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Copy pathstringid.go
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71 lines (61 loc) · 1.71 KB
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// Package stringid provides helper functions for dealing with string identifiers
package stringid
import (
"crypto/rand"
"encoding/hex"
"io"
"regexp"
"strconv"
"strings"
"github.com/docker/docker/pkg/random"
)
const shortLen = 12
var validShortID = regexp.MustCompile("^[a-z0-9]{12}$")
// IsShortID determines if an arbitrary string *looks like* a short ID.
func IsShortID(id string) bool {
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 langer prefix, or the full-length Id.
func TruncateID(id string) string {
if i := strings.IndexRune(id, ':'); i >= 0 {
id = id[i+1:]
}
trimTo := shortLen
if len(id) < shortLen {
trimTo = len(id)
}
return id[:trimTo]
}
func generateID(crypto bool) string {
b := make([]byte, 32)
r := random.Reader
if crypto {
r = rand.Reader
}
for {
if _, err := io.ReadFull(r, 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
}
}
// GenerateRandomID returns an unique id.
func GenerateRandomID() string {
return generateID(true)
}
// GenerateNonCryptoID generates unique id without using cryptographically
// secure sources of random.
// It helps you to save entropy.
func GenerateNonCryptoID() string {
return generateID(false)
}