Add slice methods for indexing via an array of indices.
Disclaimer: It's been a while since I contributed to the main Rust repo, apologies in advance if this is large enough already that it should've been an RFC.
---
# Update:
- Based on feedback, removed the `&[T]` variant of this API, and removed the requirements for the indices to be sorted.
# Description
This adds the following slice methods to `core`:
```rust
impl<T> [T] {
pub unsafe fn get_many_unchecked_mut<const N: usize>(&mut self, indices: [usize; N]) -> [&mut T; N];
pub fn get_many_mut<const N: usize>(&mut self, indices: [usize; N]) -> Option<[&mut T; N]>;
}
```
This allows creating multiple mutable references to disjunct positions in a slice, which previously required writing some awkward code with `split_at_mut()` or `iter_mut()`. For the bound-checked variant, the indices are checked against each other and against the bounds of the slice, which requires `N * (N + 1) / 2` comparison operations.
This has a proof-of-concept standalone implementation here: https://crates.io/crates/index_many
Care has been taken that the implementation passes miri borrow checks, and generates straight-forward assembly (though this was only checked on x86_64).
# Example
```rust
let v = &mut [1, 2, 3, 4];
let [a, b] = v.get_many_mut([0, 2]).unwrap();
std::mem::swap(a, b);
*v += 100;
assert_eq!(v, &[3, 2, 101, 4]);
```
# Codegen Examples
<details>
<summary>Click to expand!</summary>
Disclaimer: Taken from local tests with the standalone implementation.
## Unchecked Indexing:
```rust
pub unsafe fn example_unchecked(slice: &mut [usize], indices: [usize; 3]) -> [&mut usize; 3] {
slice.get_many_unchecked_mut(indices)
}
```
```nasm
example_unchecked:
mov rcx, qword, ptr, [r9]
mov r8, qword, ptr, [r9, +, 8]
mov r9, qword, ptr, [r9, +, 16]
lea rcx, [rdx, +, 8*rcx]
lea r8, [rdx, +, 8*r8]
lea rdx, [rdx, +, 8*r9]
mov qword, ptr, [rax], rcx
mov qword, ptr, [rax, +, 8], r8
mov qword, ptr, [rax, +, 16], rdx
ret
```
## Checked Indexing (Option):
```rust
pub unsafe fn example_option(slice: &mut [usize], indices: [usize; 3]) -> Option<[&mut usize; 3]> {
slice.get_many_mut(indices)
}
```
```nasm
mov r10, qword, ptr, [r9, +, 8]
mov rcx, qword, ptr, [r9, +, 16]
cmp rcx, r10
je .LBB0_7
mov r9, qword, ptr, [r9]
cmp rcx, r9
je .LBB0_7
cmp rcx, r8
jae .LBB0_7
cmp r10, r9
je .LBB0_7
cmp r9, r8
jae .LBB0_7
cmp r10, r8
jae .LBB0_7
lea r8, [rdx, +, 8*r9]
lea r9, [rdx, +, 8*r10]
lea rcx, [rdx, +, 8*rcx]
mov qword, ptr, [rax], r8
mov qword, ptr, [rax, +, 8], r9
mov qword, ptr, [rax, +, 16], rcx
ret
.LBB0_7:
mov qword, ptr, [rax], 0
ret
```
## Checked Indexing (Panic):
```rust
pub fn example_panic(slice: &mut [usize], indices: [usize; 3]) -> [&mut usize; 3] {
let len = slice.len();
match slice.get_many_mut(indices) {
Some(s) => s,
None => {
let tmp = indices;
index_many::sorted_bound_check_failed(&tmp, len)
}
}
}
```
```nasm
example_panic:
sub rsp, 56
mov rax, qword, ptr, [r9]
mov r10, qword, ptr, [r9, +, 8]
mov r9, qword, ptr, [r9, +, 16]
cmp r9, r10
je .LBB0_6
cmp r9, rax
je .LBB0_6
cmp r9, r8
jae .LBB0_6
cmp r10, rax
je .LBB0_6
cmp rax, r8
jae .LBB0_6
cmp r10, r8
jae .LBB0_6
lea rax, [rdx, +, 8*rax]
lea r8, [rdx, +, 8*r10]
lea rdx, [rdx, +, 8*r9]
mov qword, ptr, [rcx], rax
mov qword, ptr, [rcx, +, 8], r8
mov qword, ptr, [rcx, +, 16], rdx
mov rax, rcx
add rsp, 56
ret
.LBB0_6:
mov qword, ptr, [rsp, +, 32], rax
mov qword, ptr, [rsp, +, 40], r10
mov qword, ptr, [rsp, +, 48], r9
lea rcx, [rsp, +, 32]
mov edx, 3
call index_many::bound_check_failed
ud2
```
</details>
# Extensions
There are multiple optional extensions to this.
## Indexing With Ranges
This could easily be expanded to allow indexing with `[I; N]` where `I: SliceIndex<Self>`. I wanted to keep the initial implementation simple, so I didn't include it yet.
## Panicking Variant
We could also add this method:
```rust
impl<T> [T] {
fn index_many_mut<const N: usize>(&mut self, indices: [usize; N]) -> [&mut T; N];
}
```
This would work similar to the regular index operator and panic with out-of-bound indices. The advantage would be that we could more easily ensure good codegen with a useful panic message, which is non-trivial with the `Option` variant.
This is implemented in the standalone implementation, and used as basis for the codegen examples here and there.
