Add methods to go from a nul-terminated Vec<u8> to a CString #73139
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… and unchecked. Doc tests have been written and the documentation on the error type updated too.
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r? @cramertj (rust_highfive has picked a reviewer for you, use r? to override) |
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The job Click to expand the log.I'm a bot! I can only do what humans tell me to, so if this was not helpful or you have suggestions for improvements, please ping or otherwise contact |
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I have a link error in CI that I do not have locally and I think it's because of an unstable flag that I misplaced/incorrectly used. #[unstable(feature = "cstring_from_vec_with_nul", issue = "73179")]
impl TryFrom<Vec<u8>> for CString {
type Error = FromBytesWithNulError;
/// See the document about [`from_vec_with_nul`] for more
/// informations about the behaviour of this method.
///
/// [`from_vec_with_nul`]: struct.CString.html#method.from_vec_with_nul
fn try_from(value: Vec<u8>) -> Result<Self, Self::Error> {
Self::from_vec_with_nul(value)
}
}The link impl CString {
#[unstable(feature = "cstring_from_vec_with_nul", issue = "73179")]
pub fn from_vec_with_nul(v: Vec<u8>) -> Result<Self, FromBytesWithNulError> { /* ... */ }
}I do not have any idea about how to fix that and was advised to ask @GuillaumeGomez. |
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Replace |
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@rustbot modify labels: A-ffi, C-feature-request, T-libs |
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r? @dtolnay |
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On the recommendation of @dtolnay I added a new error type This type, defined as: #[derive(Clone, PartialEq, Eq, Debug)]
#[unstable(feature = "cstring_from_vec_with_nul", issue = "73179")]
pub struct FromVecWithNulError {
error_kind: FromBytesWithNulErrorKind,
bytes: Vec<u8>,
}It is inspired from the The #[unstable(feature = "cstring_from_vec_with_nul", issue = "73179")]
impl fmt::Display for FromVecWithNulError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self.error_kind {
FromBytesWithNulErrorKind::InteriorNul(pos) => {
write!(f, "data provided contains an interior nul byte at pos {}", pos)
}
FromBytesWithNulErrorKind::NotNulTerminated => {
write!(f, "data provided is not nul terminated")
}
}
}
} |
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@bors r+ |
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📌 Commit 47cc5cc has been approved by |
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I suggest squashing all the commits. |
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@bors rollup |
RalfJung
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…nul, r=dtolnay Add methods to go from a nul-terminated Vec<u8> to a CString Fixes rust-lang#73100. Doc tests have been written and the documentation on the error type updated too. I used `#[stable(feature = "cstring_from_vec_with_nul", since = "1.46.0")]` but I don't know if the version is correct.
This was referenced Jun 15, 2020
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Rollup of 10 pull requests Successful merges: - rust-lang#72707 (Use min_specialization in the remaining rustc crates) - rust-lang#72740 (On recursive ADT, provide indirection structured suggestion) - rust-lang#72879 (Miri: avoid tracking current location three times) - rust-lang#72938 (Stabilize Option::zip) - rust-lang#73086 (Rename "cyclone" to "apple-a7" per changes in upstream LLVM) - rust-lang#73104 (Example about explicit mutex dropping) - rust-lang#73139 (Add methods to go from a nul-terminated Vec<u8> to a CString) - rust-lang#73296 (Remove vestigial CI job msvc-aux.) - rust-lang#73304 (Revert heterogeneous SocketAddr PartialEq impls) - rust-lang#73331 (extend network support for HermitCore) Failed merges: r? @ghost
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Should I still squash if it has been approved ? (Edit: and is being merged) |
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Now it has been rolled up, so if that rollup succeeds the PR will be merged as-is. If the rollup fails, I'll r- so you can squash. |
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Thanks, I'll know for the next time. :) |
Dylan-DPC
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Mar 19, 2022
…k-Simulacrum
add `CStr` method that accepts any slice containing a nul-terminated string
I haven't created an issue (tracking or otherwise) for this yet; apologies if my approach isn't correct. This is my first code contribution.
This change adds a member fn that converts a slice into a `CStr`; it is intended to be safer than `from_ptr` (which is unsafe and may read out of bounds), and more useful than `from_bytes_with_nul` (which requires that the caller already know where the nul byte is).
