// parseVarLength parses a variable length value from a ReadSeeker.
// It returns the [up to] 32-bit value and an error.
func parseVarLength(reader io.ReadSeeker) (uint32, error) {
// Single byte buffer to read byte by byte.
var buffer []byte = make([]uint8, 1)
// The number of bytes returned.
// Should always be 1 unless we reach the EOF
var num int = 1
// Result value
var result uint32 = 0x00
// RTFM.
var first = true
for (first || (buffer[0]&0x80 == 0x80)) && (num > 0) {
result = result << 7
num, _ = reader.Read(buffer)
result |= (uint32(buffer[0]) & 0x7f)
first = false
}
if num == 0 && !first {
return result, UnexpectedEndOfFile
}
return result, nil
}
func NewReader(r io.ReadSeeker, length int64) (*Reader, error) {
footer := make([]byte, FOOTER_SIZE)
r.Seek(length-int64(FOOTER_SIZE), 0)
_, err := r.Read(footer)
if err != nil {
return nil, err
}
if string(footer[FOOTER_SIZE-len(MAGIC):FOOTER_SIZE]) != MAGIC {
return nil, errors.New("invalid sst format")
}
_, n := decodeBlockHandle(footer[:])
indexBlockHandle, n := decodeBlockHandle(footer[n:])
reader := &Reader{
reader: r,
length: length,
}
reader.index, err = reader.readBlock(indexBlockHandle)
return reader, err
}
func GetRawTileFromMetatile(r io.ReadSeeker, coord gopnik.TileCoord) ([]byte, error) {
ml, err := decodeMetatileHeader(r)
if err != nil {
return nil, err
}
size := int32(math.Sqrt(float64(ml.Count)))
index := (int32(coord.X)-ml.X)*size + (int32(coord.Y) - ml.Y)
if index >= ml.Count {
return nil, fmt.Errorf("Invalid index %v/%v", index, ml.Count)
}
entry := ml.Index[index]
if entry.Size > MAXENTRYSIZE {
return nil, fmt.Errorf("entry size > MAXENTRYSIZE (size: %v)", entry.Size)
}
r.Seek(int64(entry.Offset), 0)
buf := make([]byte, entry.Size)
l, err := r.Read(buf)
if err != nil {
return nil, err
}
if int32(l) != entry.Size {
return nil, fmt.Errorf("Invalid tile seze: %v != %v", l, entry.Size)
}
return buf, nil
}
// parseChunkHeader parses a chunk header from a ReadSeeker.
// It returns the ChunkHeader struct as a value and an error.
func parseChunkHeader(reader io.ReadSeeker) (ChunkHeader, error) {
// fmt.Println("Parse Chunk Header")
var chunk ChunkHeader
var chunkTypeBuffer []byte = make([]byte, 4)
num, err := reader.Read(chunkTypeBuffer)
// fmt.Println("Buffer type", chunkTypeBuffer, "num", num)
// If we couldn't read 4 bytes, that's a problem.
if num != 4 {
return chunk, UnexpectedEndOfFile
}
if err != nil {
return chunk, err
}
chunk.Length, err = parseUint32(reader)
chunk.ChunkType = string(chunkTypeBuffer)
// parseUint32 might return an error.
if err != nil {
return chunk, err
}
return chunk, nil
}
func parseText(reader io.ReadSeeker) (string, error) {
length, err := parseVarLength(reader)
if err != nil {
return "", err
}
var buffer []byte = make([]byte, length)
num, err := reader.Read(buffer)
// If we couldn't read the entire expected-length buffer, that's a problem.
if num != int(length) {
return "", UnexpectedEndOfFile
}
// If there was some other problem, that's also a problem.
if err != nil {
return "", err
}
// TODO: Data should be ASCII but might go up to 0xFF.
