Our usage of `ucontext_t` in the standard library was kind of
problematic. We unnecessarily mimiced libc-specific structures, and our
`getcontext` implementation was overkill for our use case of stack
tracing.
This commit introduces a new namespace, `std.debug.cpu_context`, which
contains "context" types for various architectures (currently x86,
x86_64, ARM, and AARCH64) containing the general-purpose CPU registers;
the ones needed in practice for stack unwinding. Each implementation has
a function `current` which populates the structure using inline
assembly. The structure is user-overrideable, though that should only be
necessary if the standard library does not have an implementation for
the *architecture*: that is to say, none of this is OS-dependent.
Of course, in POSIX signal handlers, we get a `ucontext_t` from the
kernel. The function `std.debug.cpu_context.fromPosixSignalContext`
converts this to a `std.debug.cpu_context.Native` with a big ol' target
switch.
This functionality is not exposed from `std.c` or `std.posix`, and
neither are `ucontext_t`, `mcontext_t`, or `getcontext`. The rationale
is that these types and functions do not conform to a specific ABI, and
in fact tend to get updated over time based on CPU features and
extensions; in addition, different libcs use different structures which
are "partially compatible" with the kernel structure. Overall, it's a
mess, but all we need is the kernel context, so we can just define a
kernel-compatible structure as long as we don't claim C compatibility by
putting it in `std.c` or `std.posix`.
This change resulted in a few nice `std.debug` simplifications, but
nothing too noteworthy. However, the main benefit of this change is that
DWARF unwinding---sometimes necessary for collecting stack traces
reliably---now requires far less target-specific integration.
Also fix a bug I noticed in `PageAllocator` (I found this due to a bug
in my distro's QEMU distribution; thanks, broken QEMU patch!) and I
think a couple of minor bugs in `std.debug`.
Resolves: #23801Resolves: #23802
Because these lists are very long in several cases and quite
varied, I opted to place them in the existing c/foo.zig files.
There are many other sets of network-related constants like this
to add over time across all the OSes. For now I picked these
because I needed a few constants from each of these namespaces for
my own project, so I tried to flesh out these namespaces
completely as best I could, at least for basic sockopt purposes.
Note windows has some of these already defined in ws2_32 as
individual constants rather than contained in a namespacing
struct. I'm not sure what to do with that in the long run (break
it and namespace them?), but this doesn't change the status quo
for windows in any case.
Previously we had a single definition of std.c.cmsghdr for all
libc-linking platforms which aliased from the Solaris definition,
a superfluous matching one in std.os.dragonfly, and no others.
The existing definition from std.c didn't actually work for Linux,
as Linux's "len" field is usize in the kernel's definition.
Emscripten follows the Linux model of course (but uses the
binary-compatible musl definition, which has an endian-sensitive
padding scheme to make the len type "socklen_t" even though the
kernel uses a usize, which is fair).
This unifies and documents all the known *nix-ish cases (I'm not
sure if wasi or windows really has cmsghdr support? Could be added
later, void for now), such that c.cmsghdr and posix.system.cmsghdr
should work correctly for all the known cases here, libc or
otherwise.
This was done by regex substitution with `sed`. I then manually went
over the entire diff and fixed any incorrect changes.
This diff also changes a lot of `callconv(.C)` to `callconv(.c)`, since
my regex happened to also trigger here. I opted to leave these changes
in, since they *are* a correct migration, even if they're not the one I
was trying to do!
It is now composed of these main sections:
* Declarations that are shared among all operating systems.
* Declarations that have the same name, but different type signatures
depending on the operating system. Often multiple operating systems
share the same type signatures however.
* Declarations that are specific to a single operating system.
- These are imported one per line so you can see where they come from,
protected by a comptime block to prevent accessing the wrong one.
Closes#19352 by changing the convention to making types `void` and
functions `{}`, so that it becomes possible to update `@hasDecl` sites
to use `@TypeOf(f) != void` or `T != void`. Happily, this ended up
removing some duplicate logic and update some bitrotted feature
detection checks.
A handful of types have been modified to gain namespacing and type
safety. This is a breaking change.
Oh, and the last usage of `usingnamespace` site is eliminated.
I believe this was accidentally broken when the E enum for errno values
was introduces. These functions are quite the special case in that they
return the error value directly rather than returning -1 and passing the
error value through the errno variable.
In any case, using a u16 as the return type at the ABI boundary where a
c_int is expected is asking for trouble.
A pointer type already has an alignment, so this information does not
need to be duplicated on the function type. This already has precedence
with addrspace which is already disallowed on function types for this
reason. Also fixes `@TypeOf(&func)` to have the correct addrspace and
alignment.
* std.c: consolidate some definitions, making them share code. For
example, freebsd, dragonfly, and openbsd can all share the same
`pthread_mutex_t` definition.
* add type safety to std.c.O
- this caught a bug where mode flags were incorrectly passed as the
open flags.
* 3 fewer uses of usingnamespace keyword
* as per convention, remove purposeless field prefixes from struct field
names even if they have those prefixes in the corresponding C code.
* fix incorrect wasi libc Stat definition
* remove C definitions from incorrectly being in std.os.wasi
* make std.os.wasi definitions type safe
* go through wasi native APIs even when linking libc because the libc
APIs are problematic and wasteful
* don't expose WASI definitions in std.posix
* remove std.os.wasi.rights_t.ALL: this is a footgun. should it be all
future rights too? or only all current rights known? both are
the wrong answer.
Most of this migration was performed automatically with `zig fmt`. There
were a few exceptions which I had to manually fix:
* `@alignCast` and `@addrSpaceCast` cannot be automatically rewritten
* `@truncate`'s fixup is incorrect for vectors
* Test cases are not formatted, and their error locations change
This allows for a more optimal std.crypto.tlcsprng codepath.
Without it a an "incorrect alignment" panic is triggered from
crypto.tlcsprng which aligns a threadlocal but it's actually
not aligned, thus detected by the safety check.
It appears that LLVM-IR does attribute the storage with alignment
but it is ultimately not respected in the final binary for netbsd
and dragonfly.
There are still a few occurrences of "stage1" in the standard library
and self-hosted compiler source, however, these instances need a bit
more careful inspection to ensure no breakage.
POSIX specifies that the sa_handler field of the sigaction struct may
be set to SIG_IGN or SIG_DFL. However, the current constants in the
standard library use the function pointer signature corresponding to
the sa_sigaction field instead.
This may not cause issues in practice because the fields usually occupy
the same memory in a union, but this isn't required by POSIX and there
may be systems we do not yet support that do this differently.
Fixing this also makes the Zig interface less confusing to use after
reading the man page.
Some systems (Solaris, OpenBSD, AIX) change their definitions of
sockaddr_storage to be larger than 128 bytes. This comment adds a new
constant in the `sockaddr` that defines the size for every system.
Fixes#9759
