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-rw-r--r--pkg/sentry/fs/ext/block_map_file.go82
-rw-r--r--pkg/sentry/fs/ext/block_map_test.go14
-rw-r--r--pkg/sentry/fs/ext/extent_file.go91
-rw-r--r--pkg/sentry/fs/ext/extent_test.go17
-rw-r--r--pkg/sentry/fs/ext/filesystem.go13
-rw-r--r--pkg/sentry/fs/ext/inline_file.go35
-rw-r--r--pkg/sentry/fs/ext/inode.go24
-rw-r--r--pkg/sentry/fs/ext/regular_file.go22
-rw-r--r--pkg/sentry/fs/ext/symlink.go9
9 files changed, 121 insertions, 186 deletions
diff --git a/pkg/sentry/fs/ext/block_map_file.go b/pkg/sentry/fs/ext/block_map_file.go
index e9b11d65d..f30c3a174 100644
--- a/pkg/sentry/fs/ext/block_map_file.go
+++ b/pkg/sentry/fs/ext/block_map_file.go
@@ -53,27 +53,17 @@ type blockMapFile struct {
coverage [4]uint64
}
-// Compiles only if blockMapFile implements fileReader.
-var _ fileReader = (*blockMapFile)(nil)
-
-// Read implements fileReader.getFileReader.
-func (f *blockMapFile) getFileReader(dev io.ReaderAt, blkSize uint64, offset uint64) io.Reader {
- return &blockMapReader{
- dev: dev,
- file: f,
- fileOff: offset,
- blkSize: blkSize,
- }
-}
+// Compiles only if blockMapFile implements io.ReaderAt.
+var _ io.ReaderAt = (*blockMapFile)(nil)
// newBlockMapFile is the blockMapFile constructor. It initializes the file to
// physical blocks map with (at most) the first 12 (direct) blocks.
-func newBlockMapFile(blkSize uint64, regFile regularFile) (*blockMapFile, error) {
+func newBlockMapFile(regFile regularFile) (*blockMapFile, error) {
file := &blockMapFile{regFile: regFile}
file.regFile.impl = file
for i := uint(0); i < 4; i++ {
- file.coverage[i] = getCoverage(blkSize, i)
+ file.coverage[i] = getCoverage(regFile.inode.blkSize, i)
}
blkMap := regFile.inode.diskInode.Data()
@@ -84,40 +74,33 @@ func newBlockMapFile(blkSize uint64, regFile regularFile) (*blockMapFile, error)
return file, nil
}
-// blockMapReader implements io.Reader which will fetch fill data from the
-// block maps and build the blockMapFile.fileToPhyBlks array if required.
-type blockMapReader struct {
- dev io.ReaderAt
- file *blockMapFile
- fileOff uint64
- blkSize uint64
-}
-
-// Compiles only if blockMapReader implements io.Reader.
-var _ io.Reader = (*blockMapReader)(nil)
-
-// Read implements io.Reader.Read.
-func (r *blockMapReader) Read(dst []byte) (int, error) {
+// ReadAt implements io.ReaderAt.ReadAt.
+func (f *blockMapFile) ReadAt(dst []byte, off int64) (int, error) {
if len(dst) == 0 {
return 0, nil
}
- if r.fileOff >= r.file.regFile.inode.diskInode.Size() {
+ if off < 0 {
+ return 0, syserror.EINVAL
+ }
+
+ offset := uint64(off)
+ if offset >= f.regFile.inode.diskInode.Size() {
return 0, io.EOF
}
// dirBlksEnd is the file offset until which direct blocks cover file data.
// Direct blocks cover 0 <= file offset < dirBlksEnd.
- dirBlksEnd := numDirectBlks * r.file.coverage[0]
+ dirBlksEnd := numDirectBlks * f.coverage[0]
// indirBlkEnd is the file offset until which the indirect block covers file
// data. The indirect block covers dirBlksEnd <= file offset < indirBlkEnd.
- indirBlkEnd := dirBlksEnd + r.file.coverage[1]
+ indirBlkEnd := dirBlksEnd + f.coverage[1]
// doubIndirBlkEnd is the file offset until which the double indirect block
// covers file data. The double indirect block covers the range
// indirBlkEnd <= file offset < doubIndirBlkEnd.