// What will Go do? Try and decode UTF-8?
return string(buffer), nil
}
func (w *WorkBook) get_string(buf io.ReadSeeker, size uint16) (res string, err error) {
if w.Is5ver {
var bts = make([]byte, size)
_, err = buf.Read(bts)
res = string(bts)
} else {
var richtext_num uint16
var phonetic_size uint32
var flag byte
err = binary.Read(buf, binary.LittleEndian, &flag)
if flag&0x8 != 0 {
err = binary.Read(buf, binary.LittleEndian, &richtext_num)
}
if flag&0x4 != 0 {
err = binary.Read(buf, binary.LittleEndian, &phonetic_size)
}
if flag&0x1 != 0 {
var bts = make([]uint16, size)
var i = uint16(0)
for ; i < size && err == nil; i++ {
err = binary.Read(buf, binary.LittleEndian, &bts[i])
}
runes := utf16.Decode(bts[:i])
res = string(runes)
if i < size {
w.continue_utf16 = size - i
}
} else {
var bts = make([]byte, size)
var n int
n, err = buf.Read(bts)
if uint16(n) < size {
w.continue_utf16 = size - uint16(n)
err = io.EOF
}
var bts1 = make([]uint16, size)
for k, v := range bts[:n] {
bts1[k] = uint16(v)
}
runes := utf16.Decode(bts1)
res = string(runes)
}
if flag&0x8 != 0 {
var bts []byte
if w.Is5ver {
bts = make([]byte, 2*richtext_num)
} else {
bts = make([]byte, 4*richtext_num)
}
err = binary.Read(buf, binary.LittleEndian, bts)
}
if flag&0x4 != 0 {
var bts []byte
bts = make([]byte, phonetic_size)
err = binary.Read(buf, binary.LittleEndian, bts)
}
}
return
}
// parsePitchWheelValue parses a 14-bit signed value, which becomes a signed int16.
// The least significant 7 bits are stored in the first byte, the 7 most significant bites are stored in the second.
// Return the signed value relative to the centre, and the absolute value.
// This is tested in midi_lexer_test.go TestPitchWheel
func parsePitchWheelValue(reader io.ReadSeeker) (relative int16, absolute uint16, err error) {
var buffer []byte = make([]byte, 2)
num, err := reader.Read(buffer)
// If we couldn't read 2 bytes, that's a problem.
if num != 2 {
return 0, 0, UnexpectedEndOfFile
}
// If there was some other problem, that's also a problem.
if err != nil {
return 0, 0, err
}
var val uint16 = 0
val = uint16((buffer[1])&0x7f) << 7
val |= uint16(buffer[0]) & 0x7f
// fmt.Println(val)
// log.Println()
// Turn into a signed value relative to the centre.
relative = int16(val) - 0x2000
return relative, val, nil
}
func OpenTlk(r io.ReadSeeker) (*TLK, error) {
tlk := &TLK{r: r, codepage: "latin1"}
tlkLen, err := r.Seek(0, os.SEEK_END)
if err != nil {
return nil, err
}
r.Seek(0, os.SEEK_SET)
err = binary.Read(r, binary.LittleEndian, &tlk.header)
if err != nil {
return nil, err
}
tlk.entries = make([]tlkEntry, tlk.header.StringCount)
err = binary.Read(r, binary.LittleEndian, &tlk.entries)
if err != nil {
return nil, err
}
tlkPos, err := r.Seek(0, os.SEEK_CUR)
tlk.stringBuf = make([]byte, tlkLen-tlkPos)
size, err := r.Read(tlk.stringBuf)
if err != nil {
return nil, err
}
if size != len(tlk.stringBuf) {
return nil, err
}
return tlk, nil
}
// tail returns the start of last nth line.
// * If n < 0, return the beginning of the file.
// * If n >= 0, return the beginning of last nth line.
