add std.os.shutdown function for sockets

[marler8997]

No description provided.

[LemonBoy]

You may be interested in #7194 and the sibling #7124

[LemonBoy]

Native zig types are preferred, why this change?

[marler8997]

ok I've removed this change and modified the new declaration in c.zig to use i32 as well.

[LemonBoy]

I'd make this a simple Zig enum enum { read_end, write_end, both_ends } and convert this to the proper flag value in fn shutdown.

[marler8997]

I dunno, this seems simpler than adding conversion logic.

[LemonBoy]

It's a leaky abstraction. The "conversion" code is a simple switch, the same you're doing here with a lot of ifs.

[marler8997]

ok I've changed it to switches internal to the function. This seems like it could be adding unnecessary overhead to me, but not a big deal.

[semarie]

for how, I would use a c_int instead of i32. c_int could have different size depending the platform.

[semarie]

oh, I see @LemonBoy said the opposite before for lib/std/os/linux.zig function.

@LemonBoy, using c_int ensure portability: C standard (on which shutdown() POSIX is based) defines no size of int (only a minimum range, and relative size compared to short and long)

[semarie]

and I think also the return value is wrong: usize is unsigned, whereas POSIX shutdown() could return -1 on error. I would use c_int here too 😄

[LemonBoy]

oh, I see @LemonBoy said the opposite before for lib/std/os/linux.zig function.

That's the Linux syscall wrapper, we're directly talking with the kernel there and don't give a damn about C/libc, the types there should be Zig's native ones.

The c.zig definitions, on the other hand, should use the C types instead to guarantee the ABI compatibility.

and I think also the return value is wrong: usize is unsigned, whereas POSIX shutdown() could return -1 on error. I would use c_int here too

Good catch, c_int is the correct return type.

[marler8997]

Ok I've modified the one in c.zig to:

pub extern "c" fn shutdown(socket: fd_t, how: c_int) c_int;