+++ /dev/null
-// Package opts helps to write commands which may take multihash
-// options.
-package opts
-
-import (
- "bytes"
- "errors"
- "flag"
- "fmt"
- "io"
- "io/ioutil"
- "sort"
- "strings"
-
- mh "github.com/multiformats/go-multihash"
-)
-
-// package errors
-var (
- ErrMatch = errors.New("multihash checksums did not match")
-)
-
-// Options is a struct used to parse cli flags.
-type Options struct {
- Encoding string
- Algorithm string
- AlgorithmCode uint64
- Length int
-
- fs *flag.FlagSet
-}
-
-// FlagValues are the values the various option flags can take.
-var FlagValues = struct {
- Encodings []string
- Algorithms []string
-}{
- Encodings: []string{"raw", "hex", "base58", "base64"},
- Algorithms: func() []string {
- names := make([]string, 0, len(mh.Names))
- for n := range mh.Names {
- // There are too many of these for now.
- // We can figure something better out later.
- if strings.HasPrefix(n, "blake2") {
- switch n {
- case "blake2s-256":
- case "blake2b-128":
- case "blake2b-224":
- case "blake2b-256":
- case "blake2b-384":
- case "blake2b-512":
- default:
- continue
- }
- }
- names = append(names, n)
- }
- sort.Strings(names)
- return names
- }(),
-}
-
-// SetupFlags adds multihash related options to given flagset.
-func SetupFlags(f *flag.FlagSet) *Options {
- // TODO: add arg for adding opt prefix and/or overriding opts
-
- o := new(Options)
- algoStr := "one of: " + strings.Join(FlagValues.Algorithms, ", ")
- f.StringVar(&o.Algorithm, "algorithm", "sha2-256", algoStr)
- f.StringVar(&o.Algorithm, "a", "sha2-256", algoStr+" (shorthand)")
-
- encStr := "one of: " + strings.Join(FlagValues.Encodings, ", ")
- f.StringVar(&o.Encoding, "encoding", "base58", encStr)
- f.StringVar(&o.Encoding, "e", "base58", encStr+" (shorthand)")
-
- lengthStr := "checksums length in bits (truncate). -1 is default"
- f.IntVar(&o.Length, "length", -1, lengthStr)
- f.IntVar(&o.Length, "l", -1, lengthStr+" (shorthand)")
- return o
-}
-
-// Parse parses the values of flags from given argument slice.
-// It is equivalent to flags.Parse(args)
-func (o *Options) Parse(args []string) error {
- if err := o.fs.Parse(args); err != nil {
- return err
- }
- return o.ParseError()
-}
-
-// ParseError checks the parsed options for errors.
-func (o *Options) ParseError() error {
- if !strIn(o.Encoding, FlagValues.Encodings) {
- return fmt.Errorf("encoding '%s' not %s", o.Encoding, FlagValues.Encodings)
- }
-
- if !strIn(o.Algorithm, FlagValues.Algorithms) {
- return fmt.Errorf("algorithm '%s' not %s", o.Algorithm, FlagValues.Algorithms)
- }
-
- var found bool
- o.AlgorithmCode, found = mh.Names[o.Algorithm]
- if !found {
- return fmt.Errorf("algorithm '%s' not found (lib error, pls report).", o.Algorithm)
- }
-
- if o.Length >= 0 {
- if o.Length%8 != 0 {
- return fmt.Errorf("length must be multiple of 8")
- }
- o.Length = o.Length / 8
-
- if o.Length > mh.DefaultLengths[o.AlgorithmCode] {
- o.Length = mh.DefaultLengths[o.AlgorithmCode]
- }
- }
- return nil
-}
-
-// strIn checks wither string a is in set.
-func strIn(a string, set []string) bool {
- for _, s := range set {
- if s == a {
- return true
- }
- }
- return false
-}
-
-// Check reads all the data in r, calculates its multihash,
-// and checks it matches h1
-func (o *Options) Check(r io.Reader, h1 mh.Multihash) error {
- h2, err := o.Multihash(r)
- if err != nil {
- return err
- }
-
- if !bytes.Equal(h1, h2) {
- return fmt.Errorf("computed checksum did not match")
- }
-
- return nil
-}
-
-// Multihash reads all the data in r and calculates its multihash.
-func (o *Options) Multihash(r io.Reader) (mh.Multihash, error) {
- b, err := ioutil.ReadAll(r)
- if err != nil {
- return nil, err
- }
-
- return mh.Sum(b, o.AlgorithmCode, o.Length)
-}
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