1 files changed, 61 insertions, 0 deletions
diff --git a/pkg/sentry/fs/proc/uptime.go b/pkg/sentry/fs/proc/uptime.go
new file mode 100644
index 000000000..4679d5821
--- /dev/null
+++ b/pkg/sentry/fs/proc/uptime.go
@@ -0,0 +1,61 @@
+// 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 proc
+
+import (
+	"fmt"
+	"io"
+
+	"gvisor.googlesource.com/gvisor/pkg/sentry/context"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/fs/ramfs"
+	ktime "gvisor.googlesource.com/gvisor/pkg/sentry/kernel/time"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/usermem"
+	"gvisor.googlesource.com/gvisor/pkg/syserror"
+)
+
+// uptime is a file containing the system uptime.
+type uptime struct {
+	ramfs.Entry
+
+	// The "start time" of the sandbox.
+	startTime ktime.Time
+}
+
+// newUptime returns a new uptime file.
+func (p *proc) newUptime(ctx context.Context, msrc *fs.MountSource) *fs.Inode {
+	u := &uptime{
+		startTime: ktime.NowFromContext(ctx),
+	}
+	u.InitEntry(ctx, fs.RootOwner, fs.FilePermsFromMode(0444))
+	return newFile(u, msrc, fs.SpecialFile, nil)
+}
+
+// DeprecatedPreadv reads the current uptime.
+func (u *uptime) DeprecatedPreadv(ctx context.Context, dst usermem.IOSequence, offset int64) (int64, error) {
+	if offset < 0 {
+		return 0, syserror.EINVAL
+	}
+
+	now := ktime.NowFromContext(ctx)
+	// Pretend that we've spent zero time sleeping (second number).
+	s := []byte(fmt.Sprintf("%.2f 0.00\n", now.Sub(u.startTime).Seconds()))
+	if offset >= int64(len(s)) {
+		return 0, io.EOF
+	}
+
+	n, err := dst.CopyOut(ctx, s[offset:])
+	return int64(n), err
+}