- doubIndirBlkEnd := indirBlkEnd + r.file.coverage[2]
+ doubIndirBlkEnd := indirBlkEnd + f.coverage[2]
read := 0
toRead := len(dst)
@@ -127,21 +110,22 @@ func (r *blockMapReader) Read(dst []byte) (int, error) {
// Figure out which block to delegate the read to.
switch {
- case r.fileOff < dirBlksEnd:
+ case offset < dirBlksEnd:
// Direct block.
- curR, err = r.read(r.file.directBlks[r.fileOff/r.blkSize], r.fileOff%r.blkSize, 0, dst[read:])
- case r.fileOff < indirBlkEnd:
+ curR, err = f.read(f.directBlks[offset/f.regFile.inode.blkSize], offset%f.regFile.inode.blkSize, 0, dst[read:])
+ case offset < indirBlkEnd:
// Indirect block.
- curR, err = r.read(r.file.indirectBlk, r.fileOff-dirBlksEnd, 1, dst[read:])
- case r.fileOff < doubIndirBlkEnd:
+ curR, err = f.read(f.indirectBlk, offset-dirBlksEnd, 1, dst[read:])
+ case offset < doubIndirBlkEnd:
// Doubly indirect block.
- curR, err = r.read(r.file.doubleIndirectBlk, r.fileOff-indirBlkEnd, 2, dst[read:])
+ curR, err = f.read(f.doubleIndirectBlk, offset-indirBlkEnd, 2, dst[read:])
default:
// Triply indirect block.
- curR, err = r.read(r.file.tripleIndirectBlk, r.fileOff-doubIndirBlkEnd, 3, dst[read:])
+ curR, err = f.read(f.tripleIndirectBlk, offset-doubIndirBlkEnd, 3, dst[read:])
}
read += curR
+ offset += uint64(curR)
if err != nil {
return read, err
}
@@ -150,30 +134,29 @@ func (r *blockMapReader) Read(dst []byte) (int, error) {
return read, nil
}
-// read is the recursive step of the Read function. It relies on knowing the
+// read is the recursive step of the ReadAt function. It relies on knowing the
// current node's location on disk (curPhyBlk) and its height in the block map
// tree. A height of 0 shows that the current node is actually holding file
// data. relFileOff tells the offset from which we need to start to reading
// under the current node. It is completely relative to the current node.
-func (r *blockMapReader) read(curPhyBlk uint32, relFileOff uint64, height uint, dst []byte) (int, error) {
- curPhyBlkOff := int64(curPhyBlk) * int64(r.blkSize)
+func (f *blockMapFile) read(curPhyBlk uint32, relFileOff uint64, height uint, dst []byte) (int, error) {
+ curPhyBlkOff := int64(curPhyBlk) * int64(f.regFile.inode.blkSize)
if height == 0 {
- toRead := int(r.blkSize - relFileOff)
+ toRead := int(f.regFile.inode.blkSize - relFileOff)
if len(dst) < toRead {
toRead = len(dst)
}
- n, _ := r.dev.ReadAt(dst[:toRead], curPhyBlkOff+int64(relFileOff))
- r.fileOff += uint64(n)
+ n, _ := f.regFile.inode.dev.ReadAt(dst[:toRead], curPhyBlkOff+int64(relFileOff))
if n < toRead {
return n, syserror.EIO
}
return n, nil
}
- childCov := r.file.coverage[height-1]
+ childCov := f.coverage[height-1]
startIdx := relFileOff / childCov
- endIdx := r.blkSize / 4 // This is exclusive.
+ endIdx := f.regFile.inode.blkSize / 4 // This is exclusive.
wantEndIdx := (relFileOff + uint64(len(dst))) / childCov
wantEndIdx++ // Make this exclusive.
if wantEndIdx < endIdx {
@@ -184,11 +167,12 @@ func (r *blockMapReader) read(curPhyBlk uint32, relFileOff uint64, height uint,
curChildOff := relFileOff % childCov
for i := startIdx; i < endIdx; i++ {
var childPhyBlk uint32
- if err := readFromDisk(r.dev, curPhyBlkOff+int64(i*4), &childPhyBlk); err != nil {
+ err := readFromDisk(f.regFile.inode.dev, curPhyBlkOff+int64(i*4), &childPhyBlk)
+ if err != nil {
return read, err
}
- n, err := r.read(childPhyBlk, curChildOff, height-1, dst[read:])
+ n, err := f.read(childPhyBlk, curChildOff, height-1, dst[read:])
read += n
if err != nil {
return read, err
diff --git a/pkg/sentry/fs/ext/block_map_test.go b/pkg/sentry/fs/ext/block_map_test.go
index b92ae80c8..f8dd6bf9f 100644
--- a/pkg/sentry/fs/ext/block_map_test.go
+++ b/pkg/sentry/fs/ext/block_map_test.go
@@ -16,7 +16,6 @@ package ext
import (
"bytes"
- "io"
"math/rand"
"testing"
@@ -34,14 +33,13 @@ const (
// TestBlockMapReader stress tests block map reader functionality. It performs
// random length reads from all possible positions in the block map structure.