Improve accuracy of asinh and acosh
This PR addresses the inaccuracy of `asinh` and `acosh` identified by the [Herbie](http://herbie.uwplse.org/) tool, `@pavpanchekha,` `@finnbear` in #104548. It also adds a couple tests that failed in the existing implementations and now pass.
Closes#104548
r? rust-lang/libs
Fix non-associativity of `Instant` math on `aarch64-apple-darwin` targets
This is a duplicate of #94100 (since the original author is unresponsive), which resolves#91417.
On `aarch64-apple-darwin` targets, the internal resolution of `Instant` is lower than that of `Duration`, so math between them becomes non-associative with small-enough durations.
This PR makes this target use the standard Unix implementation (where `Instant` has 1ns resolution), but with `CLOCK_UPTIME_RAW` so it still returns the same values as `mach_absolute_time`[^1].
(Edit: I need someone to confirm that this still works, I do not have access to an M1 device.)
[^1]: https://www.manpagez.com/man/3/clock_gettime/
There seem to be some scenarios where `cpu.cfs_period_us` can contain `0`
This causes a panic when calling `std:🧵:available_parallelism()` as is done so
from binaries built by `cargo test`, which was how the issue was
discovered. I don't feel like `0` is a good value for `cpu.cfs_period_us`, but I
also don't think applications should panic if this value is seen.
This case is handled by other projects which read this information:
- num_cpus: e437b9d908/src/linux.rs (L207-L210)
- ninja: https://github.com/ninja-build/ninja/pull/2174/files
- dotnet: c4341d45ac/src/coreclr/pal/src/misc/cgroup.cpp (L481-L483)
Before this change, this panic could be seen in environments setup as described
above:
```
$ RUST_BACKTRACE=1 cargo test
Finished test [unoptimized + debuginfo] target(s) in 3.55s
Running unittests src/main.rs (target/debug/deps/x-9a42e145aca2934d)
thread 'main' panicked at 'attempt to divide by zero', library/std/src/sys/unix/thread.rs:546:70
stack backtrace:
0: rust_begin_unwind
1: core::panicking::panic_fmt
2: core::panicking::panic
3: std::sys::unix:🧵:cgroups::quota
4: std::sys::unix:🧵:available_parallelism
5: std:🧵:available_parallelism
6: test::helpers::concurrency::get_concurrency
7: test::console::run_tests_console
8: test::test_main
9: test::test_main_static
10: x::main
at ./src/main.rs:1:1
11: core::ops::function::FnOnce::call_once
at /tmp/rust-1.64-1.64.0-1/library/core/src/ops/function.rs:248:5
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
error: test failed, to rerun pass '--bin local-rabmq-amqpprox'
```
I've tested this change in an environment which has the bad setup and
rebuilding the test executable against a fixed std library fixes the
panic.
Remove unused symbols and diagnostic items
As the title suggests, this removes unused symbols from `sym::` and `#[rustc_diagnostic_item]` annotations that weren't mentioned anywhere.
Originally I tried to use grep, to find symbols and item names that are never mentioned via `sym::name`, however this produced a lot of false positives (?), for example clippy matching on `Symbol::as_str` or macros "implicitly" adding `sym::`. I ended up fixing all these false positives (?) by hand, but tbh I'm not sure if it was worth it...
Update compiler-builtins
This was originally a part of https://github.com/rust-lang/rust/pull/100316. However, extracting it to a seperate PR should help with any extra testing that might be needed.
Signed-off-by: Ayush Singh <ayushsingh1325@gmail.com>
Move `unix_socket_abstract` feature API to `SocketAddrExt`.
The pre-stabilized API for abstract socket addresses exposes methods on `SocketAddr` that are only enabled for `cfg(any(target_os = "android", target_os = "linux"))`. Per discussion in <https://github.com/rust-lang/rust/issues/85410>, moving these methods to an OS-specific extension trait is required before stabilization can be considered.
This PR makes four changes:
1. The internal module `std::os::net` contains logic for the unstable feature `tcp_quickack` (https://github.com/rust-lang/rust/issues/96256). I moved that code into `linux_ext/tcp.rs` and tried to adjust the module tree so it could accommodate a second unstable feature there.
2. Moves the public API out of `impl SocketAddr`, into `impl SocketAddrExt for SocketAddr` (the headline change).
3. The existing function names and docs for `unix_socket_abstract` refer to addresses as being created from abstract namespaces, but a more accurate description is that they create sockets in *the* abstract namespace. I adjusted the function signatures correspondingly and tried to update the docs to be clearer.
4. I also tweaked `from_abstract_name` so it takes an `AsRef<[u8]>` instead of `&[u8]`, allowing `b""` literals to be passed directly.
Issues:
1. The public module `std::os::linux::net` is marked as part of `tcp_quickack`. I couldn't figure out how to mark a module as being part of two unstable features, so I just left the existing attributes in place. My hope is that this will be fixed as a side-effect of stabilizing either feature.
Rollup of 9 pull requests
Successful merges:
- #103709 (ci: Upgrade dist-x86_64-netbsd to NetBSD 9.0)
- #103744 (Upgrade cc for working is_flag_supported on cross-compiles)
- #104105 (llvm: dwo only emitted when object code emitted)
- #104158 (Return .efi extension for EFI executable)
- #104181 (Add a few known-bug tests)
- #104266 (Regression test for coercion of mut-ref to dyn-star)
- #104300 (Document `Path::parent` behavior around relative paths)
- #104304 (Enable profiler in dist-s390x-linux)
- #104362 (Add `delay_span_bug` to `AttrWrapper::take_for_recovery`)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Document `Path::parent` behavior around relative paths
A relative path with just one component will return `Some("")` as its parent, which wasn't clear to me from the documentation.
