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|
package main
import (
"errors"
"fmt"
"os"
"syscall"
"time"
"unsafe"
)
const (
mqPayload = "ior-mq-payload"
)
type mqAttr struct {
Flags int64
Maxmsg int64
Msgsize int64
Curmsgs int64
Pad [4]int64
}
func mqPosixBasic() error {
name := fmt.Sprintf("/ior-mq-%d-%d", os.Getpid(), time.Now().UnixNano())
attr := mqAttr{Maxmsg: 8, Msgsize: 128}
mqd, err := mqOpen(name, syscall.O_CREAT|syscall.O_EXCL|syscall.O_RDWR, 0o600, &attr)
if err != nil {
return err
}
defer syscall.Close(mqd) //nolint:errcheck
defer mqUnlink(name) //nolint:errcheck
if err := mqNotify(mqd); err != nil {
return err
}
if err := mqGetsetattr(mqd); err != nil {
return err
}
deadline := time.Now().Add(2 * time.Second)
if err := mqTimedsend(mqd, []byte(mqPayload), 0, deadline); err != nil {
return err
}
buf := make([]byte, 128)
n, err := mqTimedreceive(mqd, buf, deadline)
if err != nil {
return err
}
if got := string(buf[:n]); got != mqPayload {
return fmt.Errorf("mq_timedreceive payload = %q, want %q", got, mqPayload)
}
return nil
}
func mqOpen(name string, flags int, mode uint32, attr *mqAttr) (int, error) {
ptr, err := syscall.BytePtrFromString(name)
if err != nil {
return 0, fmt.Errorf("queue name: %w", err)
}
fd, _, errno := syscall.Syscall6(
syscall.SYS_MQ_OPEN,
uintptr(unsafe.Pointer(ptr)),
uintptr(flags),
uintptr(mode),
uintptr(unsafe.Pointer(attr)),
0,
0,
)
if errno != 0 {
return 0, fmt.Errorf("mq_open: %w", errno)
}
return int(fd), nil
}
func mqUnlink(name string) error {
ptr, err := syscall.BytePtrFromString(name)
if err != nil {
return fmt.Errorf("queue name: %w", err)
}
_, _, errno := syscall.Syscall(syscall.SYS_MQ_UNLINK, uintptr(unsafe.Pointer(ptr)), 0, 0)
if errno != 0 {
return fmt.Errorf("mq_unlink: %w", errno)
}
return nil
}
func mqNotify(mqd int) error {
_, _, errno := syscall.Syscall(syscall.SYS_MQ_NOTIFY, uintptr(mqd), 0, 0)
if errno == 0 || errors.Is(errno, syscall.EINVAL) {
return nil
}
return fmt.Errorf("mq_notify: %w", errno)
}
func mqGetsetattr(mqd int) error {
var old mqAttr
_, _, errno := syscall.Syscall(
syscall.SYS_MQ_GETSETATTR,
uintptr(mqd),
0,
uintptr(unsafe.Pointer(&old)),
)
if errno != 0 {
return fmt.Errorf("mq_getsetattr: %w", errno)
}
return nil
}
func mqTimedsend(mqd int, payload []byte, priority uint32, deadline time.Time) error {
ts := syscall.NsecToTimespec(deadline.UnixNano())
_, _, errno := syscall.Syscall6(
syscall.SYS_MQ_TIMEDSEND,
uintptr(mqd),
uintptr(unsafe.Pointer(&payload[0])),
uintptr(len(payload)),
uintptr(priority),
uintptr(unsafe.Pointer(&ts)),
0,
)
if errno != 0 {
return fmt.Errorf("mq_timedsend: %w", errno)
}
return nil
}
func mqTimedreceive(mqd int, buf []byte, deadline time.Time) (int, error) {
ts := syscall.NsecToTimespec(deadline.UnixNano())
var prio uint32
n, _, errno := syscall.Syscall6(
syscall.SYS_MQ_TIMEDRECEIVE,
uintptr(mqd),
uintptr(unsafe.Pointer(&buf[0])),
uintptr(len(buf)),
uintptr(unsafe.Pointer(&prio)),
uintptr(unsafe.Pointer(&ts)),
0,
)
if errno != 0 {
return 0, fmt.Errorf("mq_timedreceive: %w", errno)
}
return int(n), nil
}
|