func TestBlockMapReader(t *testing.T) {
- dev, mockBMFile, want := blockMapSetUp(t)
+ mockBMFile, want := blockMapSetUp(t)
n := len(want)
for from := 0; from < n; from++ {
- fileReader := mockBMFile.getFileReader(dev, uint64(mockBMBlkSize), uint64(from))
got := make([]byte, n-from)
- if read, err := io.ReadFull(fileReader, got); err != nil {
+ if read, err := mockBMFile.ReadAt(got, int64(from)); err != nil {
t.Fatalf("file read operation from offset %d to %d only read %d bytes: %v", from, n, read, err)
}
@@ -85,7 +83,7 @@ func (n *blkNumGen) next() uint32 {
// block and 1 triple indirect block (basically fill it till the rim). It
// initializes the disk to reflect the inode. Also returns the file data that
// the inode covers and that is written to disk.
-func blockMapSetUp(t *testing.T) (io.ReaderAt, *blockMapFile, []byte) {
+func blockMapSetUp(t *testing.T) (*blockMapFile, []byte) {
mockDisk := make([]byte, mockBMDiskSize)
regFile := regularFile{
inode: inode{
@@ -94,6 +92,8 @@ func blockMapSetUp(t *testing.T) (io.ReaderAt, *blockMapFile, []byte) {
SizeLo: getMockBMFileFize(),
},
},
+ dev: bytes.NewReader(mockDisk),
+ blkSize: uint64(mockBMBlkSize),
},
}
@@ -125,11 +125,11 @@ func blockMapSetUp(t *testing.T) (io.ReaderAt, *blockMapFile, []byte) {
copy(regFile.inode.diskInode.Data(), data)
- mockFile, err := newBlockMapFile(uint64(mockBMBlkSize), regFile)
+ mockFile, err := newBlockMapFile(regFile)
if err != nil {
t.Fatalf("newBlockMapFile failed: %v", err)
}
- return bytes.NewReader(mockDisk), mockFile, fileData
+ return mockFile, fileData
}
// writeFileDataToBlock writes random bytes to the block on disk.
diff --git a/pkg/sentry/fs/ext/extent_file.go b/pkg/sentry/fs/ext/extent_file.go
index aa4102dbb..44fb9c01f 100644
--- a/pkg/sentry/fs/ext/extent_file.go
+++ b/pkg/sentry/fs/ext/extent_file.go
@@ -32,26 +32,16 @@ type extentFile struct {
root disklayout.ExtentNode
}
-// Compiles only if extentFile implements fileReader.
-var _ fileReader = (*extentFile)(nil)
-
-// Read implements fileReader.getFileReader.
-func (f *extentFile) getFileReader(dev io.ReaderAt, blkSize uint64, offset uint64) io.Reader {
- return &extentReader{
- dev: dev,
- file: f,
- fileOff: offset,
- blkSize: blkSize,
- }
-}
+// Compiles only if extentFile implements io.ReaderAt.
+var _ io.ReaderAt = (*extentFile)(nil)
// newExtentFile is the extent file constructor. It reads the entire extent
// tree into memory.
// TODO(b/134676337): Build extent tree on demand to reduce memory usage.
-func newExtentFile(dev io.ReaderAt, blkSize uint64, regFile regularFile) (*extentFile, error) {
+func newExtentFile(regFile regularFile) (*extentFile, error) {
file := &extentFile{regFile: regFile}
file.regFile.impl = file
- err := file.buildExtTree(dev, blkSize)
+ err := file.buildExtTree()
if err != nil {
return nil, err
}
@@ -64,7 +54,7 @@ func newExtentFile(dev io.ReaderAt, blkSize uint64, regFile regularFile) (*exten
// disk.
//
// Precondition: inode flag InExtents must be set.
