Add cgroupv1 support to available_parallelism
Fixes#97549
My dev machine uses cgroup v2 so I was only able to test that code path. So the v1 code path is written only based on documentation. I could use some help testing that it works on a machine with cgroups v1:
```
$ x.py build --stage 1
# quota.rs
fn main() {
println!("{:?}", std:🧵:available_parallelism());
}
# assuming stage1 is linked in rustup
$ rust +stage1 quota.rs
# spawn a new cgroup scope for the current user
$ sudo systemd-run -p CPUQuota="300%" --uid=$(id -u) -tdS
# should print Ok(3)
$ ./quota
```
If it doesn't work as expected an strace, the contents of `/proc/self/cgroups` and the structure of `/sys/fs/cgroups` would help.
Fix the stable version of `AsFd for Arc<T>` and `Box<T>`
These merged in #97437 for 1.64.0, apart from the main `io_safety`
feature that stabilized in 1.63.0.
std: use futex-based locks on Fuchsia
This switches `Condvar` and `RwLock` to the futex-based implementation currently used on Linux and some BSDs. Additionally, `Mutex` now has its own, priority-inheriting implementation based on the mutex in Fuchsia's `libsync`. It differs from the original in that it panics instead of aborting when reentrant locking is detected.
````@rustbot```` ping fuchsia
r? ````@m-ou-se````
stdlib support for Apple WatchOS
This is a follow-up to https://github.com/rust-lang/rust/pull/95243 (Add Apple WatchOS compiler targets) that adds stdlib support for Apple WatchOS.
`@deg4uss3r`
`@nagisa`
Windows: Use `FindFirstFileW` for getting the metadata of locked system files
Fixes#96980
Usually opening a file handle with access set to metadata only will always succeed, even if the file is locked. However some special system files, such as `C:\hiberfil.sys`, are locked by the system in a way that denies even that. So as a fallback we try reading the cached metadata from the directory.
Note that the test is a bit iffy. I don't know if `hiberfil.sys` actually exists in the CI.
r? rust-lang/libs
* Reduce duplicate impls; show only the `fn (T)` and include a sentence
saying that there exists up to twelve of them.
* Show `Copy` and `Clone`.
* Show auto traits like `Send` and `Sync`, and blanket impls like `Any`.
Implement `fmt::Write` for `OsString`
This allows to format into an `OsString` without unnecessary
allocations. E.g.
```
let mut temp_filename = path.into_os_string();
write!(&mut temp_filename, ".tmp.{}", process::id());
```
Stabilize `core::ffi::CStr`, `alloc::ffi::CString`, and friends
Stabilize the `core_c_str` and `alloc_c_string` feature gates.
Change `std::ffi` to re-export these types rather than creating type
aliases, since they now have matching stability.
Stabilize the `core_c_str` and `alloc_c_string` feature gates.
Change `std::ffi` to re-export these types rather than creating type
aliases, since they now have matching stability.
Add `struct FileTimes` to contain the relevant file timestamps, since
most platforms require setting all of them at once. (This also allows
for future platform-specific extensions such as setting creation time.)
Add `File::set_file_time` to set the timestamps for a `File`.
Implement the `sys` backends for UNIX, macOS (which needs to fall back
to `futimes` before macOS 10.13 because it lacks `futimens`), Windows,
and WASI.
Stabilize `core::ffi:c_*` and rexport in `std::ffi`
This only stabilizes the base types, not the non-zero variants, since
those have their own separate tracking issue and have not gone through
FCP to stabilize.
This only stabilizes the base types, not the non-zero variants, since
those have their own separate tracking issue and have not gone through
FCP to stabilize.
Inline Windows `OsStrExt::encode_wide`
User crates currently produce much more code than necessary because the optimizer fails to make assumptions about this method.
