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// Copyright 2019 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 ext
import (
"bytes"
"testing"
"github.com/google/go-cmp/cmp"
"github.com/google/go-cmp/cmp/cmpopts"
"gvisor.dev/gvisor/pkg/binary"
"gvisor.dev/gvisor/pkg/sentry/fs/ext/disklayout"
)
// TestExtentTree tests the extent tree building logic.
//
// Test tree:
// 0.{Head}[Idx][Idx]
// / \
// / \
// 1.{Head}[Ext][Ext] 2.{Head}[Idx]
// / | \
// [Phy] [Phy, Phy] 3.{Head}[Ext]
// |
// [Phy, Phy, Phy]
//
// Legend:
// - Head = ExtentHeader
// - Idx = ExtentIdx
// - Ext = Extent
// - Phy = Physical Block
//
// Please note that ext4 might not construct extent trees looking like this.
// This is purely for testing the tree traversal logic.
func TestExtentTree(t *testing.T) {
blkSize := uint64(64) // No block has more than 1 header + 4 entries.
mockDisk := make([]byte, blkSize*10)
mockInode := &inode{diskInode: &disklayout.InodeNew{}}
node3 := &disklayout.ExtentNode{
Header: disklayout.ExtentHeader{
Magic: disklayout.ExtentMagic,
NumEntries: 1,
MaxEntries: 4,
Height: 0,
},
Entries: []disklayout.ExtentEntryPair{
{
Entry: &disklayout.Extent{
FirstFileBlock: 3,
Length: 3,
StartBlockLo: 6,
},
Node: nil,
},
},
}
node2 := &disklayout.ExtentNode{
Header: disklayout.ExtentHeader{
Magic: disklayout.ExtentMagic,
NumEntries: 1,
MaxEntries: 4,
Height: 1,
},
Entries: []disklayout.ExtentEntryPair{
{
Entry: &disklayout.ExtentIdx{
FirstFileBlock: 3,
ChildBlockLo: 2,
},
Node: node3,
},
},
}
node1 := &disklayout.ExtentNode{
Header: disklayout.ExtentHeader{
Magic: disklayout.ExtentMagic,
NumEntries: 2,
MaxEntries: 4,
Height: 0,
},
Entries: []disklayout.ExtentEntryPair{
{
Entry: &disklayout.Extent{
FirstFileBlock: 0,
Length: 1,
StartBlockLo: 3,
},
Node: nil,
},
{
Entry: &disklayout.Extent{
FirstFileBlock: 1,
Length: 2,
StartBlockLo: 4,
},
Node: nil,
},
},
}
node0 := &disklayout.ExtentNode{
Header: disklayout.ExtentHeader{
Magic: disklayout.ExtentMagic,
NumEntries: 2,
MaxEntries: 4,
Height: 2,
},
Entries: []disklayout.ExtentEntryPair{
{
Entry: &disklayout.ExtentIdx{
FirstFileBlock: 0,
ChildBlockLo: 0,
},
Node: node1,
},
{
Entry: &disklayout.ExtentIdx{
FirstFileBlock: 3,
ChildBlockLo: 1,
},
Node: node2,
},
},
}
writeTree(mockInode, mockDisk, node0, blkSize)
r := bytes.NewReader(mockDisk)
if err := mockInode.buildExtTree(r, blkSize); err != nil {
t.Fatalf("inode.buildExtTree failed: %v", err)
}
opt := cmpopts.IgnoreUnexported(disklayout.ExtentIdx{}, disklayout.ExtentHeader{})
if diff := cmp.Diff(mockInode.root, node0, opt); diff != "" {
t.Errorf("extent tree mismatch (-want +got):\n%s", diff)
}
}
// writeTree writes the tree represented by `root` to the inode and disk passed.
func writeTree(in *inode, disk []byte, root *disklayout.ExtentNode, blkSize uint64) {
rootData := binary.Marshal(nil, binary.LittleEndian, root.Header)
for _, ep := range root.Entries {
rootData = binary.Marshal(rootData, binary.LittleEndian, ep.Entry)
}
copy(in.diskInode.Data(), rootData)
if root.Header.Height > 0 {
for _, ep := range root.Entries {
writeTreeToDisk(disk, ep, blkSize)
}
}
}
// writeTreeToDisk is the recursive step for writeTree which writes the tree
// on the disk only.
func writeTreeToDisk(disk []byte, curNode disklayout.ExtentEntryPair, blkSize uint64) {
nodeData := binary.Marshal(nil, binary.LittleEndian, curNode.Node.Header)
for _, ep := range curNode.Node.Entries {
nodeData = binary.Marshal(nodeData, binary.LittleEndian, ep.Entry)
}
copy(disk[curNode.Entry.PhysicalBlock()*blkSize:], nodeData)
if curNode.Node.Header.Height > 0 {
for _, ep := range curNode.Node.Entries {
writeTreeToDisk(disk, ep, blkSize)
}
}
}
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