-func (f *extentFile) buildExtTree(dev io.ReaderAt, blkSize uint64) error {
+func (f *extentFile) buildExtTree() error {
rootNodeData := f.regFile.inode.diskInode.Data()
binary.Unmarshal(rootNodeData[:disklayout.ExtentStructsSize], binary.LittleEndian, &f.root.Header)
@@ -94,7 +84,7 @@ func (f *extentFile) buildExtTree(dev io.ReaderAt, blkSize uint64) error {
if f.root.Header.Height > 0 {
for i := uint16(0); i < f.root.Header.NumEntries; i++ {
var err error
- if f.root.Entries[i].Node, err = buildExtTreeFromDisk(dev, f.root.Entries[i].Entry, blkSize); err != nil {
+ if f.root.Entries[i].Node, err = f.buildExtTreeFromDisk(f.root.Entries[i].Entry); err != nil {
return err
}
}
@@ -106,10 +96,10 @@ func (f *extentFile) buildExtTree(dev io.ReaderAt, blkSize uint64) error {
// buildExtTreeFromDisk reads the extent tree nodes from disk and recursively
// builds the tree. Performs a simple DFS. It returns the ExtentNode pointed to
// by the ExtentEntry.
-func buildExtTreeFromDisk(dev io.ReaderAt, entry disklayout.ExtentEntry, blkSize uint64) (*disklayout.ExtentNode, error) {
+func (f *extentFile) buildExtTreeFromDisk(entry disklayout.ExtentEntry) (*disklayout.ExtentNode, error) {
var header disklayout.ExtentHeader
- off := entry.PhysicalBlock() * blkSize
- err := readFromDisk(dev, int64(off), &header)
+ off := entry.PhysicalBlock() * f.regFile.inode.blkSize
+ err := readFromDisk(f.regFile.inode.dev, int64(off), &header)
if err != nil {
return nil, err
}
@@ -125,7 +115,7 @@ func buildExtTreeFromDisk(dev io.ReaderAt, entry disklayout.ExtentEntry, blkSize
curEntry = &disklayout.ExtentIdx{}
}
- err := readFromDisk(dev, int64(off), curEntry)
+ err := readFromDisk(f.regFile.inode.dev, int64(off), curEntry)
if err != nil {
return nil, err
}
@@ -136,7 +126,7 @@ func buildExtTreeFromDisk(dev io.ReaderAt, entry disklayout.ExtentEntry, blkSize
if header.Height > 0 {
for i := uint16(0); i < header.NumEntries; i++ {
var err error
- entries[i].Node, err = buildExtTreeFromDisk(dev, entries[i].Entry, blkSize)
+ entries[i].Node, err = f.buildExtTreeFromDisk(entries[i].Entry)
if err != nil {
return nil, err
}
@@ -146,38 +136,31 @@ func buildExtTreeFromDisk(dev io.ReaderAt, entry disklayout.ExtentEntry, blkSize
return &disklayout.ExtentNode{header, entries}, nil
}
-// extentReader implements io.Reader which can traverse the extent tree and
-// read file data. This is not thread safe.
-type extentReader struct {
- dev io.ReaderAt
- file *extentFile
- fileOff uint64 // Represents the current file offset being read from.
- blkSize uint64
-}
-
-// Compiles only if inlineReader implements io.Reader.
-var _ io.Reader = (*extentReader)(nil)
-
-// Read implements io.Reader.Read.
-func (r *extentReader) Read(dst []byte) (int, error) {
+// ReadAt implements io.ReaderAt.ReadAt.
+func (f *extentFile) ReadAt(dst []byte, off int64) (int, error) {
if len(dst) == 0 {
return 0, nil
}
- if r.fileOff >= r.file.regFile.inode.diskInode.Size() {
+ if off < 0 {
+ return 0, syserror.EINVAL
+ }
+
+ if uint64(off) >= f.regFile.inode.diskInode.Size() {
return 0, io.EOF
}
- return r.read(&r.file.root, dst)
+ return f.read(&f.root, uint64(off), dst)
}
-// read is a helper which traverses the extent tree and reads data.
-func (r *extentReader) read(node *disklayout.ExtentNode, dst []byte) (int, error) {
+// read is the recursive step of extentFile.ReadAt which traverses the extent
+// tree from the node passed and reads file data.
+func (f *extentFile) read(node *disklayout.ExtentNode, off uint64, dst []byte) (int, error) {
// Perform a binary search for the node covering bytes starting at r.fileOff.
// A highly fragmented filesystem can have upto 340 entries and so linear
// search should be avoided. Finds the first entry which does not cover the
// file block we want and subtracts 1 to get the desired index.
