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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 syscalls
import (
"time"
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/errors/linuxerr"
"gvisor.dev/gvisor/pkg/sentry/kernel"
"gvisor.dev/gvisor/pkg/sentry/kernel/epoll"
ktime "gvisor.dev/gvisor/pkg/sentry/kernel/time"
"gvisor.dev/gvisor/pkg/syserror"
"gvisor.dev/gvisor/pkg/waiter"
)
// CreateEpoll implements the epoll_create(2) linux syscall.
func CreateEpoll(t *kernel.Task, closeOnExec bool) (int32, error) {
file := epoll.NewEventPoll(t)
defer file.DecRef(t)
fd, err := t.NewFDFrom(0, file, kernel.FDFlags{
CloseOnExec: closeOnExec,
})
if err != nil {
return 0, err
}
return fd, nil
}
// AddEpoll implements the epoll_ctl(2) linux syscall when op is EPOLL_CTL_ADD.
func AddEpoll(t *kernel.Task, epfd int32, fd int32, flags epoll.EntryFlags, mask waiter.EventMask, userData [2]int32) error {
// Get epoll from the file descriptor.
epollfile := t.GetFile(epfd)
if epollfile == nil {
return syserror.EBADF
}
defer epollfile.DecRef(t)
// Get the target file id.
file := t.GetFile(fd)
if file == nil {
return syserror.EBADF
}
defer file.DecRef(t)
// Extract the epollPoll operations.
e, ok := epollfile.FileOperations.(*epoll.EventPoll)
if !ok {
return syserror.EBADF
}
// Try to add the entry.
return e.AddEntry(epoll.FileIdentifier{file, fd}, flags, mask, userData)
}
// UpdateEpoll implements the epoll_ctl(2) linux syscall when op is EPOLL_CTL_MOD.
func UpdateEpoll(t *kernel.Task, epfd int32, fd int32, flags epoll.EntryFlags, mask waiter.EventMask, userData [2]int32) error {
// Get epoll from the file descriptor.
epollfile := t.GetFile(epfd)
if epollfile == nil {
return syserror.EBADF
}
defer epollfile.DecRef(t)
// Get the target file id.
file := t.GetFile(fd)
if file == nil {
return syserror.EBADF
}
defer file.DecRef(t)
// Extract the epollPoll operations.
e, ok := epollfile.FileOperations.(*epoll.EventPoll)
if !ok {
return syserror.EBADF
}
// Try to update the entry.
return e.UpdateEntry(epoll.FileIdentifier{file, fd}, flags, mask, userData)
}
// RemoveEpoll implements the epoll_ctl(2) linux syscall when op is EPOLL_CTL_DEL.
func RemoveEpoll(t *kernel.Task, epfd int32, fd int32) error {
// Get epoll from the file descriptor.
epollfile := t.GetFile(epfd)
if epollfile == nil {
return syserror.EBADF
}
defer epollfile.DecRef(t)
// Get the target file id.
file := t.GetFile(fd)
if file == nil {
return syserror.EBADF
}
defer file.DecRef(t)
// Extract the epollPoll operations.
e, ok := epollfile.FileOperations.(*epoll.EventPoll)
if !ok {
return syserror.EBADF
}
// Try to remove the entry.
return e.RemoveEntry(t, epoll.FileIdentifier{file, fd})
}
// WaitEpoll implements the epoll_wait(2) linux syscall.
func WaitEpoll(t *kernel.Task, fd int32, max int, timeoutInNanos int64) ([]linux.EpollEvent, error) {
// Get epoll from the file descriptor.
epollfile := t.GetFile(fd)
if epollfile == nil {
return nil, syserror.EBADF
}
defer epollfile.DecRef(t)
// Extract the epollPoll operations.
e, ok := epollfile.FileOperations.(*epoll.EventPoll)
if !ok {
return nil, syserror.EBADF
}
// Try to read events and return right away if we got them or if the
// caller requested a non-blocking "wait".
r := e.ReadEvents(max)
if len(r) != 0 || timeoutInNanos == 0 {
return r, nil
}
// We'll have to wait. Set up the timer if a timeout was specified and
// and register with the epoll object for readability events.
var haveDeadline bool
var deadline ktime.Time
if timeoutInNanos > 0 {
timeoutDur := time.Duration(timeoutInNanos) * time.Nanosecond
deadline = t.Kernel().MonotonicClock().Now().Add(timeoutDur)
haveDeadline = true
}
w, ch := waiter.NewChannelEntry(nil)
e.EventRegister(&w, waiter.ReadableEvents)
defer e.EventUnregister(&w)
// Try to read the events again until we succeed, timeout or get
// interrupted.
for {
r = e.ReadEvents(max)
if len(r) != 0 {
return r, nil
}
if err := t.BlockWithDeadline(ch, haveDeadline, deadline); err != nil {
if linuxerr.Equals(linuxerr.ETIMEDOUT, err) {
return nil, nil
}
return nil, err
}
}
}
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