1 files changed, 105 insertions, 0 deletions
diff --git a/pkg/buffer/buffer.go b/pkg/buffer/buffer.go
new file mode 100644
index 000000000..5b77a6a3f
--- /dev/null
+++ b/pkg/buffer/buffer.go
@@ -0,0 +1,105 @@
+// Copyright 2020 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 buffer provides the implementation of a buffer view.
+//
+// A view is an flexible buffer, supporting the safecopy operations natively as
+// well as the ability to grow via either prepend or append, as well as shrink.
+package buffer
+
+// buffer encapsulates a queueable byte buffer.
+//
+// +stateify savable
+type buffer struct {
+	data  []byte
+	read  int
+	write int
+	bufferEntry
+}
+
+// init performs in-place initialization for zero value.
+func (b *buffer) init(size int) {
+	b.data = make([]byte, size)
+}
+
+// initWithData initializes b with data, taking ownership.
+func (b *buffer) initWithData(data []byte) {
+	b.data = data
+	b.read = 0
+	b.write = len(data)
+}
+
+// Reset resets read and write locations, effectively emptying the buffer.
+func (b *buffer) Reset() {
+	b.read = 0
+	b.write = 0
+}
+
+// Remove removes r from the unread portion. It returns false if r does not
+// fully reside in b.
+func (b *buffer) Remove(r Range) bool {
+	sz := b.ReadSize()
+	switch {
+	case r.Len() != r.Intersect(Range{end: sz}).Len():
+		return false
+	case r.Len() == 0:
+		// Noop
+	case r.begin == 0:
+		b.read += r.end
+	case r.end == sz:
+		b.write -= r.Len()
+	default:
+		// Remove from the middle of b.data.
+		copy(b.data[b.read+r.begin:], b.data[b.read+r.end:b.write])
+		b.write -= r.Len()
+	}
+	return true
+}
+
+// Full indicates the buffer is full.
+//
+// This indicates there is no capacity left to write.
+func (b *buffer) Full() bool {
+	return b.write == len(b.data)
+}
+
+// ReadSize returns the number of bytes available for reading.
+func (b *buffer) ReadSize() int {
+	return b.write - b.read
+}
+
+// ReadMove advances the read index by the given amount.
+func (b *buffer) ReadMove(n int) {
+	b.read += n
+}
+
+// ReadSlice returns the read slice for this buffer.
+func (b *buffer) ReadSlice() []byte {
+	return b.data[b.read:b.write]
+}
+
+// WriteSize returns the number of bytes available for writing.
+func (b *buffer) WriteSize() int {
+	return len(b.data) - b.write
+}
+
+// WriteMove advances the write index by the given amount.
+func (b *buffer) WriteMove(n int) {
+	b.write += n
+}
+
+// WriteSlice returns the write slice for this buffer.
+func (b *buffer) WriteSlice() []byte {
+	return b.data[b.write:]
+}