The parent of `""` is `None`, which was missing from the documentation as well.
Change the way libunwind is linked for *-windows-gnullvm targets
I have no idea why previous way works for `x86_64-fortanix-unknown-sgx` (assuming it actually works...) but not for `gnullvm`. It fails when linking libtest during Rust build (unless somebody adds `RUSTFLAGS='-Clinkarg=-lunwind'`).
Also fixes exception handling on AArch64.
This was originally a part of https://github.com/rust-lang/rust/pull/100316.
However, extracting it to a seperate PR should help with any extra
testing that might be needed.
Signed-off-by: Ayush Singh <ayushsingh1325@gmail.com>
Merge crossbeam-channel into `std::sync::mpsc`
This PR imports the [`crossbeam-channel`](https://github.com/crossbeam-rs/crossbeam/tree/master/crossbeam-channel#crossbeam-channel) crate into the standard library as a private module, `sync::mpmc`. `sync::mpsc` is now implemented as a thin wrapper around `sync::mpmc`. The primary purpose of this PR is to resolve https://github.com/rust-lang/rust/issues/39364. The public API intentionally remains the same.
The reason https://github.com/rust-lang/rust/issues/39364 has not been fixed in over 5 years is that the current channel is *incredibly* complex. It was written many years ago and has sat mostly untouched since. `crossbeam-channel` has become the most popular alternative on crates.io, amassing over 30 million downloads. While crossbeam's channel is also complex, like all fast concurrent data structures, it avoids some of the major issues with the current implementation around dynamic flavor upgrades. The new implementation decides on the datastructure to be used when the channel is created, and the channel retains that structure until it is dropped.
Replacing `sync::mpsc` with a simpler, less performant implementation has been discussed as an alternative. However, Rust touts itself as enabling *fearless concurrency*, and having the standard library feature a subpar implementation of a core concurrency primitive doesn't feel right. The argument is that slower is better than broken, but this PR shows that we can do better.
As mentioned before, the primary purpose of this PR is to fix https://github.com/rust-lang/rust/issues/39364, and so the public API intentionally remains the same. *After* that problem is fixed, the fact that `sync::mpmc` now exists makes it easier to fix the primary limitation of `mpsc`, the fact that it only supports a single consumer. spmc and mpmc are two other common concurrency patterns, and this change enables a path to deprecating `mpsc` and exposing a general `sync::channel` module that supports multiple consumers. It also implements other useful methods such as `send_timeout`. That said, exposing MPMC and other new functionality is mostly out of scope for this PR, and it would be helpful if discussion stays on topic :)
For what it's worth, the new implementation has also been shown to be more performant in [some basic benchmarks](https://github.com/crossbeam-rs/crossbeam/tree/master/crossbeam-channel/benchmarks#results).
cc `@taiki-e`
r? rust-lang/libs
Add the `#[derive_const]` attribute
Closes#102371. This is a minimal patchset for the attribute to work. There are no restrictions on what traits this attribute applies to.
r? `````@oli-obk`````
Remove lock wrappers in `sys_common`
This moves the lazy allocation to `sys` (SGX and UNIX). While this leads to a bit more verbosity, it will simplify future improvements by making room in `sys_common` for platform-independent implementations.
This also removes the condvar check on SGX as it is not necessary for soundness and will be removed anyway once mutex has been made movable.
For simplicity's sake, `libunwind` also uses lazy allocation now on SGX. This will require an update to the C definitions before merging this (CC `@raoulstrackx).`
r? `@m-ou-se`
A relative path with just one component will return `Some("")` as its
parent, which wasn't clear to me from the documentation.
The parent of `""` is `None`, which was missing from the documentation
as well.
Make `Hash`, `Hasher` and `BuildHasher` `#[const_trait]` and make `Sip` const `Hasher`
This PR enables using Hashes in const context.
r? ``@fee1-dead``
Added documentation for IPv6 Addresses `IN6ADDR_ANY_INIT` also known as
`in6addr_any` and `IN6ADDR_LOOPBACK_INIT` also known as
`in6addr_loopback` similar to `INADDR_ANY` for IPv4 Addresses.
The new implementation doesn't use weak lang items and instead changes
`#[alloc_error_handler]` to an attribute macro just like
`#[global_allocator]`.
The attribute will generate the `__rg_oom` function which is called by
the compiler-generated `__rust_alloc_error_handler`. If no `__rg_oom`
function is defined in any crate then the compiler shim will call
`__rdl_oom` in the alloc crate which will simply panic.
This also fixes link errors with `-C link-dead-code` with
`default_alloc_error_handler`: `__rg_oom` was previously defined in the
alloc crate and would attempt to reference the `oom` lang item, even if
it didn't exist. This worked as long as `__rg_oom` was excluded from
linking since it was not called.
This is a prerequisite for the stabilization of
`default_alloc_error_handler` (#102318).
The signature for new was
```
fn new<F>(f: F) -> Lazy<T, F>
```
Notably, with `F` unconstrained, `T` can be literally anything, and just
`let _ = Lazy::new(|| 92)` would not typecheck.
