    if signature.is_empty() {
428        return Ok(());
429    }
430
431    // SAFETY: SignatureParser never calls as_str
432    let signature = unsafe { Signature::from_bytes_unchecked(signature) };
433    let mut parser = SignatureParser::new(signature);
434    while !parser.done() {
435        let _ = parser.parse_next_signature()?;
436    }
437
438    Ok(())
439}
440
441/// Owned [`Signature`](struct.Signature.html)
442#[derive(Debug, Clone, PartialEq, Eq, serde::Serialize, Type)]
443pub struct OwnedSignature(Signature<'static>);
444
445assert_impl_all!(OwnedSignature: Send, Sync, Unpin);
446
447impl OwnedSignature {
448    pub fn into_inner(self) -> Signature<'static> {
449        self.0
450    }
451}
452
453impl std::ops::Deref for OwnedSignature {
454    type Target = Signature<'static>;
455
456    fn deref(&self) -> &Self::Target {
457        &self.0
458    }
459}
460
461impl std::convert::From<OwnedSignature> for Signature<'static> {
462    fn from(o: OwnedSignature) -> Self {
463        o.into_inner()
464    }
465}
466
467impl<'a> std::convert::From<Signature<'a>> for OwnedSignature {
468    fn from(o: Signature<'a>) -> Self {
469        OwnedSignature(o.into_owned())
470    }
471}
472
473impl std::convert::From<OwnedSignature> for crate::Value<'static> {
474    fn from(o: OwnedSignature) -> Self {
475        o.into_inner().into()
476    }
477}
478
479impl<'de> Deserialize<'de> for OwnedSignature {
480    fn deserialize<D>(deserializer: D) -> core::result::Result<Self, D::Error>
481    where
482        D: Deserializer<'de>,
483    {
484        let visitor = SignatureVisitor;
485
486        deserializer
487            .deserialize_str(visitor)
488            .map(|v| OwnedSignature(v.to_owned()))
489    }
490}
491
492impl std::fmt::Display for OwnedSignature {
493    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
494        std::fmt::Display::fmt(&self.as_str(), f)
495    }
496}
497
498#[cfg(test)]
499mod tests {
500    use super::Signature;
501
502    #[test]
503    fn signature_slicing() {
504        let sig = Signature::from_str_unchecked("(asta{sv})");
505        assert_eq!(sig, "(asta{sv})");
506
507        let slice = sig.slice(1..);
508        assert_eq!(slice.len(), sig.len() - 1);
509        assert_eq!(slice, &sig[1..]);
510        assert_eq!(slice.as_bytes()[1], b's');
511        assert_eq!(slice.as_bytes()[2], b't');
512
513        let slice = slice.slice(2..3);
514        assert_eq!(slice.len(), 1);
515        assert_eq!(slice, "t");
516        assert_eq!(slice.slice(1..), "");
517    }
518}
zvariant/signature.rs

zvariant/
signature.rs