// Notice that if the last line is incomplete (no end-of-line), it will not be counted
// as one line.
func tail(f io.ReadSeeker, n int64) (int64, error) {
if n < 0 {
return 0, nil
}
size, err := f.Seek(0, os.SEEK_END)
if err != nil {
return 0, err
}
var left, cnt int64
buf := make([]byte, blockSize)
for right := size; right > 0 && cnt <= n; right -= blockSize {
left = right - blockSize
if left < 0 {
left = 0
buf = make([]byte, right)
}
if _, err := f.Seek(left, os.SEEK_SET); err != nil {
return 0, err
}
if _, err := f.Read(buf); err != nil {
return 0, err
}
cnt += int64(bytes.Count(buf, eol))
}
for ; cnt > n; cnt-- {
idx := bytes.Index(buf, eol) + 1
buf = buf[idx:]
left += int64(idx)
}
return left, nil
}
//Reads fieldinfo from DBF header, starting at pos 32.
//Reads fields until it finds the Header record terminator (0x0D).
func readHeaderFields(r io.ReadSeeker) ([]FieldHeader, error) {
fields := []FieldHeader{}
offset := int64(32)
b := make([]byte, 1)
for {
//Check if we are at 0x0D by reading one byte ahead
if _, err := r.Seek(offset, 0); err != nil {
return nil, err
}
if _, err := r.Read(b); err != nil {
return nil, err
}
if b[0] == 0x0D {
break
}
//Position back one byte and read the field
if _, err := r.Seek(-1, 1); err != nil {
return nil, err
}
field := FieldHeader{}
err := binary.Read(r, binary.LittleEndian, &field)
if err != nil {
return nil, err
}
fields = append(fields, field)
offset += 32
}
return fields, nil
}
func ChooseCompressAlgo(path string, rs io.ReadSeeker) (AlgorithmType, error) {
buf := make([]byte, Threshold)
bytesRead, err := rs.Read(buf)
if err != nil {
return AlgoNone, err
}
if _, errSeek := rs.Seek(0, os.SEEK_SET); err != nil {
return AlgoNone, errSeek
}
mime := guessMime(path, buf)
compressAble := isCompressable(mime)
if !compressAble || int64(bytesRead) != Threshold {
return AlgoNone, nil
}
if strings.HasPrefix(mime, "text/") {
return AlgoLZ4, nil
} else {
return AlgoSnappy, nil
}
}
//read line less than 1024 bytes
func ReadLine(r io.ReadSeeker, bf []byte) (n int, e error) {
newline := make([]byte, 10240)
n, e = r.Read(newline)
if e != nil && e != io.EOF {
return 0, e
}
lineTag := bytes.IndexByte(newline[:n], '\n')
if lineTag == -1 {
if e != io.EOF {
return 0, StringError(fmt.Sprintf("line too long than %d bytes", n))
}
if n > len(bf) {
return 0, StringError(fmt.Sprintf("too small bytes to hold line"))
}
copy(bf, newline[:n])
return n, io.EOF
}
if lineTag > len(bf) {
return 0, StringError(fmt.Sprintf("too small bytes to hold line"))
}
back := lineTag - n + 1
_, err := r.Seek(int64(back), 1)
if err != nil {
log.Fatal("Read error")
}
copy(bf, newline[:lineTag])
return lineTag, e
}
func readAt(r io.ReadSeeker, c int64, p []byte) (int64, error) {
if _, err := r.Seek(c, 0); err != nil {
return 0, err
}
n, err := r.Read(p)
return int64(n), err
}
// Returns new HTTP request object signed with streaming signature v4.
func newTestStreamingSignedRequest(method, urlStr string, contentLength, chunkSize int64, body io.ReadSeeker, accessKey, secretKey string) (*http.Request, error) {
req, err := newTestStreamingRequest(method, urlStr, contentLength, chunkSize, body)
if err != nil {
return nil, err
}
signature, err := signStreamingRequest(req, accessKey, secretKey)
if err != nil {
return nil, err
}
regionStr := serverConfig.GetRegion()
var stream []byte
var buffer []byte
body.Seek(0, 0)
for {
buffer = make([]byte, chunkSize)
n, err := body.Read(buffer)
if err != nil && err != io.EOF {
return nil, err
}
currTime := time.Now().UTC()
// Get scope.