This historiacally was a necessity -- `new` is a `const` function, it
couldn't have any bounds. Today though, we can move `new` under the `F:
FnOnce() -> T` bound, which gives the compiler enough data to infer the
type of T from closure.
Truncate thread names on Linux and Apple targets
These targets have system limits on the thread names, 16 and 64 bytes
respectively, and `pthread_setname_np` returns an error if the name is
longer. However, we're not in a context that can propagate errors when
we call this, and we used to implicitly truncate on Linux with `prctl`,
so now we manually truncate these names ahead of time.
r? ``````@thomcc``````
Fix grammar in docs for std::io::Read
Two independent clauses were incorrectly joined by a bare comma. The simplest fix would be to switch to a semicolon, but I think it's slightly better to keep the comma and use the coordinating conjunction "so".
Update libstd's libc to 0.2.135 (to make `libstd` no longer pull in `libiconv.dylib` on Darwin)
This is to pull in https://github.com/rust-lang/libc/pull/2944.
It's related to https://github.com/rust-lang/rust/pull/102766, in that they both remove unused dylibs from libstd on Darwin platforms. As a result, I'm marking this as relnotes since everybody agreed it was good to add it to the other as well. (The note should be about no longer linking against libiconv -- the libc update is irrelevant).
Might as well have the same reviewer too.
r? `@Mark-Simulacrum`
Don't link to `libresolv` in libstd on Darwin
Currently we link `libresolv` into every Rust program on apple targets despite never using it (as of https://github.com/rust-lang/rust/pull/44965). I had thought we needed this for `getaddrinfo` or something, but we do not / cannot safely use it.
I'd like to fix this for `libiconv` too (the other library we pull in. that's harder since it's coming in through `libc`, which is https://github.com/rust-lang/libc/pull/2944)).
---
This may warrant release notes. I'm not sure but I've added the flag regardless -- It's a change to the list of dylibs every Rust program pulls in, so it's worth mentioning.
It's pretty unlikely anybody was relying on this being pulled in, and `std` does not guarantee that it will link (and thus transitively provide access to) any particular system library -- anybody relying on that behavior would already be broken when dynamically linking std. That is, there's an outside chance something will fail to link on macOS and iOS because it was accidentally relying on our unnecessary dependency.
(If that *does* happen, that project could be easily fixed by linking libresolv explicitly on those platforms, probably via `#[link(name = "resolv")] extern {}`,` -Crustc-link-lib=resolv`, `println!("cargo:rustc-link-lib=resolv")`, or one of several places in `.config/cargo.toml`)
---
I'm also going to preemptively add the nomination for discussing this in the libs meeting. Basically: Do we care about programs that assume we will bring libraries in that we do not use. `libresolv` and `libiconv` on macOS/iOS are in this camp (`libresolv` because we used to use it, and `libiconv` because the `libc` crate was unintentionally(?) pulling it in to every Rust program).
I'd like to remove them both, but this may cause link issues programs that are relying on `std` to depend on them transitively. (Relying on std for this does not work in all build configurations, so this seems very fragile, and like a use case we should not support).
More generally, IMO we should not guarantee the specific set of system-provided libraries we use (beyond what is implied by an OS version requirement), which means we'd be free to remove this cruft.
Stabilize `duration_checked_float`
## Stabilization Report
This stabilization report is for a stabilization of `duration_checked_float`, tracking issue: https://github.com/rust-lang/rust/issues/83400.
### Implementation History
- https://github.com/rust-lang/rust/pull/82179
- https://github.com/rust-lang/rust/pull/90247
- https://github.com/rust-lang/rust/pull/96051
- Changed error type to `FromFloatSecsError` in https://github.com/rust-lang/rust/pull/90247
- https://github.com/rust-lang/rust/pull/96051 changes the rounding mode to round-to-nearest instead of truncate.
## API Summary
This stabilization report proposes the following API to be stabilized in `core`, along with their re-exports in `std`:
```rust
// core::time
impl Duration {
pub const fn try_from_secs_f32(secs: f32) -> Result<Duration, TryFromFloatSecsError>;
pub const fn try_from_secs_f64(secs: f64) -> Result<Duration, TryFromFloatSecsError>;
}
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct TryFromFloatSecsError { ... }
impl core::fmt::Display for TryFromFloatSecsError { ... }
impl core::error::Error for TryFromFloatSecsError { ... }
```
These functions are made const unstable under `duration_consts_float`, tracking issue #72440.
There is an open question in the tracking issue around what the error type should be called which I was hoping to resolve in the context of an FCP.
In this stabilization PR, I have altered the name of the error type to `TryFromFloatSecsError`. In my opinion, the error type shares the name of the method (adjusted to accommodate both types of floats), which is consistent with other error types in `core`, `alloc` and `std` like `TryReserveError` and `TryFromIntError`.
## Experience Report
Code such as this is ready to be converted to a checked API to ensure it is panic free:
```rust
impl Time {
pub fn checked_add_f64(&self, seconds: f64) -> Result<Self, TimeError> {
// Fail safely during `f64` conversion to duration
if seconds.is_nan() || seconds.is_infinite() {
return Err(TzOutOfRangeError::new().into());
}
if seconds.is_sign_positive() {
self.checked_add(Duration::from_secs_f64(seconds))
} else {
self.checked_sub(Duration::from_secs_f64(-seconds))
}
}
}
```
See: https://github.com/artichoke/artichoke/issues/2194.
