Linux doesn't allocate the whole stack right away, and the kernel has
its own stack-guard mechanism to fault when growing too close to an
existing mapping. If we map our own guard, then the kernel starts
enforcing a rather large gap above that, rendering much of the possible
stack space useless.
Instead, we'll just note where we expect rlimit to start faulting, so
our handler can report "stack overflow", and trust that the kernel's own
stack guard will work.
Fixes#43052.
rustc: Implement the #[global_allocator] attribute
This PR is an implementation of [RFC 1974] which specifies a new method of
defining a global allocator for a program. This obsoletes the old
`#![allocator]` attribute and also removes support for it.
[RFC 1974]: https://github.com/rust-lang/rfcs/pull/1974
The new `#[global_allocator]` attribute solves many issues encountered with the
`#![allocator]` attribute such as composition and restrictions on the crate
graph itself. The compiler now has much more control over the ABI of the
allocator and how it's implemented, allowing much more freedom in terms of how
this feature is implemented.
cc #27389
This PR is an implementation of [RFC 1974] which specifies a new method of
defining a global allocator for a program. This obsoletes the old
`#![allocator]` attribute and also removes support for it.
[RFC 1974]: https://github.com/rust-lang/rfcs/pull/197
The new `#[global_allocator]` attribute solves many issues encountered with the
`#![allocator]` attribute such as composition and restrictions on the crate
graph itself. The compiler now has much more control over the ABI of the
allocator and how it's implemented, allowing much more freedom in terms of how
this feature is implemented.
cc #27389
rustc: Enable #[thread_local] for Windows
I think LLVM has had support for quite some time now for this, we just never got
around to testing it out and binding it. We've had some trouble landing this in
the past I believe, but it's time to try again!
This commit flags the `#[thread_local]` attribute as being available for Windows
targets and adds an implementation of `register_dtor` in the `thread::local`
module to ensure we can destroy these keys. The same functionality is
implemented in clang via a function called `__tlregdtor` (presumably provided in
some Windows runtime somewhere), but this function unfortunately does not take a
data pointer (just a thunk) which means we can't easily call it. For now
destructors are just run in the same way the Linux fallback is implemented,
which is just keeping track via a single OS-based TLS key.
I think LLVM has had support for quite some time now for this, we just never got
around to testing it out and binding it. We've had some trouble landing this in
the past I believe, but it's time to try again!
This commit flags the `#[thread_local]` attribute as being available for Windows
targets and adds an implementation of `register_dtor` in the `thread::local`
module to ensure we can destroy these keys. The same functionality is
implemented in clang via a function called `__tlregdtor` (presumably provided in
some Windows runtime somewhere), but this function unfortunately does not take a
data pointer (just a thunk) which means we can't easily call it. For now
destructors are just run in the same way the Linux fallback is implemented,
which is just keeping track via a single OS-based TLS key.
Replaced by adding extra imports, adding hidden code (`# ...`), modifying
examples to be runnable (sorry Homura), specifying non-Rust code, and
converting to should_panic, no_run, or compile_fail.
Remaining "```ignore"s received an explanation why they are being ignored.
Fixes issue #37440: `pthread_cond_timedwait` on macOS Sierra seems
to overflow `ts_sec` parameter and returns immediately. To work
around this problem patch rounds timeout down to approximately 1000
years.
Patch also fixes overflow when converting `u64` to `time_t`.
`Stdio` now implements `From<ChildStdin>`, `From<ChildStdout>`,
`From<ChildStderr>`, and `From<File>`.
The `Command::stdin`/`stdout`/`stderr` methods now take any type that
implements `Into<Stdio>`.
This makes it much easier to write shell-like command chains, piping to
one another and redirecting to and from files. Otherwise one would need
to use the unsafe and OS-specific `from_raw_fd` or `from_raw_handle`.
Always quote program name in Command::spawn on Windows
[`CreateProcess`](https://msdn.microsoft.com/en-us/library/windows/desktop/ms682425.aspx) will interpret args as part of the binary name if it
doesn't find the binary using just the unquoted name. For example if
`foo.exe` doesn't exist, `Command::new("foo").arg("bar").spawn()` will
try to launch `foo bar.exe` which is clearly not desired.
The implementation of mx_job_default changed from a macro which
accessed the __magenta_job_default global variable to a proper
function call. This patch tracks that change.
`CreateProcess` will interpret args as part of the binary name if it
doesn't find the binary using just the unquoted name. For example if
`foo.exe` doesn't exist, `Command::new("foo").arg("bar").spawn()` will
try to launch `foo bar.exe` which is clearly not desired.
Improve the error management when /proc is not mounted
This PR does two things:
* Triggers an error on GNU/Linux & Android when /proc/self/exe doesn't exist
* Handle the error properly
Improve docs in os::windows::ffi and os::windows::fs
Part of #29367
This PR makes changes to the documentation in `os::windows::ffi` and `os::windows::fs` with the goal of fleshing them out and bringing them in line with Rust's quality standards.
r? @steveklabnik
- Remove `()` parens when referencing functions in docs.
- Change some examples to be no_run instead of ignore.
- Normalize style in examples for `OpenOptionsExt`.
- Fix typo in windows mod docs.
Windows io::Error: also format NTSTATUS error codes
`NTSTATUS` errors may be encoded as `HRESULT`, see [[MS-ERREF]](https://msdn.microsoft.com/en-us/library/cc231198.aspx). These error codes can still be formatted using `FormatMessageW` but require some different parameters to be passed in.
I wasn't sure if this needed a test and if so, how to test it. Presumably we wouldn't want to make our tests dependent on localization-dependent strings returned from `FormatMessageW`.
Users that get an `err: NTSTATUS` will need to do `io::Error::from_raw_os_error(err|0x1000_0000)` (the equivalent of [`HRESULT_FROM_NT`](https://msdn.microsoft.com/en-us/library/ms693780(VS.85).aspx))
Gecko recently had a bug reported [1] with a deadlock in the Rust TLS
implementation for Windows. TLS destructors are implemented in a sort of ad-hoc
fashion on Windows as it doesn't natively support destructors for TLS keys. To
work around this the runtime manages a list of TLS destructors and registers a
hook to get run whenever a thread exits. When a thread exits it takes a look at
the list and runs all destructors.
Unfortunately it turns out that there's a lock which is held when our "at thread
exit" callback is run. The callback then attempts to acquire a lock protecting
the list of TLS destructors. Elsewhere in the codebase while we hold a lock over
the TLS destructors we try to acquire the same lock held first before our
special callback is run. And as a result, deadlock!
This commit sidesteps the issue with a few small refactorings:
* Removed support for destroying a TLS key on Windows. We don't actually ever
exercise this as a public-facing API, and it's only used during `lazy_init`
during racy situations. To handle that we just synchronize `lazy_init`
globally on Windows so we never have to call `destroy`.
* With no need to support removal the global synchronized `Vec` was tranformed
to a lock-free linked list. With the removal of locks this means that
iteration no long requires a lock and as such we won't run into the deadlock
problem mentioned above.
Note that it's still a general problem that you have to be extra super careful
in TLS destructors. For example no code which runs a TLS destructor on Windows
can call back into the Windows API to do a dynamic library lookup. Unfortunately
I don't know of a great way around that, but this at least fixes the immediate
problem that Gecko was seeing which is that with "well behaved" destructors the
system would still deadlock!
[1]: https://bugzilla.mozilla.org/show_bug.cgi?id=1358151