Implement ExitCodeExt for Windows
Fixes#97914
### Motivation:
On Windows it is common for applications to return `HRESULT` (`i32`) or `DWORD` (`u32`) values. These stem from COM based components ([HRESULTS](https://docs.microsoft.com/en-us/windows/win32/api/objbase/nf-objbase-coinitialize)), Win32 errors ([GetLastError](https://docs.microsoft.com/en-us/windows/win32/api/errhandlingapi/nf-errhandlingapi-getlasterror)), GUI applications ([WM_QUIT](https://docs.microsoft.com/en-us/windows/win32/winmsg/wm-quit)) and more. The newly stabilized `ExitCode` provides an excellent fit for propagating these values, because `std::process::exit` does not run deconstructors which can result in errors. However, `ExitCode` currently only implements `From<u8> for ExitCode`, which disallows the full range of `i32`/`u32` values. This pull requests attempts to address that shortcoming by providing windows specific extensions that accept a `u32` value (which covers all possible `HRESULTS` and Win32 errors) analog to [ExitStatusExt::from_raw](https://doc.rust-lang.org/std/os/windows/process/trait.ExitStatusExt.html#tymethod.from_raw).
This was also intended by the original Stabilization https://github.com/rust-lang/rust/pull/93840#issue-1129209143= as pointed out by ``@eggyal`` in https://github.com/rust-lang/rust/issues/97914#issuecomment-1151076755:
> Issues around platform specific representations: We resolved this issue by changing the return type of report from i32 to the opaque type ExitCode. __That way we can change the underlying representation without affecting the API, letting us offer full support for platform specific exit code APIs in the future.__
[Emphasis added]
### API
```rust
/// Windows-specific extensions to [`process::ExitCode`].
///
/// This trait is sealed: it cannot be implemented outside the standard library.
/// This is so that future additional methods are not breaking changes.
#[stable(feature = "windows_process_exit_code_from", since = "1.63.0")]
pub trait ExitCodeExt: Sealed {
/// Creates a new `ExitCode` from the raw underlying `u32` return value of
/// a process.
#[stable(feature = "windows_process_exit_code_from", since = "1.63.0")]
fn from_raw(raw: u32) -> Self;
}
#[stable(feature = "windows_process_exit_code_from", since = "1.63.0")]
impl ExitCodeExt for process::ExitCode {
fn from_raw(raw: u32) -> Self {
process::ExitCode::from_inner(From::from(raw))
}
}
```
### Misc
I apologize in advance if I misplaced any attributes regarding stabilzation, as far as I learned traits are insta-stable so I chose to make them stable. If this is an error, please let me know and I'll correct it. I also added some additional machinery to make it work, analog to [ExitStatus](https://doc.rust-lang.org/std/process/struct.ExitStatus.html#).
EDIT: Proposal: https://github.com/rust-lang/libs-team/issues/48
Usually opening a file handle with access set to metadata only will always succeed, even if the file is locked. However some special system files, such as `C:\hiberfil.sys`, are locked by the system in a way that denies even that. So as a fallback we try reading the cached metadata from the directory.
Implement `FusedIterator` for `std::net::[Into]Incoming`
They never return `None`, so they trivially fulfill the contract.
What should I put for the stability attribute of `Incoming`?
`impl<T: AsRawFd> AsRawFd for {Arc,Box}<T>`
This allows implementing traits that require a raw FD on Arc and Box.
Previously, you'd have to add the function to the trait itself:
```rust
trait MyTrait {
fn as_raw_fd(&self) -> RawFd;
}
impl<T: MyTrait> MyTrait for Arc<T> {
fn as_raw_fd(&self) -> RawFd {
(**self).as_raw_fd()
}
}
```
In particular, this leads to lots of "multiple applicable items in scope" errors because you have to disambiguate `MyTrait::as_raw_fd` from `AsRawFd::as_raw_fd` at each call site. In generic contexts, when passing the type to a function that takes `impl AsRawFd` it's also sometimes required to use `T: MyTrait + AsRawFd`, which wouldn't be necessary if I could write `MyTrait: AsRawFd`.
After this PR, the code can be simpler:
```rust
trait MyTrait: AsRawFd {}
impl<T: MyTrait> MyTrait for Arc<T> {}
```
Fix FFI-unwind unsoundness with mixed panic mode
UB maybe introduced when an FFI exception happens in a `C-unwind` foreign function and it propagates through a crate compiled with `-C panic=unwind` into a crate compiled with `-C panic=abort` (#96926).
To prevent this unsoundness from happening, we will disallow a crate compiled with `-C panic=unwind` to be linked into `panic-abort` *if* it contains a call to `C-unwind` foreign function or function pointer. If no such call exists, then we continue to allow such mixed panic mode linking because it's sound (and stable). In fact we still need the ability to do mixed panic mode linking for std, because we only compile std once with `-C panic=unwind` and link it regardless panic strategy.
