173 lines
4.5 KiB
Go
173 lines
4.5 KiB
Go
// Copyright 2018 The gVisor Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package syscalls
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import (
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"time"
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"gvisor.dev/gvisor/pkg/sentry/kernel"
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"gvisor.dev/gvisor/pkg/sentry/kernel/epoll"
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ktime "gvisor.dev/gvisor/pkg/sentry/kernel/time"
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"gvisor.dev/gvisor/pkg/syserror"
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"gvisor.dev/gvisor/pkg/waiter"
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)
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// CreateEpoll implements the epoll_create(2) linux syscall.
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func CreateEpoll(t *kernel.Task, closeOnExec bool) (int32, error) {
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file := epoll.NewEventPoll(t)
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defer file.DecRef()
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fd, err := t.NewFDFrom(0, file, kernel.FDFlags{
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CloseOnExec: closeOnExec,
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})
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if err != nil {
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return 0, err
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}
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return fd, nil
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}
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// AddEpoll implements the epoll_ctl(2) linux syscall when op is EPOLL_CTL_ADD.
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func AddEpoll(t *kernel.Task, epfd int32, fd int32, flags epoll.EntryFlags, mask waiter.EventMask, userData [2]int32) error {
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// Get epoll from the file descriptor.
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epollfile := t.GetFile(epfd)
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if epollfile == nil {
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return syserror.EBADF
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}
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defer epollfile.DecRef()
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// Get the target file id.
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file := t.GetFile(fd)
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if file == nil {
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return syserror.EBADF
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}
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defer file.DecRef()
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// Extract the epollPoll operations.
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e, ok := epollfile.FileOperations.(*epoll.EventPoll)
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if !ok {
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return syserror.EBADF
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}
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// Try to add the entry.
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return e.AddEntry(epoll.FileIdentifier{file, fd}, flags, mask, userData)
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}
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// UpdateEpoll implements the epoll_ctl(2) linux syscall when op is EPOLL_CTL_MOD.
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func UpdateEpoll(t *kernel.Task, epfd int32, fd int32, flags epoll.EntryFlags, mask waiter.EventMask, userData [2]int32) error {
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// Get epoll from the file descriptor.
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epollfile := t.GetFile(epfd)
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if epollfile == nil {
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return syserror.EBADF
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}
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defer epollfile.DecRef()
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// Get the target file id.
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file := t.GetFile(fd)
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if file == nil {
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return syserror.EBADF
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}
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defer file.DecRef()
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// Extract the epollPoll operations.
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e, ok := epollfile.FileOperations.(*epoll.EventPoll)
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if !ok {
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return syserror.EBADF
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}
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// Try to update the entry.
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return e.UpdateEntry(epoll.FileIdentifier{file, fd}, flags, mask, userData)
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}
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// RemoveEpoll implements the epoll_ctl(2) linux syscall when op is EPOLL_CTL_DEL.
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func RemoveEpoll(t *kernel.Task, epfd int32, fd int32) error {
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// Get epoll from the file descriptor.
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epollfile := t.GetFile(epfd)
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if epollfile == nil {
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return syserror.EBADF
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}
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defer epollfile.DecRef()
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// Get the target file id.
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file := t.GetFile(fd)
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if file == nil {
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return syserror.EBADF
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}
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defer file.DecRef()
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// Extract the epollPoll operations.
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e, ok := epollfile.FileOperations.(*epoll.EventPoll)
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if !ok {
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return syserror.EBADF
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}
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// Try to remove the entry.
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return e.RemoveEntry(epoll.FileIdentifier{file, fd})
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}
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// WaitEpoll implements the epoll_wait(2) linux syscall.
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func WaitEpoll(t *kernel.Task, fd int32, max int, timeout int) ([]epoll.Event, error) {
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// Get epoll from the file descriptor.
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epollfile := t.GetFile(fd)
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if epollfile == nil {
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return nil, syserror.EBADF
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}
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defer epollfile.DecRef()
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// Extract the epollPoll operations.
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e, ok := epollfile.FileOperations.(*epoll.EventPoll)
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if !ok {
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return nil, syserror.EBADF
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}
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// Try to read events and return right away if we got them or if the
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// caller requested a non-blocking "wait".
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r := e.ReadEvents(max)
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if len(r) != 0 || timeout == 0 {
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return r, nil
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}
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// We'll have to wait. Set up the timer if a timeout was specified and
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// and register with the epoll object for readability events.
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var haveDeadline bool
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var deadline ktime.Time
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if timeout > 0 {
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timeoutDur := time.Duration(timeout) * time.Millisecond
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deadline = t.Kernel().MonotonicClock().Now().Add(timeoutDur)
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haveDeadline = true
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}
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w, ch := waiter.NewChannelEntry(nil)
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e.EventRegister(&w, waiter.EventIn)
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defer e.EventUnregister(&w)
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// Try to read the events again until we succeed, timeout or get
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// interrupted.
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for {
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r = e.ReadEvents(max)
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if len(r) != 0 {
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return r, nil
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}
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if err := t.BlockWithDeadline(ch, haveDeadline, deadline); err != nil {
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if err == syserror.ETIMEDOUT {
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return nil, nil
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}
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return nil, err
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}
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}
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}
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