Add emulated TLS support
This is a reopen of https://github.com/rust-lang/rust/pull/96317 . many android devices still only use 128 pthread keys, so using emutls can be helpful.
Currently LLVM uses emutls by default for some targets (such as android, openbsd), but rust does not use it, because `has_thread_local` is false.
This commit has some changes to allow users to enable emutls:
1. add `-Zhas-thread-local` flag to specify that std uses `#[thread_local]` instead of pthread key.
2. when using emutls, decorate symbol names to find thread local symbol correctly.
3. change `-Zforce-emulated-tls` to `-Ztls-model=emulated` to explicitly specify whether to generate emutls.
r? `@Amanieu`
Currently LLVM uses emutls by default
for some targets (such as android, openbsd),
but rust does not use it, because `has_thread_local` is false.
This commit has some changes to allow users to enable emutls:
1. add `-Zhas-thread-local` flag to specify
that std uses `#[thread_local]` instead of pthread key.
2. when using emutls, decorate symbol names
to find thread local symbol correctly.
3. change `-Zforce-emulated-tls` to `-Ztls-model=emulated`
to explicitly specify whether to generate emutls.
Use `unwinding` crate for unwinding on Xous platform
This patch adds support for using [unwinding](https://github.com/nbdd0121/unwinding) on platforms where libunwinding isn't viable. An example of such a platform is `riscv32imac-unknown-xous-elf`.
### Background
The Rust project maintains a fork of llvm at [llvm-project](https://github.com/rust-lang/llvm-project/) where it applies patches on top of the llvm project. This mostly seems to be to get unwinding support for the SGX project, and there may be other patches that I'm unaware of.
There is a lot of machinery in the build system to support compiling `libunwind` on other platforms, and I needed to add additional patches to llvm in order to add support for Xous.
Rather than continuing down this path, it seemed much easier to use a Rust-based library. The `unwinding` crate by `@nbdd0121` fits this description perfectly.
### Future work
This could potentially replace the custom patches for `libunwind` on other platforms such as SGX, and could enable unwinding support on many more exotic platforms.
### Anti-goals
This is not designed to replace `libunwind` on tier-one platforms or those where unwinding support already exists. There is already a well-established approach for unwinding there. Instead, this aims to enable unwinding on new platforms where C++ code may be difficult to compile.
The main() function takes an argument that contains the eh_frame
address. Implement `unwinding` support by looking for unwinding data at
this address.
Signed-off-by: Sean Cross <sean@xobs.io>
std: Invert logic for inclusion of `sys_common::net`
The `library/std/src/sys_common/net.rs` module is intended to define common implementations of networking-related APIs across a variety of platforms that share similar APIs (e.g. Berkeley-style sockets and all). This module is not included for more fringe targets however such as UEFI or "unknown" targets to libstd (those classified as `restricted-std`). Previously the `sys_common/net.rs` file was set up such that an allow-list indicated it shouldn't be used. This commit inverts the logic to have an allow-list of when it should be used instead.
The goal of this commit is to make it a bit easier to experiment with a new Rust target. Currently more esoteric targets are required to get an exception in this `cfg_if` block to use `crate::sys::net` such as for unsupported targets. With this inversion of logic only targets which actually support networking will be listed, where most of those are lumped under `cfg(unix)`.
Given that this change is likely to cause some breakage for some target by accident I've attempted to be somewhat robust with this by following these steps to defining the new predicate for inverted logic.
1. Take all supported targets and filter out all `cfg(unix)` ones as these should all support `sys_common/net.rs`.
2. Take remaining targets and filter out `cfg(windows)` ones.
3. The remaining dozen-or-so targets were all audited by hand. Mostly this included `target_os = "hermit"` and `target_os = "solid_asp3"` which required an allow-list entry, but remaining targets were all already excluded (didn't use `sys_common/net.rs` so they were left out.
