Dunno why the MIPS signal numbers are different, or why Zig had them
already special cased, but wrong.
We have the technology to test these constants. We should use it.
All the existing code that manipulates `ucontext_t` expects there to be a
glibc-compatible sigmask (1024-bit). The `ucontext_t` struct need to be
cleaned up so the glibc-dependent format is only used when linking
glibc/musl library, but that is a more involved change.
In practice, no Zig code looks at the sigset field contents, so it just
needs to be the right size.
By returning an initialized sigset (instead of taking the set as an output
parameter), these functions can be used to directly initialize the `mask`
parameter of a `Sigaction` instance.
When linking a libc, Zig should defer to the C library for sigset
operations. The pre-filled constants signal sets (empty_sigset,
filled_sigset) are not compatible with C library initialization, so remove
them and use the runtime `sigemptyset` and `sigfillset` methods to
initialize any sigset.
Unify the C library sigset_t and Linux native sigset_t and the accessor
operations.
Add tests that the various sigset_t operations are working. And clean up
existing tests a bit.
The kernel ABI sigset_t is smaller than the glibc one. Define the
right-sized sigset_t and fixup the sigaction() wrapper to leverage it.
The Sigaction wrapper here is not an ABI, so relax it (drop the "extern"
and the "restorer" fields), the existing `k_sigaction` is the ABI
sigaction struct.
Linux defines `sigset_t` with a c_ulong, so it can be 32-bit or 64-bit,
depending on the platform. This can make a difference on big-endian
systems.
Patch up `ucontext_t` so that this change doesn't impact its layout.
AFAICT, its currently the glibc layout.
Export the sigset_t ops (sigaddset, etc) from the C library. Don't rely
on the linux.zig defintions (which will be defined to use the kernel ABI).
Move Darwin sigset and NSIG declarations into darwin.zig. Remove
extraneous (?) sigaddset. The C library sigaddset can reject some signals
being added, so need to defer to it.
* Indexing zero-bit types should not produce AIR indexing instructions
* Getting a runtime-known element pointer from a many-pointer should
check that the many-pointer is not comptime-only
Resolves: #23405
`writeCValue` already emits a cast; including another here is, in fact,
invalid, and emits errors under MSVC. Probably this code was originally
added to work around the incorrect `.Initializer` location which was
fixed in the previous commit.
The last Intel Quark MCU was released in 2015. Quark was announced to be EOL in
2019, and stopped shipping entirely in 2022.
The OS tag was only meaningful for Intel's weird fork of Linux 3.8.7 with a
special ABI that differs from the regular i386 System V ABI; beyond that, the
CPU itself is just a plain old P54C (i586). We of course keep support for the
CPU itself, just not Intel's Linux fork.
These backends are completely unusable at the moment; they can produce neither
assembly files nor object files. So give a nicer error when users try to use
them.
Aside from adding comments to document the logic in `Cache.Manifest.hit`
better, this commit fixes two serious bugs.
The first, spotted by Andrew, is that when upgrading from a shared to an
exclusive lock on the manifest file, we do not seek it back to the
start. This is a simple fix.
The second is more subtle, and has to do with the computation of file
digests. Broadly speaking, the goal of the main loop in `hit` is to
iterate the files listed in the manifest file, and check if they've
changed, based on stat and a file hash. While doing this, the
`bin_digest` field of `std.Build.Cache.File`, which is initially
`undefined`, is populated for all files, either straight from the
manifest (if the stat matches) or recomputed from the file on-disk. This
file digest is then used to update `man.hash.hasher`, which is building
the final hash used as, for instance, the output directory name when the
compiler emits into the cache directory. When `hit` returns a cache
miss, it is expected that `man.hash.hasher` includes the digests of all
"initial files"; that is, those which have been already added with e.g.
`addFilePath`, but not those which will later be added with
`addFilePost` (even though the manifest file has told us about some such
files). Previously, `hit` was using the `unhit` function to do this in a
few cases. However, this is incorrect, because `hit` assumes that all
files already have their `bin_digest` field populated; this function is
only valid to call *after* `hit` returns. Instead, we need to actually
compute the hashes which haven't yet been populated. Even if this logic
has been working, there was still a bug here, because we called `unhit`
when upgrading from a shared to an exclusive lock, writing the
(potentially `undefined`) file digests, but the loop itself writes the
file digests *again*! All in all, the hashing logic here was actually
incredibly broken.
I've taken the opportunity to restructure this section of the code into
what I think is a more readable format. A new function,
`hitWithCurrentLock`, uses the open manifest file to try and find a
cache hit. It returns a tagged union which, in the miss case, tells the
caller (`hit`) how many files already have their hash populated. This
avoids redundant work recomputing the same hash multiple times in
situations where the lock needs upgrading. This also eliminates the
outer loop from `hit`, which was a little confusing because it iterated
no more than twice!
The bugs fixed here could manifest in several different ways depending
on how contended file locks were satisfied. Most notably, on a cache
miss, the Zig compiler might have written the compilation output to the
incorrect directory (because it incorrectly constructed a hash using
`undefined` or repeated file digests), resulting in all future hits on
this manifest causing `error.FileNotFound`. This is #23110. I have been
able to reproduce #23110 on `master`, and have not been able to after
this commit, so I am relatively sure this commit resolves that issue.
Resolves: #23110
