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validate.go
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validate.go
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// Package identifiers provides common validation for identifiers and keys
// across containerd.
//
// Identifiers in containerd must be a alphanumeric, allowing limited
// underscores, dashes and dots.
//
// While the character set may be expanded in the future, identifiers
// are guaranteed to be safely used as filesystem path components.
package identifiers
import (
"regexp"
"github.com/containerd/containerd/errdefs"
"github.com/pkg/errors"
)
const (
maxLength = 76
alphanum = `[A-Za-z0-9]+`
separators = `[._-]`
)
var (
// identifierRe defines the pattern for valid identifiers.
identifierRe = regexp.MustCompile(reAnchor(alphanum + reGroup(separators+reGroup(alphanum)) + "*"))
)
// Validate return nil if the string s is a valid identifier.
//
// identifiers must be valid domain names according to RFC 1035, section 2.3.1. To
// enforce case insensitvity, all characters must be lower case.
//
// In general, identifiers that pass this validation, should be safe for use as
// a domain names or filesystem path component.
func Validate(s string) error {
if len(s) == 0 {
return errors.Wrapf(errdefs.ErrInvalidArgument, "identifier must not be empty")
}
if len(s) > maxLength {
return errors.Wrapf(errdefs.ErrInvalidArgument, "identifier %q greater than maximum length (%d characters)", s, maxLength)
}
if !identifierRe.MatchString(s) {
return errors.Wrapf(errdefs.ErrInvalidArgument, "identifier %q must match %v", s, identifierRe)
}
return nil
}
func reGroup(s string) string {
return `(?:` + s + `)`
}
func reAnchor(s string) string {
return `^` + s + `$`
}