dotcloud/docker

// Package stringid provides helper functions for dealing with string identifiers
package stringid // import "github.com/docker/docker/pkg/stringid"

import (
    "crypto/rand"
    "encoding/hex"
    "errors"
    "regexp"
    "strconv"
    "strings"
)

const (
    shortLen = 12
    fullLen  = 64
)

var (
    validShortID = regexp.MustCompile("^[a-f0-9]{12}$")
    validHex     = regexp.MustCompile(`^[a-f0-9]{64}$`)
)

// IsShortID determines if id has the correct format and length for a short ID.
// It checks the IDs length and if it consists of valid characters for IDs (a-f0-9).
//
// Deprecated: this function is no longer used, and will be removed in the next release.
func IsShortID(id string) bool {
    if len(id) != shortLen {
        return false
    }
    return validShortID.MatchString(id)
}

// TruncateID returns a shorthand version of a string identifier for convenience.
// A collision with other shorthands is very unlikely, but possible.
// In case of a collision a lookup with TruncIndex.Get() will fail, and the caller
// will need to use a longer prefix, or the full-length Id.
func TruncateID(id string) string {
    if i := strings.IndexRune(id, ':'); i >= 0 {
        id = id[i+1:]
    }
    if len(id) > shortLen {
        id = id[:shortLen]
    }
    return id
}

// GenerateRandomID returns a unique id.
func GenerateRandomID() string {
    b := make([]byte, 32)
    for {
        if _, err := rand.Read(b); err != nil {
            panic(err) // This shouldn't happen
        }
        id := hex.EncodeToString(b)
        // if we try to parse the truncated for as an int and we don't have
        // an error then the value is all numeric and causes issues when
        // used as a hostname. ref #3869
        if _, err := strconv.ParseInt(TruncateID(id), 10, 64); err == nil {
            continue
        }
        return id
    }
}

// ValidateID checks whether an ID string is a valid, full-length image ID.
//
// Deprecated: use [github.com/docker/docker/image/v1.ValidateID] instead. Will be removed in the next release.
func ValidateID(id string) error {
    if len(id) != fullLen {
        return errors.New("image ID '" + id + "' is invalid")
    }
    if !validHex.MatchString(id) {
        return errors.New("image ID '" + id + "' is invalid")
    }
    return nil
}