4 files changed, 221 insertions, 0 deletions
diff --git a/pkg/sentry/state/BUILD b/pkg/sentry/state/BUILD
new file mode 100644
index 000000000..0ea4aab8b
--- /dev/null
+++ b/pkg/sentry/state/BUILD
@@ -0,0 +1,23 @@
+load("//tools:defs.bzl", "go_library")
+
+package(licenses = ["notice"])
+
+go_library(
+    name = "state",
+    srcs = [
+        "state.go",
+        "state_metadata.go",
+        "state_unsafe.go",
+    ],
+    visibility = ["//pkg/sentry:internal"],
+    deps = [
+        "//pkg/abi/linux",
+        "//pkg/log",
+        "//pkg/sentry/inet",
+        "//pkg/sentry/kernel",
+        "//pkg/sentry/time",
+        "//pkg/sentry/watchdog",
+        "//pkg/state/statefile",
+        "//pkg/syserror",
+    ],
+)
diff --git a/pkg/sentry/state/state.go b/pkg/sentry/state/state.go
new file mode 100644
index 000000000..9eb626b76
--- /dev/null
+++ b/pkg/sentry/state/state.go
@@ -0,0 +1,119 @@
+// 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 state provides high-level state wrappers.
+package state
+
+import (
+	"fmt"
+	"io"
+
+	"gvisor.dev/gvisor/pkg/log"
+	"gvisor.dev/gvisor/pkg/sentry/inet"
+	"gvisor.dev/gvisor/pkg/sentry/kernel"
+	"gvisor.dev/gvisor/pkg/sentry/time"
+	"gvisor.dev/gvisor/pkg/sentry/watchdog"
+	"gvisor.dev/gvisor/pkg/state/statefile"
+	"gvisor.dev/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, clocks time.Clocks) 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, clocks)
+}
diff --git a/pkg/sentry/state/state_metadata.go b/pkg/sentry/state/state_metadata.go
new file mode 100644
index 000000000..cefd20b9b
--- /dev/null
+++ b/pkg/sentry/state/state_metadata.go
@@ -0,0 +1,45 @@
+// 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 state
+
+import (
+	"fmt"
+	"time"
+
+	"gvisor.dev/gvisor/pkg/log"
+)
+
+// The save metadata keys for timestamp.
+const (
+	cpuUsage          = "cpu_usage"
+	metadataTimestamp = "timestamp"
+)
+
+func addSaveMetadata(m map[string]string) {
+	t, err := CPUTime()
+	if err != nil {
+		log.Warningf("Error getting cpu time: %v", err)
+	}
+	if previousMetadata != nil {
+		p, err := time.ParseDuration(previousMetadata[cpuUsage])
+		if err != nil {
+			log.Warningf("Error parsing previous runs' cpu time: %v", err)
+		}
+		t += p
+	}
+	m[cpuUsage] = t.String()
+
+	m[metadataTimestamp] = fmt.Sprintf("%v", time.Now())
+}
diff --git a/pkg/sentry/state/state_unsafe.go b/pkg/sentry/state/state_unsafe.go
new file mode 100644
index 000000000..d271c6fc9
--- /dev/null
+++ b/pkg/sentry/state/state_unsafe.go
@@ -0,0 +1,34 @@
+// 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 state
+
+import (
+	"fmt"
+	"syscall"
+	"time"
+	"unsafe"
+
+	"gvisor.dev/gvisor/pkg/abi/linux"
+)
+
+// CPUTime returns the CPU time usage by Sentry and app.
+func CPUTime() (time.Duration, error) {
+	var ts syscall.Timespec
+	_, _, errno := syscall.RawSyscall(syscall.SYS_CLOCK_GETTIME, uintptr(linux.CLOCK_PROCESS_CPUTIME_ID), uintptr(unsafe.Pointer(&ts)), 0)
+	if errno != 0 {
+		return 0, fmt.Errorf("failed calling clock_gettime(CLOCK_PROCESS_CPUTIME_ID): errno=%d", errno)
+	}
+	return time.Duration(ts.Nano()), nil
+}