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Refactored Hash -> Sum and fixed infinite loop issue with SumAtoms

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This commit is contained in:
David Howden 2015-04-03 14:58:49 +11:00
parent 208a9e993c
commit e9deeea0e1
2 changed files with 28 additions and 24 deletions
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46
hash.go → sum.go
View File

@ -9,34 +9,34 @@ import (
"os"
)
// Hash creates a hash of the audio file data provided by the io.ReadSeeker which metadata
// Sum creates a checksum of the audio file data provided by the io.ReadSeeker which is metadata
// (ID3, MP4) invariant.
func Hash(r io.ReadSeeker) (string, error) {
func Sum(r io.ReadSeeker) (string, error) {
b, err := readBytes(r, 11)
if err != nil {
return "", err
}
if string(b[4:11]) == "ftypM4A" {
return HashAtoms(r)
return SumAtoms(r)
}
if string(b[0:3]) == "ID3" {
return HashID3v2(r)
return SumID3v2(r)
}
h, err := HashID3v1(r)
h, err := SumID3v1(r)
if err != nil {
if err == ErrNotID3v1 {
return HashAll(r)
return SumAll(r)
}
return "", err
}
return h, nil
}
// HashAll returns a hash of the entire content.
func HashAll(r io.ReadSeeker) (string, error) {
// SumAll returns a checksum of the entire content.
func SumAll(r io.ReadSeeker) (string, error) {
_, err := r.Seek(0, os.SEEK_SET)
if err != nil {
return "", fmt.Errorf("error seeking to 0: %v", err)
@ -46,16 +46,20 @@ func HashAll(r io.ReadSeeker) (string, error) {
if err != nil {
return "", nil
}
return hash(b), nil
return sum(b), nil
}
// HashAtoms constructs a hash of MP4 audio file data provided by the io.ReadSeeker which is metadata invariant.
func HashAtoms(r io.ReadSeeker) (string, error) {
// SumAtoms constructs a checksum of MP4 audio file data provided by the io.ReadSeeker which is
// metadata invariant.
func SumAtoms(r io.ReadSeeker) (string, error) {
_, err := r.Seek(0, os.SEEK_SET)
if err != nil {
return "", fmt.Errorf("error seeking to 0: %v", err)
}
return sumAtoms(r)
}
func sumAtoms(r io.ReadSeeker) (string, error) {
for {
var size uint32
err := binary.Read(r, binary.BigEndian, &size)
@ -81,7 +85,7 @@ func HashAtoms(r io.ReadSeeker) (string, error) {
fallthrough
case "moov", "udta", "ilst":
return HashAtoms(r)
return sumAtoms(r)
case "free":
_, err = r.Seek(int64(size-8), os.SEEK_CUR)
@ -95,7 +99,7 @@ func HashAtoms(r io.ReadSeeker) (string, error) {
if err != nil {
return "", fmt.Errorf("error reading audio data: %v", err)
}
return hash(b), nil
return sum(b), nil
}
_, err = r.Seek(int64(size-8), os.SEEK_CUR)
@ -105,9 +109,9 @@ func HashAtoms(r io.ReadSeeker) (string, error) {
}
}
// HashID3v1 constructs a hash of MP3 audio file data (assumed to have ID3v1 tags) provided by the
// io.ReadSeeker which is metadata invariant.
func HashID3v1(r io.ReadSeeker) (string, error) {
// SumID3v1 constructs a checksum of MP3 audio file data (assumed to have ID3v1 tags) provided
// by the io.ReadSeeker which is metadata invariant.
func SumID3v1(r io.ReadSeeker) (string, error) {
_, err := r.Seek(0, os.SEEK_SET)
if err != nil {
return "", fmt.Errorf("error seeking to 0: %v", err)
@ -121,12 +125,12 @@ func HashID3v1(r io.ReadSeeker) (string, error) {
if len(b) < 128 {
return "", fmt.Errorf("file size must be greater than 128 bytes for ID3v1 metadata (size: %v)", len(b))
}
return hash(b[:len(b)-128]), nil
return sum(b[:len(b)-128]), nil
}
// HashID3v2 constructs a hash of MP3 audio file data (assumed to have ID3v2 tags) provided by the
// SumID3v2 constructs a hash of MP3 audio file data (assumed to have ID3v2 tags) provided by the
// io.ReadSeeker which is metadata invariant.
func HashID3v2(r io.ReadSeeker) (string, error) {
func SumID3v2(r io.ReadSeeker) (string, error) {
_, err := r.Seek(0, os.SEEK_SET)
if err != nil {
return "", fmt.Errorf("error seeking to 0: %v", err)
@ -150,9 +154,9 @@ func HashID3v2(r io.ReadSeeker) (string, error) {
if len(b) < 128 {
return "", fmt.Errorf("file size must be greater than 128 bytes for MP3 (ID3v2 header size: %d, remaining: %d)", h.Size, len(b))
}
return hash(b[:len(b)-128]), nil
return sum(b[:len(b)-128]), nil
}
func hash(b []byte) string {
func sum(b []byte) string {
return fmt.Sprintf("%x", sha1.Sum(b))
}

6
hash/hash.go → sum/sum.go
View File

@ -3,7 +3,7 @@
// license that can be found in the LICENSE file.
/*
The hash tool constructs a hash of a media file exluding any metadata
The sum tool constructs a checksum of a media file exluding any metadata
(as recognised by the tag library).
*/
package main
@ -28,9 +28,9 @@ func main() {
}
defer f.Close()
h, err := tag.Hash(f)
h, err := tag.Sum(f)
if err != nil {
fmt.Printf("error constructing hash: %v\n", err)
fmt.Printf("error constructing checksum: %v\n", err)
os.Exit(1)
}
fmt.Println(h)