`@rustbot` label +T-libs-api -T-libs
cc `@mbartlett21`
kmc-solid: Handle errors returned by `SOLID_FS_ReadDir`
Fixes the issue where the `std::fs::ReadDir` implementaton of the [`*-kmc-solid_*`](https://doc.rust-lang.org/nightly/rustc/platform-support/kmc-solid.html) Tier 3 targets silently suppressed errors returned by the underlying `SOLID_FS_ReadDir` system function. The new implementation correctly handles all cases:
- `SOLID_ERR_NOTFOUND` indicates the end of directory stream.
- `SOLID_ERR_OK` + non-empty `d_name` indicates success.
- Some old filesystem drivers may return `SOLID_ERR_OK` + empty `d_name` to indicate the end of directory stream.
- Any other negative values (per ITRON convention) represent an error.
Document surprising and dangerous fs::Permissions behaviour on Unix
This documents the very surprising behaviour that `set_readonly(false)` will make a file *world writable* on Unix. I would go so far as to say that this function should be deprecated on Unix, or maybe even entirely. But documenting the bad behaviour is a good first step.
Fixes#74895
Eliminate 280-byte memset from ReadDir iterator
This guy:
1536ab1b38/library/std/src/sys/unix/fs.rs (L589)
It turns out `libc::dirent64` is quite big—https://docs.rs/libc/0.2.135/libc/struct.dirent64.html. In #103135 this memset accounted for 0.9% of the runtime of iterating a big directory.
Almost none of the big zeroed value is ever used. We memcpy a tiny prefix (19 bytes) into it, and then read just 9 bytes (`d_ino` and `d_type`) back out. We can read exactly those 9 bytes we need directly from the original entry_ptr instead.
## History
This code got added in #93459 and tweaked in #94272 and #94750.
Prior to #93459, there was no memset but a full 280 bytes were being copied from the entry_ptr.
<table><tr><td>copy 280 bytes</td></tr></table>
This was not legal because not all of those bytes might be initialized, or even allocated, depending on the length of the directory entry's name, leading to a segfault. That PR fixed the segfault by creating a new zeroed dirent64 and copying just the guaranteed initialized prefix into it.
<table><tr><td>memset 280 bytes</td><td>copy 19 bytes</td></tr></table>
However this was still buggy because it used `addr_of!((*entry_ptr).d_name)`, which is considered UB by Miri in the case that the full extent of entry_ptr is not in bounds of the same allocation. (Arguably this shouldn't be a requirement, but here we are.)
The UB got fixed by #94272 by replacing `addr_of` with some pointer manipulation based on `offset_from`, but still fundamentally the same operation.
<table><tr><td>memset 280 bytes</td><td>copy 19 bytes</td></tr></table>
Then #94750 noticed that only 9 of those 19 bytes were even being used, so we could pick out only those 9 to put in the ReadDir value.
<table><tr><td>memset 280 bytes</td><td>copy 19 bytes</td><td>copy 9 bytes</td></tr></table>
After my PR we just grab the 9 needed bytes directly from entry_ptr.
<table><tr><td>copy 9 bytes</td></tr></table>
The resulting code is more complex but I believe still worthwhile to land for the following reason. This is an extremely straightforward thing to accomplish in C and clearly libc assumes that; literally just `entry_ptr->d_name`. The extra work in comparison to accomplish it in Rust is not an example of any actual safety being provided by Rust. I believe it's useful to have uncovered that and think about what could be done in the standard library or language to support this obvious operation better.
## References
- https://man7.org/linux/man-pages/man3/readdir.3.html
Reduce false positives in msys2 detection
Currently msys2 will be detected by getting the file path and looking to see if it contains the substrings "msys-" and "-ptr" (or "cygwin-" and "-pty"). This risks false positives, especially with filesystem files and if `GetFileInformationByHandleEx` returns a [full path](https://learn.microsoft.com/en-us/windows-hardware/drivers/ddi/ntifs/nf-ntifs-ntqueryinformationfile#remarks).
This PR adds a check to see if the handle is a pipe before doing the substring search. Additionally, for "msys2-" or "cygwin-" it only checks if the file name starts with the substring rather than looking at the whole path.
These targets have system limits on the thread names, 16 and 64 bytes
respectively, and `pthread_setname_np` returns an error if the name is
longer. However, we're not in a context that can propagate errors when
we call this, and we used to implicitly truncate on Linux with `prctl`,
so now we manually truncate these names ahead of time.
Change process spawning to inherit the parent's signal mask by default
Previously, the signal mask was always reset when a child process is
started. This breaks tools like `nohup` which expect `SIGHUP` to be
blocked for all transitive processes.
With this change, the default behavior changes to inherit the signal mask.
This also changes the signal disposition for `SIGPIPE` to only be changed if the `#[unix_sigpipe]` attribute isn't set.
Mark `std::os::wasi::io::AsFd` etc. as stable.
io_safety was stabilized in Rust 1.63, so mark the io_safety exports in `std::os::wasi::io` as stable.
Fixes#103306.
Previously, the signal mask is always reset when a child process is
started. This breaks tools like `nohup` which expect `SIGHUP` to be
blocked.
With this change, the default behavior changes to inherit the signal mask.
This also changes the signal disposition for `SIGPIPE` to only be
changed if the `#[unix_sigpipe]` attribute isn't set.
std: use `sync::Mutex` for internal statics
Since `sync::Mutex` is now `const`-constructible, it can be used for internal statics, removing the need for `sys_common::StaticMutex`. This adds some extra allocations on platforms which need to box their mutexes (currently SGX and some UNIX), but these will become unnecessary with the lock improvements tracked in #93740.
