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std: add sendmmsg on linux

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daurnimator 2019-04-21 18:03:27 +10:00
parent 217b95da31
commit fd056752da
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1 changed files with 51 additions and 0 deletions
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51
std/os/linux.zig
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@ -12,6 +12,7 @@ pub use switch (builtin.arch) {
pub use @import("linux/errno.zig");
pub const PATH_MAX = 4096;
pub const IOV_MAX = 1024;
pub const STDIN_FILENO = 0;
pub const STDOUT_FILENO = 1;
@ -1193,6 +1194,16 @@ pub const iovec_const = extern struct {
iov_len: usize,
};
pub const mmsghdr = extern struct {
msg_hdr: msghdr,
msg_len: u32,
};
pub const mmsghdr_const = extern struct {
msg_hdr: msghdr_const,
msg_len: u32,
};
pub fn getsockname(fd: i32, noalias addr: *sockaddr, noalias len: *socklen_t) usize {
return syscall3(SYS_getsockname, @bitCast(usize, isize(fd)), @ptrToInt(addr), @ptrToInt(len));
}
@ -1217,6 +1228,46 @@ pub fn sendmsg(fd: i32, msg: *msghdr_const, flags: u32) usize {
return syscall3(SYS_sendmsg, @bitCast(usize, isize(fd)), @ptrToInt(msg), flags);
}
pub fn sendmmsg(fd: i32, msgvec: [*]mmsghdr_const, vlen: u32, flags: u32) usize {
if (@typeInfo(usize).Int.bits > @typeInfo(@typeOf(mmsghdr(undefined).msg_len)).Int.bits) {
// workaround kernel brokenness:
// if adding up all iov_len overflows a i32 then split into multiple calls
// see https://www.openwall.com/lists/musl/2014/06/07/5
const kvlen = if (vlen > IOV_MAX) IOV_MAX else vlen; // matches kernel
var next_unsent: usize = 0;
for (msgvec[0..kvlen]) |*msg, i| {
var size: i32 = 0;
const msg_iovlen = @intCast(usize, msg.msg_hdr.msg_iovlen); // kernel side this is treated as unsigned
for (msg.msg_hdr.msg_iov[0..msg_iovlen]) |iov, j| {
if (iov.iov_len > std.math.maxInt(i32) or @addWithOverflow(i32, size, @intCast(i32, iov.iov_len), &size)) {
// batch-send all messages up to the current message
if (next_unsent < i) {
const batch_size = i - next_unsent;
const r = syscall4(SYS_sendmmsg, @bitCast(usize, isize(fd)), @ptrToInt(&msgvec[next_unsent]), batch_size, flags);
if (getErrno(r) != 0) return next_unsent;
if (r < batch_size) return next_unsent + r;
}
// send current message as own packet
const r = sendmsg(fd, &msg.msg_hdr, flags);
if (getErrno(r) != 0) return r;
// Linux limits the total bytes sent by sendmsg to INT_MAX, so this cast is safe.
msg.msg_len = @intCast(u32, r);
next_unsent = i + 1;
break;
}
}
}
if (next_unsent < kvlen or next_unsent == 0) { // want to make sure at least one syscall occurs (e.g. to trigger MSG_EOR)
const batch_size = kvlen - next_unsent;
const r = syscall4(SYS_sendmmsg, @bitCast(usize, isize(fd)), @ptrToInt(&msgvec[next_unsent]), batch_size, flags);
if (getErrno(r) != 0) return r;
return next_unsent + r;
}
return kvlen;
}
return syscall4(SYS_sendmmsg, @bitCast(usize, isize(fd)), @ptrToInt(msgvec), vlen, flags);
}
pub fn connect(fd: i32, addr: *const c_void, len: socklen_t) usize {
return syscall3(SYS_connect, @bitCast(usize, isize(fd)), @ptrToInt(addr), len);
}