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cloudreve/pkg/webdav/mem.go

484 lines
11 KiB

package webdav
import (
"context"
"encoding/xml"
"io"
"net/http"
"os"
"path"
"strings"
"sync"
"time"
)
// NewMemFS returns a new in-memory FileSystem implementation.
func NewMemFS() FileSystem {
return &memFS{
root: memFSNode{
children: make(map[string]*memFSNode),
mode: 0660 | os.ModeDir,
modTime: time.Now(),
},
}
}
// A memFS implements FileSystem, storing all metadata and actual file data
// in-memory. No limits on filesystem size are used, so it is not recommended
// this be used where the clients are untrusted.
//
// Concurrent access is permitted. The tree structure is protected by a mutex,
// and each node's contents and metadata are protected by a per-node mutex.
//
// TODO: Enforce file permissions.
type memFS struct {
mu sync.Mutex
root memFSNode
}
// TODO: clean up and rationalize the walk/find code.
// walk walks the directory tree for the fullname, calling f at each step. If f
// returns an error, the walk will be aborted and return that same error.
//
// dir is the directory at that step, frag is the name fragment, and final is
// whether it is the final step. For example, walking "/foo/bar/x" will result
// in 3 calls to f:
// - "/", "foo", false
// - "/foo/", "bar", false
// - "/foo/bar/", "x", true
// The frag argument will be empty only if dir is the root node and the walk
// ends at that root node.
func (fs *memFS) walk(op, fullname string, f func(dir *memFSNode, frag string, final bool) error) error {
original := fullname
fullname = slashClean(fullname)
// Strip any leading "/"s to make fullname a relative path, as the walk
// starts at fs.root.
if fullname[0] == '/' {
fullname = fullname[1:]
}
dir := &fs.root
for {
frag, remaining := fullname, ""
i := strings.IndexRune(fullname, '/')
final := i < 0
if !final {
frag, remaining = fullname[:i], fullname[i+1:]
}
if frag == "" && dir != &fs.root {
panic("webdav: empty path fragment for a clean path")
}
if err := f(dir, frag, final); err != nil {
return &os.PathError{
Op: op,
Path: original,
Err: err,
}
}
if final {
break
}
child := dir.children[frag]
if child == nil {
return &os.PathError{
Op: op,
Path: original,
Err: os.ErrNotExist,
}
}
if !child.mode.IsDir() {
return &os.PathError{
Op: op,
Path: original,
Err: os.ErrInvalid,
}
}
dir, fullname = child, remaining
}
return nil
}
// find returns the parent of the named node and the relative name fragment
// from the parent to the child. For example, if finding "/foo/bar/baz" then
// parent will be the node for "/foo/bar" and frag will be "baz".
//
// If the fullname names the root node, then parent, frag and err will be zero.
//
// find returns an error if the parent does not already exist or the parent
// isn't a directory, but it will not return an error per se if the child does
// not already exist. The error returned is either nil or an *os.PathError
// whose Op is op.
func (fs *memFS) find(op, fullname string) (parent *memFSNode, frag string, err error) {
err = fs.walk(op, fullname, func(parent0 *memFSNode, frag0 string, final bool) error {
if !final {
return nil
}
if frag0 != "" {
parent, frag = parent0, frag0
}
return nil
})
return parent, frag, err
}
func (fs *memFS) Mkdir(ctx context.Context, name string, perm os.FileMode) error {
fs.mu.Lock()
defer fs.mu.Unlock()
dir, frag, err := fs.find("mkdir", name)
if err != nil {
return err
}
if dir == nil {
// We can't create the root.
return os.ErrInvalid
}
if _, ok := dir.children[frag]; ok {
return os.ErrExist
}
dir.children[frag] = &memFSNode{
children: make(map[string]*memFSNode),
mode: perm.Perm() | os.ModeDir,
modTime: time.Now(),
}
return nil
}
func (fs *memFS) OpenFile(ctx context.Context, name string, flag int, perm os.FileMode) (File, error) {
fs.mu.Lock()
defer fs.mu.Unlock()
dir, frag, err := fs.find("open", name)
if err != nil {
return nil, err
}
var n *memFSNode
if dir == nil {
// We're opening the root.
