Add update command to schememgr executable

schememgr/cmd/update.go

+package cmd
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/go-errors/errors"
+	"github.com/privacybydesign/irmago"
+	"github.com/privacybydesign/irmago/internal/fs"
+	"github.com/spf13/cobra"
+)
+
+var updateCmd = &cobra.Command{
+	Use:   "update path...",
+	Short: "[Experimental] Update a scheme manager",
+	Long: `The update command updates a scheme manager within an irma_configuration folder by comparing its index with the online version, and downloading any new and changed files.
+
+Careful: this command could fail and invalidate or destroy your scheme manager folder! Use this only if you can restore it from git or backups.`,
+	RunE: func(cmd *cobra.Command, args []string) error {
+		return updateSchemeManager(args)
+	},
+}
+
+func init() {
+	RootCmd.AddCommand(updateCmd)
+}
+
+func updateSchemeManager(paths []string) error {
+	// Before doing anything, first check that all paths are scheme managers
+	for _, path := range paths {
+		if err := fs.AssertPathExists(filepath.Join(path, "index")); err != nil {
+			return errors.Errorf("%s is not a valid scheme manager (%s)", path, err.Error())
+		}
+	}
+
+	for _, path := range paths {
+		if strings.HasSuffix(path, string(os.PathSeparator)) {
+			path = path[:len(path)-1]
+		}
+		irmaconf, manager := filepath.Dir(path), filepath.Base(path)
+
+		// TODO: this parses all managers within the irma_configuration folder, not just the one specified
+		// Should make a Configuration constructor that parses just one manager
+		conf, err := irma.NewConfiguration(irmaconf, "")
+		if err != nil {
+			return err
+		}
+		if err := conf.ParseFolder(); err != nil {
+			return err
+		}
+
+		if err = conf.UpdateSchemeManager(irma.NewSchemeManagerIdentifier(manager), nil); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}