package hostfiles

import "fmt"

// ValidateManifest checks every entry and platform item of m against the
// admitted origins, as Restore and CopyManifest do before they touch
// anything (contracts note §1). A caller holding a manifest's exact bytes
// from somewhere other than its prefix (a relocation's retained copy)
// validates them with it before writing them under a new generation.
func ValidateManifest(m Manifest, origins []string) error {
	if m.V != ManifestVersion {
		return fmt.Errorf("hostfiles: manifest is version %d; this binary reads %d", m.V, ManifestVersion)
	}
	if len(origins) == 0 {
		return ErrOrigin
	}
	for _, o := range origins {
		if err := checkPrefix(o); err != nil {
			return err
		}
	}
	return checkManifest(m, origins)
}