- fileBlk := r.fileBlock()
+ fileBlk := uint32(off / f.regFile.inode.blkSize)
n := len(node.Entries)
found := sort.Search(n, func(i int) bool {
return node.Entries[i].Entry.FileBlock() > fileBlk
@@ -195,12 +178,13 @@ func (r *extentReader) read(node *disklayout.ExtentNode, dst []byte) (int, error
var err error
for i := found; i < n && read < toRead; i++ {
if node.Header.Height == 0 {
- curR, err = r.readFromExtent(node.Entries[i].Entry.(*disklayout.Extent), dst[read:])
+ curR, err = f.readFromExtent(node.Entries[i].Entry.(*disklayout.Extent), off, dst[read:])
} else {
- curR, err = r.read(node.Entries[i].Node, dst[read:])
+ curR, err = f.read(node.Entries[i].Node, off, dst[read:])
}
read += curR
+ off += uint64(curR)
if err != nil {
return read, err
}
@@ -211,7 +195,7 @@ func (r *extentReader) read(node *disklayout.ExtentNode, dst []byte) (int, error
// readFromExtent reads file data from the extent. It takes advantage of the
// sequential nature of extents and reads file data from multiple blocks in one
-// call. Also updates the file offset.
+// call.
//
// A non-nil error indicates that this is a partial read and there is probably
// more to read from this extent. The caller should propagate the error upward
@@ -219,8 +203,8 @@ func (r *extentReader) read(node *disklayout.ExtentNode, dst []byte) (int, error
//
// A subsequent call to extentReader.Read should continue reading from where we
// left off as expected.
-func (r *extentReader) readFromExtent(ex *disklayout.Extent, dst []byte) (int, error) {
- curFileBlk := r.fileBlock()
+func (f *extentFile) readFromExtent(ex *disklayout.Extent, off uint64, dst []byte) (int, error) {
+ curFileBlk := uint32(off / f.regFile.inode.blkSize)
exFirstFileBlk := ex.FileBlock()
exLastFileBlk := exFirstFileBlk + uint32(ex.Length) // This is exclusive.
@@ -231,30 +215,19 @@ func (r *extentReader) readFromExtent(ex *disklayout.Extent, dst []byte) (int, e
}
curPhyBlk := uint64(curFileBlk-exFirstFileBlk) + ex.PhysicalBlock()
- readStart := curPhyBlk*r.blkSize + r.fileBlockOff()
+ readStart := curPhyBlk*f.regFile.inode.blkSize + (off % f.regFile.inode.blkSize)
endPhyBlk := ex.PhysicalBlock() + uint64(ex.Length)
- extentEnd := endPhyBlk * r.blkSize // This is exclusive.
+ extentEnd := endPhyBlk * f.regFile.inode.blkSize // This is exclusive.
toRead := int(extentEnd - readStart)
if len(dst) < toRead {
toRead = len(dst)
}
- n, _ := r.dev.ReadAt(dst[:toRead], int64(readStart))
- r.fileOff += uint64(n)
+ n, _ := f.regFile.inode.dev.ReadAt(dst[:toRead], int64(readStart))
if n < toRead {
return n, syserror.EIO
}
return n, nil
}
-
-// fileBlock returns the file block number we are currently reading.
-func (r *extentReader) fileBlock() uint32 {
- return uint32(r.fileOff / r.blkSize)
-}
-
-// fileBlockOff returns the current offset within the current file block.
-func (r *extentReader) fileBlockOff() uint64 {
- return r.fileOff % r.blkSize
-}
diff --git a/pkg/sentry/fs/ext/extent_test.go b/pkg/sentry/fs/ext/extent_test.go
index 9b3f5469e..d03cd564f 100644
--- a/pkg/sentry/fs/ext/extent_test.go
+++ b/pkg/sentry/fs/ext/extent_test.go
@@ -16,7 +16,6 @@ package ext
import (
"bytes"
- "io"
"math/rand"
"testing"
@@ -145,14 +144,13 @@ var (
// TestExtentReader stress tests extentReader functionality. It performs random
// length reads from all possible positions in the extent tree.