scope := strings.Join([]string{
currTime.Format(yyyymmdd),
regionStr,
"s3",
"aws4_request",
}, "/")
stringToSign := "AWS4-HMAC-SHA256-PAYLOAD" + "\n"
stringToSign = stringToSign + currTime.Format(iso8601Format) + "\n"
stringToSign = stringToSign + scope + "\n"
stringToSign = stringToSign + signature + "\n"
stringToSign = stringToSign + "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855" + "\n" // hex(sum256(""))
stringToSign = stringToSign + hex.EncodeToString(sum256(buffer[:n]))
date := sumHMAC([]byte("AWS4"+secretKey), []byte(currTime.Format(yyyymmdd)))
region := sumHMAC(date, []byte(regionStr))
service := sumHMAC(region, []byte("s3"))
signingKey := sumHMAC(service, []byte("aws4_request"))
signature = hex.EncodeToString(sumHMAC(signingKey, []byte(stringToSign)))
stream = append(stream, []byte(fmt.Sprintf("%x", n)+";chunk-signature="+signature+"\r\n")...)
stream = append(stream, buffer[:n]...)
stream = append(stream, []byte("\r\n")...)
if n <= 0 {
break
}
}
req.Body = ioutil.NopCloser(bytes.NewReader(stream))
return req, nil
}
// cmd: 1字节
// length: 变长：1,2,4,8字节，根据cmd决定
// 内容区: 变长，长度=length
// 2015-08-10: todo: 数据压缩
func (d *delta) flushMiss(ms matchStat, src io.ReadSeeker) (err error) {
var (
//n int
ml int64 // miss length
cmd uint8
hdr []byte
buf []byte
tmp []byte
)
bytes := int64Length(uint64(ms.length))
switch bytes {
case 8:
cmd = RS_OP_LITERAL_N8
case 4:
cmd = RS_OP_LITERAL_N4
case 2:
cmd = RS_OP_LITERAL_N2
case 1:
cmd = RS_OP_LITERAL_N1
}
// 写入miss block头部
hdr = append(hdr, byte(cmd))
hdr = append(hdr, vhtonll(uint64(ms.length), int8(bytes))...)
if _, err = d.outer.Write(hdr); err != nil {
return
}
if _, err = src.Seek(ms.pos, 0); err != nil {
err = errors.New("Seek failed: " + err.Error())
return
}
ml = ms.length
buf = make([]byte, 4096)
for err == nil && ml > 0 {
if ml >= 4096 {
tmp = buf[0:4096]
ml -= 4096
} else {
tmp = buf[0:ml]
ml = 0
}
// 不应该出现错误
_, err = src.Read(tmp)
if err != nil {
panic(fmt.Sprintf("pipe: read failed: expect %d, error: %s", len(tmp), err.Error()))
}
if _, err = d.outer.Write(tmp); err != nil {
return
}
}
if d.debug {
fmt.Printf(" flush miss [where=%d len=%d], hdr len: %d miss len: %d\n",
ms.pos, ms.length, len(hdr), ms.length)
}
return
}
// Clone makes cloned copies of ReadSeeker. Reads from individual
// readSeekers are staggered to avoid duplicate reads from the source
// reader automatically.
func Clone(rs io.ReadSeeker, copies int) []io.ReadSeeker {
var readers = [copies]readSeek{}
// Initialize each of the clones.
for i = 0; i < count; i++ {
readers[i] = readSeek{
ignore: false,
mu: &sync.Mutex{},
readCh: make(chan struct{}),
readyCh: make(chan struct{}),
}
}
// IO demux copier routine.
go func() {
// 32 secs timeout.
timeout := make(chan bool, 32)
for {
var bytesReq []int
for i = 0; i < count; i++ {
if readers[i].ignore == false {
// Previously failed. Continue to ignore.
continue
}
// Wait for next read.