if flag&(os.O_WRONLY|os.O_RDWR) != 0 {
return nil, os.ErrPermission
}
n, frag = &fs.root, "/"
} else {
n = dir.children[frag]
if flag&(os.O_SYNC|os.O_APPEND) != 0 {
// memFile doesn't support these flags yet.
return nil, os.ErrInvalid
}
if flag&os.O_CREATE != 0 {
if flag&os.O_EXCL != 0 && n != nil {
return nil, os.ErrExist
}
if n == nil {
n = &memFSNode{
mode: perm.Perm(),
}
dir.children[frag] = n
}
}
if n == nil {
return nil, os.ErrNotExist
}
if flag&(os.O_WRONLY|os.O_RDWR) != 0 && flag&os.O_TRUNC != 0 {
n.mu.Lock()
n.data = nil
n.mu.Unlock()
}
}
children := make([]os.FileInfo, 0, len(n.children))
for cName, c := range n.children {
children = append(children, c.stat(cName))
}
return &memFile{
n: n,
nameSnapshot: frag,
childrenSnapshot: children,
}, nil
}
func (fs *memFS) RemoveAll(ctx context.Context, name string) error {
fs.mu.Lock()
defer fs.mu.Unlock()
dir, frag, err := fs.find("remove", name)
if err != nil {
return err
}
if dir == nil {
// We can't remove the root.
return os.ErrInvalid
}
delete(dir.children, frag)
return nil
}
func (fs *memFS) Rename(ctx context.Context, oldName, newName string) error {
fs.mu.Lock()
defer fs.mu.Unlock()
oldName = slashClean(oldName)
newName = slashClean(newName)
if oldName == newName {
return nil
}
if strings.HasPrefix(newName, oldName+"/") {
// We can't rename oldName to be a sub-directory of itself.
return os.ErrInvalid
}
oDir, oFrag, err := fs.find("rename", oldName)
if err != nil {
return err
}
if oDir == nil {
// We can't rename from the root.
return os.ErrInvalid
}
nDir, nFrag, err := fs.find("rename", newName)
if err != nil {
return err
}
if nDir == nil {
// We can't rename to the root.
return os.ErrInvalid
}
oNode, ok := oDir.children[oFrag]
if !ok {
return os.ErrNotExist
}
if oNode.children != nil {
if nNode, ok := nDir.children[nFrag]; ok {
if nNode.children == nil {
return errNotADirectory
}
if len(nNode.children) != 0 {
return errDirectoryNotEmpty
}
}
}
delete(oDir.children, oFrag)
nDir.children[nFrag] = oNode
return nil
}
func (fs *memFS) Stat(ctx context.Context, name string) (os.FileInfo, error) {
fs.mu.Lock()
defer fs.mu.Unlock()
dir, frag, err := fs.find("stat", name)
if err != nil {
return nil, err
}
if dir == nil {
// We're stat'ting the root.
return fs.root.stat("/"), nil
}
if n, ok := dir.children[frag]; ok {
return n.stat(path.Base(name)), nil
}
return nil, os.ErrNotExist
}
// A memFSNode represents a single entry in the in-memory filesystem and also
// implements os.FileInfo.
type memFSNode struct {
// children is protected by memFS.mu.
children map[string]*memFSNode
mu sync.Mutex
data []byte
mode os.FileMode
modTime time.Time
deadProps map[xml.Name]Property
}
func (n *memFSNode) stat(name string) *memFileInfo {
n.mu.Lock()
defer n.mu.Unlock()
return &memFileInfo{
name: name,
size: int64(len(n.data)),
mode: n.mode,
modTime: n.modTime,
}
}
func (n *memFSNode) DeadProps() (map[xml.Name]Property, error) {
n.mu.Lock()
defer n.mu.Unlock()
if len(n.deadProps) == 0 {
return nil, nil
}
ret := make(map[xml.Name]Property, len(n.deadProps))
for k, v := range n.deadProps {
ret[k] = v
}
return ret, nil
}
func (n *memFSNode) Patch(patches []Proppatch) ([]Propstat, error) {
n.mu.Lock()
defer n.mu.Unlock()
pstat := Propstat{Status: http.StatusOK}
for _, patch := range patches {
for _, p := range patch.Props {
pstat.Props = append(pstat.Props, Property{XMLName: p.XMLName})
if patch.Remove {
delete(n.deadProps, p.XMLName)
continue
}
if n.deadProps == nil {
n.deadProps = map[xml.Name]Property{}
}
n.deadProps[p.XMLName] = p
}
}
return []Propstat{pstat}, nil
}
type memFileInfo struct {
name string
size int64
mode os.FileMode
modTime time.Time
}
func (f *memFileInfo) Name() string { return f.name }
func (f *memFileInfo) Size() int64 { return f.size }
func (f *memFileInfo) Mode() os.FileMode { return f.mode }
func (f *memFileInfo) ModTime() time.Time { return f.modTime }
func (f *memFileInfo) IsDir() bool { return f.mode.IsDir() }
func (f *memFileInfo) Sys() interface{} { return nil }
// A memFile is a File implementation for a memFSNode. It is a per-file (not
// per-node) read/write position, and a snapshot of the memFS' tree structure
// (a node's name and children) for that node.