If this causes breakage it should be relatively easy to fix and I'd be happy to follow-up with any PRs necessary.
move exposed-provenance APIs into separate feature gate
We have already stated explicitly for all the 'exposed' functions that
> Using this method means that code is *not* following strict provenance rules.
However, they were part of the same feature gate and still described as part of the strict provenance experiment. Unfortunately, their semantics are much less clear and certainly nowhere near stabilization, so in preparation for an attempt to stabilize the strict provenance APIs, I suggest we split the things related to "exposed" into their own feature gate. I also used this opportunity to better explain how Exposed Provenance fits into the larger plan here: this is *one possible candidate* for `as` semantics, but we don't know if it is actually viable, so we can't really promise that it is equivalent to `as`. If it works out we probably want to make `as` equivalent to the 'exposed' APIs; if it doesn't, we will remove them again and try to find some other semantics for `as`.
Add substring API for `OsStr`
This adds a method for taking a substring of an `OsStr`, which in combination with [`OsStr::as_encoded_bytes()`](https://doc.rust-lang.org/std/ffi/struct.OsStr.html#method.as_encoded_bytes) makes it possible to implement most string operations in safe code.
API:
```rust
impl OsStr {
pub fn slice_encoded_bytes<R: ops::RangeBounds<usize>>(&self, range: R) -> &Self;
}
```
Motivation, examples and research at https://github.com/rust-lang/libs-team/issues/306.
Tracking issue: #118485
cc `@epage`
r? libs-api
The `library/std/src/sys_common/net.rs` module is intended to define
common implementations of networking-related APIs across a variety of
platforms that share similar APIs (e.g. Berkeley-style sockets and all).
This module is not included for more fringe targets however such as UEFI
or "unknown" targets to libstd (those classified as `restricted-std`).
Previously the `sys_common/net.rs` file was set up such that an
allow-list indicated it shouldn't be used. This commit inverts the logic
to have an allow-list of when it should be used instead.
The goal of this commit is to make it a bit easier to experiment with a
new Rust target. Currently more esoteric targets are required to get an
exception in this `cfg_if` block to use `crate::sys::net` such as for
unsupported targets. With this inversion of logic only targets which
actually support networking will be listed, where most of those are
lumped under `cfg(unix)`.
Given that this change is likely to cause some breakage for some target
by accident I've attempted to be somewhat robust with this by following
these steps to defining the new predicate for inverted logic.
1. Take all supported targets and filter out all `cfg(unix)` ones as
these should all support `sys_common/net.rs`.
2. Take remaining targets and filter out `cfg(windows)` ones.
3. The remaining dozen-or-so targets were all audited by hand. Mostly
this included `target_os = "hermit"` and `target_os = "solid_asp3"`
which required an allow-list entry, but remaining targets were all
already excluded (didn't use `sys_common/net.rs` so they were left
out.
If this causes breakage it should be relatively easy to fix and I'd be
happy to follow-up with any PRs necessary.
Implement thread parking for xous
This follows the pattern set by [the Windows parker](ddef56d5df/library/std/src/sys/windows/thread_parking.rs) when it uses keyed events. An atomic variable is used to track the state and optimize the fast path, while notifications are send via the ticktime server to block and unblock the thread.
ping `@xobs`
`@rustbot` label +T-libs +A-atomic
r? libs
unify read_to_end and io::copy impls for reading into a Vec
This ports over the initial probe (to avoid allocation) and the dynamic read sizing from the io::copy specialization to the `default_read_to_end` implementation which already had its own optimizations for different cases.
I think it should be a best-of-both now.
suggested by `@a1phyr` in https://github.com/rust-lang/rust/pull/117576#issuecomment-1803408492
Use an absolute path to the NUL device
While a bare "NUL" *should* be redirected to the NUL device, especially in this simple case, let's be explicit that we aren't opening a file called "NUL" and instead open it directly.
