[#791] neofs-lens: Implement object listing

Implement `list` command for object listing. Support listing of the objects
from write-cache and blobovnicza.

Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>

cmd/neofs-lens/internal/commands/list/list.go

@@ -0,0 +1,72 @@
+package cmdlist
+
+import (
+	"io"
+
+	"github.com/nspcc-dev/neofs-api-go/pkg/object"
+	common "github.com/nspcc-dev/neofs-node/cmd/neofs-lens/internal"
+	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/blobovnicza"
+	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/writecache"
+	"github.com/spf13/cobra"
+)
+
+const (
+	flagFile       = "path"
+	flagWriteCache = "writecache"
+)
+
+var (
+	vPath       string
+	vWriteCache bool
+)
+
+func init() {
+	Command.Flags().StringVar(&vPath, flagFile, "",
+		"Path to storage engine component",
+	)
+	_ = Command.MarkFlagFilename(flagFile)
+	_ = Command.MarkFlagRequired(flagFile)
+
+	Command.Flags().BoolVar(&vWriteCache, flagWriteCache, false,
+		"Process write-cache",
+	)
+}
+
+var Command = &cobra.Command{
+	Use:   "list",
+	Short: "Object listing",
+	Long:  `List all objects stored in storage engine component.`,
+	Run: func(cmd *cobra.Command, args []string) {
+		// other targets can be supported
+		w := cmd.OutOrStderr()
+
+		wAddr := func(addr *object.Address) error {
+			_, err := io.WriteString(w, addr.String()+"\n")
+			return err
+		}
+
+		if vWriteCache {
+			db, err := writecache.OpenDB(vPath, true)
+			common.ExitOnErr(cmd, common.Errf("could not open write-cache db: %w", err))
+
+			defer db.Close()
+
+			err = writecache.IterateDB(db, wAddr)
+			common.ExitOnErr(cmd, common.Errf("write-cache iterator failure: %w", err))
+
+			return
+		}
+
+		blz := blobovnicza.New(
+			blobovnicza.WithPath(vPath),
+			blobovnicza.ReadOnly(),
+		)
+
+		common.ExitOnErr(cmd, blz.Open())
+
+		defer blz.Close()
+
+		err := blobovnicza.IterateAddresses(blz, wAddr)
+		common.ExitOnErr(cmd, common.Errf("blobovnicza iterator failure: %w", err))
+	},
+}

cmd/neofs-lens/internal/common.go

@@ -0,0 +1,31 @@
+package common
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/spf13/cobra"
+)
+
+// Errf returns formatted error in errFmt format if err is not nil.
+func Errf(errFmt string, err error) error {
+	if err == nil {
+		return nil
+	}
+
+	return fmt.Errorf(errFmt, err)
+}
+
+// ExitOnErr calls exitOnErrCode with code 1.
+func ExitOnErr(cmd *cobra.Command, err error) {
+	exitOnErrCode(cmd, err, 1)
+}
+
+// exitOnErrCode prints error via cmd and calls os.Exit with passed exit code.
+// Does nothing if err is nil.
+func exitOnErrCode(cmd *cobra.Command, err error, code int) {
+	if err != nil {
+		cmd.PrintErrln(err)
+		os.Exit(code)
+	}
+}

cmd/neofs-lens/root.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"os"
 
+	cmdlist "github.com/nspcc-dev/neofs-node/cmd/neofs-lens/internal/commands/list"
 	"github.com/nspcc-dev/neofs-node/misc"
 	"github.com/spf13/cobra"
 )
@@ -32,7 +33,7 @@ func entryPoint(cmd *cobra.Command, _ []string) error {
 
 func init() {
 	command.AddCommand(
-	// sub-commands
+		cmdlist.Command,
 	)
 }