2 files changed, 178 insertions, 0 deletions
diff --git a/pkg/sentry/kernel/fasync/fasync.go b/pkg/sentry/kernel/fasync/fasync.go
new file mode 100644
index 000000000..84cd08501
--- /dev/null
+++ b/pkg/sentry/kernel/fasync/fasync.go
@@ -0,0 +1,148 @@
+// 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 fasync provides FIOASYNC related functionality.
+package fasync
+
+import (
+	"sync"
+
+	"gvisor.googlesource.com/gvisor/pkg/abi/linux"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/kernel"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/kernel/auth"
+	"gvisor.googlesource.com/gvisor/pkg/waiter"
+)
+
+// New creates a new FileAsync.
+func New() fs.FileAsync {
+	return &FileAsync{}
+}
+
+// FileAsync sends signals when the registered file is ready for IO.
+//
+// +stateify savable
+type FileAsync struct {
+	mu        sync.Mutex `state:"nosave"`
+	e         waiter.Entry
+	requester *auth.Credentials
+
+	// Only one of the following is allowed to be non-nil.
+	recipientPG *kernel.ProcessGroup
+	recipientTG *kernel.ThreadGroup
+	recipientT  *kernel.Task
+}
+
+// Callback sends a signal.
+func (a *FileAsync) Callback(e *waiter.Entry) {
+	a.mu.Lock()
+	if a.e.Callback == nil {
+		a.mu.Unlock()
+		return
+	}
+	t := a.recipientT
+	tg := a.recipientTG
+	if a.recipientPG != nil {
+		tg = a.recipientPG.Originator()
+	}
+	if tg != nil {
+		t = tg.Leader()
+	}
+	if t == nil {
+		// No recipient has been registered.
+		a.mu.Unlock()
+		return
+	}
+	c := t.Credentials()
+	// Logic from sigio_perm in fs/fcntl.c.
+	if a.requester.EffectiveKUID == 0 ||
+		a.requester.EffectiveKUID == c.SavedKUID ||
+		a.requester.EffectiveKUID == c.RealKUID ||
+		a.requester.RealKUID == c.SavedKUID ||
+		a.requester.RealKUID == c.RealKUID {
+		t.SendSignal(kernel.SignalInfoPriv(linux.SIGIO))
+	}
+	a.mu.Unlock()
+}
+
+// Register sets the file which will be monitored for IO events.
+//
+// The file must not be currently registered.
+func (a *FileAsync) Register(w waiter.Waitable) {
+	a.mu.Lock()
+	defer a.mu.Unlock()
+
+	if a.e.Callback != nil {
+		panic("registering already registered file")
+	}
+
+	a.e.Callback = a
+	w.EventRegister(&a.e, waiter.EventIn|waiter.EventOut|waiter.EventErr|waiter.EventHUp)
+}
+
+// Unregister stops monitoring a file.
+//
+// The file must be currently registered.
+func (a *FileAsync) Unregister(w waiter.Waitable) {
+	a.mu.Lock()
+	defer a.mu.Unlock()
+
+	if a.e.Callback == nil {
+		panic("unregistering unregistered file")
+	}
+
+	w.EventUnregister(&a.e)
+	a.e.Callback = nil
+}
+
+// Owner returns who is currently getting signals. All return values will be
+// nil if no one is set to receive signals.
+func (a *FileAsync) Owner() (*kernel.Task, *kernel.ThreadGroup, *kernel.ProcessGroup) {
+	a.mu.Lock()
+	defer a.mu.Unlock()
+	return a.recipientT, a.recipientTG, a.recipientPG
+}
+
+// SetOwnerTask sets the owner (who will receive signals) to a specified task.
+// Only this owner will receive signals.
+func (a *FileAsync) SetOwnerTask(requester *kernel.Task, recipient *kernel.Task) {
+	a.mu.Lock()
+	defer a.mu.Unlock()
+	a.requester = requester.Credentials()
+	a.recipientT = recipient
+	a.recipientTG = nil
+	a.recipientPG = nil
+}
+
+// SetOwnerThreadGroup sets the owner (who will receive signals) to a specified
+// thread group. Only this owner will receive signals.
+func (a *FileAsync) SetOwnerThreadGroup(requester *kernel.Task, recipient *kernel.ThreadGroup) {
+	a.mu.Lock()
+	defer a.mu.Unlock()
+	a.requester = requester.Credentials()
+	a.recipientT = nil
+	a.recipientTG = recipient
+	a.recipientPG = nil
+}
+
+// SetOwnerProcessGroup sets the owner (who will receive signals) to a
+// specified process group. Only this owner will receive signals.
+func (a *FileAsync) SetOwnerProcessGroup(requester *kernel.Task, recipient *kernel.ProcessGroup) {
+	a.mu.Lock()
+	defer a.mu.Unlock()
+	a.requester = requester.Credentials()
+	a.recipientT = nil
+	a.recipientTG = nil
+	a.recipientPG = recipient
+}
diff --git a/pkg/sentry/kernel/fasync/fasync_state_autogen.go b/pkg/sentry/kernel/fasync/fasync_state_autogen.go
new file mode 100755
index 000000000..e162e0033
--- /dev/null
+++ b/pkg/sentry/kernel/fasync/fasync_state_autogen.go
@@ -0,0 +1,30 @@
+// automatically generated by stateify.
+
+package fasync
+
+import (
+	"gvisor.googlesource.com/gvisor/pkg/state"
+)
+
+func (x *FileAsync) beforeSave() {}
+func (x *FileAsync) save(m state.Map) {
+	x.beforeSave()
+	m.Save("e", &x.e)
+	m.Save("requester", &x.requester)
+	m.Save("recipientPG", &x.recipientPG)
+	m.Save("recipientTG", &x.recipientTG)
+	m.Save("recipientT", &x.recipientT)
+}
+
+func (x *FileAsync) afterLoad() {}
+func (x *FileAsync) load(m state.Map) {
+	m.Load("e", &x.e)
+	m.Load("requester", &x.requester)
+	m.Load("recipientPG", &x.recipientPG)
+	m.Load("recipientTG", &x.recipientTG)
+	m.Load("recipientT", &x.recipientT)
+}
+
+func init() {
+	state.Register("fasync.FileAsync", (*FileAsync)(nil), state.Fns{Save: (*FileAsync).save, Load: (*FileAsync).load})
+}