vm+snapshot: /code+/simplify followups

- ExportToDir: replace inline mkdir + 3-state switch with utils.EnsureDirs
  (existing 0o750 helper); drop the dead snapshot.json skip in the copy
  loop since registered DataDir results never carry the envelope (Create
  doesn't write it; Import removes it via readAndRemoveSnapshotJSON).
- run.go: 'nic count mismatch' -> 'NIC count mismatch' (ALL-CAPS acronym
  rule); fixes both restoreFromDir and the pre-existing legacy Restore
  message for consistency.
- cloneFromDir: copy *config.Config locally before flipping
  UseFirecracker so the mutation doesn't leak to the caller's shared
  conf (CLI tolerates it; daemons embedding cocoon would notice).
- restoreCmd: PreRunE rejects --force without --from-dir so misuse fails
  loud instead of silently no-op.

Author: CMGS

cmd/vm/commands.go

@@ -1,6 +1,8 @@
 package vm
 
 import (
+	"fmt"
+
 	"github.com/spf13/cobra"
 
 	cmdcore "github.com/cocoonstack/cocoon/cmd/core"
@@ -114,7 +116,15 @@ func Command(h Actions) *cobra.Command {
 		Use:   "restore [flags] VM [SNAPSHOT]",
 		Short: "Restore a running VM to a previous snapshot (or a directory via --from-dir)",
 		Args:  cobra.RangeArgs(1, 2),
-		RunE:  h.Restore,
+		PreRunE: func(cmd *cobra.Command, _ []string) error {
+			force, _ := cmd.Flags().GetBool("force")
+			fromDir, _ := cmd.Flags().GetString("from-dir")
+			if force && fromDir == "" {
+				return fmt.Errorf("--force only applies with --from-dir")
+			}
+			return nil
+		},
+		RunE: h.Restore,
 	}
 	restoreCmd.Flags().Int("cpu", 0, "boot CPUs (0 = keep current)")
 	restoreCmd.Flags().String("memory", "", "memory size (empty = keep current)")

cmd/vm/run.go

@@ -182,7 +182,7 @@ func (h Handler) Restore(cmd *cobra.Command, args []string) error {
 	}
 
 	if snapInfo.NICs != len(vm.NetworkConfigs) {
-		return fmt.Errorf("nic count mismatch: vm has %d, snapshot has %d",
+		return fmt.Errorf("NIC count mismatch: vm has %d, snapshot has %d",
 			len(vm.NetworkConfigs), snapInfo.NICs)
 	}
 
@@ -249,7 +249,7 @@ func (h Handler) restoreFromDir(ctx context.Context, cmd *cobra.Command, conf *c
 		logger.Warnf(ctx, "snapshot envelope id %s does not belong to VM %s; --force in effect", cfg.ID, vmRef)
 	}
 	if cfg.NICs != len(vm.NetworkConfigs) {
-		return fmt.Errorf("nic count mismatch: vm has %d, snapshot has %d",
+		return fmt.Errorf("NIC count mismatch: vm has %d, snapshot has %d",
 			len(vm.NetworkConfigs), cfg.NICs)
 	}
 	vmCfg, err := cmdcore.RestoreVMConfigFromFlags(cmd, vm, cfg)
@@ -287,18 +287,21 @@ func (h Handler) cloneFromDir(ctx context.Context, cmd *cobra.Command, conf *con
 	if err != nil {
 		return fmt.Errorf("load envelope: %w", err)
 	}
+	// Local copy so flipping the backend selection doesn't leak to the caller's
+	// shared *config.Config (CLI is fine, daemons embedding cocoon would notice).
+	localConf := *conf
 	if cfg.Hypervisor != "" {
-		conf.UseFirecracker = cfg.Hypervisor == string(config.HypervisorFirecracker)
+		localConf.UseFirecracker = cfg.Hypervisor == string(config.HypervisorFirecracker)
 	}
-	hyper, err := cmdcore.InitHypervisor(conf)
+	hyper, err := cmdcore.InitHypervisor(&localConf)
 	if err != nil {
 		return err
 	}
 	dcr, ok := hyper.(hypervisor.Direct)
 	if !ok {
 		return fmt.Errorf("backend %s does not support direct clone", hyper.Type())
 	}
-	return h.cloneFromSrcDir(ctx, cmd, conf, dcr, cfg, dir,
+	return h.cloneFromSrcDir(ctx, cmd, &localConf, dcr, cfg, dir,
 		fmt.Sprintf("dir %s", dir), logger)
 }
 

snapshot/localfile/export.go

@@ -5,10 +5,8 @@ import (
 	"compress/gzip"
 	"context"
 	"encoding/json"
-	"errors"
 	"fmt"
 	"io"
-	"io/fs"
 	"os"
 	"path/filepath"
 	"time"
@@ -40,17 +38,16 @@ func (lf *LocalFile) ExportToDir(ctx context.Context, ref, dir string) error {
 	if err != nil {
 		return err
 	}
+	if err = utils.EnsureDirs(dir); err != nil {
+		return err
+	}
 	// Reject non-empty targets so the export can't silently merge into an
-	// unrelated tree; mkdir if absent.
+	// unrelated tree.
 	dstEntries, err := os.ReadDir(dir)
-	switch {
-	case errors.Is(err, fs.ErrNotExist):
-		if err = os.MkdirAll(dir, 0o750); err != nil {
-			return fmt.Errorf("create %s: %w", dir, err)
-		}
-	case err != nil:
-		return fmt.Errorf("stat %s: %w", dir, err)
-	case len(dstEntries) > 0:
+	if err != nil {
+		return fmt.Errorf("read %s: %w", dir, err)
+	}
+	if len(dstEntries) > 0 {
 		return fmt.Errorf("target dir %s is not empty", dir)
 	}
 	entries, err := os.ReadDir(dataDir)
@@ -62,10 +59,6 @@ func (lf *LocalFile) ExportToDir(ctx context.Context, ref, dir string) error {
 			continue
 		}
 		name := entry.Name()
-		if name == snapshot.SnapshotJSONName {
-			// re-exporting a dir that already has an envelope: ours wins
-			continue
-		}
 		src := filepath.Join(dataDir, name)
 		dst := filepath.Join(dir, name)
 		if err = utils.ReflinkCopy(dst, src); err != nil {