The reason I find this useful is for situations like this:
```rust
let mut buffer = [0u8; 32];
unsafe {
some_c_function(buffer.as_mut_ptr(), buffer.len());
}
let result = CStr::from_bytes_with_nul(&buffer).unwrap();
```
This code above returns an error with `kind = InteriorNul`, because `from_bytes_with_nul` expects that the caller has passed in a slice with the NUL byte at the end of the slice. But if I just got back a nul-terminated string from some FFI function, I probably don't know where the NUL byte is.
I would wish for a `CStr` constructor with the following properties:
- Accept `&[u8]` as input
- Scan for the first NUL byte and return the `CStr` that spans the correct sub-slice (see [future note below](rust-lang#94984 (comment))).
- Return an error if no NUL byte is found within the input slice
I asked on [Zulip](https://rust-lang.zulipchat.com/#narrow/stream/122651-general/topic/CStr.20from.20.26.5Bu8.5D.20without.20knowing.20the.20NUL.20location.3F) whether this sounded like a good idea, and got a couple of positive-sounding responses from `@joshtriplett` and `@AzureMarker.`
This is my first draft, so feedback is welcome.
A few issues that definitely need feedback:
1. Naming. `@joshtriplett` called this `from_bytes_with_internal_nul` on Zulip, but after staring at all of the available methods, I believe that this function is probably what end users want (rather than the existing fn `from_bytes_with_nul`). Giving it a simpler name (**`from_bytes`**) implies that this should be their first choice.
2. Should I add a similar method on `CString` that accepts `Vec<u8>`? I'd assume the answer is probably yes, but I figured I'd try to get early feedback before making this change bigger.
3. What should the error type look like? I made a unit struct since `CStr::from_bytes` can only fail in one obvious way, but if I need to do this for `CString` as well then that one may want to return `FromVecWithNulError`. And maybe that should dictate the shape of the `CStr` error type also?
Also, cc `@poliorcetics` who wrote rust-lang#73139 containing similar fns.
Dylan-DPC
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Mar 19, 2022
…k-Simulacrum
add `CStr` method that accepts any slice containing a nul-terminated string
I haven't created an issue (tracking or otherwise) for this yet; apologies if my approach isn't correct. This is my first code contribution.
This change adds a member fn that converts a slice into a `CStr`; it is intended to be safer than `from_ptr` (which is unsafe and may read out of bounds), and more useful than `from_bytes_with_nul` (which requires that the caller already know where the nul byte is).
The reason I find this useful is for situations like this:
```rust
let mut buffer = [0u8; 32];
unsafe {
some_c_function(buffer.as_mut_ptr(), buffer.len());
}
let result = CStr::from_bytes_with_nul(&buffer).unwrap();
```
This code above returns an error with `kind = InteriorNul`, because `from_bytes_with_nul` expects that the caller has passed in a slice with the NUL byte at the end of the slice. But if I just got back a nul-terminated string from some FFI function, I probably don't know where the NUL byte is.
I would wish for a `CStr` constructor with the following properties:
- Accept `&[u8]` as input
- Scan for the first NUL byte and return the `CStr` that spans the correct sub-slice (see [future note below](rust-lang#94984 (comment))).
- Return an error if no NUL byte is found within the input slice
I asked on [Zulip](https://rust-lang.zulipchat.com/#narrow/stream/122651-general/topic/CStr.20from.20.26.5Bu8.5D.20without.20knowing.20the.20NUL.20location.3F) whether this sounded like a good idea, and got a couple of positive-sounding responses from ``@joshtriplett`` and ``@AzureMarker.``
This is my first draft, so feedback is welcome.
A few issues that definitely need feedback:
1. Naming. ``@joshtriplett`` called this `from_bytes_with_internal_nul` on Zulip, but after staring at all of the available methods, I believe that this function is probably what end users want (rather than the existing fn `from_bytes_with_nul`). Giving it a simpler name (**`from_bytes`**) implies that this should be their first choice.
2. Should I add a similar method on `CString` that accepts `Vec<u8>`? I'd assume the answer is probably yes, but I figured I'd try to get early feedback before making this change bigger.
3. What should the error type look like? I made a unit struct since `CStr::from_bytes` can only fail in one obvious way, but if I need to do this for `CString` as well then that one may want to return `FromVecWithNulError`. And maybe that should dictate the shape of the `CStr` error type also?
Also, cc ``@poliorcetics`` who wrote rust-lang#73139 containing similar fns.
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Fixes #73100.
Doc tests have been written and the documentation on the error type
updated too.
I used
#[stable(feature = "cstring_from_vec_with_nul", since = "1.46.0")]but I don't know if the version is correct.