func TestExtentReader(t *testing.T) {
- dev, mockExtentFile, want := extentTreeSetUp(t, node0)
+ mockExtentFile, want := extentTreeSetUp(t, node0)
n := len(want)
for from := 0; from < n; from++ {
- fileReader := mockExtentFile.getFileReader(dev, mockExtentBlkSize, uint64(from))
got := make([]byte, n-from)
- if read, err := io.ReadFull(fileReader, got); err != nil {
+ if read, err := mockExtentFile.ReadAt(got, int64(from)); err != nil {
t.Fatalf("file read operation from offset %d to %d only read %d bytes: %v", from, n, read, err)
}
@@ -164,7 +162,7 @@ func TestExtentReader(t *testing.T) {
// TestBuildExtentTree tests the extent tree building logic.
func TestBuildExtentTree(t *testing.T) {
- _, mockExtentFile, _ := extentTreeSetUp(t, node0)
+ mockExtentFile, _ := extentTreeSetUp(t, node0)
opt := cmpopts.IgnoreUnexported(disklayout.ExtentIdx{}, disklayout.ExtentHeader{})
if diff := cmp.Diff(&mockExtentFile.root, node0, opt); diff != "" {
@@ -175,7 +173,7 @@ func TestBuildExtentTree(t *testing.T) {
// extentTreeSetUp writes the passed extent tree to a mock disk as an extent
// tree. It also constucts a mock extent file with the same tree built in it.
// It also writes random data file data and returns it.
-func extentTreeSetUp(t *testing.T, root *disklayout.ExtentNode) (io.ReaderAt, *extentFile, []byte) {
+func extentTreeSetUp(t *testing.T, root *disklayout.ExtentNode) (*extentFile, []byte) {
t.Helper()
mockDisk := make([]byte, mockExtentBlkSize*10)
@@ -187,17 +185,18 @@ func extentTreeSetUp(t *testing.T, root *disklayout.ExtentNode) (io.ReaderAt, *e
SizeLo: uint32(mockExtentBlkSize) * getNumPhyBlks(root),
},
},
+ blkSize: mockExtentBlkSize,
+ dev: bytes.NewReader(mockDisk),
},
},
}
fileData := writeTree(&mockExtentFile.regFile.inode, mockDisk, node0, mockExtentBlkSize)
- r := bytes.NewReader(mockDisk)
- if err := mockExtentFile.buildExtTree(r, mockExtentBlkSize); err != nil {
+ if err := mockExtentFile.buildExtTree(); err != nil {
t.Fatalf("inode.buildExtTree failed: %v", err)
}
- return r, mockExtentFile, fileData
+ return mockExtentFile, fileData
}
// writeTree writes the tree represented by `root` to the inode and disk. It
diff --git a/pkg/sentry/fs/ext/filesystem.go b/pkg/sentry/fs/ext/filesystem.go
index 12aeb5dac..45b43b9e2 100644
--- a/pkg/sentry/fs/ext/filesystem.go
+++ b/pkg/sentry/fs/ext/filesystem.go
@@ -34,12 +34,11 @@ type filesystem struct {
// mu serializes changes to the Dentry tree.
mu sync.RWMutex
- // dev is the io.ReaderAt for the underlying fs device. It does not require
- // protection because io.ReaderAt permits concurrent read calls to it. It
- // translates to the pread syscall which passes on the read request directly
- // to the device driver. Device drivers are intelligent in serving multiple
- // concurrent read requests in the optimal order (taking locality into
- // consideration).
+ // dev represents the underlying fs device. It does not require protection
+ // because io.ReaderAt permits concurrent read calls to it. It translates to
+ // the pread syscall which passes on the read request directly to the device
+ // driver. Device drivers are intelligent in serving multiple concurrent read
+ // requests in the optimal order (taking locality into consideration).
dev io.ReaderAt
// inodeCache maps absolute inode numbers to the corresponding Inode struct.
@@ -69,7 +68,7 @@ func (fs *filesystem) getOrCreateInode(ctx context.Context, inodeNum uint32) (*i
return in, nil
}
- in, err := newInode(ctx, fs.dev, fs.sb, fs.bgs, inodeNum)
+ in, err := newInode(ctx, fs, inodeNum)
if err != nil {
return nil, err
}
diff --git a/pkg/sentry/fs/ext/inline_file.go b/pkg/sentry/fs/ext/inline_file.go
index b9adfe548..67a538ba0 100644
--- a/pkg/sentry/fs/ext/inline_file.go
+++ b/pkg/sentry/fs/ext/inline_file.go
@@ -24,14 +24,8 @@ type inlineFile struct {
regFile regularFile
}
-// Compiles only if inlineFile implements fileReader.