I changed the program argument implementation on Hermit, it does not need `Mutex` but can use atomics like some UNIX systems (ping `@mkroening` `@stlankes).`
Use semaphores for thread parking on Apple platforms
Currently we use a mutex-condvar pair for thread parking on Apple systems. Unfortunately, `pthread_cond_timedwait` uses the real-time clock for measuring time, which causes problems when the system time changes. The parking implementation in this PR uses a semaphore instead, which measures monotonic time by default, avoiding these issues. As a further benefit, this has the potential to improve performance a bit, since `unpark` does not need to wait for a lock to be released.
Since the Mach semaphores are poorly documented (I could not find availability or stability guarantees for instance), this uses a [dispatch semaphore](https://developer.apple.com/documentation/dispatch/dispatch_semaphore?language=objc) instead. While it adds a layer of indirection (it uses Mach semaphores internally), the overhead is probably negligible.
Tested on macOS 12.5.
r? ``````@thomcc``````
Add `IsTerminal` trait to determine if a descriptor or handle is a terminal
The UNIX implementation uses `isatty`. The Windows implementation uses
the same logic the `atty` crate uses, including the hack needed to
detect msys terminals.
Implement this trait for `Stdin`/`Stdout`/`Stderr`/`File` on all
platforms. On Unix, implement it for `BorrowedFd`/`OwnedFd`. On Windows,
implement it for `BorrowedHandle`/`OwnedHandle`.
Based on https://github.com/rust-lang/rust/pull/91121
Co-authored-by: Matt Wilkinson <mattwilki17@gmail.com>
Rather than referencing a slice's pointer and then creating a new slice
with a longer length, offset from the base structure pointer instead.
This makes some choices of Rust semantics happier.
The UNIX and WASI implementations use `isatty`. The Windows
implementation uses the same logic the `atty` crate uses, including the
hack needed to detect msys terminals.
Implement this trait for `File` and for `Stdin`/`Stdout`/`Stderr` and
their locked counterparts on all platforms. On UNIX and WASI, implement
it for `BorrowedFd`/`OwnedFd`. On Windows, implement it for
`BorrowedHandle`/`OwnedHandle`.
Based on https://github.com/rust-lang/rust/pull/91121
Co-authored-by: Matt Wilkinson <mattwilki17@gmail.com>
sync thread_local key conditions exactly with what the macro uses
This makes the `cfg` in `mod.rs` syntactically the same as those in `local.rs`.
I don't think this should actually change anything, but seems better to be consistent?
I looked into this due to https://github.com/rust-lang/rust/issues/102549, but this PR would make it *less* likely that `__OsLocalKeyInner` is going to get provided, so this cannot help with that issue.
r? `@thomcc`
More dupe word typos
I only picked those changes (from the regex search) that I am pretty certain doesn't change meaning and is just a typo fix. Do correct me if any fix is undesirable and I can revert those. Thanks.
impl AsFd and AsRawFd for io::{Stdin, Stdout, Stderr}, not the sys versions
https://github.com/rust-lang/rust/pull/100892 implemented AsFd for the
sys versions, rather than for the public types. Change the
implementations to apply to the public types.
openbsd: don't reallocate a guard page on the stack.
the kernel currently enforce that a stack is immutable. calling mmap(2) or mprotect(2) to change it will result in EPERM, which generate a panic!().
so just do like for Linux, and trust the kernel to do the right thing.
Optimize TLS on Windows
This implements the suggestion in the current TLS code to embed the linked list of destructors in the `StaticKey` structure to save allocations. Additionally, locking is avoided when no destructor needs to be run. By using one Windows-provided `Once` per key instead of a global lock, locking is more finely-grained (this unblocks #100579).
Allow compiling the `wasm32-wasi` std library with atomics
The issue #102157 demonstrates how currently the `-Z build-std` option will fail when re-compiling the standard library with `RUSTFLAGS` like `RUSTFLAGS="-C target-feature=+atomics,+bulk-memory -C link-args=--shared-memory"`. This change attempts to resolve those build issues by depending on the the WebAssembly `futex` module and providing an implementation for `env_lock`. Fixes#102157.
Prevent UB in child process after calling libc::fork
After calling libc::fork, the child process tried to access a TLS variable when processing a panic. This caused a memory allocation which is UB in the child.
To prevent this from happening, the panic handler will not access the TLS variable in case `panic::always_abort` was called before.
Fixes#85261 (not only on Android systems, but also on Linux/QNX with TLS disabled, see issue for more details)
Main drawbacks of this fix:
* Panic messages can incorrectly omit `core::panic::PanicInfo` struct in case several panics (of multiple threads) occur at the same time. The handler cannot distinguish between multiple panics in different threads or recursive ones in the same thread, but the message will contain a hint about the uncertainty.
* `panic_count::increase()` will be a bit slower as it has an additional `if`, but this should be irrelevant as it is only called in case of a panic.
Use memset to initialize readbuf
The write loop was found to be slow in #102727
The proper fix is in #102760 but this might still help debug builds and code running under miri by using the write_bytes intrinsic instead of writing one byte at a time.
Interpret EH actions properly
The EH actions stored in the LSDA follows the format of GCC except table (even for LLVM-generated code). An missing action in the table is the encoding for `Terminate`, see https://github.com/gcc-mirror/gcc/blob/master/libstdc%2B%2B-v3/libsupc%2B%2B/eh_personality.cc#L522-L526.
