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PiperOrigin-RevId: 194583126
Change-Id: Ica1d8821a90f74e7e745962d71801c598c652463

1 files changed, 174 insertions, 0 deletions

diff --git a/pkg/sentry/syscalls/epoll.go b/pkg/sentry/syscalls/epoll.go
new file mode 100644
index 000000000..01dd6fa71
--- /dev/null
+++ b/pkg/sentry/syscalls/epoll.go
@@ -0,0 +1,174 @@
+// 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 syscalls
+
+import (
+	"syscall"
+	"time"
+
+	"gvisor.googlesource.com/gvisor/pkg/sentry/kernel"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/kernel/epoll"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/kernel/kdefs"
+	ktime "gvisor.googlesource.com/gvisor/pkg/sentry/kernel/time"
+	"gvisor.googlesource.com/gvisor/pkg/waiter"
+)
+
+// CreateEpoll implements the epoll_create(2) linux syscall.
+func CreateEpoll(t *kernel.Task, closeOnExec bool) (kdefs.FD, error) {
+	file := epoll.NewEventPoll(t)
+	defer file.DecRef()
+
+	flags := kernel.FDFlags{
+		CloseOnExec: closeOnExec,
+	}
+	fd, err := t.FDMap().NewFDFrom(0, file, flags, t.ThreadGroup().Limits())
+	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 kdefs.FD, fd kdefs.FD, flags epoll.EntryFlags, mask waiter.EventMask, userData [2]int32) error {
+	// Get epoll from the file descriptor.
+	epollfile := t.FDMap().GetFile(epfd)
+	if epollfile == nil {
+		return syscall.EBADF
+	}
+	defer epollfile.DecRef()
+
+	// Get the target file id.
+	file := t.FDMap().GetFile(fd)
+	if file == nil {
+		return syscall.EBADF
+	}
+	defer file.DecRef()
+
+	// Extract the epollPoll operations.
+	e, ok := epollfile.FileOperations.(*epoll.EventPoll)
+	if !ok {
+		return syscall.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 kdefs.FD, fd kdefs.FD, flags epoll.EntryFlags, mask waiter.EventMask, userData [2]int32) error {
+	// Get epoll from the file descriptor.
+	epollfile := t.FDMap().GetFile(epfd)
+	if epollfile == nil {
+		return syscall.EBADF
+	}
+	defer epollfile.DecRef()
+
+	// Get the target file id.
+	file := t.FDMap().GetFile(fd)
+	if file == nil {
+		return syscall.EBADF
+	}
+	defer file.DecRef()
+
+	// Extract the epollPoll operations.
+	e, ok := epollfile.FileOperations.(*epoll.EventPoll)
+	if !ok {
+		return syscall.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 kdefs.FD, fd kdefs.FD) error {
+	// Get epoll from the file descriptor.
+	epollfile := t.FDMap().GetFile(epfd)
+	if epollfile == nil {
+		return syscall.EBADF
+	}
+	defer epollfile.DecRef()
+
+	// Get the target file id.
+	file := t.FDMap().GetFile(fd)
+	if file == nil {
+		return syscall.EBADF
+	}
+	defer file.DecRef()
+
+	// Extract the epollPoll operations.
+	e, ok := epollfile.FileOperations.(*epoll.EventPoll)
+	if !ok {
+		return syscall.EBADF
+	}
+
+	// Try to remove the entry.
+	return e.RemoveEntry(epoll.FileIdentifier{file, fd})
+}
+
+// WaitEpoll implements the epoll_wait(2) linux syscall.
+func WaitEpoll(t *kernel.Task, fd kdefs.FD, max int, timeout int) ([]epoll.Event, error) {
+	// Get epoll from the file descriptor.
+	epollfile := t.FDMap().GetFile(fd)
+	if epollfile == nil {
+		return nil, syscall.EBADF
+	}
+	defer epollfile.DecRef()
+
+	// Extract the epollPoll operations.
+	e, ok := epollfile.FileOperations.(*epoll.EventPoll)
+	if !ok {
+		return nil, syscall.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 || timeout == 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 timeout > 0 {
+		timeoutDur := time.Duration(timeout) * time.Millisecond
+		deadline = t.Kernel().MonotonicClock().Now().Add(timeoutDur)
+		haveDeadline = true
+	}
+
+	w, ch := waiter.NewChannelEntry(nil)
+	e.EventRegister(&w, waiter.EventIn)
+	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 err == syscall.ETIMEDOUT {
+				return nil, nil
+			}
+
+			return nil, err
+		}
+	}
+}