-var _ fileReader = (*inlineFile)(nil)
-
-// getFileReader implements fileReader.getFileReader.
-func (f *inlineFile) getFileReader(_ io.ReaderAt, _ uint64, offset uint64) io.Reader {
- diskInode := f.regFile.inode.diskInode
- return &inlineReader{offset: offset, data: diskInode.Data()[:diskInode.Size()]}
-}
+// Compiles only if inlineFile implements io.ReaderAt.
+var _ io.ReaderAt = (*inlineFile)(nil)
// newInlineFile is the inlineFile constructor.
func newInlineFile(regFile regularFile) *inlineFile {
@@ -40,27 +34,22 @@ func newInlineFile(regFile regularFile) *inlineFile {
return file
}
-// inlineReader implements io.Reader which can read the underlying data. This
-// is not thread safe.
-type inlineReader struct {
- offset uint64
- data []byte
-}
-
-// Compiles only if inlineReader implements io.Reader.
-var _ io.Reader = (*inlineReader)(nil)
-
-// Read implements io.Reader.Read.
-func (r *inlineReader) Read(dst []byte) (int, error) {
+// ReadAt implements io.ReaderAt.ReadAt.
+func (f *inlineFile) ReadAt(dst []byte, off int64) (int, error) {
if len(dst) == 0 {
return 0, nil
}
- if int(r.offset) >= len(r.data) {
+ size := f.regFile.inode.diskInode.Size()
+ if uint64(off) >= size {
return 0, io.EOF
}
- n := copy(dst, r.data[r.offset:])
- r.offset += uint64(n)
+ to := uint64(off) + uint64(len(dst))
+ if to > size {
+ to = size
+ }
+
+ n := copy(dst, f.regFile.inode.diskInode.Data()[off:to])
return n, nil
}
diff --git a/pkg/sentry/fs/ext/inode.go b/pkg/sentry/fs/ext/inode.go
index 00e022953..364980e4c 100644
--- a/pkg/sentry/fs/ext/inode.go
+++ b/pkg/sentry/fs/ext/inode.go
@@ -46,6 +46,12 @@ type inode struct {
// identify inodes within the ext filesystem.
inodeNum uint32
+ // dev represents the underlying device. Same as filesystem.dev.
+ dev io.ReaderAt
+
+ // blkSize is the fs data block size. Same as filesystem.sb.BlockSize().
+ blkSize uint64
+
// diskInode gives us access to the inode struct on disk. Immutable.
diskInode disklayout.Inode
@@ -86,12 +92,12 @@ func (in *inode) decRef(fs *filesystem) {
// newInode is the inode constructor. Reads the inode off disk. Identifies
// inodes based on the absolute inode number on disk.
-func newInode(ctx context.Context, dev io.ReaderAt, sb disklayout.SuperBlock, bgs []disklayout.BlockGroup, inodeNum uint32) (*inode, error) {
+func newInode(ctx context.Context, fs *filesystem, inodeNum uint32) (*inode, error) {
if inodeNum == 0 {
panic("inode number 0 on ext filesystems is not possible")
}
- inodeRecordSize := sb.InodeSize()
+ inodeRecordSize := fs.sb.InodeSize()
var diskInode disklayout.Inode
if inodeRecordSize == disklayout.OldInodeSize {
diskInode = &disklayout.InodeOld{}
@@ -100,12 +106,12 @@ func newInode(ctx context.Context, dev io.ReaderAt, sb disklayout.SuperBlock, bg
}
// Calculate where the inode is actually placed.
