Previously, the `guard::init()` and `guard::current()` functions were
returning a `usize` address representing the top of the stack guard,
respectively for the main thread and for spawned threads. The `SIGSEGV`
handler on `unix` targets checked if a fault was within one page below
that address, if so reporting it as a stack overflow.
Now `unix` targets report a `Range<usize>` representing the guard
memory, so it can cover arbitrary guard sizes. Non-`unix` targets which
always return `None` for guards now do so with `Option<!>`, so they
don't pay any overhead.
For `linux-gnu` in particular, the previous guard upper-bound was
`stackaddr + guardsize`, as the protected memory was *inside* the stack.
This was a glibc bug, and starting from 2.27 they are moving the guard
*past* the end of the stack. However, there's no simple way for us to
know where the guard page actually lies, so now we declare it as the
whole range of `stackaddr ± guardsize`, and any fault therein will be
called a stack overflow. This fixes#47863.
To workaround a bug in glibc <= 2.26 lookup_host() calls res_init()
based on the glibc version detected at runtime. While this avoids
calling res_init() on platforms where it's not required we will still
end up linking against the symbol.
This causes an issue on macOS where res_init() is implemented in a
separate library (libresolv.9.dylib) from the main libc. While this is
harmless for standalone programs it becomes a problem if Rust code is
statically linked against another program. If the linked program doesn't
already specify -lresolv it will cause the link to fail. This is
captured in issue #46797
Fix this by hooking in to the glibc workaround in `cvt_gai` and only
activating it for the "gnu" environment on Unix This should include all
glibc platforms while excluding musl, windows-gnu, macOS, FreeBSD, etc.
This has the side benefit of removing the #[cfg] in sys_common; only
unix.rs has code related to the workaround now.
As discussed in #47268, libstd isn't ready to have certain functionality
disabled yet. Follow wasm's approach of adding no-op modules for all of
the features that we can't implement.
I've placed all of those shims in a shims/ subdirectory, so we (the
CloudABI folks) can experiment with removing them more easily. It also
ensures that the code that does work doesn't get polluted with lots of
useless boilerplate code.
Though CloudABI is strongly inspired by POSIX, its absence of features
that don't work well with capability-based sandboxing makes it different
enough that adding bits to sys/unix will make things a mess. This change
therefore adds CloudABI specific platform code under sys/cloudabi and
borrows parts from sys/unix that can be used without changes.
One of the goals of this implementation is to build as much as possible
directly on top of CloudABI's system call layer, as opposed to using the
C library. This is preferred, as the system call layer is supposed to be
stable, whereas the C library ABI technically is not. An advantage of
this approach is that it allows us to implement certain interfaces, such
as mutexes and condition variables more optimally. They can be lighter
than the ones provided by pthreads.
This change disables some modules that cannot realistically be
implemented right now. For example, libstd's pathname abstraction is not
designed with POSIX *at() (e.g., openat()) in mind. The *at() functions
are the only set of file system APIs available on CloudABI. There is no
global file system namespace, nor a process working directory.
Discussions on how to port these modules over are outside the scope of
this change.
Apart from this change, there are still some other minor fixups that
need to be made to platform independent code to make things build. These
will be sent out separately, so they can be reviewed more thoroughly.
Convert warning about `*const _` to a future-compat lint
#46664 was merged before I could convert the soft warning about method lookup on `*const _` into a future-compatibility lint. This PR makes that change.
fixes#46837
tracking issue for the future-compatibility lint: #46906
r? @arielb1
This commit prepares to enable ThinLTO and multiple codegen units in release
mode by default. We've still got a debuginfo bug or two to sort out before
actually turning it on by default.
Provides the following conversion implementations:
* `From<`{`CString`,`&CStr`}`>` for {`Arc`,`Rc`}`<CStr>`
* `From<`{`OsString`,`&OsStr`}`>` for {`Arc`,`Rc`}`<OsStr>`
* `From<`{`PathBuf`,`&Path`}`>` for {`Arc`,`Rc`}`<Path>`
This commit adds a new target to the compiler: wasm32-unknown-unknown. This
target is a reimagining of what it looks like to generate WebAssembly code from
Rust. Instead of using Emscripten which can bring with it a weighty runtime this
instead is a target which uses only the LLVM backend for WebAssembly and a
"custom linker" for now which will hopefully one day be direct calls to lld.
Notable features of this target include:
* There is zero runtime footprint. The target assumes nothing exists other than
the wasm32 instruction set.
* There is zero toolchain footprint beyond adding the target. No custom linker
is needed, rustc contains everything.
* Very small wasm modules can be generated directly from Rust code using this
target.
* Most of the standard library is stubbed out to return an error, but anything
related to allocation works (aka `HashMap`, `Vec`, etc).
* Naturally, any `#[no_std]` crate should be 100% compatible with this new
target.
This target is currently somewhat janky due to how linking works. The "linking"
is currently unconditional whole program LTO (aka LLVM is being used as a
linker). Naturally that means compiling programs is pretty slow! Eventually
though this target should have a linker.
This target is also intended to be quite experimental. I'm hoping that this can
act as a catalyst for further experimentation in Rust with WebAssembly. Breaking
changes are very likely to land to this target, so it's not recommended to rely
on it in any critical capacity yet. We'll let you know when it's "production
ready".
---
Currently testing-wise this target is looking pretty good but isn't complete.