select {
case <-readChs[i]: //bytes requested.
bytesReq[i] = len(readers[i].buf)
case timeout: // Timeout.
readers[i].ignore = true
}
}
// Find the next smallest data block to read.
bytes2Read := smallestInt(bytesReq)
buf := [bytes2Read]byte{}
n, e := rs.Read(buf)
// Copy the data to clones and notify them.
for i = 0; i < count; i++ {
// Copy the data to clones.
readers[i].buf = buf
readers[i].n = n
readers[i].e = e
// Notify ready.
readyChs[i] <- struct{}{}
}
}
}()
// Return the clones to the caller.
return readers
}
// OpemROM creates a pkm.Version that reads a GameBoy Advance ROM file. If the
// contents are identified as an unsupported version, then a nil value is
// returned.
func OpenROM(rom io.ReadSeeker) pkm.Version {
var gc pkm.GameCode
rom.Seek(addrGameCode.ROM(), 0)
rom.Read(gc[:])
if v, ok := versionLookup[gc]; ok {
v.ROM = rom
return &v
}
return nil
}
func utf16Seekable(in io.ReadSeeker, endianness endianness) (Encoding, error) {
// remember file offset in case we have to back off
offset, err := in.Seek(0, os.SEEK_CUR)
if err != nil {
return nil, err
}
// goto beginning of file
keepOffset := offset == 0
if _, err = in.Seek(0, os.SEEK_SET); err != nil {
return nil, err
}
// read Byte Order Marker (BOM)
var buf [2]byte
n, err := in.Read(buf[:])
if err != nil {
in.Seek(offset, os.SEEK_SET)
return nil, err
}
if n < 2 {
in.Seek(offset, os.SEEK_SET)
return nil, transform.ErrShortSrc
}
// determine endianess from BOM
inEndiannes := unknownEndianess
switch {
case buf[0] == 0xfe && buf[1] == 0xff:
inEndiannes = bigEndian
case buf[0] == 0xff && buf[1] == 0xfe:
inEndiannes = littleEndian
}
// restore offset if BOM is missing or this function was not
// called with read pointer at beginning of file
if !keepOffset || inEndiannes == unknownEndianess {
if _, err = in.Seek(offset, os.SEEK_SET); err != nil {
return nil, err
}
}
// choose encoding based on BOM
if encoding, ok := utf16Map[inEndiannes]; ok {
return encoding, nil
}
// fall back to configured endianess
if encoding, ok := utf16Map[endianness]; ok {
return encoding, nil
}
// no encoding for configured endianess found => fail
return nil, unicode.ErrMissingBOM
}
func loadAndCompare(t testing.TB, rd io.ReadSeeker, size int, offset int64, expected []byte) {
var (
pos int64
err error
)
if offset >= 0 {
pos, err = rd.Seek(offset, 0)
} else {
pos, err = rd.Seek(offset, 2)
}
if err != nil {
t.Errorf("Seek(%d, 0) returned error: %v", offset, err)
return
}
if offset >= 0 && pos != offset {
t.Errorf("pos after seek is wrong, want %d, got %d", offset, pos)
} else if offset < 0 && pos != int64(size)+offset {
t.Errorf("pos after relative seek is wrong, want %d, got %d", int64(size)+offset, pos)
}
buf := make([]byte, len(expected))
n, err := rd.Read(buf)
// if we requested data beyond the end of the file, ignore
// ErrUnexpectedEOF error
if offset > 0 && len(buf) > size && err == io.ErrUnexpectedEOF {
err = nil
buf = buf[:size]
}
if offset < 0 && len(buf) > abs(int(offset)) && err == io.ErrUnexpectedEOF {
err = nil
buf = buf[:abs(int(offset))]
}
if n != len(buf) {
