added sftp client implementation

pkg/fs/fs.go

@@ -7,6 +7,7 @@ import (
 	"cachefs/pkg/provider/parse"
 	"context"
 	"errors"
+	"fmt"
 	stdfs "io/fs"
 	"net/http"
 	"os"
@@ -36,11 +37,11 @@ func NewFS(quota int64, max int, src, dst, metadata string, log logr.Logger) (fs
 	}
 	srcfs, err := parse.FS(src)
 	if err != nil {
-		return
+		return nil, fmt.Errorf("srcfs: %w", err)
 	}
 	dstfs, err := parse.FS(dst)
 	if err != nil {
-		return
+		return nil, fmt.Errorf("dstfs: %w", err)
 	}
 
 	ctx, cancel := context.WithCancel(context.Background())
@@ -57,11 +58,11 @@ func NewFS(quota int64, max int, src, dst, metadata string, log logr.Logger) (fs
 
 	fs.mh, err = NewMetadataHandler(ctx, fs, metadata, dst, log.WithName("metadata"))
 	if err != nil {
-		return
+		return nil, fmt.Errorf("metadata: %w", err)
 	}
 	fs.q, err = NewQuota(fs.mh.Size(), quota, fs, log.WithName("quota"))
 	if err != nil {
-		return
+		return nil, fmt.Errorf("quota: %w", err)
 	}
 	fs.ph = NewPreloadHandler(ctx, fs, max, log.WithName("preload"))
 	fs.sc = NewStatCache(ctx)
@@ -235,5 +236,7 @@ func (fs *FS) CacheStatus(name string) int {
 
 func (fs *FS) Close() {
 	fs.cancel()
+	fs.src.Close()
+	fs.dst.Close()
 	<-fs.done
 }

pkg/fs/metadata.go

@@ -40,6 +40,10 @@ func MetadataGenerator(file string, dst provider.FS) error {
 	if !filepath.IsAbs(file) {
 		return errors.New("metadata path is not absolute")
 	}
+	_, err := dst.Fstat(0)
+	if err == provider.ErrFstat {
+		return err
+	}
 	f, err := os.OpenFile(file, os.O_RDWR|os.O_CREATE, 0o640)
 	if err != nil {
 		return err
@@ -99,7 +103,7 @@ func NewMetadataHandler(ctx context.Context, fs *FS, file, dst string, log logr.
 		return
 	}
 	err = json.NewDecoder(mh.f).Decode(&mh.md)
-	if err != nil && err == io.EOF {
+	if err != nil && err != io.EOF {
 		return
 	}
 	mh.enc = json.NewEncoder(mh.f)
@@ -281,8 +285,10 @@ func (mh *MetadataHandler) flush() {
 func (mh *MetadataHandler) close() {
 	mh.mu.Lock()
 	for _, md := range mh.md {
-		md.f.Sync()
-		md.f.Close()
+		if md.f != nil {
+			md.f.Sync()
+			md.f.Close()
+		}
 	}
 	mh.mu.Unlock()
 	mh.flush()