Function surgeryMetaUpdateFunc

cmd/bbolt/command/command_surgery_meta.go:137–182

(srcDBPath string, cfg surgeryMetaUpdateOptions)

}

func surgeryMetaUpdateFunc(srcDBPath string, cfg surgeryMetaUpdateOptions) error {
	if _, err := checkSourceDBPath(srcDBPath); err != nil {
		return err
	}

	if err := common.CopyFile(srcDBPath, cfg.outputDBFilePath); err != nil {
		return fmt.Errorf("[meta update] copy file failed: %w", err)
	}

	// read the page size from the first meta page if we want to edit the second meta page.
	var pageSize uint32
	if cfg.metaPageId == 1 {
		m0, _, err := ReadMetaPageAt(cfg.outputDBFilePath, 0, pageSize)
		if err != nil {
			return fmt.Errorf("read the first meta page failed: %w", err)
		}
		pageSize = m0.PageSize()
	}

	// update the specified meta page
	m, buf, err := ReadMetaPageAt(cfg.outputDBFilePath, cfg.metaPageId, pageSize)
	if err != nil {
		return fmt.Errorf("read meta page %d failed: %w", cfg.metaPageId, err)
	}
	mChanged := updateMetaField(m, parseFields(cfg.fields))
	if mChanged {
		if err := writeMetaPageAt(cfg.outputDBFilePath, buf, cfg.metaPageId, pageSize); err != nil {
			return fmt.Errorf("[meta update] write meta page %d failed: %w", cfg.metaPageId, err)
		}
	}

	if cfg.metaPageId == 1 && pageSize != m.PageSize() {
		fmt.Fprintf(os.Stdout, "WARNING: The page size (%d) in the first meta page doesn't match the second meta page (%d)\n", pageSize, m.PageSize())
	}

	// Display results
	if !mChanged {
		fmt.Fprintln(os.Stdout, "Nothing changed!")
	}

	if mChanged {
		fmt.Fprintf(os.Stdout, "The meta page %d has been updated!\n", cfg.metaPageId)
	}

	return nil
}

func parseFields(fields []string) map[string]uint64 {
	fieldsMap := make(map[string]uint64)