t.Errorf("Load(%d, %d): wrong length returned, want %d, got %d",
len(buf), offset, len(buf), n)
return
}
if err != nil {
t.Errorf("Load(%d, %d): unexpected error: %v", len(buf), offset, err)
return
}
buf = buf[:n]
if !bytes.Equal(buf, expected) {
t.Errorf("Load(%d, %d) returned wrong bytes", len(buf), offset)
return
}
}
func read4pop(reader io.ReadSeeker) ([]byte, error) {
var data = make([]byte, 4)
if currpos, err := reader.Seek(0, 1); err != nil {
return nil, err
} else if _, err := reader.Read(data); err != nil {
return nil, err
} else if _, err = reader.Seek(currpos, 0); err != nil {
return nil, err
}
return data, nil
}
func getFanoutValue(index int64, in io.ReadSeeker) (int, error) {
if index < 0 {
return 0, nil
}
_, err := in.Seek(8+index*4, os.SEEK_SET)
indexBuff := make([]byte, 4)
_, err = in.Read(indexBuff)
if err != nil {
return 0, err
}
return int(binary.BigEndian.Uint32(indexBuff)), nil
}
func readChunks(reader io.ReadSeeker) []pngChunk {
chunks := []pngChunk{}
reader.Seek(chunkStartOffset, os.SEEK_SET)
readChunk := func() (*pngChunk, error) {
var chunk pngChunk
chunk.Offset, _ = reader.Seek(0, os.SEEK_CUR)
binary.Read(reader, binary.BigEndian, &chunk.Length)
chunk.Data = make([]byte, chunk.Length)
err := binary.Read(reader, binary.BigEndian, &chunk.Type)
if err != nil {
goto read_error
}
if read, err := reader.Read(chunk.Data); read == 0 || err != nil {
goto read_error
}
err = binary.Read(reader, binary.BigEndian, &chunk.CRC)
if err != nil {
goto read_error
}
return &chunk, nil
read_error:
return nil, fmt.Errorf("Read error")
}
chunk, err := readChunk()
if err != nil {
return chunks
}
chunks = append(chunks, *chunk)
// Read the first chunk
for string(chunks[len(chunks)-1].Type[:]) != endChunk {
chunk, err := readChunk()
if err != nil {
break
}
chunks = append(chunks, *chunk)
}
return chunks
}
func getNext(file io.ReadSeeker) (byte, error) {
if nextIndex < bufferSize {
retVal := readBuffer[nextIndex]
nextIndex++
return retVal, nil
}
_, err := file.Read(readBuffer)
if err != nil {
return byte(0), err
}
nextIndex = 1
return readBuffer[0], nil
}
func GetTotalCount(in io.ReadSeeker) (uint, error) {
_, err := in.Seek(0x404, os.SEEK_SET)
if err != nil {
return 0, err
}
buff := make([]byte, 4)
_, err = in.Read(buff)
if err != nil {
return 0, err
}
count := binary.BigEndian.Uint32(buff)
return uint(count), nil
}
func readHashAt(indexAt int, in io.ReadSeeker) ([]byte, error) {
hashOffset := 0x408 + int64(indexAt)*0x14
_, err := in.Seek(hashOffset, os.SEEK_SET)
if err != nil {
return nil, err
}
hashBuff := make([]byte, 20)
_, err = in.Read(hashBuff)
if err != nil {
return nil, err
}
return hashBuff, nil
}
func readCRCAt(indexAt int, count uint, in io.ReadSeeker) ([]byte, error) {
crcOffset := 0x408 + int64(count)*0x14 + int64(indexAt)*4
_, err := in.Seek(crcOffset, os.SEEK_SET)
if err != nil {
return nil, err
}
crcBuff := make([]byte, 4)
_, err = in.Read(crcBuff)
if err != nil {
return nil, err
}
return crcBuff, nil
}
//to find the creation date from the "mvhd" atom, take bytes 5-8 as
//a Big Endian uint32, as the number of seconds since
// 1904-01-01 00:00:00 (?)