The currently code interprets it as `None`, as a workaround for #35011, an issue that seems to occur in LLVM 3.7 and not after 3.9. These are very old versions of LLVM and we don't support them anymore, so remove this workaround and interpret them properly.
Note that LLVM currently does not emit any `Terminate` actions, but GCC does. Although GCC backend currently doesn't do unwinding, removing it preemptively would prevent future developers from wasting time to figure out what's wrong.
``@rustbot`` label: +T-compiler
fs::get_path solarish version.
similar to linux, albeit there is no /proc/self notion on solaris
based system thus flattening the difference for simplification sake.
scoped threads: pass closure through MaybeUninit to avoid invalid dangling references
The `main` function defined here looks roughly like this, if it were written as a more explicit stand-alone function:
```rust
// Not showing all the `'lifetime` tracking, the point is that
// this closure might live shorter than `thread`.
fn thread(control: ..., closure: impl FnOnce() + 'lifetime) {
closure();
control.signal_done();
// A lot of time can pass here.
}
```
Note that `thread` continues to run even after `signal_done`! Now consider what happens if the `closure` captures a reference of lifetime `'lifetime`:
- The type of `closure` is a struct (the implicit unnameable closure type) with a `&'lifetime mut T` field. References passed to a function are marked with `dereferenceable`, which is LLVM speak for *this reference will remain live for the entire duration of this function*.
- The closure runs, `signal_done` runs. Then -- potentially -- this thread gets scheduled away and the main thread runs, seeing the signal and returning to the user. Now `'lifetime` ends and the memory the reference points to might be deallocated.
- Now we have UB! The reference that as passed to `thread` with the promise of remaining live for the entire duration of the function, actually got deallocated while the function still runs. Oops.
Long-term I think we should be able to use `ManuallyDrop` to fix this without `unsafe`, or maybe a new `MaybeDangling` type. I am working on an RFC for that. But in the mean time it'd be nice to fix this so that Miri with `-Zmiri-retag-fields` (which is needed for "full enforcement" of all the LLVM flags we generate) stops erroring on scoped threads.
Fixes https://github.com/rust-lang/rust/issues/101983
r? `@m-ou-se`
Copying the approach of the Unix target, this change uses the standard
`RwLock` to protect against concurrent access of libc's environment.
This locking is only enabled when WebAssembly's `atomics` feature is
also enabled.
The issue #102157 demonstrates how currently the `-Z build-std` option
will fail when re-compiling the standard library with `RUSTFLAGS` like
`RUSTFLAGS="-C target-feature=+atomics,+bulk-memory -C
link-args=--shared-memory"`. This change attempts to resolve those build
issues by depending on the the WebAssembly `futex` module and providing
an implementation for `env_lock`. Fixes#102157.
Make tests capture the error printed by a Result return
An error returned by tests previously would get written directly to stderr, instead of to the capture buffer set up by the test harness. This PR makes it write to the capture buffer so that it can be integrated as part of the test output by build tools such as `buck test`, since being able to read the error message returned by a test is pretty critical to debugging why the test failed.
<br>
**Before:**
```rust
// tests/test.rs
#[test]
fn test() -> Result<(), &'static str> {
println!("STDOUT");
eprintln!("STDERR");
Err("RESULT")
}
```
```console
$ cargo build --test test
$ target/debug/deps/test-???????????????? -Z unstable-options --format=json
{ "type": "suite", "event": "started", "test_count": 1 }
{ "type": "test", "event": "started", "name": "test" }
Error: "RESULT"
{ "type": "test", "name": "test", "event": "failed", "stdout": "STDOUT\nSTDERR\n" }
{ "type": "suite", "event": "failed", "passed": 0, "failed": 1, "ignored": 0, "measured": 0, "filtered_out": 0, "exec_time": 0.00040313 }
```
**After:**
```console
$ target/debug/deps/test-???????????????? -Z unstable-options --format=json
{ "type": "suite", "event": "started", "test_count": 1 }
{ "type": "test", "event": "started", "name": "test" }
{ "type": "test", "name": "test", "event": "failed", "stdout": "STDOUT\nSTDERR\nError: \"RESULT\"" }
{ "type": "suite", "event": "failed", "passed": 0, "failed": 1, "ignored": 0, "measured": 0, "filtered_out": 0, "exec_time": 0.000261894 }
```
Rollup of 8 pull requests
Successful merges:
- #101118 (fs::get_mode enable getting the data via fcntl/F_GETFL on major BSD)
- #102072 (Add `ptr::Alignment` type)
- #102799 (rustdoc: remove hover gap in file picker)
- #102820 (Show let-else suggestion on stable.)
- #102829 (rename `ImplItemKind::TyAlias` to `ImplItemKind::Type`)
- #102831 (Don't use unnormalized type in `Ty::fn_sig` call in rustdoc `clean_middle_ty`)
- #102834 (Remove unnecessary `lift`/`lift_to_tcx` calls from rustdoc)
- #102838 (remove cfg(bootstrap) from Miri)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
the kernel currently enforce that a stack is immutable. calling mmap(2) or
mprotect(2) to change it will result in EPERM, which generate a panic!().
so just do like for Linux, and trust the kernel to do the right thing.
Reduce CString allocations in std as much as possible
Currently, every operation involving paths in `fs` allocates memory to hold the path before sending it through the syscall. This PR instead uses a stack allocation (chosen size is somewhat arbitrary) when the path is short before falling back to heap allocations for long paths.
