- Add syscall bindings/structures for the `futex2` family.
The documentation is taken from the syscall definitions.
- Add documnentation for the `cachestat` bindings and structures.
Taken from work I did in Cosmopolitian libc.
- Add binding for `map_shadow_stack`.
No documentation for this one, since the kernel devs didn't bother to
do it ¯\_(ツ)_/¯.
This syscall was added to simplify the the libc implementations of
fchmodat, as the original syscall does not take a `flags` argument.
Another syscall, `map_shadow_stack`, was also added for x86_64.
Requires an extra NtQueryInformationFile call when FILE_ATTRIBUTE_REPARSE_POINT is set to determine if it's actually a symlink or some other kind of reparse point (https://learn.microsoft.com/en-us/windows/win32/fileio/reparse-point-tags). This is something that `File.Metadata.kind` was already doing, so the same technique is used in `stat`.
Also, replace the std.os.windows.DeviceIoControl call in `metadata` with NtQueryInformationFile (NtQueryInformationFile is what gets called during kernel32.GetFileInformationByHandleEx with FileAttributeTagInfo, verified using NtTrace).
Getting this error in ci:
run test std-arm-linux-none-generic-Debug: error: 'test.accept/connect/send_zc/recv' failed: /home/ci/actions-runner1/_work/zig/zig/lib/std/os/linux/io_uring.zig:60:23: 0x70b06b in init_params (test)
.NOSYS => return error.SystemOutdated,
^
/home/ci/actions-runner1/_work/zig/zig/lib/std/os/linux/io_uring.zig:27:16: 0x70b6b7 in init (test)
return try IO_Uring.init_params(entries, ¶ms);
^
/home/ci/actions-runner1/_work/zig/zig/lib/std/os/linux/io_uring.zig:3807:16: 0x72405b in test.accept/connect/send_zc/recv (test)
var ring = try IO_Uring.init(16, 0);
https://github.com/ziglang/zig/actions/runs/6909813408/job/18801841015?pr=18025
Reverting previous change.
I'm building test bin and then running it in virtual machines with different
kernels. So Linux kernel checks has to be runtime instead of comptime.
So far we relied on getting EINVAL in CQE for operations that kernel don't
support. The problem with that approach is that there are many other reasons
(like wrong params) to get EINVAL. The other problem is when we have an
operation that existed before and gets new behavior via different attributes,
like accept and accept_direct. Older kernels can fall back to non direct
operation although we set attributes for direct operation. Operation completes
successfully in both cases but with different results.
This commit introduces kernel version check at the start of the test. Making
body of the test free of checking for various kernel version differences.
Feature availability references:
* https://manpages.debian.org/unstable/liburing-dev/io_uring_enter.2.en.html
* https://kernel.dk/axboe-kr2022.pdf
* 5acf7969bc/lib/std/os/linux.zig (L3727)
* 5acf7969bc/lib/std/os/linux.zig (L3993)
`send_zc` tries to avoid making intermediate copies of data. Zerocopy execution
is not guaranteed and may fall back to copying.
The flags field of the first struct io_uring_cqe may likely contain
IORING_CQE_F_MORE , which means that there will be a second completion event /
notification for the request, with the user_data field set to the same value.
The user must not modify the data buffer until the notification is posted. The
first cqe follows the usual rules and so its res field will contain the number
of bytes sent or a negative error code. The notification's res field will be set
to zero and the flags field will contain IORING_CQE_F_NOTIF. The two step model
is needed because the kernel may hold on to buffers for a long time, e.g.
waiting for a TCP ACK, and having a separate cqe for request completions allows
userspace to push more data without extra delays. Note, notifications are only
responsible for controlling the lifetime of the buffers, and as such don't mean
anything about whether the data has atually been sent out or received by the
other end. Even errored requests may generate a notification, and the user must
check for IORING_CQE_F_MORE rather than relying on the result.
Available since kernel 6.0.
References:
https://man7.org/linux/man-pages/man3/io_uring_prep_send_zc.3.htmlhttps://man7.org/linux/man-pages/man2/io_uring_enter.2.html
There is no grantee that `copy_cqes` will return exactly wait_nr number of cqes.
If there are ready cqes it can return > 0 but < wait_nr number of cqes.
Server networking application typically accept multiple connections. Multishot
accept simplifies handling these situations. Applications submits once and
receives CQE whenever a new connection request comes in.
Multishot is active until it is canceled or experience error. While active, and
further notification are expected CQE completion will have IORING_CQE_F_MORE set
in the flags. If this flag isn't set, the application must re-arm this request
by submitting a new one.
Reference: [io_uring and networking in 2023](https://github.com/axboe/liburing/wiki/io_uring-and-networking-in-2023#multi-shot)
Use inline to vastly simplify the exposed API. This allows a
comptime-known endian parameter to be propogated, making extra functions
for a specific endianness completely unnecessary.