func getMp4CreationTimeFromMvhdAtom(f io.ReadSeeker) (time.Time, error) {
//now we have it! bytes 5-8
f.Seek(4, 1)
buff := make([]byte, 4, 4)
_, err := f.Read(buff)
if err != nil {
err = fmt.Errorf("read error: %s", err)
return time.Time{}, err
}
createdUint := binary.BigEndian.Uint32(buff)
//and add our seconds
return mp4DateEpoch.Add(time.Second * time.Duration(createdUint)), nil
}
func (w *WorkBook) get_string(buf io.ReadSeeker, size uint16) string {
var res string
if w.Is5ver {
var bts = make([]byte, size)
buf.Read(bts)
return string(bts)
} else {
var richtext_num uint16
var phonetic_size uint32
var flag byte
binary.Read(buf, binary.LittleEndian, &flag)
if flag&0x8 != 0 {
binary.Read(buf, binary.LittleEndian, &richtext_num)
}
if flag&0x4 != 0 {
binary.Read(buf, binary.LittleEndian, &phonetic_size)
}
if flag&0x1 != 0 {
var bts = make([]uint16, size)
var err error
var i = uint16(0)
for ; i < size && err == nil; i++ {
err = binary.Read(buf, binary.LittleEndian, &bts[i])
}
runes := utf16.Decode(bts[:i])
res = string(runes)
if i < size {
w.continue_utf16 = size - i + 1
}
} else {
var bts = make([]byte, size)
binary.Read(buf, binary.LittleEndian, &bts)
res = string(bts)
}
if flag&0x8 != 0 {
var bts []byte
if w.Is5ver {
bts = make([]byte, 2*richtext_num)
} else {
bts = make([]byte, 4*richtext_num)
}
binary.Read(buf, binary.LittleEndian, bts)
}
if flag&0x4 != 0 {
var bts []byte
bts = make([]byte, phonetic_size)
binary.Read(buf, binary.LittleEndian, bts)
}
}
return res
}
// Returns
func (p packfile) ReadEntryDataStream(r io.ReadSeeker) (uncompressed []byte, compressed []byte) {
b := new(bytes.Buffer)
bookmark, _ := r.Seek(0, 1)
zr, err := zlib.NewReader(r)
if err != nil {
panic(err)
}
defer zr.Close()
io.Copy(b, zr)
// Go's zlib implementation is greedy, so we need some hacks to
// get r back to the right place in the file.
// We use a modified version of compress/zlib which exposes the
// digest. Before reading, we take a bookmark of the address
// that we're starting at, then after reading we go back there.
// Starting from there, look through the reader until we find the
// compressed object's zlib digest.
// This is stupid, but necessary because git's packfile format
// is *very* stupid.
digest := zr.Digest.Sum32()
r.Seek(bookmark, 0)
address := make([]byte, 4)
var i int64
var finalAddress int64
for {
n, err := r.Read(address)
// This probably means we reached the end of the io.Reader.
// It might be the last read, so break out of the loop instead
// of getting caught in an infinite loop.
if n < 4 || err != nil {
break
}
var intAddress uint32 = (uint32(address[3]) | uint32(address[2])<<8 | uint32(address[1])<<16 | uint32(address[0])<<24)
if intAddress == digest {
finalAddress = bookmark + i + 4
break
}
// Advance a byte
i += 1
r.Seek(bookmark+i, 0)
}
r.Seek(bookmark, 0)
compressed = make([]byte, finalAddress-bookmark)
r.Read(compressed)
r.Seek(finalAddress, 0)
return b.Bytes(), compressed
}
func validMapHeader(rom io.ReadSeeker, p ptr) bool {
maph := make([]byte, structMapHeader.Size())
rom.Seek(p.ROM(), 0)
rom.Read(maph)
if p := decPtr(maph[0:4]); !p.ValidROM() {
return false
}
if p := decPtr(maph[4:8]); !p.ValidROM() {
return false
}
if p := decPtr(maph[8:12]); !p.ValidROM() {
return false
}
return true
}