Benchmarks show that the stack allocation is ~2x faster for short paths:
```
test sys::unix::fd::tests::bench_heap_path_alloc ... bench: 34 ns/iter (+/- 2)
test sys::unix::fd::tests::bench_stack_path_alloc ... bench: 15 ns/iter (+/- 1)
```
For long paths, I couldn't find any measurable difference.
---
I'd be surprised if I was the first to think of this, so I didn't fully flush out the PR. If this change is desirable, I'll make use of `run_with_cstr` across all platforms in every fs method (currently just unix open for testing). I also added an `impl From<FromBytesWithNulError>` which is presumably a no-no (or at least needs to be done in another PR).
---
Also see https://github.com/nix-rust/nix/pull/1655 with a bunch of discussion where I'm doing something similar.
Remove empty core::lazy and std::lazy
PR #98165 with commits 7c360dc117 and c1a2db3372 has moved all of the components of these modules into different places, namely {std,core}::sync and {std,core}::cell. The empty modules remained. As they are unstable, we can simply remove them.
PR #98165 with commits 7c360dc117 and c1a2db3372
has moved all of the components of these modules into different places,
namely {std,core}::sync and {std,core}::cell. The empty
modules remained. As they are unstable, we can simply remove them.
std: use futex in `Once`
Now that we have efficient locks, let's optimize the rest of `sync` as well. This PR adds a futex-based implementation for `Once`, which drastically simplifies the implementation compared to the generic version, which is provided as fallback for platforms without futex (Windows only supports them on newer versions, so it uses the fallback for now).
Instead of storing a linked list of waiters, the new implementation adds another state (`QUEUED`), which is set when there are waiting threads. These now use `futex_wait` on that state and are woken by the running thread when it finishes and notices the `QUEUED` state, thereby avoiding unnecessary calls to `futex_wake_all`.
Avoid repeated re-initialization of the BufReader buffer
Fixes https://github.com/rust-lang/rust/issues/102727
We accidentally removed this in https://github.com/rust-lang/rust/pull/98748. It looks so redundant. But it isn't.
The default `Read::read_buf` will defensively initialize the whole buffer, if any of it is indicated to be uninitialized. In uses where reads from the wrapped `Read` impl completely fill the `BufReader`, `initialized` and `filled` are the same, and this extra member isn't required. But in the reported issue, the `BufReader` wraps a `Read` impl which will _never_ fill the whole buffer. So the default `Read::read_buf` implementation repeatedly re-initializes the extra space in the buffer.
This adds back the extra `initialized` member, which ensures that the default `Read::read_buf` only zero-initialized the buffer once, and I've tried to add a comment which explains this whole situation.
unsafe keyword: trait examples and unsafe_op_in_unsafe_fn update
Having a safe `fn` in an `unsafe trait` vs an `unsafe fn` in a safe `trait` are pretty different situations, but the distinction is subtle and can confuse even seasoned Rust developers. So let's have explicit examples of both. I also removed the existing `unsafe trait` example since it was rather strange.
Also the `unsafe_op_in_unsafe_fn` lint can help disentangle the two sides of `unsafe`, so update the docs to account for that.
After calling libc::fork, the child process tried to access
a TLS variable when processing a panic. This caused
a memory allocation which is UB in the child.
To prevent this from happening, the panic handler will
not access the TLS variable in case `panic::always_abort`
was called before.
The EH actions stored in the LSDA follows the format of GCC except table
(even for LLVM-generated code). An missing action in the table is the
encoding for `Terminate`, see [1].
The currently code interprets it as `None`, as a workaround for #35011,
an issue that seems to occur in LLVM 3.7 and not after 3.9. These are
very old versions of LLVM and we don't support them anymore, so remove
this workaround and interpret them properly.
Note that LLVM currently does not emit any `Terminate` actions, but GCC
does. Although GCC backend currently doesn't do unwinding, removing it
preemptively would prevent future developers from wasting time to figure
out what's wrong.
[1]: https://github.com/gcc-mirror/gcc/blob/master/libstdc%2B%2B-v3/libsupc%2B%2B/eh_personality.cc#L522-L526
Add `AsFd` implementations for stdio lock types on WASI.
This mirrors the implementations on Unix platforms, and also mirrors the existing `AsRawFd` impls.
This is similar to #100892, but is for the `*Lock` types.
Update docs so that deprecated method points to relevant method
The docs for the deprecated 'park_timeout_ms' method suggests that the user 'use park_timeout' method instead (at https://doc.rust-lang.org/std/thread/index.html).
Making a similar change so that the docs for the deprecated `sleep_ms` method suggest that the user `use sleep` method instead.
Add a niche to `Duration`, unix `SystemTime`, and non-apple `Instant`
As the nanoseconds fields is always between `0` and `(NANOS_PER_SEC - 1)` inclusive, use the `rustc_layout_scalar_valid_range` attributes to create a niche in the nanosecond field of `Duration` and `Timespec` (which is used to implement unix `SystemTime` and non-apple unix `Instant`; windows `Instant` is implemented with `Duration` and therefore will also benefit). This change has the benefit of making `Option<T>` the same size as `T` for the previously mentioned types. Also shrinks the nanoseconds field of `Timespec` to a `u32` as nanoseconds do not need the extra range of an `i64`, shrinking `Timespec` by 4 bytes on 32-bit platforms.
r? ```@joshtriplett```
