Updated ReadFrom to take io.ReadSeeker

This commit is contained in:
David Howden 2015-04-15 00:06:32 +10:00
parent 23f80edc48
commit 1fc6cacf34
4 changed files with 35 additions and 27 deletions

View File

@ -5,10 +5,9 @@
package tag
import (
"bytes"
"errors"
"io"
"io/ioutil"
"os"
"strconv"
"strings"
)
@ -42,16 +41,14 @@ var id3v1Genres = [...]string{
// ErrNotID3v1 is an error which is returned when no ID3v1 header is found.
var ErrNotID3v1 = errors.New("invalid ID3v1 header")
// ReadID3v1Tags reads ID3v1 tags from the given io.Reader. Returns a non-nil error
// if there was a problem.
func ReadID3v1Tags(r io.Reader) (Metadata, error) {
b, err := ioutil.ReadAll(r)
// ReadID3v1Tags reads ID3v1 tags from the io.ReadSeeker. Returns ErrNotID3v1
// if there are no ID3v1 tags, otherwise non-nil error if there was a problem.
func ReadID3v1Tags(r io.ReadSeeker) (Metadata, error) {
_, err := r.Seek(-128, os.SEEK_END)
if err != nil {
return nil, err
}
b = b[len(b)-128 : len(b)]
r = bytes.NewReader(b)
if tag, err := readString(r, 3); err != nil {
return nil, err
} else if tag != "TAG" {

View File

@ -7,6 +7,7 @@ package tag
import (
"fmt"
"io"
"os"
"strings"
)
@ -219,9 +220,14 @@ func readID3v2Frames(r io.Reader, h *ID3v2Header) (map[string]interface{}, error
return result, nil
}
// ReadID3v2Tags parses ID3v2.{2,3,4} tags from the given io.Reader into a Metadata, returning
// ReadID3v2Tags parses ID3v2.{2,3,4} tags from the io.ReadSeeker into a Metadata, returning
// non-nil error on failure.
func ReadID3v2Tags(r io.Reader) (Metadata, error) {
func ReadID3v2Tags(r io.ReadSeeker) (Metadata, error) {
_, err := r.Seek(0, os.SEEK_SET)
if err != nil {
return nil, err
}
h, err := readID3v2Header(r)
if err != nil {
return nil, err

13
mp4.go
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@ -8,6 +8,7 @@ import (
"encoding/binary"
"fmt"
"io"
"os"
"strconv"
)
@ -56,11 +57,15 @@ func (f atomNames) Name(n string) []string {
// metadataMP4 is the implementation of Metadata for MP4 tag (atom) data.
type metadataMP4 map[string]interface{}
// ReadAtoms reads MP4 metadata atoms from the reader into a Metadata, returning non-nil
// error if there was a problem.
func ReadAtoms(r io.Reader) (Metadata, error) {
// ReadAtoms reads MP4 metadata atoms from the io.ReadSeeker into a Metadata, returning
// non-nil error if there was a problem.
func ReadAtoms(r io.ReadSeeker) (Metadata, error) {
_, err := r.Seek(0, os.SEEK_SET)
if err != nil {
return nil, err
}
m := make(metadataMP4)
err := m.readAtoms(r)
err = m.readAtoms(r)
return m, err
}

26
tag.go
View File

@ -6,7 +6,6 @@
package tag
import (
"bytes"
"errors"
"io"
)
@ -16,25 +15,26 @@ import (
var ErrNoTagsFound = errors.New("no tags found")
// ReadFrom parses audio file metadata tags (currently supports ID3v1,2.{2,3,4} and MP4).
// This method attempts to determine the format of the data provided by the reader, and then
// chooses ReadAtoms (MP4), ReadID3v2Tags (ID3v2.{2,3,4}) or ReadID3v1Tags as appropriate.
// Returns non-nil error if the format of the given data could not be determined, or if
// there was a problem parsing the data.
func ReadFrom(r io.Reader) (Metadata, error) {
// This method attempts to determine the format of the data provided by the io.ReadSeeker,
// and then chooses ReadAtoms (MP4), ReadID3v2Tags (ID3v2.{2,3,4}) or ReadID3v1Tags as
// appropriate. Returns non-nil error if the format of the given data could not be determined,
// or if there was a problem parsing the data.
func ReadFrom(r io.ReadSeeker) (Metadata, error) {
b, err := readBytes(r, 11)
if err != nil {
return nil, err
}
rr := io.MultiReader(bytes.NewReader(b), r)
if string(b[4:11]) == "ftypM4A" {
return ReadAtoms(rr)
}
if string(b[0:3]) == "ID3" {
return ReadID3v2Tags(rr)
switch {
case string(b[4:11]) == "ftypM4A":
return ReadAtoms(r)
case string(b[0:3]) == "ID3":
return ReadID3v2Tags(r)
}
m, err := ReadID3v1Tags(rr)
m, err := ReadID3v1Tags(r)
if err != nil {
if err == ErrNotID3v1 {
err = ErrNoTagsFound