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moby--moby/pkg/common/randomid.go
Srini Brahmaroutu 7a9c944b82 Removing dependencies from pkg into Docker internal code
Closes #10922

Signed-off-by: Srini Brahmaroutu <srbrahma@us.ibm.com>
2015-02-23 18:43:10 +00:00

38 lines
1,019 B
Go

package common
import (
"crypto/rand"
"encoding/hex"
"io"
"strconv"
)
// 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 {
shortLen := 12
if len(id) < shortLen {
shortLen = len(id)
}
return id[:shortLen]
}
// GenerateRandomID returns an unique id
func GenerateRandomID() string {
for {
id := make([]byte, 32)
if _, err := io.ReadFull(rand.Reader, id); err != nil {
panic(err) // This shouldn't happen
}
value := hex.EncodeToString(id)
// if we try to parse the truncated for as an int and we don't have
// an error then the value is all numberic and causes issues when
// used as a hostname. ref #3869
if _, err := strconv.ParseInt(TruncateID(value), 10, 64); err == nil {
continue
}
return value
}
}