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validate.go
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validate.go
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// Package namespaces provides tools for working with namespaces across
// containerd.
//
// Namespaces collect resources such as containers and images, into a unique
// identifier space. This means that two applications can use the same
// identifiers and not conflict while using containerd.
//
// This package can be used to ensure that client and server functions
// correctly store the namespace on the context.
package namespaces
import (
"regexp"
"github.com/containerd/containerd/errdefs"
"github.com/pkg/errors"
)
const (
maxLength = 76
alpha = `[A-Za-z]`
alphanum = `[A-Za-z0-9]+`
label = alpha + alphanum + `(:?[-]+` + alpha + alphanum + `)*`
)
var (
// namespaceRe validates that a namespace matches valid identifiers.
//
// Rules for domains, defined in RFC 1035, section 2.3.1, are used for
// namespaces.
namespaceRe = regexp.MustCompile(reAnchor(label + reGroup("[.]"+reGroup(label)) + "*"))
)
// Validate returns nil if the string s is a valid namespace.
//
// To allow such namespace identifiers to be used across various contexts
// safely, the character set has been restricted to that defined for domains in
// RFC 1035, section 2.3.1. This will make namespace identifiers safe for use
// across networks, filesystems and other media.
//
// The identifier specification departs from RFC 1035 in that it allows
// "labels" to start with number and only enforces a total length restriction
// of 76 characters.
//
// While the character set may be expanded in the future, namespace identifiers
// are guaranteed to be safely used as filesystem path components.
//
// For the most part, this doesn't need to be called directly when using the
// context-oriented functions.
func Validate(s string) error {
if len(s) > maxLength {
return errors.Wrapf(errdefs.ErrInvalidArgument, "namespace %q greater than maximum length (%d characters)", s, maxLength)
}
if !namespaceRe.MatchString(s) {
return errors.Wrapf(errdefs.ErrInvalidArgument, "namespace %q must match %v", s, namespaceRe)
}
return nil
}
func reGroup(s string) string {
return `(?:` + s + `)`
}
func reAnchor(s string) string {
return `^` + s + `$`
}