For libraries that wish to remain compile-once-and-linkable-to-both-panic-runtimes, a `ffi_unwind_calls` lint is added (gated under `c_unwind` feature gate) to flag any FFI unwind calls that will cause the linkable panic runtime be restricted.
In summary:
```rust
#![warn(ffi_unwind_calls)]
mod foo {
#[no_mangle]
pub extern "C-unwind" fn foo() {}
}
extern "C-unwind" {
fn foo();
}
fn main() {
// Call to Rust function is fine regardless ABI.
foo::foo();
// Call to foreign function, will cause the crate to be unlinkable to panic-abort if compiled with `-Cpanic=unwind`.
unsafe { foo(); }
//~^ WARNING call to foreign function with FFI-unwind ABI
let ptr: extern "C-unwind" fn() = foo::foo;
// Call to function pointer, will cause the crate to be unlinkable to panic-abort if compiled with `-Cpanic=unwind`.
ptr();
//~^ WARNING call to function pointer with FFI-unwind ABI
}
```
Fix#96926
`@rustbot` label: T-compiler F-c_unwind
fix data race in thread::scope
Puts the `ScopeData` into an `Arc` so it sticks around as long as we need it.
This means one extra `Arc::clone` per spawned scoped thread, which I hope is fine.
Fixes https://github.com/rust-lang/rust/issues/98498
r? `````@m-ou-se`````
[core] add `Exclusive` to sync
(discussed here: https://rust-lang.zulipchat.com/#narrow/stream/219381-t-libs/topic/Adding.20.60SyncWrapper.60.20to.20std)
`Exclusive` is a wrapper that exclusively allows mutable access to the inner value if you have exclusive access to the wrapper. It acts like a compile time mutex, and hold an unconditional `Sync` implementation.
## Justification for inclusion into std
- This wrapper unblocks actual problems:
- The example that I hit was a vector of `futures::future::BoxFuture`'s causing a central struct in a script to be non-`Sync`. To work around it, you either write really difficult code, or wrap the futures in a needless mutex.
- Easy to maintain: this struct is as simple as a wrapper can get, and its `Sync` implementation has very clear reasoning
- Fills a gap: `&/&mut` are to `RwLock` as `Exclusive` is to `Mutex`
## Public Api
```rust
// core::sync
#[derive(Default)]
struct Exclusive<T: ?Sized> { ... }
impl<T: ?Sized> Sync for Exclusive {}
impl<T> Exclusive<T> {
pub const fn new(t: T) -> Self;
pub const fn into_inner(self) -> T;
}
impl<T: ?Sized> Exclusive<T> {
pub const fn get_mut(&mut self) -> &mut T;
pub const fn get_pin_mut(Pin<&mut self>) -> Pin<&mut T>;
pub const fn from_mut(&mut T) -> &mut Exclusive<T>;
pub const fn from_pin_mut(Pin<&mut T>) -> Pin<&mut Exclusive<T>>;
}
impl<T: Future> Future for Exclusive { ... }
impl<T> From<T> for Exclusive<T> { ... }
impl<T: ?Sized> Debug for Exclusive { ... }
```
## Naming
This is a big bikeshed, but I felt that `Exclusive` captured its general purpose quite well.
## Stability and location
As this is so simple, it can be in `core`. I feel that it can be stabilized quite soon after it is merged, if the libs teams feels its reasonable to add. Also, I don't really know how unstable feature work in std/core's codebases, so I might need help fixing them
## Tips for review
The docs probably are the thing that needs to be reviewed! I tried my best, but I'm sure people have more experience than me writing docs for `Core`
### Implementation:
The API is mostly pulled from https://docs.rs/sync_wrapper/latest/sync_wrapper/struct.SyncWrapper.html (which is apache 2.0 licenesed), and the implementation is trivial:
- its an unsafe justification for pinning
- its an unsafe justification for the `Sync` impl (mostly reasoned about by ````@danielhenrymantilla```` here: https://github.com/Actyx/sync_wrapper/pull/2)
- and forwarding impls, starting with derivable ones and `Future`
Remove feature `const_option` from std
This is part of the effort to reduce the number of unstable features used by std. This one is easy as it's only used in one place.
