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// Copyright 2018 The gVisor Authors.
//
// 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 linux
import (
"syscall"
"gvisor.googlesource.com/gvisor/pkg/sentry/arch"
"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
"gvisor.googlesource.com/gvisor/pkg/sentry/kernel"
"gvisor.googlesource.com/gvisor/pkg/sentry/kernel/eventfd"
)
const (
// EFD_SEMAPHORE is a flag used in syscall eventfd(2) and eventfd2(2). Please
// see its man page for more information.
EFD_SEMAPHORE = 1
EFD_NONBLOCK = 0x800
EFD_CLOEXEC = 0x80000
)
// Eventfd2 implements linux syscall eventfd2(2).
func Eventfd2(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
initVal := args[0].Int()
flags := uint(args[1].Uint())
allOps := uint(EFD_SEMAPHORE | EFD_NONBLOCK | EFD_CLOEXEC)
if flags & ^allOps != 0 {
return 0, nil, syscall.EINVAL
}
event := eventfd.New(t, uint64(initVal), flags&EFD_SEMAPHORE != 0)
event.SetFlags(fs.SettableFileFlags{
NonBlocking: flags&EFD_NONBLOCK != 0,
})
defer event.DecRef()
fd, err := t.FDMap().NewFDFrom(0, event, kernel.FDFlags{
CloseOnExec: flags&EFD_CLOEXEC != 0,
},
t.ThreadGroup().Limits())
if err != nil {
return 0, nil, err
}
return uintptr(fd), nil, nil
}
// Eventfd implements linux syscall eventfd(2).
func Eventfd(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
args[1].Value = 0
return Eventfd2(t, args)
}
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