/
filesystem.go
224 lines (189 loc) · 4.92 KB
/
filesystem.go
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package main
import (
"context"
"fmt"
"io"
"net/http"
"os"
"strings"
"time"
"unsafe"
"github.com/jacobsa/fuse/fuseops"
"github.com/jacobsa/fuse/fuseutil"
)
type FileSystem struct {
fs fuseutil.FileSystem
}
func (fs *FileSystem) Open(name string) (http.File, error) {
ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
defer cancel()
if name == "/" {
op := &fuseops.GetInodeAttributesOp{Inode: fuseops.RootInodeID}
if err := fs.fs.GetInodeAttributes(ctx, op); err != nil {
return nil, err
}
return &File{
fs: fs.fs,
inode: fuseops.RootInodeID,
fi: newFileInfo("", op.Attributes),
}, nil
}
var (
inode = fuseops.InodeID(fuseops.RootInodeID)
fi *FileInfo
)
for _, part := range strings.Split(name, "/")[1:] {
op := &fuseops.LookUpInodeOp{Parent: inode, Name: part}
if err := fs.fs.LookUpInode(ctx, op); err != nil {
return nil, err
}
inode = op.Entry.Child
fi = newFileInfo(part, op.Entry.Attributes)
}
return &File{
fs: fs.fs,
inode: inode,
fi: fi,
}, nil
}
type File struct {
fs fuseutil.FileSystem
inode fuseops.InodeID
fi *FileInfo
pos int64
}
func (f *File) Close() error { return nil }
func (f *File) Read(p []byte) (int, error) {
if f.pos == f.fi.size {
return 0, io.EOF
}
op := &fuseops.ReadFileOp{Inode: f.inode, Offset: f.pos, Dst: p}
if err := f.fs.ReadFile(context.Background(), op); err != nil {
return 0, err
}
f.pos += int64(op.BytesRead)
return op.BytesRead, nil
}
func (f *File) Seek(offset int64, whence int) (int64, error) {
if whence == io.SeekStart {
// Offset is already in correct form.
} else if whence == io.SeekCurrent {
offset += f.pos
} else if whence == io.SeekEnd {
offset = f.fi.size - offset
} else {
return 0, fmt.Errorf("unexpected value for whence")
}
if offset > f.fi.size {
return 0, fmt.Errorf("cannot seek past end of file")
}
f.pos = offset
return offset, nil
}
func (f *File) Readdir(count int) ([]os.FileInfo, error) {
if !f.fi.IsDir() {
return nil, fmt.Errorf("file is not a directory")
}
ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
defer cancel()
open := &fuseops.OpenDirOp{Inode: f.inode}
if err := f.fs.OpenDir(ctx, open); err != nil {
return nil, err
}
defer func() {
release := &fuseops.ReleaseDirHandleOp{Handle: open.Handle}
f.fs.ReleaseDirHandle(ctx, release)
}()
entries := make([]os.FileInfo, 0)
for {
// Read the next chunk of entries from the directory.
dst := make([]byte, 2048)
op := &fuseops.ReadDirOp{
Inode: f.inode,
Handle: open.Handle,
Offset: fuseops.DirOffset(len(entries)),
Dst: dst,
}
if err := f.fs.ReadDir(ctx, op); err != nil {
return nil, err
} else if op.BytesRead == 0 {
break
}
dst = dst[:op.BytesRead]
// Parse the names returned.
for len(dst) > 0 {
var (
de fuseutil.Dirent
err error
)
dst, de, err = parseDirent(dst)
if err != nil {
return nil, err
}
// Look up the full info for the entry and convert it to a FileInfo.
op := &fuseops.LookUpInodeOp{Parent: f.inode, Name: de.Name}
if err := f.fs.LookUpInode(ctx, op); err != nil {
return nil, err
}
entries = append(entries, newFileInfo(de.Name, op.Entry.Attributes))
}
}
return entries, nil
}
func (f *File) Stat() (os.FileInfo, error) { return f.fi, nil }
type FileInfo struct {
name string
size int64
mode os.FileMode
modTime time.Time
}
func newFileInfo(name string, attrs fuseops.InodeAttributes) *FileInfo {
return &FileInfo{
name: name,
size: int64(attrs.Size),
mode: attrs.Mode,
modTime: attrs.Mtime,
}
}
func (fi *FileInfo) Name() string { return fi.name }
func (fi *FileInfo) Size() int64 { return fi.size }
func (fi *FileInfo) Mode() os.FileMode { return fi.mode }
func (fi *FileInfo) ModTime() time.Time { return fi.modTime }
func (fi *FileInfo) IsDir() bool { return fi.Mode().IsDir() }
func (fi *FileInfo) Sys() interface{} { return nil }
func parseDirent(buf []byte) ([]byte, fuseutil.Dirent, error) {
type fuse_dirent struct {
ino uint64
off uint64
namelen uint32
type_ uint32
name [0]byte
}
const direntAlignment = 8
const direntSize = 8 + 8 + 4 + 4
if len(buf) < direntSize {
return nil, fuseutil.Dirent{}, fmt.Errorf("buffer is too short")
}
de := fuse_dirent{}
n := copy((*[direntSize]byte)(unsafe.Pointer(&de))[:], buf)
buf = buf[n:]
if len(buf) < int(de.namelen) {
return nil, fuseutil.Dirent{}, fmt.Errorf("buffer is too short")
}
name := string(buf[:de.namelen])
buf = buf[de.namelen:]
var padLen int
if len(name)%direntAlignment != 0 {
padLen = direntAlignment - (len(name) % direntAlignment)
}
if len(buf) < padLen {
return nil, fuseutil.Dirent{}, fmt.Errorf("buffer is too short")
}
buf = buf[padLen:]
return buf, fuseutil.Dirent{
Offset: fuseops.DirOffset(de.off),
Inode: fuseops.InodeID(de.ino),
Name: name,
Type: fuseutil.DirentType(de.type_),
}, nil
}