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/*
*------------------------------------------------------------------
* Copyright (c) 2020 Cisco and/or its affiliates.
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*------------------------------------------------------------------
*/
package memif
import (
"fmt"
"os"
"syscall"
"unsafe"
)
// sendMsg sends a control message from contorl channels message queue
func (cc *controlChannel) sendMsg() (err error) {
if len(cc.msgQueue) < 1 {
return nil
}
// Get message buffer
msg := cc.msgQueue[0]
// Dequeue
cc.msgQueue = cc.msgQueue[1:]
iov := &syscall.Iovec{
Base: &msg.Buffer.Bytes()[0],
Len: msgSize,
}
msgh := syscall.Msghdr{
Iov: iov,
Iovlen: 1,
}
if msg.Fd > 0 {
oob := syscall.UnixRights(msg.Fd)
msgh.Control = &oob[0]
msgh.Controllen = uint64(syscall.CmsgSpace(4))
}
_, _, errno := syscall.Syscall(syscall.SYS_SENDMSG, uintptr(cc.event.Fd), uintptr(unsafe.Pointer(&msgh)), uintptr(0))
if errno != 0 {
err = os.NewSyscallError("sendmsg", errno)
return fmt.Errorf("SYS_SENDMSG: %s", errno)
}
return nil
}
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