type memFile struct {
n *memFSNode
nameSnapshot string
childrenSnapshot []os.FileInfo
// pos is protected by n.mu.
pos int
}
// A *memFile implements the optional DeadPropsHolder interface.
var _ DeadPropsHolder = (*memFile)(nil)
func (f *memFile) DeadProps() (map[xml.Name]Property, error) { return f.n.DeadProps() }
func (f *memFile) Patch(patches []Proppatch) ([]Propstat, error) { return f.n.Patch(patches) }
func (f *memFile) Close() error {
return nil
}
func (f *memFile) Read(p []byte) (int, error) {
f.n.mu.Lock()
defer f.n.mu.Unlock()
if f.n.mode.IsDir() {
return 0, os.ErrInvalid
}
if f.pos >= len(f.n.data) {
return 0, io.EOF
}
n := copy(p, f.n.data[f.pos:])
f.pos += n
return n, nil
}
func (f *memFile) Readdir(count int) ([]os.FileInfo, error) {
f.n.mu.Lock()
defer f.n.mu.Unlock()
if !f.n.mode.IsDir() {
return nil, os.ErrInvalid
}
old := f.pos
if old >= len(f.childrenSnapshot) {
// The os.File Readdir docs say that at the end of a directory,
// the error is io.EOF if count > 0 and nil if count <= 0.
if count > 0 {
return nil, io.EOF
}
return nil, nil
}
if count > 0 {
f.pos += count
if f.pos > len(f.childrenSnapshot) {
f.pos = len(f.childrenSnapshot)
}
} else {
f.pos = len(f.childrenSnapshot)
old = 0
}
return f.childrenSnapshot[old:f.pos], nil
}
func (f *memFile) Seek(offset int64, whence int) (int64, error) {
f.n.mu.Lock()
defer f.n.mu.Unlock()
npos := f.pos
// TODO: How to handle offsets greater than the size of system int?
switch whence {
case os.SEEK_SET:
npos = int(offset)
case os.SEEK_CUR:
npos += int(offset)
case os.SEEK_END:
npos = len(f.n.data) + int(offset)
default:
npos = -1
}
if npos < 0 {
return 0, os.ErrInvalid
}
f.pos = npos
return int64(f.pos), nil
}
func (f *memFile) Stat() (os.FileInfo, error) {
return f.n.stat(f.nameSnapshot), nil
}
func (f *memFile) Write(p []byte) (int, error) {
lenp := len(p)
f.n.mu.Lock()
defer f.n.mu.Unlock()
if f.n.mode.IsDir() {
return 0, os.ErrInvalid
}
if f.pos < len(f.n.data) {
n := copy(f.n.data[f.pos:], p)
f.pos += n
p = p[n:]
} else if f.pos > len(f.n.data) {
// Write permits the creation of holes, if we've seek'ed past the
// existing end of file.
if f.pos <= cap(f.n.data) {
oldLen := len(f.n.data)
f.n.data = f.n.data[:f.pos]
hole := f.n.data[oldLen:]
for i := range hole {
hole[i] = 0
}
} else {
d := make([]byte, f.pos, f.pos+len(p))
copy(d, f.n.data)
f.n.data = d
}
}
if len(p) > 0 {
// We should only get here if f.pos == len(f.n.data).
f.n.data = append(f.n.data, p...)
f.pos = len(f.n.data)
}
f.n.modTime = time.Now()
return lenp, nil
}