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PiperOrigin-RevId: 194583126
Change-Id: Ica1d8821a90f74e7e745962d71801c598c652463

1 files changed, 65 insertions, 0 deletions

diff --git a/pkg/sentry/syscalls/linux/sys_eventfd.go b/pkg/sentry/syscalls/linux/sys_eventfd.go
new file mode 100644
index 000000000..60fe5a133
--- /dev/null
+++ b/pkg/sentry/syscalls/linux/sys_eventfd.go
@@ -0,0 +1,65 @@
+// 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 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)
+}