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package uuid
import (
"crypto/rand"
"encoding/hex"
"fmt"
"io"
)
// GenerateRandomBytes is used to generate random bytes of given size.
func GenerateRandomBytes(size int) ([]byte, error) {
return GenerateRandomBytesWithReader(size, rand.Reader)
}
// GenerateRandomBytesWithReader is used to generate random bytes of given size read from a given reader.
func GenerateRandomBytesWithReader(size int, reader io.Reader) ([]byte, error) {
if reader == nil {
return nil, fmt.Errorf("provided reader is nil")
}
buf := make([]byte, size)
if _, err := io.ReadFull(reader, buf); err != nil {
return nil, fmt.Errorf("failed to read random bytes: %v", err)
}
return buf, nil
}
const uuidLen = 16
// GenerateUUID is used to generate a random UUID
func GenerateUUID() (string, error) {
return GenerateUUIDWithReader(rand.Reader)
}
// GenerateUUIDWithReader is used to generate a random UUID with a given Reader
func GenerateUUIDWithReader(reader io.Reader) (string, error) {
if reader == nil {
return "", fmt.Errorf("provided reader is nil")
}
buf, err := GenerateRandomBytesWithReader(uuidLen, reader)
if err != nil {
return "", err
}
return FormatUUID(buf)
}
func FormatUUID(buf []byte) (string, error) {
if buflen := len(buf); buflen != uuidLen {
return "", fmt.Errorf("wrong length byte slice (%d)", buflen)
}
return fmt.Sprintf("%x-%x-%x-%x-%x",
buf[0:4],
buf[4:6],
buf[6:8],
buf[8:10],
buf[10:16]), nil
}
func ParseUUID(uuid string) ([]byte, error) {
if len(uuid) != 2 * uuidLen + 4 {
return nil, fmt.Errorf("uuid string is wrong length")
}
if uuid[8] != '-' ||
uuid[13] != '-' ||
uuid[18] != '-' ||
uuid[23] != '-' {
return nil, fmt.Errorf("uuid is improperly formatted")
}
hexStr := uuid[0:8] + uuid[9:13] + uuid[14:18] + uuid[19:23] + uuid[24:36]
ret, err := hex.DecodeString(hexStr)
if err != nil {
return nil, err
}
if len(ret) != uuidLen {
return nil, fmt.Errorf("decoded hex is the wrong length")
}
return ret, nil
}
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