- inodesPerGrp := sb.InodesPerGroup()
- blkSize := sb.BlockSize()
- inodeTableOff := bgs[getBGNum(inodeNum, inodesPerGrp)].InodeTable() * blkSize
+ inodesPerGrp := fs.sb.InodesPerGroup()
+ blkSize := fs.sb.BlockSize()
+ inodeTableOff := fs.bgs[getBGNum(inodeNum, inodesPerGrp)].InodeTable() * blkSize
inodeOff := inodeTableOff + uint64(uint32(inodeRecordSize)*getBGOff(inodeNum, inodesPerGrp))
- if err := readFromDisk(dev, int64(inodeOff), diskInode); err != nil {
+ if err := readFromDisk(fs.dev, int64(inodeOff), diskInode); err != nil {
return nil, err
}
@@ -113,18 +119,20 @@ func newInode(ctx context.Context, dev io.ReaderAt, sb disklayout.SuperBlock, bg
inode := inode{
refs: 1,
inodeNum: inodeNum,
+ dev: fs.dev,
+ blkSize: blkSize,
diskInode: diskInode,
}
switch diskInode.Mode().FileType() {
case linux.ModeSymlink:
- f, err := newSymlink(dev, blkSize, inode)
+ f, err := newSymlink(inode)
if err != nil {
return nil, err
}
return &f.inode, nil
case linux.ModeRegular:
- f, err := newRegularFile(dev, blkSize, inode)
+ f, err := newRegularFile(inode)
if err != nil {
return nil, err
}
diff --git a/pkg/sentry/fs/ext/regular_file.go b/pkg/sentry/fs/ext/regular_file.go
index b48f61795..fb1bd38ef 100644
--- a/pkg/sentry/fs/ext/regular_file.go
+++ b/pkg/sentry/fs/ext/regular_file.go
@@ -18,20 +18,6 @@ import (
"io"
)
-// fileReader is used to abstact away the complexity of how the file data is
-// stored under the hood. Provides a method to get a file reader which can be
-// used to read file data without worrying about how it is organized on disk.
-type fileReader interface {
-
- // getFileReader returns a Reader implementation which can be used to read a
- // file. It abstracts away the complexity of how the file is actually
- // organized on disk. The reader is initialized with the passed offset.
- //
- // This reader is not meant to be retained across Read operations as it needs
- // to be reinitialized with the correct offset for every Read.
- getFileReader(dev io.ReaderAt, blkSize uint64, offset uint64) io.Reader
-}
-
// regularFile represents a regular file's inode. This too follows the
// inheritance pattern prevelant in the vfs layer described in
// pkg/sentry/vfs/README.md.
@@ -40,12 +26,12 @@ type regularFile struct {
// This is immutable. The first field of fileReader implementations must be
// regularFile to ensure temporality.
- impl fileReader
+ impl io.ReaderAt
}
// newRegularFile is the regularFile constructor. It figures out what kind of
// file this is and initializes the fileReader.
-func newRegularFile(dev io.ReaderAt, blkSize uint64, inode inode) (*regularFile, error) {
+func newRegularFile(inode inode) (*regularFile, error) {
regFile := regularFile{
inode: inode,
}
@@ -53,7 +39,7 @@ func newRegularFile(dev io.ReaderAt, blkSize uint64, inode inode) (*regularFile,
inodeFlags := inode.diskInode.Flags()
if inodeFlags.Extents {
- file, err := newExtentFile(dev, blkSize, regFile)
+ file, err := newExtentFile(regFile)
if err != nil {
return nil, err
}
@@ -72,7 +58,7 @@ func newRegularFile(dev io.ReaderAt, blkSize uint64, inode inode) (*regularFile,
return &file.regFile, nil
}
- file, err := newBlockMapFile(blkSize, regFile)
+ file, err := newBlockMapFile(regFile)
if err != nil {
return nil, err
}
diff --git a/pkg/sentry/fs/ext/symlink.go b/pkg/sentry/fs/ext/symlink.go
index 6a55c1a7b..9f498d989 100644
--- a/pkg/sentry/fs/ext/symlink.go
+++ b/pkg/sentry/fs/ext/symlink.go
@@ -15,8 +15,6 @@
package ext
import (
- "io"
-
"gvisor.dev/gvisor/pkg/syserror"
)
@@ -28,7 +26,7 @@ type symlink struct {
// newSymlink is the symlink constructor. It reads out the symlink target from
// the inode (however it might have been stored).
-func newSymlink(dev io.ReaderAt, blkSize uint64, inode inode) (*symlink, error) {
+func newSymlink(inode inode) (*symlink, error) {
var file *symlink
var link []byte
@@ -39,14 +37,13 @@ func newSymlink(dev io.ReaderAt, blkSize uint64, inode inode) (*symlink, error)
link = inode.diskInode.Data()[:size]
} else {
// Create a regular file out of this inode and read out the target.
- regFile, err := newRegularFile(dev, blkSize, inode)
+ regFile, err := newRegularFile(inode)
if err != nil {
return nil, err
}
link = make([]byte, size)
- reader := regFile.impl.getFileReader(dev, blkSize, 0)
- if _, err := io.ReadFull(reader, link); err != nil {
+ if n, _ := regFile.impl.ReadAt(link, 0); uint64(n) < size {
return nil, syserror.EIO
}
}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-08 04:35:07 +0000