This will also set a good example for people copying std code.
r? libs
Update windows-bindgen and define `INVALID_HANDLE_VALUE` ourselves
We generate bindings to the Windows API via the `windows-bindgen` crate, which is ultimately what's also used to generate the `windows-sys` and `windows` crates. However, there currently is some custom sauce just for std which makes it a bit different from the vanilla bindings. I would love for us to reduce and eventually remove the differences entirely so that std is using the exact same bindings as everyone else. Maybe in the future we can even just have a normal dependency on `windows-sys`.
This PR removes one of those special things. Our definition of `INVALID_HANDLE_VALUE` relies on an experimental nightly feature for strict provenance, so lets bring that back in house. It also excludes it from the codegen step though that isn't strictly necessary as we override it in any case.
This PR also updates windows-bingen to 0.52.0.
Improve rewind documentation
The persistent use of an internal cursor for readers is expected for buffer data types that aren't read all at once, but for files it leads to the confusing situation where calling `read_to_end` on the same file handle multiple times only returns the contents of the file for the first call. This PR adds a note to the documentation clarifying that in that case, `rewind()` must first be called.
I'm unsure if this is the right location for the docs update. Maybe it should also be duplicated on `File`?
kmc-solid: I/O safety
Adds the I/O safety API (#87329) for socket file descriptors in [`*-kmc-solid_*`](https://doc.rust-lang.org/nightly/rustc/platform-support/kmc-solid.html) Tier 3 targets. All new public items are gated by the `solid_ext` library feature.
This PR adds the following public types and traits:
std::os::solid::io::AsFd
std::os::solid::io::BorrowedFd
std::os::solid::io::OwnedFd
std::os::solid::prelude::AsFd (re-export)
std::os::solid::prelude::BorrowedFd (re-export)
std::os::solid::prelude::OwnedFd (re-export)
And trait implementations:
From<std::net::TcpListener> for std::os::solid::io::OwnedFd
From<std::net::TcpStream> for std::os::solid::io::OwnedFd
From<std::net::UdpSocket> for std::os::solid::io::OwnedFd
From<std::os::solid::io::OwnedFd> for std::net::TcpListener
From<std::os::solid::io::OwnedFd> for std::net::TcpStream
From<std::os::solid::io::OwnedFd> for std::net::UdpSocket
std::fmt::Debug for std::os::solid::io::BorrowedFd<'_>
std::fmt::Debug for std::os::solid::io::OwnedFd
std::io::IsTerminal for std::os::solid::io::BorrowedFd<'_>
std::io::IsTerminal for std::os::solid::io::OwnedFd
std::os::fd::AsRawFd for std::os::solid::io::BorrowedFd<'_>
std::os::fd::AsRawFd for std::os::solid::io::OwnedFd
std::os::fd::FromRawFd for std::os::solid::io::OwnedFd
std::os::fd::IntoRawFd for std::os::solid::io::OwnedFd
std::os::solid::io::AsFd for &impl std::os::solid::io::AsFd
std::os::solid::io::AsFd for &mut impl std::os::solid::io::AsFd
std::os::solid::io::AsFd for Arc<impl std::os::solid::io::AsFd>
std::os::solid::io::AsFd for Box<impl std::os::solid::io::AsFd>
std::os::solid::io::AsFd for Rc<impl std::os::solid::io::AsFd>
std::os::solid::io::AsFd for std::net::TcpListener
std::os::solid::io::AsFd for std::net::TcpStream
std::os::solid::io::AsFd for std::net::UdpSocket
std::os::solid::io::AsFd for std::os::solid::io::BorrowedFd<'_>
std::os::solid::io::AsFd for std::os::solid::io::OwnedFd
Taking advantage of the above change, this PR also refactors the internal details of `std::sys::solid::net` to match the design of other targets, e.g., by redefining `Socket` as a newtype of `OwnedFd`.
This is where our Windows API bindings previously (and incorrectly) used `*mut` instead of `*const` pointers. Now that the bindings have been corrected, the mutable references (which auto-convert to `*mut`) are unnecessary and we can use shared references.
