func()

in wim/wim.go [650:778]

• 108 lines of code
• 28 McCabe index (conditional complexity)

func (img *Image) readNextEntry(r io.Reader) (*File, int64, error) {
	var length int64
	err := binary.Read(r, binary.LittleEndian, &length)
	if err != nil {
		return nil, 0, &ParseError{Oper: "directory length check", Err: err}
	}

	if length == 0 {
		return nil, 8, io.EOF
	}

	left := length
	if left < direntrySize {
		return nil, 0, &ParseError{Oper: "directory entry", Err: errors.New("size too short")}
	}

	var dentry direntry
	err = binary.Read(r, binary.LittleEndian, &dentry)
	if err != nil {
		return nil, 0, &ParseError{Oper: "directory entry", Err: err}
	}

	left -= direntrySize

	namesLen := int64(dentry.FileNameLength + 2 + dentry.ShortNameLength)
	if left < namesLen {
		return nil, 0, &ParseError{Oper: "directory entry", Err: errors.New("size too short for names")}
	}

	names := make([]uint16, namesLen/2)
	err = binary.Read(r, binary.LittleEndian, names)
	if err != nil {
		return nil, 0, &ParseError{Oper: "file name", Err: err}
	}

	left -= namesLen

	var name, shortName string
	if dentry.FileNameLength > 0 {
		name = string(utf16.Decode(names[:dentry.FileNameLength/2]))
	}

	if dentry.ShortNameLength > 0 {
		shortName = string(utf16.Decode(names[dentry.FileNameLength/2+1:]))
	}

	var offset resourceDescriptor
	zerohash := SHA1Hash{}
	if dentry.Hash != zerohash {
		var ok bool
		offset, ok = img.wim.fileData[dentry.Hash]
		if !ok {
			return nil, 0, &ParseError{Oper: "directory entry", Path: name, Err: fmt.Errorf("could not find file data matching hash %#v", dentry)}
		}
	}

	f := &File{
		FileHeader: FileHeader{
			Attributes:     dentry.Attributes,
			CreationTime:   dentry.CreationTime,
			LastAccessTime: dentry.LastAccessTime,
			LastWriteTime:  dentry.LastWriteTime,
			Hash:           dentry.Hash,
			Size:           offset.OriginalSize,
			Name:           name,
			ShortName:      shortName,
		},

		offset:       offset,
		img:          img,
		subdirOffset: dentry.SubdirOffset,
	}

	isDir := false

	if dentry.Attributes&FILE_ATTRIBUTE_REPARSE_POINT == 0 {
		f.LinkID = dentry.ReparseHardLink
		if dentry.Attributes&FILE_ATTRIBUTE_DIRECTORY != 0 {
			isDir = true
		}
	} else {
		f.ReparseTag = uint32(dentry.ReparseHardLink)
		f.ReparseReserved = uint32(dentry.ReparseHardLink >> 32)
	}

	if isDir && f.subdirOffset == 0 {
		return nil, 0, &ParseError{Oper: "directory entry", Path: name, Err: errors.New("no subdirectory data for directory")}
	} else if !isDir && f.subdirOffset != 0 {
		return nil, 0, &ParseError{Oper: "directory entry", Path: name, Err: errors.New("unexpected subdirectory data for non-directory")}
	}

	if dentry.SecurityID != 0xffffffff {
		f.SecurityDescriptor = img.sds[dentry.SecurityID]
	}

	_, err = io.CopyN(ioutil.Discard, r, left)
	if err != nil {
		if err == io.EOF {
			err = io.ErrUnexpectedEOF
		}
		return nil, 0, err
	}

	if dentry.StreamCount > 0 {
		var streams []*Stream
		for i := uint16(0); i < dentry.StreamCount; i++ {
			s, n, err := img.readNextStream(r)
			length += n
			if err != nil {
				return nil, 0, err
			}
			// The first unnamed stream should be treated as the file stream.
			if i == 0 && s.Name == "" {
				f.Hash = s.Hash
				f.Size = s.Size
				f.offset = s.offset
			} else if s.Name != "" {
				streams = append(streams, s)
			}
		}
		f.Streams = streams
	}

	if dentry.Attributes&FILE_ATTRIBUTE_REPARSE_POINT != 0 && f.Size == 0 {
		return nil, 0, &ParseError{Oper: "directory entry", Path: name, Err: errors.New("reparse point is missing reparse stream")}
	}

	return f, length, nil
}