Check in gVisor.

PiperOrigin-RevId: 194583126
Change-Id: Ica1d8821a90f74e7e745962d71801c598c652463

1 files changed, 50 insertions, 0 deletions

diff --git a/pkg/sentry/kernel/pipe/buffers.go b/pkg/sentry/kernel/pipe/buffers.go
new file mode 100644
index 000000000..f300537c5
--- /dev/null
+++ b/pkg/sentry/kernel/pipe/buffers.go
@@ -0,0 +1,50 @@
+// 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 pipe
+
+import (
+	"gvisor.googlesource.com/gvisor/pkg/ilist"
+)
+
+// Buffer encapsulates a queueable byte buffer that can
+// easily be truncated.  It is designed only for use with pipes.
+type Buffer struct {
+	ilist.Entry
+	data []byte
+}
+
+// newBuffer initializes a Buffer.
+func newBuffer(buf []byte) *Buffer {
+	return &Buffer{data: buf}
+}
+
+// bytes returns the bytes contained in the buffer.
+func (b *Buffer) bytes() []byte {
+	return b.data
+}
+
+// size returns the number of bytes contained in the buffer.
+func (b *Buffer) size() int {
+	return len(b.data)
+}
+
+// truncate removes the first n bytes from the buffer.
+func (b *Buffer) truncate(n int) int {
+	if n > len(b.data) {
+		panic("Trying to truncate past end of array.")
+	}
+	b.data = b.data[n:]
+	return len(b.data)
+}