WIP: WebDAV server

internal/serve/fs.go

@@ -0,0 +1,231 @@
+package serve
+
+import (
+	"context"
+	"os"
+	"path"
+	"sync"
+	"time"
+
+	"github.com/restic/restic/internal/errors"
+
+	"github.com/restic/restic/internal/debug"
+	"github.com/restic/restic/internal/restic"
+	"golang.org/x/net/webdav"
+)
+
+// Config holds settings for the file system served.
+type Config struct {
+	Host  string
+	Tags  []restic.TagList
+	Paths []string
+}
+
+const snapshotFormat = "2006-01-02_150405"
+
+// RepoFileSystem implements a read-only file system on top of a repositoy.
+type RepoFileSystem struct {
+	repo      restic.Repository
+	lastCheck time.Time
+
+	entries map[string]webdav.File
+	m       sync.Mutex
+}
+
+// NewRepoFileSystem returns a new file system for the repo.
+func NewRepoFileSystem(ctx context.Context, repo restic.Repository, cfg Config) (*RepoFileSystem, error) {
+	snapshots := restic.FindFilteredSnapshots(ctx, repo, cfg.Host, cfg.Tags, cfg.Paths)
+
+	lastcheck := time.Now()
+
+	nodes := make([]*restic.Node, 0, len(snapshots))
+	entries := make(map[string]webdav.File)
+
+	for _, sn := range snapshots {
+		name := sn.Time.Format(snapshotFormat)
+		snFileInfo := virtFileInfo{
+			name:    name,
+			size:    0,
+			mode:    0755 | os.ModeDir,
+			modtime: sn.Time,
+			isdir:   true,
+		}
+
+		if sn.Tree == nil {
+			return nil, errors.Errorf("snapshot %v has nil tree", sn.ID().Str())
+		}
+
+		tree, err := repo.LoadTree(ctx, *sn.Tree)
+		if err != nil {
+			return nil, err
+		}
+
+		p := path.Join("/", name)
+		entries[p] = &RepoDir{
+			fi:    snFileInfo,
+			nodes: tree.Nodes,
+		}
+
+		nodes = append(nodes, &restic.Node{
+			Name: name,
+			Type: "dir",
+		})
+	}
+
+	entries["/"] = &RepoDir{
+		nodes: nodes,
+		fi: virtFileInfo{
+			name:    "root",
+			size:    0,
+			mode:    0755 | os.ModeDir,
+			modtime: lastcheck,
+			isdir:   true,
+		},
+	}
+
+	fs := &RepoFileSystem{
+		repo:      repo,
+		lastCheck: lastcheck,
+		entries:   entries,
+	}
+
+	return fs, nil
+}
+
+// statically ensure that RepoFileSystem implements webdav.FileSystem
+var _ webdav.FileSystem = &RepoFileSystem{}
+
+// Mkdir creates a new directory, it is not available for RepoFileSystem.
+func (fs *RepoFileSystem) Mkdir(ctx context.Context, name string, perm os.FileMode) error {
+	return webdav.ErrForbidden
+}
+
+func (fs *RepoFileSystem) loadPath(ctx context.Context, name string) error {
+	debug.Log("%v", name)
+
+	fs.m.Lock()
+	_, ok := fs.entries[name]
+	fs.m.Unlock()
+	if ok {
+		return nil
+	}
+
+	dirname := path.Dir(name)
+	if dirname == "/" {
+		return nil
+	}
+
+	err := fs.loadPath(ctx, dirname)
+	if err != nil {
+		return err
+	}
+
+	entry, ok := fs.entries[dirname]
+	if !ok {
+		// loadPath did not succeed
+		return nil
+	}
+
+	repodir, ok := entry.(*RepoDir)
+	if !ok {
+		return nil
+	}
+
+	filename := path.Base(name)
+	for _, node := range repodir.nodes {
+		if node.Name != filename {
+			continue
+		}
+
+		debug.Log("found item %v :%v", filename, node)
+
+		switch node.Type {
+		case "dir":
+			if node.Subtree == nil {
+				return errors.Errorf("tree %v has nil tree", dirname)
+			}
+
+			tree, err := fs.repo.LoadTree(ctx, *node.Subtree)
+			if err != nil {
+				return err
+			}
+
+			newEntry := &RepoDir{
+				fi:    fileInfoFromNode(node),
+				nodes: tree.Nodes,
+			}
+
+			fs.m.Lock()
+			fs.entries[name] = newEntry
+			fs.m.Unlock()
+		case "file":
+			newEntry := &RepoFile{
+				fi:   fileInfoFromNode(node),
+				node: node,
+			}
+			fs.m.Lock()
+			fs.entries[name] = newEntry
+			fs.m.Unlock()
+		}
+
+		return nil
+	}
+
+	return nil
+}
+
+// OpenFile opens a file for reading.
+func (fs *RepoFileSystem) OpenFile(ctx context.Context, name string, flag int, perm os.FileMode) (webdav.File, error) {
+	name = path.Clean(name)
+	debug.Log("%v", name)
+	if flag != os.O_RDONLY {
+		return nil, webdav.ErrForbidden
+	}
+
+	err := fs.loadPath(ctx, name)
+	if err != nil {
+		return nil, err
+	}
+
+	fs.m.Lock()
+	entry, ok := fs.entries[name]
+	fs.m.Unlock()
+	if !ok {
+		return nil, os.ErrNotExist
+	}
+
+	return entry, nil
+}
+
+// RemoveAll recursively removes files and directories, it is not available for RepoFileSystem.
+func (fs *RepoFileSystem) RemoveAll(ctx context.Context, name string) error {
+	debug.Log("%v", name)
+	return webdav.ErrForbidden
+}
+
+// Rename renames files or directories, it is not available for RepoFileSystem.
+func (fs *RepoFileSystem) Rename(ctx context.Context, oldName, newName string) error {
+	debug.Log("%v -> %v", oldName, newName)
+	return webdav.ErrForbidden
+}
+
+// Stat returns information on a file or directory.
+func (fs *RepoFileSystem) Stat(ctx context.Context, name string) (os.FileInfo, error) {
+	name = path.Clean(name)
+	err := fs.loadPath(ctx, name)
+	if err != nil {
+		return nil, err
+	}
+
+	fs.m.Lock()
+	entry, ok := fs.entries[name]
+	fs.m.Unlock()
+	if !ok {
+		debug.Log("%v not found", name)
+		return nil, os.ErrNotExist
+	}
+
+	fi, err := entry.Stat()
+	debug.Log("%v %v", name, fi)
+	return fi, err
+}