package id3ed import ( "bytes" "fmt" "io" ) // Shortcut function to read n bytes from reader. Peeked from here: https://github.com/dhowden/tag/blob/master/util.go func read(rs io.Reader, n int) ([]byte, error) { read := make([]byte, n) _, err := rs.Read(read) if err != nil { return nil, fmt.Errorf("could not read from reader: %s", err) } return read, nil } // Shortcut function to read n bytes and convert them into string. // If encountered zero-byte - converts to string only previously read bytes func readToString(rs io.Reader, n int) (string, error) { read := make([]byte, n) _, err := rs.Read(read) if err != nil { return "", fmt.Errorf("could not read from reader: %s", err) } var readString string for _, b := range read { if b == 0 { break } readString += string(b) } return readString, nil } // Writes data to wr, if len(data) is less than lenNeeded - adds null bytes until written lenNeeded bytes func writeToExtent(wr io.Writer, data []byte, lenNeeded int) error { if len(data) > lenNeeded { return fmt.Errorf("length of given data bytes is bigger than length needed") } buff := new(bytes.Buffer) for i := 0; i < lenNeeded; i++ { if i < len(data) { err := buff.WriteByte(data[i]) if err != nil { return err } } else { err := buff.WriteByte(0) if err != nil { return err } } } _, err := wr.Write(buff.Bytes()) if err != nil { return err } return nil } // Returns found key (int) in provided map by value (string); // If key does not exist in map - returns -1 func getKey(mp map[int]string, givenValue string) int { for key, value := range mp { if value == givenValue { return key } } return -1 }