Make pipe buffer implementation standard.

A follow-up change will convert the networking code to use this standard
pipe implementation.

PiperOrigin-RevId: 297903206

1 files changed, 233 insertions, 0 deletions

diff --git a/pkg/buffer/view_test.go b/pkg/buffer/view_test.go
new file mode 100644
index 000000000..37e652f16
--- /dev/null
+++ b/pkg/buffer/view_test.go
@@ -0,0 +1,233 @@
+// 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
+
+import (
+	"bytes"
+	"strings"
+	"testing"
+)
+
+func TestView(t *testing.T) {
+	testCases := []struct {
+		name   string
+		input  string
+		output string
+		ops    []func(*View)
+	}{
+		// Prepend.
+		{
+			name:  "prepend",
+			input: "world",
+			ops: []func(*View){
+				func(v *View) {
+					v.Prepend([]byte("hello "))
+				},
+			},
+			output: "hello world",
+		},
+		{
+			name:  "prepend fill",
+			input: strings.Repeat("1", bufferSize-1),
+			ops: []func(*View){
+				func(v *View) {
+					v.Prepend([]byte("0"))
+				},
+			},
+			output: "0" + strings.Repeat("1", bufferSize-1),
+		},
+		{
+			name:  "prepend overflow",
+			input: strings.Repeat("1", bufferSize),
+			ops: []func(*View){
+				func(v *View) {
+					v.Prepend([]byte("0"))
+				},
+			},
+			output: "0" + strings.Repeat("1", bufferSize),
+		},
+		{
+			name:  "prepend multiple buffers",
+			input: strings.Repeat("1", bufferSize-1),
+			ops: []func(*View){
+				func(v *View) {
+					v.Prepend([]byte(strings.Repeat("0", bufferSize*3)))
+				},
+			},
+			output: strings.Repeat("0", bufferSize*3) + strings.Repeat("1", bufferSize-1),
+		},
+
+		// Append.
+		{
+			name:  "append",
+			input: "hello",
+			ops: []func(*View){
+				func(v *View) {
+					v.Append([]byte(" world"))
+				},
+			},
+			output: "hello world",
+		},
+		{
+			name:  "append fill",
+			input: strings.Repeat("1", bufferSize-1),
+			ops: []func(*View){
+				func(v *View) {
+					v.Append([]byte("0"))
+				},
+			},
+			output: strings.Repeat("1", bufferSize-1) + "0",
+		},
+		{
+			name:  "append overflow",
+			input: strings.Repeat("1", bufferSize),
+			ops: []func(*View){
+				func(v *View) {
+					v.Append([]byte("0"))
+				},
+			},
+			output: strings.Repeat("1", bufferSize) + "0",
+		},
+		{
+			name:  "append multiple buffers",
+			input: strings.Repeat("1", bufferSize-1),
+			ops: []func(*View){
+				func(v *View) {
+					v.Append([]byte(strings.Repeat("0", bufferSize*3)))
+				},
+			},
+			output: strings.Repeat("1", bufferSize-1) + strings.Repeat("0", bufferSize*3),
+		},
+
+		// Truncate.
+		{
+			name:  "truncate",
+			input: "hello world",
+			ops: []func(*View){
+				func(v *View) {
+					v.Truncate(5)
+				},
+			},
+			output: "hello",
+		},
+		{
+			name:  "truncate multiple buffers",
+			input: strings.Repeat("1", bufferSize*2),
+			ops: []func(*View){
+				func(v *View) {
+					v.Truncate(bufferSize*2 - 1)
+				},
+			},
+			output: strings.Repeat("1", bufferSize*2-1),
+		},
+		{
+			name:  "truncate multiple buffers to one buffer",
+			input: strings.Repeat("1", bufferSize*2),
+			ops: []func(*View){
+				func(v *View) {
+					v.Truncate(5)
+				},
+			},
+			output: "11111",
+		},
+
+		// TrimFront.
+		{
+			name:  "trim",
+			input: "hello world",
+			ops: []func(*View){
+				func(v *View) {
+					v.TrimFront(6)
+				},
+			},
+			output: "world",
+		},
+		{
+			name:  "trim multiple buffers",
+			input: strings.Repeat("1", bufferSize*2),
+			ops: []func(*View){
+				func(v *View) {
+					v.TrimFront(1)
+				},
+			},
+			output: strings.Repeat("1", bufferSize*2-1),
+		},
+		{
+			name:  "trim multiple buffers to one buffer",
+			input: strings.Repeat("1", bufferSize*2),
+			ops: []func(*View){
+				func(v *View) {
+					v.TrimFront(bufferSize*2 - 1)
+				},
+			},
+			output: "1",
+		},
+
+		// Grow.
+		{
+			name:  "grow",
+			input: "hello world",
+			ops: []func(*View){
+				func(v *View) {
+					v.Grow(1, true)
+				},
+			},
+			output: "hello world",
+		},
+		{
+			name: "grow from zero",
+			ops: []func(*View){
+				func(v *View) {
+					v.Grow(1024, true)
+				},
+			},
+			output: strings.Repeat("\x00", 1024),
+		},
+		{
+			name:  "grow from non-zero",
+			input: strings.Repeat("1", bufferSize),
+			ops: []func(*View){
+				func(v *View) {
+					v.Grow(bufferSize*2, true)
+				},
+			},
+			output: strings.Repeat("1", bufferSize) + strings.Repeat("\x00", bufferSize),
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			// Construct the new view.
+			var view View
+			view.Append([]byte(tc.input))
+
+			// Run all operations.
+			for _, op := range tc.ops {
+				op(&view)
+			}
+
+			// Flatten and validate.
+			out := view.Flatten()
+			if !bytes.Equal([]byte(tc.output), out) {
+				t.Errorf("expected %q, got %q", tc.output, string(out))
+			}
+
+			// Ensure the size is correct.
+			if len(out) != int(view.Size()) {
+				t.Errorf("size is wrong: expected %d, got %d", len(out), view.Size())
+			}
+		})
+	}
+}