Abhilash S.L | 3b49463 | 2019-07-16 15:51:09 +0530 | [diff] [blame] | 1 | package mstypes |
| 2 | |
| 3 | import ( |
| 4 | "bufio" |
| 5 | "encoding/binary" |
| 6 | "fmt" |
| 7 | "io" |
| 8 | ) |
| 9 | |
| 10 | // Byte sizes of primitive types |
| 11 | const ( |
| 12 | SizeBool = 1 |
| 13 | SizeChar = 1 |
| 14 | SizeUint8 = 1 |
| 15 | SizeUint16 = 2 |
| 16 | SizeUint32 = 4 |
| 17 | SizeUint64 = 8 |
| 18 | SizeEnum = 2 |
| 19 | SizeSingle = 4 |
| 20 | SizeDouble = 8 |
| 21 | SizePtr = 4 |
| 22 | ) |
| 23 | |
| 24 | // Reader reads simple byte stream data into a Go representations |
| 25 | type Reader struct { |
| 26 | r *bufio.Reader // source of the data |
| 27 | } |
| 28 | |
| 29 | // NewReader creates a new instance of a simple Reader. |
| 30 | func NewReader(r io.Reader) *Reader { |
| 31 | reader := new(Reader) |
| 32 | reader.r = bufio.NewReader(r) |
| 33 | return reader |
| 34 | } |
| 35 | |
| 36 | func (r *Reader) Read(p []byte) (n int, err error) { |
| 37 | return r.r.Read(p) |
| 38 | } |
| 39 | |
| 40 | func (r *Reader) Uint8() (uint8, error) { |
| 41 | b, err := r.r.ReadByte() |
| 42 | if err != nil { |
| 43 | return uint8(0), err |
| 44 | } |
| 45 | return uint8(b), nil |
| 46 | } |
| 47 | |
| 48 | func (r *Reader) Uint16() (uint16, error) { |
| 49 | b, err := r.ReadBytes(SizeUint16) |
| 50 | if err != nil { |
| 51 | return uint16(0), err |
| 52 | } |
| 53 | return binary.LittleEndian.Uint16(b), nil |
| 54 | } |
| 55 | |
| 56 | func (r *Reader) Uint32() (uint32, error) { |
| 57 | b, err := r.ReadBytes(SizeUint32) |
| 58 | if err != nil { |
| 59 | return uint32(0), err |
| 60 | } |
| 61 | return binary.LittleEndian.Uint32(b), nil |
| 62 | } |
| 63 | |
| 64 | func (r *Reader) Uint64() (uint64, error) { |
| 65 | b, err := r.ReadBytes(SizeUint64) |
| 66 | if err != nil { |
| 67 | return uint64(0), err |
| 68 | } |
| 69 | return binary.LittleEndian.Uint64(b), nil |
| 70 | } |
| 71 | |
| 72 | func (r *Reader) FileTime() (f FileTime, err error) { |
| 73 | f.LowDateTime, err = r.Uint32() |
| 74 | if err != nil { |
| 75 | return |
| 76 | } |
| 77 | f.HighDateTime, err = r.Uint32() |
| 78 | if err != nil { |
| 79 | return |
| 80 | } |
| 81 | return |
| 82 | } |
| 83 | |
| 84 | // UTF16String returns a string that is UTF16 encoded in a byte slice. n is the number of bytes representing the string |
| 85 | func (r *Reader) UTF16String(n int) (str string, err error) { |
| 86 | //Length divided by 2 as each run is 16bits = 2bytes |
| 87 | s := make([]rune, n/2, n/2) |
| 88 | for i := 0; i < len(s); i++ { |
| 89 | var u uint16 |
| 90 | u, err = r.Uint16() |
| 91 | if err != nil { |
| 92 | return |
| 93 | } |
| 94 | s[i] = rune(u) |
| 95 | } |
| 96 | str = string(s) |
| 97 | return |
| 98 | } |
| 99 | |
| 100 | // readBytes returns a number of bytes from the NDR byte stream. |
| 101 | func (r *Reader) ReadBytes(n int) ([]byte, error) { |
| 102 | //TODO make this take an int64 as input to allow for larger values on all systems? |
| 103 | b := make([]byte, n, n) |
| 104 | m, err := r.r.Read(b) |
| 105 | if err != nil || m != n { |
| 106 | return b, fmt.Errorf("error reading bytes from stream: %v", err) |
| 107 | } |
| 108 | return b, nil |
| 109 | } |