125 lines
3.5 KiB
Go
125 lines
3.5 KiB
Go
// Copyright 2017 The Periph Authors. All rights reserved.
|
|
// Use of this source code is governed under the Apache License, Version 2.0
|
|
// that can be found in the LICENSE file.
|
|
|
|
package fs
|
|
|
|
import (
|
|
"strconv"
|
|
"strings"
|
|
"syscall"
|
|
)
|
|
|
|
const isLinux = true
|
|
|
|
// syscall.EpollCtl() commands.
|
|
//
|
|
// These are defined here so we don't need to import golang.org/x/sys/unix.
|
|
//
|
|
// http://man7.org/linux/man-pages/man2/epoll_ctl.2.html
|
|
const (
|
|
epollCTLAdd = 1 // EPOLL_CTL_ADD
|
|
epollCTLDel = 2 // EPOLL_CTL_DEL
|
|
epollCTLMod = 3 // EPOLL_CTL_MOD
|
|
)
|
|
|
|
// Bitmask for field syscall.EpollEvent.Events.
|
|
//
|
|
// These are defined here so we don't need to import golang.org/x/sys/unix.
|
|
//
|
|
// http://man7.org/linux/man-pages/man2/epoll_ctl.2.html
|
|
type epollEvent uint32
|
|
|
|
const (
|
|
epollIN epollEvent = 0x1 // EPOLLIN: available for read
|
|
epollOUT epollEvent = 0x4 // EPOLLOUT: available for write
|
|
epollPRI epollEvent = 0x2 // EPOLLPRI: exceptional urgent condition
|
|
epollERR epollEvent = 0x8 // EPOLLERR: error
|
|
epollHUP epollEvent = 0x10 // EPOLLHUP: hangup
|
|
epollET epollEvent = 0x80000000 // EPOLLET: Edge Triggered behavior
|
|
epollONESHOT epollEvent = 0x40000000 // EPOLLONESHOT: One shot
|
|
epollWAKEUP epollEvent = 0x20000000 // EPOLLWAKEUP: disable system sleep; kernel >=3.5
|
|
epollEXCLUSIVE epollEvent = 0x10000000 // EPOLLEXCLUSIVE: only wake one; kernel >=4.5
|
|
)
|
|
|
|
var bitmaskString = [...]struct {
|
|
e epollEvent
|
|
s string
|
|
}{
|
|
{epollIN, "IN"},
|
|
{epollOUT, "OUT"},
|
|
{epollPRI, "PRI"},
|
|
{epollERR, "ERR"},
|
|
{epollHUP, "HUP"},
|
|
{epollET, "ET"},
|
|
{epollONESHOT, "ONESHOT"},
|
|
{epollWAKEUP, "WAKEUP"},
|
|
{epollEXCLUSIVE, "EXCLUSIVE"},
|
|
}
|
|
|
|
// String is useful for debugging.
|
|
func (e epollEvent) String() string {
|
|
var out []string
|
|
for _, b := range bitmaskString {
|
|
if e&b.e != 0 {
|
|
out = append(out, b.s)
|
|
e &^= b.e
|
|
}
|
|
}
|
|
if e != 0 {
|
|
out = append(out, "0x"+strconv.FormatUint(uint64(e), 16))
|
|
}
|
|
if len(out) == 0 {
|
|
out = []string{"0"}
|
|
}
|
|
return strings.Join(out, "|")
|
|
}
|
|
|
|
func ioctl(f uintptr, op uint, arg uintptr) error {
|
|
if _, _, errno := syscall.Syscall(syscall.SYS_IOCTL, f, uintptr(op), arg); errno != 0 {
|
|
return syscall.Errno(errno)
|
|
}
|
|
return nil
|
|
}
|
|
|
|
type event struct {
|
|
event [1]syscall.EpollEvent
|
|
epollFd int
|
|
fd int
|
|
}
|
|
|
|
// makeEvent creates an epoll *edge* triggered event.
|
|
//
|
|
// References:
|
|
// behavior and flags: http://man7.org/linux/man-pages/man7/epoll.7.html
|
|
// syscall.EpollCreate: http://man7.org/linux/man-pages/man2/epoll_create.2.html
|
|
// syscall.EpollCtl: http://man7.org/linux/man-pages/man2/epoll_ctl.2.html
|
|
func (e *event) makeEvent(fd uintptr) error {
|
|
epollFd, err := syscall.EpollCreate(1)
|
|
switch {
|
|
case err == nil:
|
|
break
|
|
case err.Error() == "function not implemented":
|
|
// Some arch (arm64) do not implement EpollCreate().
|
|
if epollFd, err = syscall.EpollCreate1(0); err != nil {
|
|
return err
|
|
}
|
|
default:
|
|
return err
|
|
}
|
|
e.epollFd = epollFd
|
|
e.fd = int(fd)
|
|
// EPOLLWAKEUP could be used to force the system to not go do sleep while
|
|
// waiting for an edge. This is generally a bad idea, as we'd instead have
|
|
// the system to *wake up* when an edge is triggered. Achieving this is
|
|
// outside the scope of this interface.
|
|
e.event[0].Events = uint32(epollPRI | epollET)
|
|
e.event[0].Fd = int32(e.fd)
|
|
return syscall.EpollCtl(e.epollFd, epollCTLAdd, e.fd, &e.event[0])
|
|
}
|
|
|
|
func (e *event) wait(timeoutms int) (int, error) {
|
|
// http://man7.org/linux/man-pages/man2/epoll_wait.2.html
|
|
return syscall.EpollWait(e.epollFd, e.event[:], timeoutms)
|
|
}
|