I've got almost the entire `run-pass` test suite working with this target (lots
of tests ignored, but many passing as well). The `core` test suite is still
getting LLVM bugs fixed to get that working and will take some time. Relatively
simple programs all seem to work though!
---
It's worth nothing that you may not immediately see the "smallest possible wasm
module" for the input you feed to rustc. For various reasons it's very difficult
to get rid of the final "bloat" in vanilla rustc (again, a real linker should
fix all this). For now what you'll have to do is:
cargo install --git https://github.com/alexcrichton/wasm-gc
wasm-gc foo.wasm bar.wasm
And then `bar.wasm` should be the smallest we can get it!
---
In any case for now I'd love feedback on this, particularly on the various
integration points if you've got better ideas of how to approach them!
This commit removes usage of the `libc` crate in "portable" modules like
those at the top level and `sys_common`. Instead common types like `*mut
u8` or `u32` are used instead of `*mut c_void` or `c_int` as well as
switching to platform-specific functions like `sys::strlen` instead of
`libc::strlen`.
Remove support for the PNaCl target (le32-unknown-nacl)
This removes support for the `le32-unknown-nacl` target which is currently supported by rustc on tier 3. Despite the "nacl" in the name, the target doesn't output native code (x86, ARM, MIPS), instead it outputs binaries in the PNaCl format.
There are two reasons for the removal:
* Google [has announced](https://blog.chromium.org/2017/05/goodbye-pnacl-hello-webassembly.html) deprecation of the PNaCl format. The suggestion is to migrate to wasm. Happens we already have a wasm backend!
* Our PNaCl LLVM backend is provided by the fastcomp patch set that the LLVM fork used by rustc contains in addition to vanilla LLVM (`src/llvm/lib/Target/JSBackend/NaCl`). Upstream LLVM doesn't have PNaCl support. Removing PNaCl support will enable us to move away from fastcomp (#44006) and have a lighter set of patches on top of upstream LLVM inside our LLVM fork. This will help distribution packagers of Rust.
Fixes#42420
The previous workaround for gibc's res_init bug is not thread-safe on
other implementations of libc, and it can cause crashes. Use a runtime
check to make sure we only call res_init when we need to, which is also
when it's safe. See https://github.com/rust-lang/rust/issues/43592.
Correctly bubble up errors from libbacktrace
Previously the first part of this code didn't check for a null pointer and blindly passed it back down, causing a segfault if libbacktrace failed to initialise. I've changed this to check and bubble up the error if relevant.
Suggested diff view: https://github.com/rust-lang/rust/pull/44525/files?w=1
Add the libstd-modifications needed for the L4Re target
This commit adds the needed modifications to compile the std crate for the L4 Runtime environment (L4Re).
A target for the L4Re was introduced in commit: c151220a84
In many aspects implementations for linux also apply for the L4Re microkernel.
Some uncommon characteristics had to be resolved:
* L4Re has no network funktionality
* L4Re has a maximum stacksize of 1Mb for threads
* L4Re has no uid or gid
Co-authored-by: Sebastian Humenda <sebastian.humenda@tu-dresden.de>
As suggested in the discussion of PR #43972, std should provide a uniform API to
all platforms. Since there's no networking on L4Re, this now is a module in
`sys::net` providing types and functions/methods returning an error for each
action.
This commit adds the needed modifications to compile the std crate
for the L4 Runtime environment (L4Re).
A target for the L4Re was introduced in commit:
c151220a84
In many aspects implementations for linux also apply for the L4Re
microkernel.
Two uncommon characteristics had to be resolved:
* L4Re has no network funktionality
* L4Re has a maximum stacksize of 1Mb for threads
Co-authored-by: Sebastian Humenda <sebastian.humenda@tu-dresden.de>
std: Respect formatting flags for str-like OsStr
Historically many `Display` and `Debug` implementations for `OsStr`-like
abstractions have gone through `String::from_utf8_lossy`, but this was updated
in #42613 to use an internal `Utf8Lossy` abstraction instead. This had the
unfortunate side effect of causing a regression (#43765) in code which relied on
these `fmt` trait implementations respecting the various formatting flags
specified.
This commit opportunistically adds back interpretation of formatting trait flags
in the "common case" where where `OsStr`-like "thing" is all valid utf-8 and can
delegate to the formatting implementation for `str`. This doesn't entirely solve
the regression as non-utf8 paths will format differently than they did before
still (in that they will not respect formatting flags), but this should solve
the regression for all "real world" use cases of paths and such. The door's also
still open for handling these flags in the future!
Closes#43765
Historically many `Display` and `Debug` implementations for `OsStr`-like
abstractions have gone through `String::from_utf8_lossy`, but this was updated
in #42613 to use an internal `Utf8Lossy` abstraction instead. This had the
unfortunate side effect of causing a regression (#43765) in code which relied on
these `fmt` trait implementations respecting the various formatting flags
specified.
This commit opportunistically adds back interpretation of formatting trait flags
in the "common case" where where `OsStr`-like "thing" is all valid utf-8 and can
delegate to the formatting implementation for `str`. This doesn't entirely solve
the regression as non-utf8 paths will format differently than they did before
still (in that they will not respect formatting flags), but this should solve
the regression for all "real world" use cases of paths and such. The door's also
still open for handling these flags in the future!
Closes#43765
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.
