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// Copyright 2018 Google LLC
//
// 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 state provides high-level state wrappers.
package state
import (
"fmt"
"io"
"gvisor.googlesource.com/gvisor/pkg/log"
"gvisor.googlesource.com/gvisor/pkg/sentry/inet"
"gvisor.googlesource.com/gvisor/pkg/sentry/kernel"
"gvisor.googlesource.com/gvisor/pkg/sentry/watchdog"
"gvisor.googlesource.com/gvisor/pkg/state/statefile"
"gvisor.googlesource.com/gvisor/pkg/syserror"
)
var previousMetadata map[string]string
// ErrStateFile is returned when an error is encountered writing the statefile
// (which may occur during open or close calls in addition to write).
type ErrStateFile struct {
err error
}
// Error implements error.Error().
func (e ErrStateFile) Error() string {
return fmt.Sprintf("statefile error: %v", e.err)
}
// SaveOpts contains save-related options.
type SaveOpts struct {
// Destination is the save target.
Destination io.Writer
// Key is used for state integrity check.
Key []byte
// Metadata is save metadata.
Metadata map[string]string
// Callback is called prior to unpause, with any save error.
Callback func(err error)
}
// Save saves the system state.
func (opts SaveOpts) Save(k *kernel.Kernel, w *watchdog.Watchdog) error {
log.Infof("Sandbox save started, pausing all tasks.")
k.Pause()
defer k.Unpause()
defer log.Infof("Tasks resumed after save.")
w.Stop()
defer w.Start()
// Supplement the metadata.
if opts.Metadata == nil {
opts.Metadata = make(map[string]string)
}
addSaveMetadata(opts.Metadata)
// Open the statefile.
wc, err := statefile.NewWriter(opts.Destination, opts.Key, opts.Metadata)
if err != nil {
err = ErrStateFile{err}
} else {
// Save the kernel.
err = k.SaveTo(wc)
// ENOSPC is a state file error. This error can only come from
// writing the state file, and not from fs.FileOperations.Fsync
// because we wrap those in kernel.TaskSet.flushWritesToFiles.
if err == syserror.ENOSPC {
err = ErrStateFile{err}
}
if closeErr := wc.Close(); err == nil && closeErr != nil {
err = ErrStateFile{closeErr}
}
}
opts.Callback(err)
return err
}
// LoadOpts contains load-related options.
type LoadOpts struct {
// Destination is the load source.
Source io.Reader
// Key is used for state integrity check.
Key []byte
}
// Load loads the given kernel, setting the provided platform and stack.
func (opts LoadOpts) Load(k *kernel.Kernel, n inet.Stack) error {
// Open the file.
r, m, err := statefile.NewReader(opts.Source, opts.Key)
if err != nil {
return ErrStateFile{err}
}
previousMetadata = m
// Restore the Kernel object graph.
return k.LoadFrom(r, n)
}
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