this gets the build runner compiling again on linux
this work is incomplete; it only moves code around so that environment
variables can be wrangled properly. a future commit will need to audit
the cancelation and error handling of this moved logic.
The most interesting thing here is the replacement of the pthread futex
implementation with an implementation based on thread park/unpark APIs.
Thread parking tends to be the primitive provided by systems which do
not have a futex primitive, such as NetBSD, so this implementation is
far more efficient than the pthread one. It is also useful on Windows,
where `RtlWaitOnAddress` is itself a userland implementation based on
thread park/unpark; we can implement it ourselves including support for
features which Windows' implementation lacks, such as cancelation and
waking a number of waiters with 1<n<infinity.
Compared to the pthread implementation, this thread-parking-based one
also supports full robust cancelation. Thread parking also turns out to
be useful for implementing `sleep`, so is now used for that on Windows
and NetBSD.
This commit also introduces proper cancelation support for most Windows
operations. The most notable omission right now is DNS lookups through
`GetAddrInfoEx`, just because they're a little more work due to having
a unique cancelation mechanism---but the machinery is all there, so I'll
finish gluing it together soon.
As of this commit, there are very few parts of `Io.Threaded` which do
not support full robust cancelation. The only ones which actually really
matter (because they could block for a prolonged period of time) are DNS
lookups on Windows (as discussed above) and futex waits on WASM.
This reverts commit c9fa8e46df.
This commit was failing CI checks. This failure was unfortunately not
noticed before merge, due in part to the build runner bug fixed in the
last commit.
When linking libc, it should be the libc that manages the heap. The main
Wasm memory might have been configured as non-growable, which makes
`WasmAllocator` a poor default and causes the common `DebugAllocator`
use case fail with OOM errors unless the user uses `std_options` to
override the default page allocator. Additionally, on Emscripten,
growing Wasm memory without notifying the JS glue code will cause array
buffers to get detached and lead to spurious crashes.
Some filesystems, such as ZFS, do not report atime. It's pretty useless
in general, so make it an optional field in File.Stat.
Also take the opportunity to make setting timestamps API more flexible
and match the APIs widely available, which have UTIME_OMIT and UTIME_NOW
constants that can be independently set for both fields.
This is needed to handle smoothly the case when atime is null.
There's a good argument to not have this in the std lib but it's more
work to remove it than to leave it in, and this branch is already
20,000+ lines changed.
This is one way of addressing/closing https://github.com/ziglang/zig/issues/16738
Previously, there was a mismatch between the default behaviors on Windows vs other platforms, where Windows was implicitly using .NON_DIRECTORY_FILE for its `openFile` implementation which caused `error.IsDir` when opening a directory, while on other platforms there is no equivalent flag for the `open` syscall. This meant that `openFile` on a path of a directory would fail on Windows but succeed on other platforms.
Adding `allow_directory` to `File.OpenFlags` serves two purposes:
1. It provides a cross-platform way to get the `.NON_DIRECTORY_FILE` behavior in the most efficient available way for the platform (on Windows, no extra syscalls are required, on other systems, an extra `fstat` is required)
2. It allows `statFile` to be implemented on top of `openFile` on Windows while still allowing `statFile` to work on directory paths. Before this commit, `statFile` on a directory path on Windows failed with `error.IsDir`
Note: The second purpose could have been addressed in different ways (bespoke call to NtCreateFile in the `statFile` implementation to avoid passing `NON_DIRECTORY_FILE`, or just never pass `NON_DIRECTORY_FILE` in the `openFile` implementation), so the first purpose is the more relevant/motivating force behind this change.
The default being `true` is intended to cut down on the number of syscalls as much as possible when using the default flags.
The 6.17 kernel added[1] syscalls for getting/setting certain file flags
and attributes. It's meant to be a more extensible replacement for these
ioctl's:
- `FS_IOC_GETFLAGS`/`FS_IOC_SETFLAGS`.
- `FS_IOC_FSGETXATTR`/`FS_IOC_FSSETXATTR`.
The definitions of these calls are as follows:
```zig
const file_attr = extern struct {
/// Extended flags that apply to this file. (get/set).
xflags: u64,
/// Preferred extent allocation size, in bytes. (get/set).
extsize: u32,
/// One of:
/// - The number of data extents in this file.
/// - If `FS_IOC_FSGETXATTRA` is set, the number of extended attribute events in the file.
/// (get)
nextents: u32,
/// Project Identifier (get/set).
projid: u32,
/// Preferred extent allocation size for CoW operations, in bytes (get/set).
cowextsize: u32,
};
// size=@sizeOf(file_attr)
fn file_getattr(dirfd: fd_t, path: [*:0], fattr: *file_attr, size: usize, at_flags: u32) {}
fn file_setattr(dirfd: fd_t, path: [*:0], fattr: *file_attr, size: usize, at_flags: u32) {}
```
Users need to set/check `xflags` with the `FS_XFLAG` flags defined in
`linux/fs.h`. `ioctl_xfs_fsgetxattr(2)` has more information about the
type of information one can retrieve.
[1]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=57fcb7d930d8f00f383e995aeebdcd2b416a187a
Andrew Kelley