75 lines
2.0 KiB
Go
75 lines
2.0 KiB
Go
|
// Copyright 2018 Google Inc.
|
||
|
//
|
||
|
// 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 fdnotifier
|
||
|
|
||
|
import (
|
||
|
"syscall"
|
||
|
"unsafe"
|
||
|
|
||
|
"gvisor.googlesource.com/gvisor/pkg/waiter"
|
||
|
)
|
||
|
|
||
|
// NonBlockingPoll polls the given FD in non-blocking fashion. It is used just
|
||
|
// to query the FD's current state.
|
||
|
func NonBlockingPoll(fd int32, mask waiter.EventMask) waiter.EventMask {
|
||
|
e := struct {
|
||
|
fd int32
|
||
|
events int16
|
||
|
revents int16
|
||
|
}{
|
||
|
fd: fd,
|
||
|
events: int16(mask),
|
||
|
}
|
||
|
|
||
|
for {
|
||
|
n, _, err := syscall.RawSyscall(syscall.SYS_POLL, uintptr(unsafe.Pointer(&e)), 1, 0)
|
||
|
// Interrupted by signal, try again.
|
||
|
if err == syscall.EINTR {
|
||
|
continue
|
||
|
}
|
||
|
// If an error occur we'll conservatively say the FD is ready for
|
||
|
// whatever is being checked.
|
||
|
if err != 0 {
|
||
|
return mask
|
||
|
}
|
||
|
|
||
|
// If no FDs were returned, it wasn't ready for anything.
|
||
|
if n == 0 {
|
||
|
return 0
|
||
|
}
|
||
|
|
||
|
// Otherwise we got the ready events in the revents field.
|
||
|
return waiter.EventMask(e.revents)
|
||
|
}
|
||
|
}
|
||
|
|
||
|
// epollWait performs a blocking wait on epfd.
|
||
|
//
|
||
|
// Preconditions:
|
||
|
// * len(events) > 0
|
||
|
func epollWait(epfd int, events []syscall.EpollEvent, msec int) (int, error) {
|
||
|
if len(events) == 0 {
|
||
|
panic("Empty events passed to EpollWait")
|
||
|
}
|
||
|
|
||
|
// We actually use epoll_pwait with NULL sigmask instead of epoll_wait
|
||
|
// since that is what the Go >= 1.11 runtime prefers.
|
||
|
r, _, e := syscall.Syscall6(syscall.SYS_EPOLL_PWAIT, uintptr(epfd), uintptr(unsafe.Pointer(&events[0])), uintptr(len(events)), uintptr(msec), 0, 0)
|
||
|
if e != 0 {
|
||
|
return 0, e
|
||
|
}
|
||
|
return int(r), nil
|
||
|
}
|