attempt to optimise vectored write
benchmarked:
old:
```
test io::cursor::tests::bench_write_vec ... bench: 68 ns/iter (+/- 2)
test io::cursor::tests::bench_write_vec_vectored ... bench: 913 ns/iter (+/- 31)
```
new:
```
test io::cursor::tests::bench_write_vec ... bench: 64 ns/iter (+/- 0)
test io::cursor::tests::bench_write_vec_vectored ... bench: 747 ns/iter (+/- 27)
```
More unsafe than I wanted (and less gains) in the end, but it still does the job
These calls allow detecting whether a symlink is a file or a directory,
a distinction Windows maintains, and one important to software that
wants to do further operations on the symlink (e.g. removing it).
Update `std::alloc::System` doc example code style
`return` on the last line of a block is unidiomatic so I don't think the example should be using that here
std: use an event-flag-based thread parker on SOLID
`Mutex` and `Condvar` are being replaced by more efficient implementations, which need thread parking themselves (see #93740). Therefore, the generic `Parker` needs to be replaced on all platforms where the new lock implementation will be used, which, after #96393, are SOLID, SGX and Hermit (more PRs coming soon).
SOLID, conforming to the [μITRON specification](http://www.ertl.jp/ITRON/SPEC/FILE/mitron-400e.pdf), has event flags, which are a thread parking primitive very similar to `Parker`. However, they do not make any atomic ordering guarantees (even though those can probably be assumed) and necessitate a system call even when the thread token is already available. Hence, this `Parker`, like the Windows parker, uses an extra atomic state variable.
I future-proofed the code by wrapping the event flag in a `WaitFlag` structure, as both SGX and Hermit can share the Parker implementation, they just have slightly different primitives (SGX uses signals and Hermit has a thread blocking API).
`````@kawadakk````` I assume you are the target maintainer? Could you test this for me?
Mitigate MMIO stale data vulnerability
Intel publicly disclosed the MMIO stale data vulnerability on June 14. To mitigate this vulnerability, compiler changes are required for the `x86_64-fortanix-unknown-sgx` target.
cc: ````@jethrogb````
Windows: Iterative `remove_dir_all`
This will allow better strategies for use of memory and File handles. However, fully taking advantage of that is left to future work.
Note to reviewer: It's probably best to view the `remove_dir_all_recursive` as a new function. The diff is not very helpful (imho).
Make RwLockReadGuard covariant
Hi, first time contributor here, if anything is not as expected, please let me know.
`RwLockReadGoard`'s type constructor is invariant. Since it behaves like a smart pointer to an immutable reference, there is no reason that it should not be covariant. Take e.g.
```
fn test_read_guard_covariance() {
fn do_stuff<'a>(_: RwLockReadGuard<'_, &'a i32>, _: &'a i32) {}
let j: i32 = 5;
let lock = RwLock::new(&j);
{
let i = 6;
do_stuff(lock.read().unwrap(), &i);
}
drop(lock);
}
```
where the compiler complains that &i doesn't live long enough. If `RwLockReadGuard` is covariant, then the above code is accepted because the lifetime can be shorter than `'a`.
In order for `RwLockReadGuard` to be covariant, it can't contain a full reference to the `RwLock`, which can never be covariant (because it exposes a mutable reference to the underlying data structure). By reducing the data structure to the required pieces of `RwLock`, the rest falls in place.
If there is a better way to do a test that tests successful compilation, please let me know.
Fixes#80392
Fix documentation for `with_capacity` and `reserve` families of methods
Fixes#95614
Documentation for the following methods
- `with_capacity`
- `with_capacity_in`
- `with_capacity_and_hasher`
- `reserve`
- `reserve_exact`
- `try_reserve`
- `try_reserve_exact`
was inconsistent and often not entirely correct where they existed on the following types
- `Vec`
- `VecDeque`
- `String`
- `OsString`
- `PathBuf`
- `BinaryHeap`
- `HashSet`
- `HashMap`
- `BufWriter`
- `LineWriter`
since the allocator is allowed to allocate more than the requested capacity in all such cases, and will frequently "allocate" much more in the case of zero-sized types (I also checked `BufReader`, but there the docs appear to be accurate as it appears to actually allocate the exact capacity).
Some effort was made to make the documentation more consistent between types as well.
