github.com/Prakhar-Agarwal-byte/moby@v0.0.0-20231027092010-a14e3e8ab87e/pkg/stringid/stringid.go (about)

     1  // Package stringid provides helper functions for dealing with string identifiers
     2  package stringid // import "github.com/Prakhar-Agarwal-byte/moby/pkg/stringid"
     3  
     4  import (
     5  	"crypto/rand"
     6  	"encoding/hex"
     7  	"errors"
     8  	"regexp"
     9  	"strconv"
    10  	"strings"
    11  )
    12  
    13  const (
    14  	shortLen = 12
    15  	fullLen  = 64
    16  )
    17  
    18  var (
    19  	validShortID = regexp.MustCompile("^[a-f0-9]{12}$")
    20  	validHex     = regexp.MustCompile(`^[a-f0-9]{64}$`)
    21  )
    22  
    23  // IsShortID determines if id has the correct format and length for a short ID.
    24  // It checks the IDs length and if it consists of valid characters for IDs (a-f0-9).
    25  func IsShortID(id string) bool {
    26  	if len(id) != shortLen {
    27  		return false
    28  	}
    29  	return validShortID.MatchString(id)
    30  }
    31  
    32  // TruncateID returns a shorthand version of a string identifier for convenience.
    33  // A collision with other shorthands is very unlikely, but possible.
    34  // In case of a collision a lookup with TruncIndex.Get() will fail, and the caller
    35  // will need to use a longer prefix, or the full-length Id.
    36  func TruncateID(id string) string {
    37  	if i := strings.IndexRune(id, ':'); i >= 0 {
    38  		id = id[i+1:]
    39  	}
    40  	if len(id) > shortLen {
    41  		id = id[:shortLen]
    42  	}
    43  	return id
    44  }
    45  
    46  // GenerateRandomID returns a unique id.
    47  func GenerateRandomID() string {
    48  	b := make([]byte, 32)
    49  	for {
    50  		if _, err := rand.Read(b); err != nil {
    51  			panic(err) // This shouldn't happen
    52  		}
    53  		id := hex.EncodeToString(b)
    54  		// if we try to parse the truncated for as an int and we don't have
    55  		// an error then the value is all numeric and causes issues when
    56  		// used as a hostname. ref #3869
    57  		if _, err := strconv.ParseInt(TruncateID(id), 10, 64); err == nil {
    58  			continue
    59  		}
    60  		return id
    61  	}
    62  }
    63  
    64  // ValidateID checks whether an ID string is a valid, full-length image ID.
    65  func ValidateID(id string) error {
    66  	if len(id) != fullLen {
    67  		return errors.New("image ID '" + id + "' is invalid")
    68  	}
    69  	if !validHex.MatchString(id) {
    70  		return errors.New("image ID '" + id + "' is invalid")
    71  	}
    72  	return nil
    73  }